# Charge your EV for free



## PhantomPholly (Aug 20, 2008)

Indirectly related to EVs, but I know most of you are interested.

Only a couple of months ago I pointed out how the retail price for a 10Kw solar system was about $30k. I thought that was a great deal, because the mortgage payment on $30k was about the same as the utilities would cost today, with advantage tipping to the solar system over time. How times change.

10.42Kw Grid Tie Complete Solar Kit - $19,358.00. That's a payment of about $300/month for a 15 year loan at current mortgage rates (home equity?) of 4%.

I'll bet that government credits and giveaways reduce it still further.

In the Southern U.S., that equates to about 2,000KwHrs per month averaged over the year. That's plenty for a super-insulated house ~ 3,000' sq. (e.g. foam attic insulation, low energy lights, on-demand water heater).


----------



## cruisin (Jun 3, 2009)

PhantomPholly said:


> Indirectly related to EVs, but I know most of you are interested.
> 
> Only a couple of months ago I pointed out how the retail price for a 10Kw solar system was about $30k. I thought that was a great deal, because the mortgage payment on $30k was about the same as the utilities would cost today, with advantage tipping to the solar system over time. How times change.
> 
> ...


When you buy that package, you are buying price. Very low quality chinese non anadized, not black aluminum collectors that will not put out rated KW for many years. The inverter is the worlds worst in dependability. You get what you pay for, crap.


----------



## PhantomPholly (Aug 20, 2008)

cruisin said:


> When you buy that package, you are buying price. Very low quality chinese non anadized, not black aluminum collectors that will not put out rated KW for many years. The inverter is the worlds worst in dependability. You get what you pay for, crap.


Understood, and not promoting a particular product. 

The point is that prices are dropping quickly, and will soon make sense for many people.

Caveat Emptor.


----------



## ElectriCar (Jun 15, 2008)

You must have read my post last week about how it's falling like a rock, like by 3/4ths in 3 years.


----------



## tomofreno (Mar 3, 2009)

There are good quality panels available for very good prices now, especially if you purchase by the pallet. Prices at Affordable Solar range from $1.54/W to $1.73/W for good quality panels from REC, Sharp, LG, and others. Panels I paid $4.50/W for 3 years ago are now $1.64/W. Of course the power company administered rebate (ratepayer financed) was much higher then too, resulting in $3.60/W installed cost for me for everything, including Unirac mounting system. I installed them, except for final connect to the main service panel which had to be done by a licensed electrical contractor. All the power for the house and car are supplied by the panels, with enough left for another about 20 miles/day for another car. We will likely add more when my wife gets an ev.


----------



## Jason Lattimer (Dec 27, 2008)

Why would I pay 300 dollars a month for solar cells when my electric bill is less than 100?


----------



## ElectriCar (Jun 15, 2008)

Jason Lattimer said:


> Why would I pay 300 dollars a month for solar cells when my electric bill is less than 100?


Same here. I'm 48 now and have wanted solar panels since my 20's. I built a solar water heater in my early 20's that did a great job. Still I'm not buying something that will cost me more than I'm paying now, about $110/month for less power than I'll need. At the rate of price fall today however it may become cost effective very soon, especially with our utility looking to increase rates 17%.


----------



## Guest (Nov 20, 2011)

We purchased a 7.2KW solar system for our home 6 years ago and we opened a home improvement loan to do that and some other items that were needed. All said we are paying less than our normal electric bill would have been for the loan. That alone is a savings. We have been paying more than needed on the loan to shorten the loan life and lessen the overall cost of the loan. In 4 years we will have it paid off and from that point there will be no more payments unless we need to replace a panel or inverter. The overall investment is excellent as it raised the value of our home considerably. Not to mention we are totally solar. I also purchased a used Solar System to add to the existing one and paid for that in cash. It is a 6KW system with a 5KW inverter. This system is only 4 years old. It's paid for. So all total we have a 13KW system on our home to cover all our electric needs. Crunch the numbers before saying why pay 300 a month. In the end you will pay far less than if you never got a system. Granted some folks still can't afford them but in time many will. It took me over 35 years to be able to afford them. Not until I went back to college to learn a better trade did I realize I could afford them. It is worth it to go learn a better trade if your stuck in some dead end crap. It was for me. 

Pete 

I can also go totally off grid too if I want with our smaller solar setup. I plan on doing just that.


----------



## ElectriCar (Jun 15, 2008)

Don't they have net metering now? If you go off grid you have to store power. I imagine it would be worth it to pay the utility a few dollars each month for banking your extra daytime power and in case you lose an inverter or such you won't be DIW.


----------



## Guest (Nov 20, 2011)

ElectriCar said:


> Don't they have net metering now? If you go off grid you have to store power. I imagine it would be worth it to pay the utility a few dollars each month for banking your extra daytime power and in case you lose an inverter or such you won't be DIW.


Yes we have net metering. I take out what I put in before I get charged any thing. The utility grid is the battery. When we have a power outage we loose power. The solar is not directly connected to the house. It goes directly to the grid. We had to get a propane generator for the house when power goes out. Some day I'd like to ditch that as well. There are now systems that are Grid Tied and Battery back up so you don't need a generator. However the generator does provide enough to run the entire house. Longest we were without power was 3 days since we went solar. 

I want to be free of the utility company even though it is great to not have to deal with batteries at this time. 

Pete 

Some day things will change and I want to be off the grid by then. I like the idea of my own private grid.


----------



## ElectriCar (Jun 15, 2008)

By going "off grid" I took that to mean you wanted to ditch the utility company. Maybe I'm not understanding something. If you rely on solar for all your power, you either have to have the utility company to bank your extra power for night use and cloudy times, rely on a generator or store it in batteries. If the utility remains connected to your system you're not off grid, though you may generate enough power you don't need theirs, you're still not off grid.

So if you go off grid and disconnect the utility, are you going to build a battery bank to store power? That sounds like it would be very expensive unless you have gas appliances and only need power to run lights, refer and AC blowers. In that case if a battery bank proved cost effective, I'd go off grid as well. It doesn't take much to run tv's, lights & fans.


----------



## tomofreno (Mar 3, 2009)

> Some day things will change and I want to be off the grid by then. I like the idea of my own private grid.


