When you go from using grid electricity to having to be independent or make sure there’s enough juice by yourself, the reality of the problem can quickly set in. No one ever really thinks about the actual wattage that they suck down every month, unless it’s about the actual bill. Now with the installation of solar power, you have to figure out how much power is enough power for your life to go on uninterrupted.

If you come up short on a grid-independent system, the consequences are basically some flat batteries and not enough power to serve your needs. If your system is tied into the grid, it means that you’ll end up still paying for grid power, which is fine if you just want to reduce your overall bill, but does defeat the point somewhat.

That means you need to have some sort of way to size your system in such a way that you don’t end up short of power, but don’t pay for capacity that you don’t really need.

Two Approaches

Broadly, there are two ways you can look at determining how much power you actually need. The first and most conventional is to take your power bills for the last year and look at the amount of power the utility company says you needed over that time. Obviously, there are seasonal differences in power needs, so you have to take peak demand into account as well. Then buy enough solar and battery capacity to cover your needs.

Alternatively, if you are using a grid-tied system you can just take the raw average power you use per day and match your solar power to that. If you are using battery backup and are tied into the grid, then the grid will take care of peak needs and the batteries will ensure you don’t waste solar power that you don’t need right away.

The other way you can look at it is as a project where you also reduce the amount of power that you use. You could switch your heating and cooking energy source to gas. You can also change your appliances to more energy-efficient versions. Be sure to check out my article on choosing solar-friendly products. Overall, this is the most cost-effective option, although replacing your most energy-hungry appliances all at once could be a sizable upfront outlay.

solar needs

Figuring Out Your Cap

One of the most important things you need to know is how much solar power you have space for in principle. If your solar installation is going to be roof-mounted, you’ll tend to have less maximum capacity. If you can do a ground installation, you’ll probably have a bit more space.

Either way, measure the amount of space you have for panels and then figure out how much power you could generate if you filled it all. This is not how much you need to buy! This is just how much you could have if money were no object and you were limited only by space. Now when you look at your energy consumption needs, you’ll have a frame of reference to know how realistic it is. If your current energy usage is more than you could theoretically install in terms of solar energy, then you know the only option is to rethink your usage patterns or live with partial grid dependence.

Figuring Out How Much Sun You Can Get

While you may have a panel that can, for example, generate 200W, that doesn’t mean you’ll get that out. If the quality of the sunlight that falls on the panel isn’t enough for that power level, you’re out of luck.

The quality of solar radiation per square meter is referred to as solar insolation. This will tell you how much solar radiation falls on the Earth. You can search the web for a solar insolation map to figure out what quality of sunshine you get. This will help determine how much power you can actually get from your panels, notwithstanding what they are rated for.

Professional Help

This information will give you a general idea of how much solar power you will need, but it’s very important that you get a professional to actually do an assessment and give you a quotation. There are many factors involved, and a solar power company that works where you live will have a lot of experience with the local climate and solar conditions. You can discuss how you would like to approach the problem of carrying your energy needs on a solar platform.