As you can see in the table above, different parts of the world get vastly different amounts of solar energy. If you're closer to one of the poles, you'll get a lot less sunlight (none in some cases as I learnt when I spent s. Solar panels are typically marketed with a “watt peak” number. This is the amount they should produce in ideal conditions. Our calculator is based on one of the most efficient solar panels on the market, a 540wp model fro. Solar panels work best when they are directly facing the sun. Unless you have a solar tracker installed (which in most cases isn't worth the extra cost), then the fixed angle they should be installed at depends on your location. The orientation of your roof (or wherever the panels are installed) makes a large difference. In the northern hemisphere, it's typically best to have south facing panels. During winter there is a lot less total sunlight, and it's more likely to be cloudy on top of that. Our calculator gives you an average for the whole year and also a breakdown month by month in your location.