You might consider installing a service disconnect like the one at this link:
http://www.electricgeneratorsdirect.com/Generac-Guardian-RTSD200A3/p4808.html

With a service disconnect you just use all the existing house circuits, powered either from the grid or from your inverter. That way you can continue to use the grid as your battery as long as it is up. I plan to install one someday along with some flooded lead acid batts for around 3 days backup, which for us is less than 40kWh for the house, and could be reduced to much less if necessary. Three days should be enough for us since we rarely go without sun for longer than that. We loose power around 5 - 6 times per year here, usually during high winds (up to 74 mph last Thursday when the Reno fire was raging).


----------



## Guest (Nov 20, 2011)

A step towards being off grid completely is to get set up with the new systems available that allow grid tie and battery back up. The battery back up is for when you loose power of at night if you choose and not rely upon the grid as much. I plan on going completely off grid. For now I will remain on grid and play with an off grid system. When I go off grid I plan on buying used lithium cells for my storage. I will need a large enough battery bank when totally off grid to power all our components including the AC heat pump and our well pump which is a fat 5 hp electric motor single phase. It will be expensive but worth it to me. I will be using old worn out 80% or less capacity lithium cells. I'd like to use the LiFePO4 cells more than anything. I will be getting soon a bunch of large solar lead acid batteries that still have some good life left it them for free. A friend is upgrading. 


Our home is totally electric.

Pete


----------



## Guest (Nov 20, 2011)

tomofreno said:


> You might consider installing a service disconnect like the one at this link:
> http://www.electricgeneratorsdirect.com/Generac-Guardian-RTSD200A3/p4808.html
> 
> With a service disconnect you just use all the existing house circuits, powered either from the grid or from your inverter. That way you can continue to use the grid as your battery as long as it is up. I plan to install one someday along with some flooded lead acid batts for around 3 days backup, which for us is less than 40kWh for the house, and could be reduced to much less if necessary. Three days should be enough for us since we rarely go without sun for longer than that. We loose power around 5 - 6 times per year here, usually during high winds (up to 74 mph last Thursday when the Reno fire was raging).



We do have a service disconnect but its connected to our generator in case of power outages. Once a setup is done with batteries we may use that switch to switch to battery power then if that goes low to the generator or during the day to solar. Usually the power goes out during low solar days around here or in the evening so it really does not matter if we loose solar but we do need either the generator or battery backup.


----------



## tomofreno (Mar 3, 2009)

> I will need a large enough battery bank when totally off grid to power all our components including the AC heat pump...


 Do you know how much AC power your heat pump consumes per BTU/hr output? What make is it?


----------



## ElectriCar (Jun 15, 2008)

If you have a stream on your property, I just ran across this. Pretty cheap!


----------



## PhantomPholly (Aug 20, 2008)

Jason Lattimer said:


> Why would I pay 300 dollars a month for solar cells when my electric bill is less than 100?


Electricity prices are certainly different in different places. How many KwHrs per month are you using? If the answer is 700 or less, then you would only install 1/3 as many cells and would come out ahead over the long run. If it is more than 700, then you have very good utility rates - and it may be another year or so before break-even is reached.


----------



## PhantomPholly (Aug 20, 2008)

gottdi said:


> A step towards being off grid completely is to get set up with the new systems available that allow grid tie and battery back up. The battery back up is for when you loose power of at night if you choose and not rely upon the grid as much. I plan on going completely off grid. For now I will remain on grid and play with an off grid system. When I go off grid I plan on buying used lithium cells for my storage. I will need a large enough battery bank when totally off grid to power all our components including the AC heat pump and our well pump which is a fat 5 hp electric motor single phase. It will be expensive but worth it to me. I will be using old worn out 80% or less capacity lithium cells. I'd like to use the LiFePO4 cells more than anything. I will be getting soon a bunch of large solar lead acid batteries that still have some good life left it them for free. A friend is upgrading.
> 
> 
> Our home is totally electric.
> ...


Lithium seems like a poor choice for a system which does not require high energy density. These folks are in low volume production today of batteries specifically targeting mass storage, and they expect to begin high volume production next year at prices 1/2 to 1/3 of lithium per KwHr. Don't need special balancing, fairly temperature insensitive, can be run dead with no ill effect, thousands of 100% cycles, non-toxic (salt; water; plastic; carbon). Only downside is that they are bulky.


----------



## Guest (Nov 20, 2011)

Aaaaaaaaa. More unobtainium. LiFePO4 would be great for solar back up. Buy the old 08 stock up for pennies on the dollar and use them in a huge solar back up array. If it becomes available at the prices you say then yes it would be good. In a stationary situation bulky is fine. Bulky can be buried in a hole too. 


Don't know the power needs of the AC but the system is new and very energy efficient. I do not have the emergency toaster installed in the AC system either. Those just suck out way to much power. I am in Northern California with mild winters and in the flat land. Lots of solar days here. 


No stream on our property. If I had I would have already gone hydro. Way cheaper and 24/7 operation if the water flows 24/7.


----------



## JRoque (Mar 9, 2010)

gottdi said:


> When we have a power outage we loose power


Hey Pete, it could be that your "grid-tied" inverter trips when it doesn't see A/C present from the utility co. That's done for safety reasons so you don't fry a lineman working on a pole down the street. 

Check your inverter to see if it has an override for missing grid signal. If not, and I'm shooting in the dark here, you might be able to make it work if you trip the main house breaker so there's no connection to the grid and then feed an A/C signal from a small inverter into it to trick it. A small PC UPS that regulates the output might do. Set it to slightly higher voltage than what you get from your solar inverter in the PC configuration program. Did I mention I'm shooting the dark here and have never actually tried it? Proceed with caution...

JR


----------



## Guest (Nov 20, 2011)

My setup trips when no power is present from the utility grid. It disconnects from the grid to protect the lineman. At the same time the generator is started up. There is a one minute delay to be sure that the grid has been successfully disconnected. Once that is done the generator provides home power. When the utility grid comes on line the generator disconnects and goes into cool down mode. They do have inverters now that take care of the grid and battery back up all at once. Like the generator it switches from grid to battery instead of generator. 

