Solar doesn’t need bright sunlight to operate the worlds solar leader is Germany which has a similar climate to the UK
Importance of performance
A funny thing called kWp’s explained
Every PV array is rated in peak watts (Wp). This effectively allows you the consumer to compare the performance that you can expect from each manufacturer’s solar panels. You could say it’s similar to looking at the horsepower rating of a car in that they both give you a basis for understanding the amount of power that can be produced under ideal conditions.
The peak watts (Wp) of each manufacturer’s solar panel are determined by measuring the voltage output of each panel under specific laboratory conditions whilst varying the climate and radiation it receives. The maximum power measured is the nominal power of the module known as the “Wp”.
So you have an array of panels that will typically be rated anywhere between 185Wp-245Wp, times that Wp by the number of panels you get installed on your roof-top. For example 16 × 245Wp modules would make an array rated at 3.92 kWp
To translate this slightly non-telling Wp number into a language that matters (how much electricity can you expect your system to produce year on year) we use the governments complicated but remarkably effective, SAP (Standard Assessment Procedure) calculator. The SAP provides a calculated estimate for how much electricity will be produced per kWp taking into account everything from pitch and orientation losses, shading, local irradiance and general system losses. As a whole the SAP calculator is quite pessimistic so you shouldn’t be disappointed by the actual generation of your system!
How your Feed-in Tariff income is calculated
Once you know the size of your solar system (as explained above) you can establish which feed-in tariff rate you will be eligible to receive. We calculate how much you could expect to earn annually from your installation by multiplying the appropriate feed-in tariff rate by your generation predictions.
Note that the savings you’ll make in your energy bill will not be added to the calculation on your returns.
The annual feed-in tariff income that you can expect to receive from your solar system will be included in your quote and will depend on the orientation of your roof, shading and the size of system that you install.
The Energy Savings Trust has a really useful cashback calculator tool which can help you suss out what you could expect in terms of income and electricity from a solar system. We will provide a more accurate calculation in your quote.
