Solar Panels + Tesla

[raynewman]

With all this discussion of long distance driving, I have a technical question for those of you who know a bit about Solar Panels (I don't as I currently live in an apartment and nowhere to put any).

Is there any way to connect (how many) panels together to produce circa 40 AMP, 240 V AC so that one could unload the boot and charge a Model S during the day and then drive all night (slowly)?

 

[L-P-G]

Your best bet would be a grid backed system. You'd use the grid to charge the car at a consistent rate. Hen you panels would offset the kw you used by putting them back into the grid.

Or

Use a battery backed system, the panels charge your home batteries, then you home batteries charge your car batteries, the issue with this is you home batteries are DC, so you'd need DC-DC charger in order to avoid DC to AC then back to DC which is very inefficient. Then also keep in mind if you don't have enough panels or use up your home batteries at night you'll have to use the grid.

 

[Ben_333]

I think your problem would be boot space. 240V, 40A is ~9.6KW. A decent rooftop home system would be 5KW and that would probably be made of 20x250W panels.

Maybe if you were willing to take an aerodynamic trailer?

 

[paulp]

My 3.5kw system for the car produced 19kwh today, which would be the maximum for this time of year, and in summer peak its 25kwh. Hence the system today would fill 25% of the battery, which is more than what we consume typically.
As suggested by LPG we are grid connected, which is free storage as our feed in tarrif is near identical to the charge rate. Hence we can use the solar at night if necessary.
There is a new battery launched this week called sonnen, which allow you to export the power to another user. You could potentially set the array and battery up elsewhere, and "buy" your own power from any location.
A typical panel is around 1.4x1m , 50mm thick. The enphase system has a microinvertor on each panel, so you could plug them together and have your portable connector on the end. Ultimately each panel today makes 1.3kwh, so dont plan too much night driving, as not many will fit in the boot.

 

[bradjc]

I have a 6Kw system, although actual output is much less. What's the best way to match the charge rate of a MS to the output of the solar panels to try and use sun power only? I'd love to just run on sun. If I adjust the charge rate in car to lower amperage, that the best way? Any tips to going pure sun powered? (Or not possible without a home battery).

 

[Ben_333]

I have a 6Kw system, although actual output is much less. What's the best way to match the charge rate of a MS to the output of the solar panels to try and use sun power only? I'd love to just run on sun. If I adjust the charge rate in car to lower amperage, that the best way? Any tips to going pure sun powered? (Or not possible without a home battery).

Well for starters you're only going to be able to charge during daylight hours (obviously), and then you're going to have to limit your charge current to match whatever the inverter is outputting. Being mindful though that your household will be consuming power as well in the background (washing machine, fridge, etc), so if you want to 'hand on heart' say you only charge using solar power you'd have to watch the household use and adjust charge rate accordingly. Or switch off your home circuits while the Tesla is charging, but your food intake the fridge and anyone watching TV might not be happy...

 

[bradjc]

Well for starters you're only going to be able to charge during daylight hours (obviously), and then you're going to have to limit your charge current to match whatever the inverter is outputting. Being mindful though that your household will be consuming power as well in the background (washing machine, fridge, etc), so if you want to 'hand on heart' say you only charge using solar power you'd have to watch the household use and adjust charge rate accordingly. Or switch off your home circuits while the Tesla is charging, but your food intake the fridge and anyone watching TV might not be happy...

Thanks do that. Pretty much what I had thought, and in reality it will be hard to optimise the solar panel output, it fluctuates a lot through the day. Might have to look at more as a daily trickle top up to my overnight charge for longer trips. As soon as a cloud crosses the house, it will be pulling in day time top tier electricity fees. Powerwall etc will be the only way I guess, might wait a few years for prices to drop then seriously look at going the next step.

 

[raynewman]

I'm trying to get a feeling for mobile charging. Did anyone see 'The Martian'?

 

[bradjc]

I thought that when I saw the movie, might take a month to charge it with panels that would squeeze in the frunk.

 

[paulp]

I have a 6Kw system, although actual output is much less. What's the best way to match the charge rate of a MS to the output of the solar panels to try and use sun power only? I'd love to just run on sun. If I adjust the charge rate in car to lower amperage, that the best way? Any tips to going pure sun powered? (Or not possible without a home battery).

You can achieve it with a zennio automation system. It measues the current from your panels, and you program it to do what you want when power is available. Once that is setup, the car amperage isnt relevant, as the car will only draw the available power, and the zennio will only make solar power available.
Alternatvely, take half your system off the house and make a dedicated car curcuit. 240v microinvertors make this very easy to do, and a simple changeover switch puts that power elsewhere when you arent charging.
So yes there are ways to guarantee you are driving on sunlight, and with minimal management of your charging process.

 

[garyjac]

I might be misunderstanding Ray's question, but there is, to my knowledge, no solar panel so efficient that a small number would fit in a car boot and provide enough output to charge a Tesla in any reasonable time. Roll on the day when there is!

 

[raynewman]

I might be misunderstanding Ray's question, but there is, to my knowledge, no solar panel so efficient that a a small number would fit in a car boot and provide enough output to charge a Tesla in any reasonable time. Roll on the day when there is!

That was what I am looking for. Guess I'll have to wait.

 

[Jimat]

With all this discussion of long distance driving, I have a technical question for those of you who know a bit about Solar Panels (I don't as I currently live in an apartment and nowhere to put any).

Is there any way to connect (how many) panels together to produce circa 40 AMP, 240 V AC so that one could unload the boot and charge a Model S during the day and then drive all night (slowly)?

Ray,
I charge my car almost entirely ( ie when not at a supercharger) from my home PV arrays which total 11Kw.
I tell folks who ask about having PV panels on the car that I need about 80 square meters of panels to get a 32A charge rate
Jim

 

[garyjac]

Then, of course, there's Solar Impulse 2 - flying around the world on solar power.

 

[eye.surgeon]

Not even close.

 

[garyjac]

You have to start somewhere. I think the future of heavy, long distance freight lies in dirigible airships.

 

[Ben_333]

Two things this thread has made really clear to me
1. Just how much energy is in fossil fuels. My rough calculations are that the 50L of petrol in my car equates to around 485kWh of stored energy.
2. How rediculously good Teslas (and other EV's) are at converting energy into travel. By Tesla standards that 485kWh should get me around 2500km range. I'm lucky to get 500km thanks to all that wasted energy.

 

[NovoCasGreeny]

A custom built aero dynamic trailer (aluminium) and Sunpower 22% efficient panels with microinverters.

1.6*2.2*1 would house about 45 Panels would have you generating 10 KW during peak conditions. In many areas where you may require such a system you would be getting a lot of peak sun hours. You might be able to get 40-60 KWH of production out of that system, maybe more.

 

[paulp]

Two things this thread has made really clear to me
1. Just how much energy is in fossil fuels. My rough calculations are that the 50L of petrol in my car equates to around 485kWh of stored energy.
2. How rediculously good Teslas (and other EV's) are at converting energy into travel. By Tesla standards that 485kWh should get me around 2500km range. I'm lucky to get 500km thanks to all that wasted energy.

Great comparison!

 

[paulp]

A custom built aero dynamic trailer (aluminium) and Sunpower 22% efficient panels with microinverters.

1.6*2.2*1 would house about 45 Panels would have you generating 10 KW during peak conditions. In many areas where you may require such a system you would be getting a lot of peak sun hours. You might be able to get 40-60 KWH of production out of that system, maybe more.

But less range due to towing a very heavy trailor with load