Pete


----------



## PhantomPholly (Aug 20, 2008)

For safety, make sure that your inverter does NOT work unless either
a) the grid is active and available
b) your entire system is isolated from the grid

Overriding those would be bad, Egon... 

Sorry, bad movie reference (Ghostbusters)


----------



## Guest (Nov 21, 2011)

I won't do the work myself. I will have a professional come do that. I have not taken the courses required for doing installs. Good reference to ghost busters. Egon 

What we have right now is a normal grid tie system. I am planning for the other stuff later. No hurry to get the other system going right now. We are still in the black. We use less than what we make and that includes charging the Leaf daily. I am well pleased.


----------



## Ziggythewiz (May 16, 2010)

Are you actually in the black? Do they pay you for what you overproduce, or do you just get the bill reduced to $0. Also, is the total bill $0, or just the consumption part, but you still pay a monthly service fee?


----------



## Guest (Nov 21, 2011)

It works like this. During the year we produce electricity and it goes back into the grid. We use electricity from the grid at night and low solar days. What we produce in abundance we stock pile during the year. When the year is over we usually break nearly even and yes we pay a $4 something service bill for our paperwork. We are considered a power company and we get all the paperwork as any power company would. Low cost to pay. We are still in the black but will begin to use up the stock piled electricity we put into the grid and will more than likely use most if not all of it up. PG&E does not pay you the extra if you have extra but luck us if we did have extra they must give us a voucher for the excess and we then get to take that voucher to another local electric utility that is an all green company and they will pay us what the voucher is worth. Once we have the other system up we will be over our needs by the end of the year and we will get a voucher. 

So, yes we still in the black and if the voucher is large enough it will also pay for the paperwork as well. 

PG&E is not the best company but it is what we have. At least we get to take out what we put in on a 1 to 1 basis. 1 KW in 1 KW out. 

Pete


----------



## Ziggythewiz (May 16, 2010)

Not bad. Using the grid as a battery is a great way to keep costs down, when I get around to going solar I plan to do a minimal battery backup though just to keep the panels flowing in an outtage. 

I've heard in some places they charge normal usage rates and credit at wholesale rates, so even with a large net excess they end up paying.


----------



## Guest (Nov 21, 2011)

Ziggythewiz said:


> Not bad. Using the grid as a battery is a great way to keep costs down, when I get around to going solar I plan to do a minimal battery backup though just to keep the panels flowing in an outtage.
> 
> I've heard in some places they charge normal usage rates and credit at wholesale rates, so even with a large net excess they end up paying.


Yes that is correct but in California they can't do that at least for now. When the laws change I want to be ready to go off grid 100%. That is my goal.


----------



## ElectriCar (Jun 15, 2008)

The EPAct of 200? required all states to do net metering by 2010 I believe, allowing you to bank your overproduction during the day and use it at night with no charge. I don't believe they can charge you one rate anymore and purchase at another rate. 

I'm not sure though that you can carry a surplus for several months ie summer time and use it in the winter. They do give the utilities some flexibility to hose you but it's nothing like it was where they could deny you net metering or buy it at a discount and sell it back at retail. 

South Carolina is deciding in December whether to allow Duke Energy to have a 15-17% rate hike as requested or make it lower. I am contacting some people this week to try and get a electric vehicle rate where you install a dedicated meter for your car and get a discounted rate. They offered that back in 2007 when nobody had electric vehicles but have since discontinued it.


----------



## JRoque (Mar 9, 2010)

Hi.

I thought electric companies had weaseled their way out of that 2007 law but it'd be great if they didn't.



ElectriCar said:


> I am contacting some people this week to try and get a electric vehicle rate where you install a dedicated meter for your car and get a discounted rate. They offered that back in 2007 when nobody had electric vehicles but have since discontinued it.


That would be good if you can get it. But how about going by an estimate so you don't have the extra cost of the additional meter + install? They might not be motivated to install the extra meter and do additional billing for someone consuming just $1.50 per day. 

If you estimate that you'll use x amount of power each day (or night) to charge your daily use vehicle, they might be able to arrange a fixed amount discount out of your main meter. I know it's apples and oranges but my water company does this for the estimated use of my garden sprinkler and once per year refill of the swimming pool. They don't charge me for drainage on those estimates.

JR


----------



## ElectriCar (Jun 15, 2008)

I emailed the Public Service Commission and Municipal Association this morning about it, explaining how if it is within their power, they could stipulate that in exchange for a higher rate the utility must provide an EV rate. 

It would benefit the state in multiple ways, reducing pollution which some cities struggle with during long periods of hot days, provide more discretionary spending with EV'ers, most of which will be spent in the state helping to create more jobs and revenue via sales tax.


----------



## lockduke (Dec 25, 2009)

Gentlemen, I just found this subject on the forum and thought you might look to a little bit of ancient technology, close to a hundred years old that is still going strong and simple for off grid systems. Just a few weeks ago I stumbled onto the old set of Edison batteries that a friend had they were over 86 years old and still working to provide his cabin in the woods power to work his lights and well pump. they don't seem to care about overcharging or under charging either, they just keep working. There is a set in the Smithsonian that is near a 100 years old in an electric car and still works and if my memory serves me well and sometimes it does not, Jay Leno also has a Baker electric that still has it's original Edison electric batteries intact and still working. These nickle iron batteries are recyclable and virtually impossible to kill and are being made again they look real good for storage systems for off grid use. The railroad companies did use them for most of their remote switching terminals and signal systems. I am looking at replacing my FLA with these next year when I can try and sell my old backup storage bank to a friend when he gets moved into his farm and can go off grid for all his needs. With a windmill you can also stay topped at night since the wind picks up around here at night. And also you can also direct any unused voltage to a load coil in a electric water heater and heat water for the house or extra heat with a coil in the furnace and that system can be backed up with a wood burner if you have no wind for heat in the winter.  Just some ramblings from a old timer with too much time on his hands for the slow time of the year hope to finish my garage next spring to get after most of the projects planned for next year. particularly the nickle iron storage battery bank also you can add to the banks any time you want with no adverse effects like you do with FLA and Lithium or any of the other chemistry's. So you can start small and add to the system as you can afford it. Which you can not do with the other chemistry's


----------



## rochesterricer (Jan 5, 2011)

Last I saw, Jay Leno's Baker Electric was using lead acid batteries. Optima Yellow Tops IIRC. Although I remember him saying that the original Edison batteries still worked fine.


