There are a lot of factors that go into figuring out the total number of Solar Panels that your tiny house needs. The size of the house, the number, sizes, and types of appliances you will have, the number of people living in the home, and the location where your tiny home will be built or parked most of the time. A single person who builds their home in Southern California, and who doesn’t include things like a dishwasher or washing machine, will need much less power than a family of 4, who have all standard appliances, and who live in Seattle.
The first step is to figure out what appliances will be running off of the solar panels, and the typical energy draw in kilowatt-hours of each appliance, including air conditioner. These can all be looked up on the manufacturer’s website, or you can make an estimate based on the size of the appliance, and the number of hours per day that you typically use it. For example, and 18 cubic foot refrigerator typically requires about 189 kWh per month, or about 6.3 kWh per day. Don’t forget to include appliances like your water heater, stove/oven, and washing machine! These can be huge contributors to your electricity usage, but they’re often overlooked.
Once you’ve calculated the energy draw of your appliances, you need to figure out The approximate electricity usage of your lights and minor appliances. Lights includes overhead lighting, lamps, and even nightlighta, while your minor appliances include microwaves, TVs, gaming consoles, toasters, coffee makers, and vacuum cleaners. You will need to know how much time you spend each day using your lights and each small appliance. You can again find the average electricity draw of these items online, so just remember to adjust for your usage, and make sure you know how many kWh per day, rather than per month. Once you add up the energy usage for your large and small appliances, and your lighting, you should have a good estimate of your household’s daily electricity usage.
Now that you know how much electricity you need each day, it’s fairly straightforward to find out how many solar panels you’re likely to need. The average single solar panel will provide about 250 watts/hour during peak sun exposure, or about 0.25kWh/hour. For comparison, the fridge mentioned above would require about 0.26kWh per hour. It’s likely safest to assume that you will only get about 75% efficiency from your solar panels, and they will only produce electricity for about 12 hours per day. This will go up if you live closer to the equator, and down the further away you get. Based on the averages, a tiny house with 7 solar panels will generate about 15.75kWh per day. While this certainly won’t support central A/C or heat, it may allow for most other appliances, especially if a tankless water heater is used.