# Vehicle rooftop/Solar



## Ziggythewiz (May 16, 2010)

There's several threads on the topic; general consensus is not worth the effort for the power, but many of us want it anyway for the cool/buzz factor.


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## bjfreeman (Dec 7, 2011)

you can get the crystalline solars with 300 watt @37Volts.
http://www.soldist.com/wp-content/uploads/2011/08/CNPV-290P-300P.pdf

I have four 75 watt on my RV and they don't really do well in Washington State.

that said there are some "Go Karts" size that do well on a full sun day.


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## EVfun (Mar 14, 2010)

Uh... sunshine doesn't do real well in Washington State.


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## bjfreeman (Dec 7, 2011)

EVfun said:


> Uh... sunshine doesn't do real well in Washington State.


yup we had 200 days till there was sun this summer. lasted for less than 20 days.


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## dougingraham (Jul 26, 2011)

TexasCotton said:


> I have seen solar cars and am just curious if a DIY VEHICLE Roof solar pv would be too difficult?


Most of the solar cars don't run on the solar cells. They run off of a battery. The solar cells help very little while the vehicle is in motion. They mostly use the solar cells to recharge the battery when they aren't racing.

If you want to charge your batteries while the car is parked and you are at work this might help. You can probably put around 300 watts of solar cells on the hood of the car. Hinge the hood at the front and face the car to the south. Raise the hood to the proper angle for your latitude. If your car uses 300wh per mile then you will get about 1 mile of range extension per hour of charging. In the summer you will get lots of charging, in the winter not so much. Look up the solar insolation value for where you live to find out how many sun hours equivalent you can expect in the winter. For me it is about 3 hours. As it turns out I would expect to see enough charge on an average winter day to half fill my battery from my daily commute. It might be worth doing for about half the year. If you happen to drive much more than 10 or so miles per day I doubt it would be worth it. Better to put in a larger fixed bank at home and charge batteries. That way you can run your house off of it and charge the car at night from the house batteries. This decreases the car complexity.


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## ishiwgao (May 5, 2011)

bjfreeman said:


> you can get the crystalline solars with 300 watt @37Volts.
> http://www.soldist.com/wp-content/uploads/2011/08/CNPV-290P-300P.pdf
> 
> I have four 75 watt on my RV and they don't really do well in Washington State.


what kind of pricing did you get the CNPV-300P for? You have 4 of these in your vehicle connected in series to get you approx 140V?


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## PZigouras (Jun 5, 2010)

Most people feel that solar is relatively useless because you need direct sunlight to get any real power out of PV cells… and even then, you get 15% to 17% efficiency at best.

I thought about CPV (concentrated PV), like the ones pictured below, because the efficiency is great, even without direct sunlight. But how on earth do you get a curved cell onto a car’s hood??? Well, one of you smart guys showed me that Mythbusters episode that I missed… the one with the Taurus that had golf-ball style dimples on it.

 So put it all together and what do you get…

A car with low drag AND tons of charging power! Now, which one of you guys has the time to build one of these and see if it works....


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## Guest (Dec 22, 2011)

> Now, which one of you guys has the time to build one of these and see if it works....


I nominate you.


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## bjfreeman (Dec 7, 2011)

ishiwgao said:


> what kind of pricing did you get the CNPV-300P for? You have 4 of these in your vehicle connected in series to get you approx 140V?


$2.13 per watt, in non volume buys.
the ones I have are used to charge my 12volt deep charge house batteries in my RV. I also have a 400 watt wind Generator that I set up when stationary.

As I said the PV does not well in areas that have a lot of cloud cover.


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## PZigouras (Jun 5, 2010)

gottdi said:


> I nominate you.


Sorry, I already has 125mm cells on my car, and I'm not taking them off.

I'm also not using a large sledge hammer on my car to create big dimples.


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## Guest (Dec 22, 2011)

PZigouras said:


> Sorry, I already has 125mm cells on my car, and I'm not taking them off.
> 
> I'm also not using a large sledge hammer on my car to create big dimples.



You mean you HAVE not HAS. How many cells do you have on your car and what is the total wattage of your cars cells? 

Well, I did not think of using a sledge nor using your main ride. I was more thinking of using an old junkyard junker to do the test. Making even one dimple with your magnifier mirror onto a tiny but very high out put solar cell would be the first thing to build and it would have to be able to withstand the rigors of the automobile and weather from summer through winter and handle the wind across the unit. 

Actually it may be much harder to implement and not really worth the time or money involved. But if you were to do something like this you'd need to build ONE first. 

