With the current soaring costs of energy and the Government’s goal to be carbon neutral as a nation by 2050, there is a real focus on sustainable energy production both to reduce CO2 emissions and also energy costs. One technology that can provide a solution to both issues is Solar Panels, or as they are properly known. photovoltaic cells. The question a lot of people have is are they suitable for their homes and are they worth the relatively large financial outlay? In this article we explore solar panels to help you to decide if they are right for you and your property.
What are solar panels?
Solar panels are panels which are almost predominately (95% of solar panels) mono- or polycrystalline silicon. This material absorbs the electromagnetic radiation from the sun and converts it into electricity. Put simply, the sun shines on them and they convert this sunlight into electricity which can be used in your home.
Are they efficient?
The answer is actually no, not really but that doesn’t really matter in the grand scheme. Typically, a solar panel will only convert 15-20% of the sun’s energy into electricity at best and this is reduced depending on how and where they are installed. What matters, in reality, is whether they can generate enough electricity to power your home. The answer to that depends on how many solar panels you install and the orientation and pitch of your roof.
How can they save money?
Solar panels will save you money in two ways:
- “free” electricity. Once you have paid for the panels, assuming the system is sized right, your electricity is essentially free or at the worst there is a significant reduction. On average the savings are £330 per year
- Any spare electricity can be pumped back into the grid for which electricity suppliers will pay you relatively small amounts, this can be down as low as 1.5p per kilowatt hour. The best rate currently is 7.5p/kWh and the average property can generate a further £112 per year in income.
What are the installation restrictions?
First let’s cover planning. For the most part, solar panels are considered a permitted development and do not need planning permission unless the property is listed or is in a conservation area.
The pitch and orientation of your roof is also important!
In terms of pitch there is a sweet spot at 30 – 40° from horizontal. Anything over that, i.e. steeper roofs will see a loss of efficiency. For roofs which are less steep, i.e. tending towards horizontal, the efficiency doesn’t drop off as much but the panels lose their ability to self-clean and so lose some efficiency.
The orientation of your roof is important and the further it is from due South the less efficient the panels will be, due East and Due West, for example will lose about 18% efficiency if they are at the right roof pitch of 30-40°.
Your roof should ideally not be shaded at any stage so it gets full sunlight all day. If you have trees or other houses which shade your property during the day, then the panels will absorb less sunlight.
The structure of your roof is also important. Solar panels are not weightless and your roof structure will need to be assessed to ensure it is capable of taking the extra load. Modern houses are likely to be OK, but older houses might need bracing. Added to this, the material from which your roof is made could make a difference too. For example, thatched roofs are not suitable for solar panels at all.
Finally, the available space on your roof is important and how much space you need depends on the amount of electricity you want to generate, but for a 4kW system you would need something like 30m2 of roof space and for a 2.5kW system you would need just over 19m2
How much do the panels cost?
This again depends on the size of the system, but for a 3kW system you can expect to pay around £5,000 – £6,000 and for a 5kW system you could pay £7,000 – £9,000. If you want to be able to store electricity so that there is supply for when the sun goes down, a battery is needed and this would typically cost around £3,400 to nearly £6,000 depending on the battery size.
How long till the initial investment pays back?
Due to the high upfront costs and relatively low annual savings/revenue, typical systems take anywhere from 13 – 24 years to pay for themselves depending on the price of electricity and the size of the system.
It is clear that solar panels are rather expensive to install and that the payback periods can be quite long, even longer for systems that are poorly oriented. Installing solar panels certainly makes sense if you plan to stay in your property for at least 10 years and you have the spare cash to pay for the installation. If you are planning on moving anytime soon, i.e. anytime in the next 10 years, then the installation probably doesn’t make a lot of sense, financially at least. What it will do, however, is raise your green credentials considerably and significantly reduce your carbon footprint.