----------



## Guest (Nov 21, 2011)

A good set of large Edison Batteries would be an excellent source for storage power.


----------



## PhantomPholly (Aug 20, 2008)

Several threads have discussed the Edison batteries - among their drawbacks is the fact that that they are relatively expensive and in limited production only in China (?).

Other drawbacks - the charge / discharge efficiency is a bit low compared to other batteries (e.g. you only get out about 70% of what you put in); they require regular servicing to insure their electrolyte levels are correct; and their charge / discharge rates are rather limited (so you need a rather oversized system to handle peak loads).

If you have a set for free, by all means keep them and use them. They never wear out.


----------



## Guest (Nov 22, 2011)

I would never go out and purchase a new set. I'd rather use the lithium batteries. In this sort of situation they should last just about forever. Maybe not quite that long but hey, you never know. 

Pete 

Edison Cells are good but they do have to be maintained and watered and all that sort of stuff. But large ones take a lot less work. Finding them is not going to be easy and if I got them free or nearly so I'd use them.


----------



## spdas (Nov 28, 2009)

I am totally off the grid and have 2 solar systems. One for the welding/fabricating shop that welds, grinds, saws, etc. with 3 employees. The other is for my office that also charges my car and runs the pool pump. I spent about $45K on 17kw of panels, 9 charge controllers, 3 inverters, wiring, misc. and use 8 discarded 650ah 36v forklift batteries that I pick up free or for $100 at a scrap yard. 

It has never let me down, yet and in the last 3 1/2 years i have saved $33,500 in estimated electric bills, so it is almost paid off. Panels now are under $1.35/watt (I just bot some more "A panels" for $0.78/watt from sunelec.com) as I want to charge my car in a total of 6 sun hours. Now is the time to scrape the $ together to go solar as it will pay you back more in elec. savings per month than any interest that you may have to pay to get the $ together in the first place.

francis


----------



## PhantomPholly (Aug 20, 2008)

spdas said:


> I am totally off the grid and have 2 solar systems. One for the welding/fabricating shop that welds, grinds, saws, etc. with 3 employees. The other is for my office that also charges my car and runs the pool pump. I spent about $45K on 17kw of panels, 9 charge controllers, 3 inverters, wiring, misc. and use 8 discarded 650ah 36v forklift batteries that I pick up free or for $100 at a scrap yard.
> 
> It has never let me down, yet and in the last 3 1/2 years i have saved $33,500 in estimated electric bills, so it is almost paid off. Panels now are under $1.35/watt (I just bot some more "A panels" for $0.78/watt from sunelec.com) as I want to charge my car in a total of 6 sun hours. Now is the time to scrape the $ together to go solar as it will pay you back more in elec. savings per month than any interest that you may have to pay to get the $ together in the first place.
> 
> francis


Just looked at their site - it is advertising $0.50/watt (pallet quantities, laminates without frames) with 20-25 year warranties! That's a serious move towards affordability...


----------



## spdas (Nov 28, 2009)

Laminates are a lot of work to put together. They may have some UL approved 200~235w panels that the company bought at an auction from a German company that went broke due to competition from China. If anyone is serious call and see if they any left. They had over 35,000 panels a week ago. 

Whoops I see the notice on their site now:
"Evergreen 7 MW Being Counted
As of November 18, We have to stop selling Evergreen. If any become available, we will keep you updated on the website.

ETA: MIAMI PORT TO PORT 16 DAYS, PLUS LOADING, UNLOADING, AND TRUCKING TIME TO YOUR SHIPPING DESTINATION."

Francis


----------



## lockduke (Dec 25, 2009)

Hay Gottdi the Edison batteries dont need to be maintained like FLA. Just once a year, not near as often as you do with FLA or balancing lithium. If you don't charge them past 80 % they generally don't boil, and maintenance drops off to even less but who cares if you water these batteries every couple of months you could also use a catalyst cap with platinum wire in it and not have to maintain them but once a year maybe a little more often. Plus they don't care if you dump charge them into your EV you just charge them up again and again for oh maybe the next 80-100 years and only have to change the electrolyte every 20-30 years


----------



## Sunking (Aug 10, 2009)

gottdi said:


> Some day I'd like to ditch that as well. There are now systems that are Grid Tied and Battery back up so you don't need a generator.


Do not kid yourself Pete. You are talking a hybrid system. There are a few ways to configure the batteries for hybrid system but all include needing a generator. Basically they work like a UPS. When power fails, the transfer switches to emergency circuits and the batteries take over until the emergency generator comes on-line to keep the batteries up. In addition they are very inefficient because you have to configure your panels at much lower voltages, rather than higher for GTI.

Going off grid battery is just plain foolish. You end up paying 8 to 20 times more for power the rest of your life, and will never offset carbon use. They are horrible financially and environmentally. As with hybrid off-grid requires a generator and AC charger.


----------



## ElectriCar (Jun 15, 2008)

spdas said:


> I am totally off the grid and have 2 solar systems. One for the welding/fabricating shop that welds, grinds, saws, etc. with 3 employees. The other is for my office that also charges my car and runs the pool pump. I spent about $45K on 17kw of panels, 9 charge controllers, 3 inverters, wiring, misc. and use 8 discarded 650ah 36v forklift batteries that I pick up free or for $100 at a scrap yard.
> 
> It has never let me down, yet and in the last 3 1/2 years i have saved $33,500 in estimated electric bills, so it is almost paid off. Panels now are under $1.35/watt (I just bot some more "A panels" for $0.78/watt from sunelec.com) as I want to charge my car in a total of 6 sun hours. Now is the time to scrape the $ together to go solar as it will pay you back more in elec. savings per month than any interest that you may have to pay to get the $ together in the first place.
> 
> francis


Jeez what sort of electric rates are you paying? 33500 in 42 months is like 800/month! For me to save that much power I'd have to use 8000Kw per month! I use like 1500 at home and even less at the office.

I wonder what size I'd need at home for an average of maybe 1500kw/month. Live in South Carolina, 34 latitude I believe and we have net metering.


