How we're handling offgrid/backup power needs

Off grid power

We primarily live on grid. However, I wanted to design a system that would allow me to provide power to a large shed, run power tools, and provide a backup power system that, during an outage, would provide basic power needs and in a pinch provide whole house power. The design is primarily solar, with generators providing supplemental power when needed.

Solar system

I found someone selling used 250watt panels on craigs list for 100$ per panel. These panels were two years old, and had been removed from an install gone bad; the installer damaged the roof they went on, and were removed as part of the settlement. Panels have an extremely long life span, and are expected to produce at least 80% of their rated power 30 years from now. So, I don’t have a problem buying “used” panels as long as they are not damaged. I purchased 10 of them, and they are mounted to the roof of the shed. The panels are setup in two arrays, each providing solar energy to two 80 amp outback charge controllers. The charge controllers charge a battery array of 12 trojan batteries in a 12v setup. There are two 2k watt inverter/chargers. The inverter/chargers were chosen because they provide pure sine power and give me the ability to use a generator to top off the batteries when the solar array can’t keep up with the demand on the system during cloudy periods. All that is necessary is to run a generator and plug it directly into the inverter/charger. We can top off the batteries in a few hours. The 2500 watt system won’t run the gas heater or AC, but it will make life much more comfortable long term. It would be impossible for us to store enough fuel to run the whole house generator for a year. I chose to stick with a 12v system, which is not as efficient as 24 or 48v systems, because so many of our systems use 12v. Commo gear, on demand water pumps and other equipment can run directly off the battery array. At some point I may go with a hybrid system, leveraging the efficiencies of 24 or 48v. Generators

I have a 5k watt and 2k watt honda generator. Both are setup with tri-fuel adapters, which allow me to run them on gasoline, propane or Nat Gas(our house uses nat gas appliances). The workhorse generator is the little 2k honda, it’s quiet and efficient, using 1 gallon of fuel every 5ish hours. We use the little honda to top off the array during cloudy periods. Because the inverters have a charging capability(30amps), all that is necessary to top off the batteries is to run the honda for 2-3 hours a day. During that time, we’ll also charge up two dewalt power stations, run a well pump to move water to storage tanks, run a chest freezer. The 5k watt generator is used if we need whole house power and or run high draw equipment like welding equipment. Should we have an outage of significant duration, we’ll use hookups to the house nat gas lines to power either generator. There are multiple reasons for doing so, 1, nat gas is going to last for a while during a shtf event, it will be one of the last utilities to go offline. 2, it prevents us from tapping into our stores of gasoline and propane. At the point where Nat gas is no longer an option, we’ll switch to one of 4 100lb propane bottles to power the generators. Once those are exhausted, we have a number of 20lb tanks we can use. Because we only need to run the generators a few hours a day when the solar system can’t keep up, I expect that we’ve covered our power needs for several years. Additionally, the propane and nat gas access give us the ability to run big buddy heaters for additional heat if required. We also have two dewalt 1800 watt power stations. These leverage all off the cordless tool batteries that we have available for our power tools. The power station gives you the ability to charge 6 dewalt batteries at once as well as the ability to use the power station to provide quiet power to any location. What can they power? they give us the ability to run lights, fans, refrigeration, in an enclosed environment silently. They are highly portable and can be used inside the house. If need be, we could charge them while the gensets are running and then go quiet, running lights and running/recharging commo gear as needed. The 1800 watt inverter has been helpful on construction projects and in places on the property where it’s not convenient to get power to.