There are 6 key factors that influence this:
1) Location – Where your house is located will determine both the intensity and number of hours of sunshine your roof will receive. This is known as “solar irradiation”.
2) Orientation – Your roof orientation has a big impact on the number of hours of direct sunlight it receives. A roof facing South will yield the best overall performance, but installations facing anywhere to the South-East and South-West are also feasible. Installations using panels facing East and West are also possible. North-facing installations are not recommended.
3) Roof Pitch – You can’t change the pitch of your roof, but the optimum angle for achieving the maximum yield from your solar installation is between 30° and 40°, depending on your location.
4) Shade - Any shade will reduce the overall performance of a solar array. Whilst shading cannot always be avoided, the solar panels should not be shaded between 10am and 4pm. Your installer should assess the estimated impact of obstacles like chimneys, aerials, satellite dishes, dormer windows etc in their survey.
5) Size of Your Roof – Quite simply, the number of solar panels you have installed will determine how much electricity you can generate.
6) Product Choice – Solar panels are not that different to many other products like a TV or mobile phone, where we decide how much we want to pay in return for the number and quality of features we want. Different brands of solar panel will generate different amounts of electricity, plus panels and the inverters will vary in how efficient they are in converting the daylight that hits the panels into electricity for your home.