----------



## spdas (Nov 28, 2009)

I have one mig welder going most of the time and sometimes 2 welders. 3 grinders, 4 fridges, lights, pool pump. 4 computers, and misc, so it adds up. Our rates are 0.40 kwh + add-ons. Fuel surcharge, taxes. etc. It adds up fast, 
francis


----------



## ElectriCar (Jun 15, 2008)

Wow! Well Obama said a while back under his plan, electricity rates will need to skyrocket. In the last year they already went up once for commercial customers and now they want to do it again along with residential rates. At the office I now pay about .11 plus demand charges etc. At home it's about .08 up to 1000kw then it goes to .10 per kw. 

This thread has me thinking again. I looked into it last year but it just wasn't worth it even with gov. incentives. At these prices though it's looking better.


----------



## Sunking (Aug 10, 2009)

spdas said:


> I am totally off the grid and have 2 solar systems. One for the welding/fabricating shop that welds, grinds, saws, etc. with 3 employees. The other is for my office that also charges my car and runs the pool pump. I spent about $45K on 17kw of panels, 9 charge controllers, 3 inverters, wiring, misc. and use 8 discarded 650ah 36v forklift batteries that I pick up free or for $100 at a scrap yard.
> 
> It has never let me down, yet and in the last 3 1/2 years i have saved $33,500 in estimated electric bills, so it is almost paid off. Panels now are under $1.35/watt (I just bot some more "A panels" for $0.78/watt from sunelec.com) as I want to charge my car in a total of 6 sun hours. Now is the time to scrape the $ together to go solar as it will pay you back more in elec. savings per month than any interest that you may have to pay to get the $ together in the first place.


Sorry but I do not believe a single word of that.


----------



## Sunking (Aug 10, 2009)

ElectriCar said:


> Wow! Well Obama said a while back under his plan, electricity rates will need to skyrocket. In the last year they already went up once for commercial customers and now they want to do it again along with residential rates. At the office I now pay about .11 plus demand charges etc. At home it's about .08 up to 1000kw then it goes to .10 per kw.
> 
> This thread has me thinking again. I looked into it last year but it just wasn't worth it even with gov. incentives. At these prices though it's looking better.


Wow that is amazing because nationally electric rates have dropped 11% since 2008 and some states like TX where I live has dropped 27% on average statewide. I was paying $0.121/Kwh, and now pay $0.0884/Kwh locked in for 3 years.


----------



## Sunking (Aug 10, 2009)

ElectriCar said:


> Jeez what sort of electric rates are you paying? 33500 in 42 months is like 800/month! For me to save that much power I'd have to use 8000Kw per month! I use like 1500 at home and even less at the office.
> 
> I wonder what size I'd need at home for an average of maybe 1500kw/month. Live in South Carolina, 34 latitude I believe and we have net metering.


I can answer that, depends on where exactly you live in SC but assuming Charleston to deliver 1500Kwh/month or 50 Kwh/day averaged over a year would take roughly 13 Kw at minimum under idea conditions and quite possible more depending on your exact location, orientation, and shading issues.


----------



## spdas (Nov 28, 2009)

Sunking said:


> Sorry but I do not believe a single word of that.



What do u find unbelievable in my case? Please point it out and I will further explain.

francis


----------



## Sunking (Aug 10, 2009)

spdas said:


> What do u find unbelievable in my case? Please point it out and I will further explain.


Your numbers do not add up.

Example a 17 Kw battery system in Honolulu with a 5.1 Sun Hours yearly average (which you should not use, but I will this time since it leans in your favor) will generate roughly 55 Kwh/day of usable power if you could possible utilize that much. That works out to 1650 Kwh/month and at $0.40/Kwh charge is a $660/month bill. So after 3-1/2 years or 42 months you would pay the POCO roughly $27,720 in that time. 

Next problem is your batteries could not likely support 55 Kwh per day use, especially old shot forklift batteries. you would be draining them some 40% or more per day for mint condition new ones and you have no allowance for cloudy rainy days to carry you through. The 36 volt 650 AH batteries are worth more than $100 if completely shot and worthless because the lead inside them are worth more than that. To replace then with a good set made for RE system would require a 2275 Kwh storage capacity and cost Roughly $50,000, and the fun part is you get to replace those 16,000 pound monsters every 3 to 7 years depending on the quality and care you give them.

I mean no offense, but I have designed/built about 115 or more Off-Grid battery systems for wireless telephone companies and a number of large scale Grid Tied systems for commercial users.


----------



## spdas (Nov 28, 2009)

Sunking said:


> Your numbers do not add up.
> 
> Example a 17 Kw battery system in Honolulu with a 5.1 Sun Hours yearly average (which you should not use, but I will this time since it leans in your favor) will generate roughly 55 Kwh/day of usable power if you could possible utilize that much. That works out to 1650 Kwh/month and at $0.40/Kwh charge is a $660/month bill. So after 3-1/2 years or 42 months you would pay the POCO roughly $27,720 in that time.
> 
> ...


No problem, glad you were not a Hit and Run person, but most of your calc's are right. I tended to shoot from the hip, but even so we are not far apart. Point is that for me the payback whether 27k or 33k puts me quickly to the payoff and would be a smart move to invest in a solar system now and use the Elec savings to pay off any interest needed to borrow the $. (even though i used $600 panels back 3 years ago and if I had $200 panels like there are today, the system would have already been paid off)

I am on the dry sunny side of Oahu, almost desert and 5.1+ hrs per day probably is accurate. My friend downtown has a small grid-tied store with a few less panels and reduced his electric bill from $1200. a month to $50 (the min I think).

My 9 Outbacks run 8-9+ KW per day each so 76.5kwh/day is about right.
so giving me 2300kwh per month. The rate now when I saw a notice come in the mail was .36 and wanting to raise it to .38 immed and .40 the first of the year. (I may be wrong though as i did not pay a lot of attention to it.)
On top of the .38 rate I remember there being a lot of add-ons, so $800-900 a month is about right.

My batteries are on the last legs, no doubt. I pick them up from the scrap yard for free (If i exchange him a similar "really dead, shorted battery". I just missed out on a brand new 800ah battery from him and the forklift dealer who got it told him that the battery costs $3000. Since he opened up his big month, the scrap guy now wants $300 each. The batteries come in with equipment and are in unknown condition. So they are not junk batteries a dealer is tossing.

