Re: [RE-wrenches] Fwd: Car charging station without grid

[Allan Sindelar]

On 7/14/2011 6:09 PM, Joel Davidson wrote: Hi Allan, Off-grid batteryless EV charging? Perhaps if the EV battery was tapped to keep the off-grid inverter awake, but that would void the vehicle warranty. I'm sure you considered PV into Sunny Islands (or similar) with a small sealed battery into Sunny Boys. I question if a person in SF who wants an off-grid PV system without batteries to charge a battery vehicle is really a customer. Good luck,Joel Davidson Actually, Joel, we *almost* have one already... A woman who is a long-time political and environmental activist, and is now in her 70s, built her off-grid passive solar adobe in the mid-nineties, right in a nice middle-class residential area in town, and has been living that way ever since. For years her well-constructed home was available for solar and green-built tours. She bought the first Prius in Santa Fe and put a sign on it. We have taken care of her system since shortly after it was built. She had gotten by on 8 Siemens M55s and 8 Arco 16-2000s for years (660 watts of PV!), but a few years ago we added a kilowatt on a pole. She had us install a second pole for a future array upgrade "to charge an electric car". When I questioned how realistic this was, she explained that she only drove occasionally (especially as she got older), most trips were local, and she had a circle of friends to call on if she needed to get somewhere when the sun wasn't charging enough. Given that she lived for years leaving a very light footprint, I accept her approach as entirely reasonable and hope to get to make it happen for her. But yes, Joel, it would classic charging from an inverter and batteries, sort of setting up the car as a diversion load. As far as the other request ("batteryless off-grid") all pretty much agree that there's no simple and practical way to do this as stated. But a grid-tied system with or without batteries could do the job if properly sized. The SMA approach would work but is an expensive way to go. Thank you, all, for your replies, all of which I have forwarded to Karlis, our salesperson who asked me for a solution that I couldn't provide. Allan Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com ----- Original Message ----- From: Allan Sindelar To: RE-wrenches Sent: Thursday, July 14, 2011 1:43 PM Subject: [RE-wrenches] Fwd: Car charging station without grid Wrenches, I'm stumped as to the best approach for a customer who wants a non-grid-tied, batteryless PV-powered EV charging station. See below, from one of our salespeople. Any ideas? Thank you, Allan -------- Original Message -------- Allan: Monday I sit down with an interesting fellow who sounds like a potential good customer (has money and right enviro goals) - in SF. He brought up the idea of discussing a car charging station for future electric car that: stands alone, no grid connection no batteries - he pictures his car is home most days - he parks it and when the sun shines it gets charged directly Why that approach? He is thinking this must be the most efficient conversion, i.e. directly without batteries or line loss of electrons to and from utility Wants the car to function independent of dirty fuel/dirty electrons He assumes less equipment; maybe less cost but the cost is not important other than as example for others Issues I see: All inverters that can produce the high voltage needed need grid power or if off grid need batteries - know of anything stand alone available? Power or voltage fluctuation as panels see more or less sun; ie hours of day or clouds, etc - what will be the output from inverter? Without tieing into grid investment in PVs (both his financial and the embodied for manuf.) gets wasted when car fully charged or car not home and sunny. Is total amps output in peak sun even going to meet the charging requirements? ie takes 10 days to recharge instead of 4 hours - or overly massive system to match rate of charge? Your thoughts? Karlis

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