Let’s look at the figures…
A good quality solar panel in 2021 will be approximately 20.5% efficient. (20.5% x 1000W/m2 = 205W).
A property in the South East with a South facing 40-degree sloping roof will receive approximately 1132 W/m2 per year.
Using the standard MCS performance calculation with 0 shade, each square meter will generate 232 kWh. 205W x 1132W = 232,000W = 232 kWh.
An average home in the UK uses 3650 kWh per year, therefore we need just 15.7 m2 of roof space (plus clearance) to generate the equivalent electricity an average home uses per year.
One of our customer’s in Devon is able to generate 21% more energy than they consume
*Since this article was published in 2021, this customer has installed a heat pump and an additional solar array - after powering and heating the house and charging the car - his yearlly electricity bill is now negative in 2023.
Imagine heating your home, charging your car and powering your house whilst having a negative electricity bill. Solar panels can definitely power a home in the UK. In 6 years, it would have paid for itself, it will go on producing more power than he uses for 30+ years.
Despite not having a South-facing roof and with shading from nearby trees.
This customer has installed enough battery capacity that they can store and use the excess electricity at night throughout most of the year.
They will not need the grid between March and October!
A good rule of thumb is that a South-facing roof will receive 15% more irradiation than an East or West facing roof.
You don’t need a South facing or unshaded roof.
It is arguably better to have an East and West facing roof so you can install twice the capacity. Or enough space that the optimum orientation is less important.
Not everyone is suitable for solar panels. If you do not use much electricity (less than £50 per month) then the financial payback may not be worth it.
If you use more than this, or your electricity usage is increasing - generating your own electricity would be a good option.