Usually the one who suggested the idea would be the one to actually try building one. Can't wait to see a working model. That is all you need. 

Pete


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## TexasCotton (Sep 18, 2008)

dougingraham said:


> Most of the solar cars don't run on the solar cells. They run off of a battery. The solar cells help very little while the vehicle is in motion. They mostly use the solar cells to recharge the battery when they aren't racing.
> 
> If you want to charge your batteries while the car is parked and you are at work this might help. You can probably put around 300 watts of solar cells on the hood of the car. Hinge the hood at the front and face the car to the south. Raise the hood to the proper angle for your latitude. If your car uses 300wh per mile then you will get about 1 mile of range extension per hour of charging. In the summer you will get lots of charging, in the winter not so much. Look up the solar insolation value for where you live to find out how many sun hours equivalent you can expect in the winter. For me it is about 3 hours. As it turns out I would expect to see enough charge on an average winter day to half fill my battery from my daily commute. It might be worth doing for about half the year. If you happen to drive much more than 10 or so miles per day I doubt it would be worth it. Better to put in a larger fixed bank at home and charge batteries. That way you can run your house off of it and charge the car at night from the house batteries. This decreases the car complexity.


You kinda stating the obvious 4 most of us I get the concept PV----Battery----charge -- the motion


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## dougingraham (Jul 26, 2011)

TexasCotton said:


> You kinda stating the obvious 4 most of us I get the concept PV----Battery----charge -- the motion


Well then what did you want to know? That seemed to be the answer to the question you asked.


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## PZigouras (Jun 5, 2010)

gottdi said:


> How many cells do you have on your car and what is the total wattage of your cars cells?
> 
> 
> Pete


The 125mm cells are pretty much standard... they are about 1/2 a volt, 2.65W

I have 80 (40 volts, 212W) so it's not a lot of power, but it looks cool on the car. I use a 3;1 switching supply to tripple the voltage to charge the 144V pack.

There is really no way to use the CPV cells on a regular car, because the mirrors would need constant cleaning... and water would collect in them and freeze in the winter (unless you could put a clear cover over them???).

The standard PV cells that I use are very easy to work with...you simply epoxy them onto the body, then put a heavy clear coat on them to protect and seal them. I clear coat over the bus wires as well.

Make sure you use clearcoat WITHOUT the UV inhibitor (most of them have it in them nowadays).


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## TexasCotton (Sep 18, 2008)

dougingraham said:


> Well then what did you want to know? That seemed to be the answer to the question you asked.


Okay here is the thing!! repeat after me rooftop application not hood.
I wanna know how you do this from start to finish go to youtube 
"turning your prius into a solar" by (lloydalter) once you have fully watched and have a knowledge base to step by step process let me know.


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## Ziggythewiz (May 16, 2010)

PZigouras said:


> I use a 2;1 switching supply to double the voltage to charge the 144V pack.
> 
> The standard PV cells that I use are very easy to work with...you simply epoxy them onto the body, then put a heavy clear coat on them to protect and seal them. I clear coat over the bus wires as well.
> 
> Make sure you use clearcoat WITHOUT the UV inhibitor (most of them have it in them nowadays).


Do you have details on your booster or the whole epoxy/coating process posted anywhere?


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## dougingraham (Jul 26, 2011)

TexasCotton said:


> Okay here is the thing!! repeat after me rooftop application not hood.
> I wanna know how you do this from start to finish go to youtube
> "turning your prius into a solar" by (lloydalter) once you have fully watched and have a knowledge base to step by step process let me know.


Rooftop application not hood.

Ok. Watched the video. Its straightforward to do all of this. My point is that it won't extend your range enough to be worth it even in the summer. It certainly isn't worth it in the winter. Even if you live in Phoenix or Tucson you will only extend your range in the winter about 5 miles. (You might get close to double that if you covered your hood too.) And almost everywhere else in the United States is going to be quite a lot less. In the summer you could expect three times that. If you do all the work yourself and scrounge for everything you might be able to do it for $1000 but I bet it will cost closer to $2000. That money will buy a lot of miles of electricity (approx 40000 miles for $1000.) Or it could buy more batteries.

Of course all of that changes if solar cells get more efficient because right now you just can't put enough on the car to matter while you are moving (unless you are moving only a few miles per hour.)

And yes I think it would be cool, just not practical yet.


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## dougingraham (Jul 26, 2011)

PZigouras said:


> The standard PV cells that I use are very easy to work with...you simply epoxy them onto the body, then put a heavy clear coat on them to protect and seal them. I clear coat over the bus wires as well.
> 
> Make sure you use clearcoat WITHOUT the UV inhibitor (most of them have it in them nowadays).


