# PV tricycle problem



## Functional Artist (Aug 8, 2016)

When your battery is "fully charged" divert the extra energy to "light" a light bulb
...it would also act as an "indicator light"that your battery pack is charged 

or

Some solar set-ups divert the extra energy to "heat" a tank of water "Solar Water Heater"
...so, you could have hot tea "on tap"


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## Duncan (Dec 8, 2008)

Re solar panels
Just use a switch - the panel will go to max voltage and stay there - no current will flow

My panels - 250 watt house panels
Max power ------------------ 250 watts
Max voltage (open circuit) - 37.5v
Optimum voltage ------------30.1v
Short circuit current --------- 8.74 amps
Optimum Current -------------8.31 amps


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## electric_driver (Feb 4, 2017)

Duncan said:


> Just use a switch - the panel will go to max voltage and stay there - no current will flow


Yes, but won't that damage the PV panel ? See previous post:
"a switch could be integrated but then the electric power would build up between the PV panel and switch, which could potentially damage the PV panel". There are also "DC isolators" that can be used appearantly (see http://www.pvstop.com.au/faq/ ) but that too doesn't solve the issue of the energy buildup.

A stainless steel ground rod , or blanket would solve the issue, but don't allow the PV panel to recharge the battery untill full while parked.

Functional Artist's idea of just rerouting the power for another use -LED lights or fan- (or simply rerouting it to the ground) is probably best, but technically complex. We're probably going to use batteries that have a capacity in the range of 360 Wh - 612Wh, but voltage is probably going to be lower (12V) than the motor (36V). At first, we'll use 12V car batteries (these have about 600 watt/hr -12V, 50A- so in line with the previous power range). This requires a DC-to-DC converter (https://www.alibaba.com/showroom/step-up-dc-dc-converter-12v-to-36v.html ). For the LED lights, AFAIK 12V bicycle LED lights don't exist. There is a 36V front light (Spanninga Galeo 36V) but I found no red back lights on 36V, so that might become a dynamo-powered light (like http://www.herrmans.eu/start-english/products?familyId=1097 ). So yes that would work. I could throw in a fan too since that runs on 12V DC, and can keep the battery or PV panel cool (important to extend the lifespan of them especially when parked in full sun. Could I run the fan directly from the PV panel btw (when parked) ?
Advantage would be that that wouldn't reduce the amount of usable cycles from my battery, so extend battery life even more. Problem then is that it shouldn't be allowed to provide too much amps (otherwise it will break the fan).

Regarding the PV panel: is 60 x 60 cm (= 0,36m²) going to be big enough ?
For recharging a 12V car battery, a voltage of 14,1-14,7V at 12A is needed, so the panel should be able to supply that (169 to 176 watt). I read that under STC conditions and 20% panel efficiency, a panel gives off 200W/m², so 200Wh. So with a 1m² panel, it would be fully charged in under 3 hours. The 0,36m² panel is 2,7x smaller, so it takes that much longer, so 8,1 hours. I guess that's too long (although it depends how much the battery is drained after every trip, probably it's never going to be drained more than half, so recharged in under 4 hours then). 
The 120 cm x 60 cm panel is nonetheless probably better as it would do the job in half the time. (between 4 and 2 hours depending on drainage battery).


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## Duncan (Dec 8, 2008)

The panels are designed for open circuit under full sun - the voltage is only a little higher than the operating voltage and no current flows

No Problem!! - in fact on a house system you can open the switch - its designed to be OK


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## electric_driver (Feb 4, 2017)

Duncan said:


> No Problem


Ok. Back to the other question then:
Adding a motor doesn't seem to be a problem, as long as motor power remains under 250W and pedal assistance remains under 25km/h and a "declaration of conformity" is provided or at least that's how it is with electric bicycles (not electric tricycles). Read http://www.bike-eu.com/laws-regulat...oval-for-speed-e-bikes-now-effective-10125384 I'm still not sure whether the vehicle (tricycle) then needs inspection or not.

