Just for a Chevy Volt.

Re: Just for a Chevy Volt.

I am going to have to buy a new car for him anyway. The Volt holds enough charge for the round trip. He leaves in the AM before the sun comes up and gets home about 2:30 PM so not enough daylight for a recharge. What about a small off-grid that has no other function but to charge the Volt at night?

Just to put some numbers on a battery-based system: the Volt has about 10.5 KWh usable on its 16 KWh battery. So assuming your son used the whole 10.5 KWh/day for his commute, that much would have to be replaced. Battery-based pv systems have major efficiency losses, mostly due to the batteries, although there are efficiency losses in the inverter, the charge controllers for the batteries, and the wiring. Also, the charging of the Volt itself is only about 80% efficient, from what I've seen. As a guess, you'd probably need to generate over 2 times the 10.5 KWh/day to overcome these, or over 21 KWh/day from the pv panels themselves. A deep-cycle battery bank can only be safely discharged to about 1/2 capacity at most for long life (ideally less), so at a minimum, the bank would also have to be at least 21 KWh, but you'd really want a lot more for cloudy day charging, unless you relied on the grid those days. But in that case, you'd quickly be asking yourself why not rely on the grid everyday.

On the plus side, since he's home at 2:30 you could get some charging in before the sun went down if he plugged it in immediately. If that were consistent it might lower the system size slightly, but it would still be big.

A battery-based system of the size you'd need is doable; many people here have even larger ones. But it would cost tens of thousands of dollars and, as BB mentioned, would have additional battery replacement costs every few years. It would never save you any money but in fact cost many thousands more.

Re: Just for a Chevy Volt.

Is there a reason you want an off-grid system? As stephen and BB pointed out, a grid tied system is vastly more economically sensible if your utility supports net metering or has some other feed in tariff arrangement.

Even if you go with day time charging, if the system is off-grid, you'd still need a sizable battery bank, although it could be smaller than the night-time charging scenario. Off-grid systems still need to deal with interruptions from clouds and so on, and need the battery bank for voltage regulation as well. The battery bank thus has to be big enough to support the load from the Volt charger when it's cloudy (this could be significant, especially at 220 volts charging). I'd say there's still little chance you'd save any money with an off-grid daytime charging set-up. Depending on what your utility offers though, a grid-tie system could potentially save money. So assuming savings is your goal (from your first post it seems to be), you've got to find out what your utility offers to grid-tie customers before you'd know if solar+EV would make any sense.

Re: Just for a Chevy Volt.

The right way to do this is to grid tie an get the full benefit of your solar system and net meter. Then if you have TOU charge on your cheap rate. The Volt uses about 10.5 kWh and it takes about 13.4 kWh to fill the battery from the wall.

This is how we do both our Volts.

Edit
There is a,guy over Gm-volt.com that is,off grid and has a bang bang type of controller that takes his afternoon excess solar and uses it to charge his volt. He uses his charge controller to controll the input to the car.

Re: Just for a Chevy Volt.

niel wrote: »

the problem with trying to directly charge the volts' batteries is that the car can't be driven until night or it will be away from the home where all of the solar charging would take place. to charge other batteries to be used through an inverter to facilitate the ability to drive during the day and still capture the energy from the sun to enable night charging would be vastly more expensive and far more inefficient than using a straight grid tie solar setup. let the grid be your battery and use the straight gt method. i did briefly mention this in my previous post.

He has a 220 AC inverter and he runs it via his AC side. Just as an FYI, not as a recommended method. He is off grid and needs to do it that way. Down side is the car needs to be there to get the solar watts.

Yes agreed the grid is the best battery as it gives you the full potential of the panels as usable power even after dark.

Re: Just for a Chevy Volt.

techntrek wrote: »

Can't do that, you must have a battery in the PV --> inverter setup.

On the other hand, if the charger will accept direct PV (like any solar CC) then the vehicles batteries will be the batteries charged by the CC.
Chargers for home brew EVs can be made to do that. For a Volt, without breaking the warranty, probably not.

Re: Just for a Chevy Volt.

techntrek wrote: »

Can't do that, you must have a battery in the PV --> inverter setup.

Unless you grid tie. I know the OP was talking direct solar/off grid but that is not the way to do it.

Re: Just for a Chevy Volt.

Interesting read on that Prius manual, CDN_VT. I have pics of my own torn down (only the rear) in the link in my signature.

Re: Just for a Chevy Volt.

techntrek ,That is not really a manual , just a collective page.
Manuals are much more in depth.

What I'm trying to get at is the days of thinking you can tweak anything , if you have no tools/ OEM equipment (Audi-Volvo 4 me) with "Manuals" then the Vehicles of now-a-year are the most unusual electronic systems. Dynamos/Generator/Alternator now do a battery equalization to 15-17.~ Volt while the Control Modules do a PWM to keep the voltages safe to around 14.~ so the bulbs etc. don't burn out. This is controlled from the LIN after all other systems say's it's cool to equeak now, you would,t see a flicker. It's also when this happens , the fiber system can diagnose it's beam / optical power checks and then it now can adjust it's normal beam range.

I'm probably not making any cents 8) , but if you fool with these systems , it's hundreds plus if you get it wrong.

These new electronic toys are very voltage sensitive !!!! 11.3 and lower , has caused Module death , while "Noisy" battery chargers/jumper packs can do the same.

Now we have over 200~300 acronyms & Nodes / Modules .
Just so many can realize the madness.

VT