However I can power our house from, solar PV, the grid, one of two backup gensets, an idling vehicle or the Leaf
To me, this is the key thing to have in place. I have a similar array of options for our home:Heat:
- Air-source heat pump: Strictly grid-tied. I do not even have this set up to run from the generator.
- Wood pellet stove: We used to heat the entire house for the winter with this unit, but the price of pellets has doubled and we now have net-metered photovoltaic electricity that cover our heat pump's consumption. The fans and auger only consume about 120W of electricity when operating.Cooking:
- Everything is electric except we have a propane cooktop (and a propane oven which draws about 300W for its igniter).Water:
- We have a well pumped by a 1/2 HP submersible. The pump is 240VAC, but I added an autotransformer after the pressure switch to allow it to be run from 120VAC if needed. It has a high starting surge, but only draws about 1000VA when operating.Hot Water:
- We have a heat-pump water heater that only draws 600W when running. It is also 240VAC, but I do not have it set up to run from 120VAC through an autotransformer since we sometimes (but rarely) use the 4.5kW resistive heaters. I have a couple of autotransformers kicking around here, so I certainly could wire it for 120V if needed.Dryer:
- We have BOTH a propane dryer AND an electric dryer. We used to use propane when the house was off-grid, but I switched it for an electric unit when we decided to move to a grid-tied arrangement. The propane unit could be switched in if needed for emergencies (or we could simply hang the clothes to dry).Electricity:
- Our house is powered by grid electricity with just over 100% of our consumption offset by net-metered, grid-tied PV.
- We have a 6500VA Honda generator which is connected to run everything except our heat pump and our electric double oven. It can simultaneously run the wood pellet stove, the well pump, the water heater and charge the LEAF.
- We have 800Ah (nameplate) of 12V AGM batteries. I got them for free because they were badly sulfated down to only 200Ah of capacity. My little BatteryMinder 1500 is dutifully pounding away on them to try to recover their capacity. Last time I tested them, they were up to 300Ah! Since there's no hurry, I just let that thing continue to do its work of recovering capacity.
- To go with the 12V batteries, we have a 2000VA Outback inverter that puts out 120VAC. This should be able to run any of the loads which the generator is connected to, although I have not tested it with the surges of the well pump or water heater yet. The most important load for these batteries is the pellet stove, which it should be able to run for a day with the current capacity of the batteries or three days if they ever get fully desulfated.
- In a pinch, I could rewire one or more PV panels to charge the 12V batteries.
- Then there is the LEAF. I have a couple of 120VAC inverters which work with it. Since there is a fridge and deep freeze in the garage, those are its primary loads, but I have used it to run the pellet stove in the past, since it is easy to set up.
Overall, we are set up to provide the essentials and more in case of an emergency.