SOLAR PV PANELS
Installing solar PV panels is a brilliant way of using the sun’s energy to generate electricity for your home. David Hilton explains everything you need to know
Generating electricity from the sun, solar PV (photovoltaic) panels are a great eco-friendly addition to any home, but there are several considerations to be made before you commit.
Solar PV panels contain silicon cells that are fused with a tiny amount of chemicals. Silicon is the main component of sand and is the second most abundant product in the world, but converting the ‘sand’ into usable PV cells uses a lot of energy. When the sunlight hits the cells they create an electric current. By stringing lots of cells together the electric current is increased. A typical solar PV panel will have around 60 cells and modern panels will be able to generate around 320 Watts in strong sunlight.
DO I NEED PLANNING PERMISSION?
Installation usually falls under Permitted Development (PD) but always check as different rules apply if you’re in a conservation area, for example, and PD doesn’t cover the elevation of the property that faces the road.
HOW MUCH DOES IT COST?
A typical 4kwp solar PV system will cost between £5,500 and £9,000 for an on-roof system. Allow an additional £600-£1,000 to replace the inverter unit after 10+ years.
Any additional framework will carry additional cost. Integrated panels such as those that look like slates or tiles, or those that are bedded into the roof to replace the roof cladding, will also have additional costs and range in price between £9,000 and £15,000.
HOW MUCH MONEY WILL I SAVE ON MY ELECTRICITY BILL?
The amount of money that you will save on your electricity bill will depend on how much of the generation you actually use.
If you are not at home most days then the solar PV generation will only power the fridge and any other electrical appliances that happen to be running during the daylight hours (unless you introduce solar battery storage).
Payback on a PV system is still on average 10 years+ but as electricity costs escalate and we move to electric vehicles the potential to use more of the summer solar generation could result in much shorter payback periods.
WHERE SHOULD I PLACE THEM?
Solar PV panels are typically installed on a pitched roof in a southerly direction (or on a pitched frame on a flat roof ). Panels can also be installed on outbuildings or on purpose-built frames in a paddock or large garden. There are some frames that can also
move to track the sun and optimise the generation.
Integrated solar PV panels, often referred to as building integrated photovoltaics (BIPV), are panels that replace the cladding and become part of the roof.
A typical solar PV panel measures around 1m x 1.6m and will generate between 250 and 350W depending on the panel. A typical solar array (a few panels together) will have a peak output of around 4kwp so you would expect an array to typically have between 12 and 16 panels. Any installation on the roof cannot protrude more than 150mm above the plane of the roof and cannot protrude at all above the highest part of the roof (usually regarded as the ridge, not the chimney).
HOW MUCH ELECTRICITY IS GENERATED?
Depending on where you are in the UK the generation output from a PV array will be different. As an example, if we look at London we would expect an unshaded 4kwp system to generate around 4,000kwh (units of electricity) per year but in Edinburgh this figure would drop to around 3,400kwh per year.
AND WHAT ABOUT MAINTENANCE?
The maintenance requirements for solar PV panels are minimal. Usually it is simple visual checks to make sure that the panels are clean and that there are no signs of wear and tear; you’ll also need to carry out a periodic inspection of the wiring. If you have a generation app, then it is also easy to track the generation so that you can be aware of any changes that may be caused by deterioration in the system.