One final point about grid down charging (under a must have armagedon scenario): (And only for those fully experienced in HVDC)
Remember that Solar panels are current limited power sources. This means It will provide its rated current at ANY voltage from 0 (short circuit) up to its nominal operating voltage. This means I can just clip the 450 volts DC straight from any one of my 3 kW solar panel arrays and run it straight to a 12, 24, 48, or 72 volt battery (or 240v prius) directly for a temoporary 7 to 9 amp charge. WHICH ONE MUST MONITOR to know when to disconnect. AND one must have arc-flash eye protection because you will draw a lightening bright arc flash when you disconnect (and or while connecting if the connection is not made cleanly). But you will get a 7 amp charge (in my case of older panels). New 300W panels can give 9 amps. (You MUST disconnect from your GT inverter of course,. You do not want any capacitor holding the 450v or it is no longer a perfect current limited source). And with 6 such separate panel arrays, I can combine the currents at the battery to give me up to 42 amps at 12, 24, 48, 72... (or 240) volts if needed. But again MUST human monitor in real time. It is not easy to throw together a charge regulating circuit to open a relay when the charge is complete as agaiin, you must use very expensive HVDC contactors and or snubbers. And by th time you do all that , you could have build a more direct DC/DC converter. So again, this is just an emergency data point. For example, while drawing 1 kW (80 amps) from my prius 12v battery to power the house, all I need at 240v DC is 4 amps from the solar array. And in my 14 year old Priuses I know exactly where the HV battery posts are and can connect there and am happy to take the risk. Not sure I wouild take the risk for the 350v battry in the newer Volt (which could give me 2 kW from its DC/DC converter).. Anyway. just thought I would mention it. Oh, and the open circuit voltage of the solar arrays on the brightest and coldest day can approach 600 volts, not the 450 nominal load point... But again, just short that 600 volts with an ampmeter and you will still see only the 7, 8 or 9 amp current from your arry even at zero volts. Just protect your eyes from the arc flash when you disconnect (oh, it will also vaporize pieces off your clip leads too each time), and it can just melt the tip off the copper wire to molten copper and catch fire to the insulation and anything else within a few inches if you let the arc continue...).. NOT SOMETHING TO PLAY AROUND WITH! But you can charge any battery... ;-) Bob On Sun, Sep 1, 2019 at 2:17 PM Robert Bruninga <[email protected]> wrote: > Again, if you find a 72v UPS (6 12v batteries) then you can tap your > arrays in groups of three and use that to provide the current to the UPS to > dirive your car charger. Just 9 panels in 3 parallel strings of 90v will > give maybe 20 amps (or the minimum needed to charge L1) But 12 panels (or > about one string array) will give you plenty of current over more hours of > the day. That's why I like string inverters beccause I have access to all > the DC inputs and ground mount so I can get to them any time I want. > > Bob > > On Sun, Sep 1, 2019 at 1:20 PM Robert Bruninga <[email protected]> wrote: > >> You already have what you need for continuous operation at night in the 1 >> kW class (refrigerator, well pump and lights, etc) >> See http://aprs.org/powerwheels.html >> >> But it assumes you have the Sunny Boy GT inverter with "secure" power >> when the grid goes down to charge your EV. $1500 >> Or if you are lucky to find a UPS of at least 1800W capacity to charge >> the car, and then you can drive that from batteries that you charge from >> voltage taps on y our DC array that match the input voltage of the UPS. >> But ONLY if you seriouisly know what you are doing and do not overcharge >> the intermediate battery., etc. >> >> Bob >> >> On Sun, Sep 1, 2019 at 12:28 PM Damon Henry via EV <[email protected]> >> wrote: >> >>> I know there has been a lot of churn the last few years over Vehicle to >>> Grid technology. I'm not sure how many people really want the utilities to >>> take over their vehicle state of charge, so I'm not sure how viable the >>> whole concept is. >>> >>> With my grid tied solar system my solar stops producing if the grid goes >>> down. One way to prevent this is to have a battery backup system in >>> place. That's usually an investment of at least several thousand dollars. >>> >>> I have two factory OEM PHEVs sitting in my driveway with significant >>> battery packs. I also have a Juicebox 40 for charging which has some >>> charging intelligence already built into it for their Juicenet program, but >>> not really V2G. I feel like I am tantalizingly close to a great solution. >>> >>> So here is the question that I have. How far am I from being able to >>> utilize my car batteries through the OEM port and an EVSE charger, to feed >>> an inverter and keep my house alive and my solar producing during a power >>> outage? Is this tech currently being developed, or is it still just a >>> dream that my come true some day? >>> >>> BTW - I have lived in my house for 20+ years and rarely lose power, but >>> "being prepared" is always on my agenda. I suspect that if I really want a >>> solution within the next couple of years I will need to buy a separate >>> battery for my solar system, or a generator... >>> >>> thanks >>> Damon >>> -------------- next part -------------- >>> An HTML attachment was scrubbed... >>> URL: < >>> http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20190901/f59128c8/attachment.html >>> > >>> _______________________________________________ >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >>> ARCHIVE: http://www.evdl.org/archive/index.html >>> INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org >>> Please discuss EV drag racing at NEDRA ( >>> http://groups.yahoo.com/group/NEDRA) >>> >>> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20190902/742eb592/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
