Work in progress. Options ordered in increasing cost:
1) There are MANY examples of extracting 120vac power from the 12vdc battery of a car. This is a very good one:
http://aprs.org/FD-Prius-Power.html
Best choices of 12v power would be either a hybrid such as Prius or Volt or a real EV including Tesla, Leaf, Bolt, etc. The hybrids have the advantage (or disadvantage) of charging from the car's engine.
I believe 12v powers should be limited to about 2kw.
2) Small engine driven generator. I think the 12v car battery is cheaper. Not a good solution because of engine maintenance, noise, fuel.
3) MPP with PV panels. I hope others will supply more data for this one. There are a number of such "hybrid inverters" out there. In my opinion, grid tie is required in order to justify the cost. Other suppliers are SolArk and Growatt MPP has a good reputation.
I think two friends might be successfully using this MPP:
About $350. Requires a 24v battery and low voltage PV string.
I expect a full house 240vac split phase will require two MPP inverters and either one or two 48vdc batteries as well as the needed PV panels. An advantage (and disadvantage) is that all major components (inverter (both grid tie and islanding) and battery charger) is incorporated and integrated in one unit. A much smaller and less expensive system can be configured to supply 120vac only.
Maybe someone will supply costs for both a minimal 120vac, 2kw system and a full 240vac ~5kw system.
4) Whole house 5+kw engine driven generator from Generac or other
Cost is likely to be $5k+. Engine problems of 2). Preferred fuel would likely be propane.
5) Whole house PV with battery back up. Though there are others, IMHO Tesla PowerWall is the Cadillac. Cost about $13k minimum plus PV.
https://wmckemie.blogspot.com/2021/01/testing-powerwall-off-grid.html
In looking at the MPP systems in 3), I see one great advantage of a PW is the PV versatility. One can use any combination of grid tie inverters and panel strings.
The MPP Solar unit is the LV2424 Hybrid unit. It has MPPT tracking, and can be connected to the grid. Cost is around $750, delivered. It does not have UL certification. A 24 volt battery is required. The LV means Low Voltage string of solar panels, so two of the 250 watt panels is series, and then four of these strings hooked together in a combiner box. (about $100) The output of the combiner box will carry about 30 amps, so heavy duty wiring run through a conduit to the LV2424 mounted in a protected area. The unit has a built-in sine wave inverter that is turned on with a switch at the bottom of the unit. The inverter will charge an electric car using the 115 volt EVSE that comes with most cars. My unit will charge a 2011 Nissan Leaf, or a 2018 Tesla Model 3. The charge rate is about 4 or 5 miles/hour, and it will do this even when the grid is down, during periods of maximum sunshine. If a larger battery is used, more hours of charging can be done. I'm using a very small Lithium ion battery, so if anyone is considering using the LV2424, get a large battery so you can charge earlier in the morning, or later in the afternoon.
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