I also looked into the efficiencies:
based on the performance curves of the goldenmotor 500W engine (I couldn't find any other -250W- ebike motor power curves), it seems most efficient to use a low-power engine and push a lot of energy into it (untill well above its 500W). Can the motor also take more power than the wattage it is designed for, without damage being inflicted ? Ideally, we'd like an efficiency of 70-90%. By using a 250W engine and pushing 250W or more into it, I guess efficiency is increased already, but is it possible to engage the engine only at a voltage/amp rate that allows 80% or more efficiency for instance (either by tweaking the motor controller somehow or leaving it out alltogether) ? Reason is that even a 10-20% efficiency drop is still 25-50 watt, or about 1/3 of pedalling force for a regular rider, and we'd like to have actual gain from pedalling -else, it makes more sense to use only the motor with no pedalling and setting it to a power setting that works at 80-90% efficiency all the time-. Another question: does the pedalling itself damage the motor by forcing it -thus increasing resistance-? Or could it damage it depending on what motor types are used ?


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## brian_ (Feb 7, 2017)

electric_driver said:


> I read that under STC conditions and 20% panel efficiency, a panel gives off 200W/m², so 200Wh. So with a 1m² panel, it would be fully charged in under 3 hours.


Unfortunately, you will never see standard conditions... unless you only park at the equator in clear weather at mid-day. Plan on much lower real output.


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## electric_driver (Feb 4, 2017)

I did some more calculations and it seems to me that the system can't be improved much more. I didn't factor in the depth of discharge, which means that the 600W (12V, 50A) car battery can only hold about 420 watt (70% discharge) of usable energy.

When parked in the Netherlands between 09.00h and 17.00h, there's an 8 hour stretch in where at least 2h of sunlight (@ 1000 watt/h/m²) is probable. At the equator, output of about 2000 watt/hr/m² and even more hours of sunlight is probable. So STC conditions are indeed realistic in the Netherlands.

A 1m² panel doesn't exist, general size is 1,58 m² (99 cm x 1,6m). At 15% efficiency, this output 237 watts per hour, at 20% efficiency, output is 316 watts. With 2 hours of sunshine @ 1000 watt/h/m² that makes 474 - 632 watts, so more than enough (as I don't expect to lose more than 25% of energy during the charging). 

Range would be double (90-150km) as the vehicle is completely recharged in between stops (to and from workplace).


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## brian_ (Feb 7, 2017)

electric_driver said:


> ... the 600W (12V, 50A) car battery can only hold about 420 watt (70% discharge) of usable energy.
> 
> When parked in the Netherlands between 09.00h and 17.00h, there's an 8 hour stretch in where at least 2h of sunlight (@ 1000 watt/h/m²) is probable. At the equator, output of about 2000 watt/hr/m² and even more hours of sunlight is probable. So STC conditions are indeed realistic in the Netherlands.
> 
> A 1m² panel doesn't exist, general size is 1,58 m² (99 cm x 1,6m). At 15% efficiency, this output 237 watts per hour, at 20% efficiency, output is 316 watts. With 2 hours of sunshine @ 1000 watt/h/m² that makes 474 - 632 watts...


It seems like you're randomly interchanging power and energy units (watts and watt-hours), but I get what you're saying. I won't bother looking at the numbers with random units, though.


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## electric_driver (Feb 4, 2017)

Attached is the schematic.

S2 (= switch 2): would be automatically deactivated when battery is fully charged, and automatically activated when partially discharged (i.e. this could be needed for when the fan is manually activated before parking it). It would also reduce engy buildup on the PV circuit to the charge controller. It's probably not needed, but I still have my reservations on whether or not it would increase life expectancy of the PV panel, so included the feature just in case. I'm not completely certain on how this needs to be done though; it will need to be done by the "speedometer/charge indicator" part (which will be a speedometer found on any one of the dutch sites:
https://www.rat-holland.nl/Onderdelen/
http://www.e-fietsspecialist.nl/ombouwset-onderdelen/
https://www.fietsunie.nl/motoren-elektrische-fiets/voorwielmotor.html
https://fon.bike/product-categorie/onderdelen/onderdelen-ombouwset-voorwielmotor/
http://www.v-fiets.com/shop/onderdelen/motoren
)

Also included on the bike would be:
- a bike trailer
- pullover, breathable rain jacket and pants (almost no time lost for changing clothes)
- front fairing/windscreen (either Zzipper, Terracycle, ... or custom-made, using a flat plastic sheet, mounted in the upwards sloping angle, at leg-to-head height)


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## brian_ (Feb 7, 2017)

electric_driver said:


> Attached is the schematic.
> 
> S2 (= switch 2)...
> It would also reduce engy buildup on the PV circuit to the charge controller.