I basically use the batteries to tide me over the night, but during the day they are just used as a buffer and are not accepting all that the Outbacks are putting out. Lead price here is .06 for iron clad batteries so worth about $150.00 @2500#. I started with 10 of these batteries for free 3.5 years ago from a freight forwarder who was happy to get them hauled off. 
6 were 24v and are still working fine and 4 were 36v and i have needed to bypass some bad cells so I am still over 24v.

My friend and i bought 4 pallets of the .78 cells from John's fire sale in Florida, (i am taking one pallet) so why not add another 28 cells and a couple controllers and get more juice as I am adding a power shear and other equipment.

But i am not in the business as a solar installer, just a Mcgiver type.

francis


----------



## PhantomPholly (Aug 20, 2008)

ElectriCar said:


> I wonder what size I'd need at home for an average of maybe 1500kw/month. Live in South Carolina, 34 latitude I believe and we have net metering.


A couple of sites have estimators. At our latitude (I'm in Atlanta, about the same as you) a 10Kw system will generate about 2,000KwHrs per month averaged over the entire year, so for 1,500KwHrs / month you'd need around a 7.5Kw system.

Regulations vary by State; you may need to check to see how your utility credits you for months you have a surplus (i.e. do they "buy it" or simply record your credit in KwHrs?). If they are using a credit system but first convert to dollars, you may get screwed on spring/fall credits when they up the price per KwHr in the summer.

Edit: Pending SunKing's reply I am inclined to believe that his values may be closer to the truth than what is advertised, simply because advertisements typically exaggerate. If his numbers are right, then you would need closer to a 15Kw system for your needs.


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> I can answer that, depends on where exactly you live in SC but assuming Charleston to deliver 1500Kwh/month or 50 Kwh/day averaged over a year would take roughly 13 Kw at minimum under idea conditions and quite possible more depending on your exact location, orientation, and shading issues.


The rule of thumb being posted by multiple sites I visited is that if you mount your panels angled up about 30 degrees (for this latitude, and based on the sunniness in this region), your KwHrs per month is roughly equal to the max rated Kw of the system time 0.2, or roughly 1/4 of rated power over a 24 hr time span. On the face of it, it sounds fairly reasonable - you average just a tad over 1/2 capability over the daylight hours. 

Your figure is only about half that efficiency. Where are you pulling your values from?


----------



## ElectriCar (Jun 15, 2008)

Thanks Phantom. Here's a link I bookmarked last year when I was researching this for locating the best PV panel pricing. I found it very helpful.


----------



## Sunking (Aug 10, 2009)

PhantomPholly said:


> The rule of thumb being posted by multiple sites I visited is that if you mount your panels angled up about 30 degrees (for this latitude, and based on the sunniness in this region), your KwHrs per month is roughly equal to the max rated Kw of the system time 0.2, or roughly 1/4 of rated power over a 24 hr time span. On the face of it, it sounds fairly reasonable - you average just a tad over 1/2 capability over the daylight hours.
> 
> Your figure is only about half that efficiency. Where are you pulling your values from?


Philly it is simple math a 5th grader can do to make a bar napkin estimate under ideal conditions for the local area. 

Grid tied systems are fairly easy to estimate. All you need to know for a GTI system is the yearly average of Insolation expressed in watt hours/meter squared aka Sun Hours at a given fixed tilt angle, daily average usage in Kwh over a year, and the efficiency of the system.

All of which is pretty much known. Your electric bills tell you how much you use each year which you can average out on a per day basis. All you got to do is pull a years worth of data from your bills and average it out. If you do not have your bills (shame on you) your POCO has a full history on your home electric use.

Then go to a site like this one by NREL and obtain your yearly average Insolation in Sun Hours. Select your state, city , and highest harvest averaged over a year vs tilt angle.

After that you are set to go with a very simple formula. GTI systems have an efficiency of 75 to 80%. So the formula is:

Daily Average Watt Hours Consumed / System Efficiency / Yearly Sun Hours = Solar Panel Wattage Required.

So if you use an average of 50 Kwh, have a 5 Sun Hour day of 5 Hours Average, and System Efficiency of 77% (*Kwh / E% / Hours = Watts*) so you have 50 Kwh / .77 / 5 h = 12.98 Kw for an example.

It is so easy your kids can do it.

Now Off-Grid battery systems are another animal. System efficiency is 50% at the very best if you could even remotely possible utilize all the potential power which you cannot. And you have to use worse case months like winter or else you go dark. Plus very expensive battery replacement every few years.  You cannot afford it and very environmentally unfriendly. Battery systems will cost you anywhere from $3K to $5K per Kwh initially up front cost depending on your location and local conditions and $1000/Kwh for batteries which have to be replace every few years at even higher cost. You end up paying 5 to 20 times more for electricity the rest of your life and be limited on use with daily chores to monitor/maintain the system. Yuck!


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> Philly it is simple math a 5th grader can do to make a bar napkin estimate under ideal conditions for the local area.


I'm neither simple, nor a 5th grader - just haven't studied this. No need to be evil... 



> Grid tied systems are fairly easy to estimate. All you need to know for a GTI system is the yearly average of Insolation expressed in watt hours/meter squared aka Sun Hours at a given fixed tilt angle, daily average usage in Kwh over a year, and the efficiency of the system.
> 
> All of which is pretty much known. Your electric bills tell you how much you use each year which you can average out on a per day basis. All you got to do is pull a years worth of data from your bills and average it out. If you do not have your bills (shame on you) your POCO has a full history on your home electric use.
> 
> Then go to a site like this one by NREL and obtain your yearly average Insolation in Sun Hours. Select your state, city , and highest harvest averaged over a year vs tilt angle.


Yep, I have total energy consumption plotted and averaged over 7 years of bills. Looking at the UNITS that the link you provided gives, it looks like we are "solving" for the number of square meters of panel we need based on efficiency, rather "solving" for the number of panels we need based on theoretical capability and actual sunlight available. Is that correct?