Interesting approach. If I did this I would have to put plexiglass or lexan over the cells or I would be replacing them a couple of times per summer from hail damage. Pea or even marble size hail that doesn't bother the painted body of the car would destroy the fragile solar cells.


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## Guest (Dec 23, 2011)

Do it the easy way. Go get 30 200 watt Solar panels and install the panels on the roof and connect a grid tie system and be happy for the next 25 or so years. Enough to power your home and a couple electric cars as well. 

We have a 7.1 Kw system currently on the house and I just picked up another 6 Kw system to install as well to cover the extra needed for the electric cars. A damn good investment you know. Better than risky stock market options at this time. 

Pete


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## TexasCotton (Sep 18, 2008)

dougingraham said:


> Interesting approach. If I did this I would have to put plexiglass or lexan over the cells or I would be replacing them a couple of times per summer from hail damage. Pea or even marble size hail that doesn't bother the painted body of the car would destroy the fragile solar cells.


Hail damage in 2011 Texas made my Prius roof /hood get depression dents.


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## jehan12413 (Feb 4, 2010)

TexasCotton said:


> Depends on the the residence aka location to grid tie because city,county, state, and feds must have their thumb in the pie!!


Not necessarily. If your grid tie system does not generate more than your house uses then it will not run your power meter backwards, it will simply slow it down a bit. This method is much more cost effective than using a battery bank. In fact if you are only talking a couple hundred watts then the inverters are just over $100 each and they are stackable.


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## PZigouras (Jun 5, 2010)

Ziggythewiz said:


> Do you have details on your booster or the whole epoxy/coating process posted anywhere?


I'm making a blog about it now. It's a fairly simple process... simply epoxy them on, wire them together, then put a fat layer of clear coat on the whole car.

It's an extremely time-consuming process.... it takes well over a month do to a car if you only work on it a little each day. 

Any adjustable switching supply can be used to charge the pack, as long as it can step the voltage high enough to charge the pack.


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## TexasCotton (Sep 18, 2008)

PZigouras said:


> Sorry, I already has 125mm cells on my car, and I'm not taking them off.
> 
> I'm also not using a large sledge hammer on my car to create big dimples.


 Are these the same PV cells youtube video by greg johanson SOLAR Powered TOYOTA Prius New Feature.///www.solarelectricvehicles.com 215watt roof


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## Guest (Jan 1, 2012)

jehan12413 said:


> Not necessarily. If your grid tie system does not generate more than your house uses then it will not run your power meter backwards, it will simply slow it down a bit. This method is much more cost effective than using a battery bank. In fact if you are only talking a couple hundred watts then the inverters are just over $100 each and they are stackable.


Not entirely true. There are plenty of times during the day when I am not home but at work where there is nothing running and even a small system will turn the meter backwards but you will gobble up the saved power real fast when you get home. But yes, mostly if you have a small system it will just slow things down a tad. If you set up your solar with a decent panel and a mini inverter you can build your system as you can afford it. 

Pete


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## TexasCotton (Sep 18, 2008)

dougingraham said:


> Rooftop application not hood.
> 
> Ok. Watched the video. Its straightforward to do all of this. My point is that it won't extend your range enough to be worth it even in the summer. It certainly isn't worth it in the winter. Even if you live in Phoenix or Tucson you will only extend your range in the winter about 5 miles. (You might get close to double that if you covered your hood too.) And almost everywhere else in the United States is going to be quite a lot less. In the summer you could expect three times that. If you do all the work yourself and scrounge for everything you might be able to do it for $1000 but I bet it will cost closer to $2000. That money will buy a lot of miles of electricity (approx 40000 miles for $1000.) Or it could buy more batteries.
> 
> ...


If I could get more than 200watts and would make the application somewhat more do able. I just wanna know how to do the layout, some soldering, cell encaps, battery current trickle and vehicle wiring for toyota prius


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## TexasCotton (Sep 18, 2008)

gottdi said:


> Do it the easy way. Go get 30 200 watt Solar panels and install the panels on the roof and connect a grid tie system and be happy for the next 25 or so years. Enough to power your home and a couple electric cars as well.
> 
> We have a 7.1 Kw system currently on the house and I just picked up another 6 Kw system to install as well to cover the extra needed for the electric cars. A damn good investment you know. Better than risky stock market options at this time.
> 
> Pete


Vehicle roof your above statement sounds like for solar panel forum aka house roof solar panel


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