Home Backup Power Systems

[Larry Caldwell]

I have leaned heavily on technology that does not require electricity. The wood stove provides heat in winter outages and low head water allows flushing and cooking without electricity. I installed a 60 amp transfer switch to power the water heater and well pump for showers, plus refrigerator and freezer. The generator is a 6500w propane electric start. A top of the line lithium battery UPS will keep the modem and router up for at least 12 hours between generator runs.

I have spent far more on energy efficiency than on backup power. New doors and windows, plus Hunter-Douglas fitted cellular blinds for the windows, roll-up awning for a full glass double door on the south side to cut summer heat and allow winter solar gain. Insulated the attic, subfloor, plumbing, and ductwork.

We have a mild climate. Average winter nighttime heating is only 40 degrees, often only 30 degrees. Maximum summer cooling is only 30 degrees, and the heat pump doesn't kick on until 3:30 PM on the hottest days, 6 PM if it only gets to 90. We could be fairly comfortable without AC. If I lived in a more severe climate, I would make very different decisions. Thanks to geology, I have a poor site for solar, though I do have a couple acres of 100% slope south facing bare rock a couple hundred yards from the house.

My choices are also a lifestyle decision. The silence of a winter outage is glorious. The last thing I want is to listen to the sound of a generator, so I try to minimize runtime as much as possible. Before I bought the UPS I used a little ultra-muffled 1000w camp generator to keep the electronics up. It wasn't too obnoxious on the other end of a 100' extension cord. If you are beset by neighbor noise, silence might not even be a consideration for you.

 

[dmccarty]

I have been around and around and around on this issue.

So to skip to what I would do today, go to the last two paragraphs. The rest of this long post is how I got to the last two paragraphs.

When we first bought the land, well before we owned land, I thought that having a passive solar home with solar panels was they thing to do. When we designed our house, it was sited to maximize solar power and passive solar heat gain.

The problem back then was the limitations with lead acid batteries. I had kept up with solar power technology for decades, and maybe 20 years ago, went to a class taught by a local developer who built a quite a few homes with solar power. Lead acid batteries were a limitation but also the NC system for paying for surplus power production. Basically, back then, and now, it is not worth over producing power to sell to the grid. Just not worth it.

I have recorded every power build we have had since we moved into the house two decades ago. Our power bill has gone from 8 cents to a maximum of 18 cents per kilowatt hour. This includes the cost of power, taxes and fees. The highest payment was 18 cents but that was a one off when we built the house, and the recent cost has been 16/17 cents a kilowatt hour. That is a long winded way of saying saying our cost for power has gone up very little, compared to how much money we can make in the stock market. I could never justify spending money on a solar power system.

In the class I took, we lost quite a few "students" when they found out that they could not just put up some solar panels and have power during a power outage. They just got up and left. The solar panel and inverter costs are only part of a back up solution since one needs batteries. Lead acid batteries were just really expensive back then, and even today, but there are better solutions now.

While all of this was going on the with the house, we became interesting in buying a boat and seeing the world. Solar power production and energy storage is a much bigger problem/solution on boats than in houses. LiFePo batteries have greatly changed boating. Simply a game changer. If we build a boat, it would have 7,000+ watts of solar power, at least 25kwh of battery storage, and maybe around 100kwh and hybrid propulsion.

I have not looked at the power wall solutions in years. What turned me off to them was they were Lithium batteries and one could not charge with a generator. That is absurd. There are many Lithium battery chemistries but the safest is LiFePo. I would not use any battery chemistry in a house or boat other than LiFePo.

Over the years, even though we are rural, we have only lost power for more than 12-25 hours 2-3 times. It has been a PITA for sure, but money wise, it does not make sense to spend tens of thousands of dollars to provide power for a few day of outages. Part of our power backup system is a wood stove which easily heats the house. When I had time to make firewood, we heated the house full time with the wood stove. I plan to get back to heating the house with the wood stove. We really miss it and forgot how well it worked. We started the wood stove for the first time in years this month and we had forgotten how well it heated the house. <sigh>

Today, if I was going to put in a back up power system, I would buy Victron inverter/chargers and LiFePo batteries. Victron equipment is used in RV, boats, and homes to provide power and they have a well integrated system to do so. Having the batteries charged by the grid, solar, or generators is what Victron equipment is setup to do and does world wide on boats, houses and RVs. No need to be limited by the power wall companies. LiFePo batteries are not 100% safe but they are the best that is out there right now. They can still produce explosive gases if over charged but nothing like other Lithium battery chemistry. Having said that, I would put the batteries in their own enclosure away from the house. No way am I hanging a power wall with Lithium batteries on the house. Not happening.

With Victron, and there are similar companies out there, one can charge the batteries with the grid, a generator, solar, or even wind. Since our power outages are mostly 12 hours or so, we could build a battery system that could easily provide power for these shorter time frame outages, but we could also simply add more batteries to provide power for longer periods of time. Just a question of money.

 

[orezok]

When I built my system here in the desert, it was the most efficient both production and cost effective. It’s a ground mount system that I installed myself. I’m a GC so no issue. We have a 2450SF all electric house. Annually (2025) my 7530 watt solar system produced 15.4 kW in ‘25 and I consumed 17.1 kW for the year. My annual settle up with SCE has been $1200 for the last 2 years. $100 a month is hard to beat. It’s necessary when summer temps go above 115º. I looked at batteries which are very expensive, the ROI would never make sense at $100 a month electric cost.

We did install a 22kW Generac for the longer term outages as we are old and don’t tolerate excessive summer heat without AC.

 

[ultrarunner]

I’ve seen some expat off grid million dollar properties on 40 acres or so…

The only monthly house expense is satellite internet…

Those that have designed their systems are very pleased…

I confess that for a long time I would check my surplus solar generation from the day before… it was rare for me not to have a slight surplus from my 6kW ground mount and every year at true up I receive a few hundred which easily covered the $15 monthly meter fee…

I expect this to change under the equity legislation where solar producers will have much higher monthly fee plus for new producers almost no buyback income…

 

[hayden]

Today, if I was going to put in a back up power system, I would buy Victron inverter/chargers and LiFePo batteries. Victron equipment is used in RV, boats, and homes to provide power and they have a well integrated system to do so. Having the batteries charged by the grid, solar, or generators is what Victron equipment is setup to do and does world wide on boats, houses and RVs. No need to be limited by the power wall companies. LiFePo batteries are not 100% safe but they are the best that is out there right now. They can still produce explosive gases if over charged but nothing like other Lithium battery chemistry. Having said that, I would put the batteries in their own enclosure away from the house. No way am I hanging a power wall with Lithium batteries on the house. Not happening.

With Victron, and there are similar companies out there, one can charge the batteries with the grid, a generator, solar, or even wind. Since our power outages are mostly 12 hours or so, we could build a battery system that could easily provide power for these shorter time frame outages, but we could also simply add more batteries to provide power for longer periods of time. Just a question of money.

This is how my off-grid house is powered, with solar as the primary power source, and backup diesel generator. I have only 30 hrs on the generator so far this winter, and it never runs spring, summer, and fall.