> After that you are set to go with a very simple formula. GTI systems have an efficiency of 75 to 80%. So the formula is:
> 
> Daily Average Watt Hours Consumed / System Efficiency / Yearly Sun Hours = Solar Panel Wattage Required.
> 
> ...


So, for example, if I use an average of 3,000Kwh per month and an average month is 30 days, my daily average is 3,000/30 = 100Kwh / day. I had gotten that far myself. The next part is less obvious. I can't use your formula because the site provides data in Kwh / m2 / day, the average for my area being 5.1. If I multiply that by a system efficiency of 75%, I get 3.825 Kwh / m2 / day of energy for each square meter of panels, and must ignore the total wattage rating of the panel and focus instead on the size. Divide my total energy budget of 100 Kwh/day by 3.825 Kwy/m2/day and I arrive at a solution of 26.1 m2 of panels, irrespective of their watt rating (the Kwh/day units cancel out, leaving m2). So, I have to look at the size of my prospective panels in m2, and divide 26.1 / panel size to calculate the number of panels.

It's not the easy answer I was hoping for, but I can work that through. These panels are 1.575m x .826m, or 1.3m2. 26.1 / 1.3 = roughly 20 panels IF my math is correct. Since these panels happen to be rated at 175 watts, I can now infer that if I'm buying panels by the watt instead of panels by the square meter, I need about 3,500 watts worth of panels to provide 3,000Kwh / month. That's WAY less than the 10Kw worth of panels I thought I needed, and less by half again what your answer suggests.


I think what I'm missing here is the actual efficiency of the panels themselves. If I multiply the 20 panels times the panel efficiency (say, 15%, which is about the efficiency of the cheaper panels) , I come up with 133 panels / 23.333Kw worth of panels. That sounds more like your number, so I'm guessing that is the missing element? There are 3.825 theoretical Kwh / m2 for a system that is 75% efficient, but due to the inefficiency of the cells only 15% of that power is collectible?



> It is so easy your kids can do it.


All my children have 4 legs, and are likely to drink out of the toilet if I leave the lid up. Since I don't have any 2-legged ones, I'll have to turn elsewhere for help...

Seriously, I'm thinking of pulling the trigger in the next year but if I need 23Kwh instead of 15Kwh as I had previously figured I don't think it makes sense economically.

Oh, and btw most 5th graders would not have been able to solve that Algebra problem in this country. It's generally at least High School math or physics (the latter 's where they teach you about cancelling out disparate units) or later for story-problems of that level...


----------



## Sunking (Aug 10, 2009)

PhantomPholly said:


> I'm neither simple, nor a 5th grader - just haven't studied this. No need to be evil...


Sorry was not trying to insult you, just letting you know it is easy to get into the ball park with decent estimate so you know what your are getting into. 


PhantomPholly said:


> Yep, I have total energy consumption plotted and averaged over 7 years of bills. Looking at the UNITS that the link you provided gives, it looks like we are "solving" for the number of square meters of panel we need based on efficiency, rather "solving" for the number of panels we need based on theoretical capability and actual sunlight available. Is that correct?


If I understand you correctly yes. Do not confuse panel efficiency with System Efficiency, they are not related or have anything to do with each other. 

All Panel Efficiency means is how much square area it takes to make a watt output. All panels are measured against 1000 watts/M^2. So if you have a panel that is 1 square meter in area with 10% efficiency means it has a STC power rating of 100 watts. Panel efficiency varies from less than 10% for Thin films (amorphous silicon, cadmium telluride, copper indium gallium (di)selenide) up to as high as 19 to 20% for Monocrystalline panels. 

FWIW stay away from the Thin Film types. They cost less but will only last a few years. You want Monocrystalline as a first choice and Polycrystalline second. They will last at least 20 years before power generation falls below 80% rated spec. 



PhantomPholly said:


> So, for example, if I use an average of 3,000Kwh per month and an average month is 30 days, my daily average is 3,000/30 = 100Kwh / day. I had gotten that far myself. The next part is less obvious. I can't use your formula because the site provides data in *Kwh/M2/Day*, the average


You are making it more difficult than it really is. Like I said a 5th grader can do it with 30 minutes of instruction. 

*Kwh/M2/Day = Sun Hours*. So if your area yearly average is *5.1 Kwh / M2 /Day = 5.1 Sun Hours.
* 
So now let's say you average 100 Kwh per day usage, and receive an 5.1 Sun Hours per day yearly average

So if you use a yearly overage of 100 Kwh/day, and have a daily yearly 5.1 Sun Hours the first step is to account for system efficiency of 75 to 80%. Let's split the difference and say 77%. 

*100 Kwh / .77 = 129.87* Kwh is what the panels will need to generate to make up for the losses or overall efficiency.

All that is left to do is factor out the time element to find that panel wattage and the time element is 5.1 Hours. So:

*129.87 Kwh / 5.1 h = 25.46 Kw*

Now with that said no where in Philly do you get 5.1 Sun Hours yearly average. More like 4.5 hours. You know what that means right? Location means everything. You could live in gloomy-doomy Seattle WS with a yearly average insolation of 3.5 Sun Hours. 

Last note do not use STC power ratings of panels as you will under estimate panel wattage. STC is a LAB Rating and no where on earth will produce that much power. Use the PTC or CEC rating which is a 3rd party rating and real world application to make the formulas and calculations work. Typically depending on the manufacture PTC/CEC ratings will be anywhere from 80 to 97% of the STC rating. If the panel you are looking at does not have PTC/CEC ratings, look elsewhere. 

Hope that helps.


----------



## aeroscott (Jan 5, 2008)

don't try to build a solar system to get thew Dec,Jan . You will end up with over capacity in the other months . A generator with a belt driven car/truck alternator and a with PM armature (or PM brush motor) for dc charging (efficiency) .use engine heat . With a this system you will start finding ways of saving power , like doing wash when the sun is shining , better appliances etc. grab the low hanging fruit first .


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> *Kwh/M2/Day = Sun Hours*. So if your area yearly average is *5.1 Kwh / M2 /Day = 5.1 Sun Hours.
> *
> So now let's say you average 100 Kwh per day usage, and receive an 5.1 Sun Hours per day yearly average
> 
> ...