There is no "energy buildup on the PV circuit to the charge controller". You're still trying to solve a non-existent problem. What do you think would happen here? "Energy buildup" suggests that you think the panel (or just the wire?) is a battery or a capacitor, but it is not.

If you are concerned about the panel output voltage going too high, don't - it will only go to the panel's open-circuit voltage, which is not a problem. Solar panels don't blow themselves up (or hurt themselves at all) when exposed to light while no wires are attached.


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## rafeh1 (Jan 13, 2013)

electric_driver said:


> I would like to transform a tricycle into an electric tricycle and also attach a PV panel on a custom-made roof frame. When the tricycle is parked outside, the PV panel will continue to produce power. the battery will, at some point, become fully charged and thus won't be able to take up any more power (or well, it will but will then overcharge and become damaged). PV panels also can't be "turned off" as far as I know (a switch could be integrated but then the electric power would build up between the PV panel and switch, which could potentially damage the PV panel). The only solution I came up with is
> * either pulling a blanket over the PV panel when parked
> * or grounding the PV panel the second the battery is fully charged
> I doubt either are used in commercial solar trikes ?
> ...


this is most interesting. i am looking to do same
some concerns i have read is the shaking damages solar panels ?
which mmpt charger are you looking at?
how are you going to mount the panels
how to mount the side windows panels?

pls post some pictures


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## electric_driver (Feb 4, 2017)

rafeh1 said:


> A concern I have is whether the shaking damages the solar panel ?
> Which mmpt charger are you looking at?
> How are you going to mount the panels
> How to mount the side windows panels?
> pls post some pictures


Hi rafeh,

The plan is to make a sort of "universal upgrade package" for several types of vehicles:
- tricycle (for 1 person)
- tricycle (for 2 people; either next to each other or behind each other)
- quadricycle (for 1 person)
- quadricycle (for 2 people, next to each other)

I attached 2 images showing how the PV panel is normally attached to a tricycle or quadricycle. There's not much special about it, but the clever thing is that it doesn't matter how the tricycle is made (delta or tadpole), both works by just rotating the frame around.

Side windows/panels wouldn't be mounted at all, they're kept open. A pullover, breathable rainjacket and pullover breathable waterproof pants is used to protect the rider from rain (along with an optional fairing/windscreen).

Regarding the shaking: there are 2 methods to counteract that:
* tyres take up some of the vibrations/shaking; lowering the tyre pressure helps
* bicycle suspension, either on the front fork, or back wheels
Since the plan is to just upgrade existing tricycles or quadricycles, suspension should already be on it; if not I wouldn't really add any unless absolutely necessary.
I'm not aware of anyone adding suspension on the PV panel frame itself.
You could look at how other people are doing it at:
https://www.thesuntrip.com/presentation/nos-velos-solaires/
https://www.thesuntrip.com/sun-trip-2018/participants/


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## prof.fate (Jan 22, 2019)

You need a simple float charger that gets it's power from the panels instead of the wall or a car 12v outlet - essentially a simple electrical circuit.

Something like this - you can google and search for what you need.

https://www.instructables.com/id/Battery-Float-Charger/




electric_driver said:


> Yes, but won't that damage the PV panel ? See previous post:
> "a switch could be integrated but then the electric power would build up between the PV panel and switch, which could potentially damage the PV panel". There are also "DC isolators" that can be used appearantly (see http://www.pvstop.com.au/faq/ ) but that too doesn't solve the issue of the energy buildup.
> 
> A stainless steel ground rod , or blanket would solve the issue, but don't allow the PV panel to recharge the battery untill full while parked.
> ...


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