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What if I need more electricity than I can generate with solar power?

In the case of a microFIT system like ours, this is not a problem, because you are still connected to the public power grid. You can always get more power from the grid if you need it.

In fact, the grid acts kind of like a giant battery. On a sunny day, while the sun is shining you will often produce more power than you would use. That power gets sent to the grid. Later, when you need to use power and the sun isn’t shining, you can get energy back from the grid.

We have graphs that show our export and import of electricity for each day and month. The export/import situation is changing all the time, since the amount of sunlight varies all day, and our use of electricity also varies. So at one moment we might be using all the solar power plus some grid power, and ten minutes later we might be exporting solar power to the grid.

In a solar power system that is not tied to the grid, you need to do some careful analysis of your base load and peak load requirements (the ongoing minimum amount of power you need, and the maximum power you need at any one moment). You need to make sure you design a battery system that can meet that need, and you need to install an array of panels that will generate enough power to keep the batteries charged.

To determine that, one key thing you need to know is the amount of sunlight you’re likely to get in your area. In southern Ontario, we get enough for an unshaded system, that faces mostly south, to produce at least three times its nameplate capacity (ie: the manufacturer’s rating its for maximum output). So a south-facing array rated for 5,000 watts should produce a daily average of at least 15,000 watt hours of electricity per day, as long as it’s not shaded for any part of the day.