 Ok, got it - that actually gets to about the same number I got when I estimated panel efficiency; your method is better because it calculates the # of panels is based on dividing the target watts by the laboratory watt rating of the panels (which is a measured value, rather than my estimate for panel efficiency).



> Now with that said no where in Philly do you get 5.1 Sun Hours yearly average. More like 4.5 hours. You know what that means right? Location means everything. You could live in gloomy-doomy Seattle WS with a yearly average insolation of 3.5 Sun Hours.


 Yes, I pulled 5.1 directly from the link you provided, using Athens, GA (which is almost exactly at the latitude and within 20 miles of where my next home will be within the next few months). Not sure where you got Philly from; my monicker (PhantomPholly)is simply a whimisical play on the jets I flew in my mis-spent and Phulish youth.



> Last note do not use STC power ratings of panels as you will under estimate panel wattage. STC is a LAB Rating and no where on earth will produce that much power. Use the PTC or CEC rating which is a 3rd party rating and real world application to make the formulas and calculations work. Typically depending on the manufacture PTC/CEC ratings will be anywhere from 80 to 97% of the STC rating. If the panel you are looking at does not have PTC/CEC ratings, look elsewhere.
> 
> Hope that helps.


It does indeed! To wrap it up, it sounds like a good "rule of thumb" for sizing a system of today's capabilities would be:

Total Required System Size (in Kilowatts, based on PTC or CEC ratings only) = Monthly Kwh consumption / 30 (gives you daily Kwh) / System Efficiency (adjusts watts upwards for inefficiency) / Solar Insolation (more sun-hours per day requires fewer panels).


----------



## Sunking (Aug 10, 2009)

PhantomPholly said:


> Yes, I pulled 5.1 directly from the link you provided, using Athens, GA Not sure where you got Philly from; my monicker (PhantomPholly)is simply a whimisical play on the jets I flew in my mis-spent and Phulish youth.


From your username, my bad.



PhantomPholly said:


> It does indeed! To wrap it up, it sounds like a good "rule of thumb" for sizing a system of today's capabilities would be:


It is a good tool for estimations and can be within a few percentage points of real world application. It can also be way off on the low side. It assumes perfect solar south orientation, tilt angles, and no shade problems. So if any of those factors come into play the real number will be larger. In Georgia I can imagine orientation and shading from trees are a real problem. Times I have been there like in Atlanta roads meander every which way, and you cannot see the homes from the road because of all the dang trees.  I swear when they laid out the roads in Atlanta they just used deer and wildlife trails.


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> It is a good tool for estimations and can be within a few percentage points of real world application. It can also be way off on the low side. It assumes perfect solar south orientation, tilt angles, and no shade problems. So if any of those factors come into play the real number will be larger. In Georgia I can imagine orientation and shading from trees are a real problem. Times I have been there like in Atlanta roads meander every which way, and you cannot see the homes from the road because of all the dang trees.  I swear when they laid out the roads in Atlanta they just used deer and wildlife trails.


Yes indeedee - was assuming perfect instalation. BTW, the chart on that link you provided also provided adjusted insolation based on install angle (degrees variation from latitude, eg. if you are at 30 degrees latitude a "perfect" install is 30 degrees angled south, 0 north, for 0 degrees incidence from average noon sun angle).


----------



## Sunking (Aug 10, 2009)

PhantomPholly said:


> BTW, the chart on that link you provided also provided adjusted insolation based on install angle (degrees variation from latitude, eg. if you are at 30 degrees latitude a "perfect" install is 30 degrees angled south, 0 north, for 0 degrees incidence from average noon sun angle).


Yeah that becomes really useful for things like battery systems, or if you have a mean to adjust tilt angle during the year. It also assumes true solar south orientation.

If you look down at the next set of data, you can also see what 1 and 2 axis trackers will get you. Rarely are those used.

Hope you found the info useful.


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> Yeah that becomes really useful for things like battery systems, or if you have a mean to adjust tilt angle during the year. It also assumes true solar south orientation.
> 
> If you look down at the next set of data, you can also see what 1 and 2 axis trackers will get you. Rarely are those used.
> 
> Hope you found the info useful.


The daytime tracking systems are obviously the best, but would be prohibitively expensive. A single vertical tilt system would be easier, and perhaps you could rig one so you just use a power wrench a few times per year to adjust the set - but I would weigh that cost and effort against simply buying a few extra panels before going for the "gold-plated solution."


----------



## Sunking (Aug 10, 2009)

PhantomPholly said:


> The daytime tracking systems are obviously the best, but would be prohibitively expensive. A single vertical tilt system would be easier, and perhaps you could rig one so you just use a power wrench a few times per year to adjust the set - but I would weigh that cost and effort against simply buying a few extra panels before going for the "gold-plated solution."


Darn right, in most circumstances it is far less expensive to just buy more panels. Not too mention Tracking systems are prone to failures and replacement cost.


----------



## Adventureman (Nov 27, 2011)

In the Nevada you have to plug in to the grid by law and if you have a surplus you don't get paid anything, you only get power credit...


----------



## ElectriCar (Jun 15, 2008)

Per the EPact, all utilities in each state have to offer net metering. They have to purchase your power or give you credit, however you look at it, for whatever rate they charge you. None of them will write you a check if you produce more than you use I don't think. They are not required to do that but may have to carry over the credit for a few months which you can recoup in the winter. But if you continue to overproduce, no you're not getting a check.


----------



## Sunking (Aug 10, 2009)

ElectriCar said:


> Per the EPact, all utilities in each state have to offer net metering.


Not true in all states. TX where I live has no Net Metering laws. Many of the utilities will not even connect you. Ones that do, do not have to pay you retail, whatever they want which is wholesale. The only exception is on the left coast island we call Austin metro area.


----------



## lockduke (Dec 25, 2009)

Here in Indiana it is the same way. You only get credit, not a check unless you are a major supplier of power like our Indianapolis airport is installing a large photovoltaic array that they will recieve payment for. Since those grounds can not be used for anything else the panels are a smart move to the use of the land.


----------



## PhantomPholly (Aug 20, 2008)

Credit would be good enough, as long as it carried over into other months. Just make sure you use just about all the energy you produce over a year. After all, you are getting to use the grid as a "free battery," so complaining is a bit unreasonable.


----------

