Solar Power (Math, Yay!)

Deciding how to power our cabin has been on our minds lately. When deciding where to place our cabin, we had to take into consideration the placement of our solar panels as well.

I created a spreadsheet to try and determine how much power our appliances and such would take.

My Solar Needs Calculator

After calculating our usage, I found an online solar calculator to determine how many panels would be needed. I am not sure I agree with them, as it seems this would be only if we are using everything at once. Which would never happen.

Offgrid Solar Calculator

Solar Calculator

63 panels at 200 watts each is a lot of panels and A LOT of money. We have a place where we can buy solar panels that average about $1 per watt. That works up to $12, 600!!! Yeah, not going to happen. I tried a couple of different options for calculators and each gave me pretty much the same answer. I am still not sure I believe them.

Despite these calculators, I think we could get away with less than 5000 watts. The largest usage item we probably own is our toaster (1800 watts according to the owner’s manual). I think we may just do without a toaster anyway, so then it is a mute point. If you limit yourself to only using a few items at a time, or one depending on wattage requirements, I think you could get away with far less.

Our neighbor powers his travel trailer lights, television, fridge and water pump. He currently has only 560 watts at 48 volts going through an inverter to 120 volts. They use propane for the stove and water heater.

Anyone have any better ideas, thoughts, insights? Post in comments below. 🙂


8 thoughts on “Solar Power (Math, Yay!)

  1. Off-grid calculations are about watts x time – how many watts used for how many hours or minutes a day. A 100 watt bulb left on for 10 hours would equal 1 kwh, kilowatt-hour per DAY. Since the sun is producing at its peak at about 6 or 7 hours a day a 200 watt panel would keep this light lit. You must also include power needed to recharge the battery bank (for power at night) while the appliances are running.

    Liked by 1 person

    1. depends on their energy usage and if they are plugged into local energy company. We were looking at I think 20 panels to power our house because we were legally not allowed to produce more than our base usage for the year, and we had gas heat and clothes dryer. I really am not to confident in the calculators. Seems like you would only need that many if you plan to operate every piece of equipment at the same time.


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