Does your house have a sunny roof? If so, have you thought about installing solar panels? You can save on energy bills, cut your carbon footprint, and put a smile on your face every time the sun comes out!
There’s two types of solar panels:
- Some produce hot water – known as solar thermal panels
- Others generate electricity– known as photovoltaic or ‘PV’ panels
Solar thermal systems usually consist of a series of tubes on the roof through which fluid circulates and heats up your hot water cylinder. Typically, they cost between £3000 and £5000 to install and will provide free hot water for most households for 9-10 months of the year.
With costs of PV panels falling, solar thermal systems are now being superceded – except for homes with a particularly large hot water need, like those with swimming pools. Solar PV is a more practical solution in most situations as it not only provides electricity but can also heat hot water via a cylinder’s immersion heater – known as a solar diverter.
A PV panel consists of cells made from layers of semi-conducting material, usually silicon. When light shines on it, a flow of electricity is created. Typical systems contain around 10-15 panels and generate direct current (DC) electricity. Because the electricity used for household appliances is alternating current (AC), an ‘inverter’ is installed to convert DC electricity to AC. This can then be used throughout your home, or exported to the grid.
Economics of solar PV
The price of PV panels has fallen dramatically in the last decade. A 3 kilowattt (kW) system that would have cost £12,000 ten years ago, can now be bought for under £5000. This has transformed the economics. At one time the government provided incentives to encourage uptake of PV panels via the so-called ‘Feed In Tariff’. This was steadily reduced over the years and in 2019 ended entirely.
The main financial benefit from PV panels comes from the fact that they replace electricity you would otherwise need to buy from the grid, which under the new price cap now costs around 34p per kilowatt hour (kWh). This generates significant savings over the year.
A secondary benefit is the income you can earn by exporting excess power to the grid, to be used by somebody else. You can now be paid for this via the Smart Export Guarantee (SEG) mechanism, which is arranged through your electricity supplier. Rates vary but are typically between 3 and 7p per kWh – so it’s worth shopping around.
The precise economics depend on local factors like the angle and orientation of your roof and the degree of shading, and also your electricity usage pattern. The Energy Saving Trust have an online calculator that helps you work out expected returns and carbon savings.
With the prices falling, battery storage is also becoming a much more attractive option. This allows you to store surplus energy generated during the day and use it in the evening. That way you can use much more of the free solar power you produce and cut your electricity bills even further. Costs vary depending on the capacity and type the battery but typically range between £1,200 and £6,000. Bear in mind that a battery’s lifespan is shorter, so it may have to be replaced more than once over the lifetime of your solar panels. So make sure you check the warrenty before buying.
Solar EV charging
PV panels can be combined neatly with electric vehicle charging using intelligent charging units such as the Zappi. These can be set to charge up your EV only when there is excess solar power available. That way you can have the satisfaction of knowing you are running your car on 100% renewable home made energy!
Factors to consider
Saving carbon: Installing PV panels will make a significant dent in your carbon emissions. A typical system will save 650-1,000 kg of CO2e per year – which is 20-25% of a typical homes carbon footprint due to heating and power use.
Lifestyle: An important financial issue to consider when installing solar PV is your lifestyle. If you’re out of the home most of the day, then you will have limited use of the benefits as the bulk of the power generated would go directly to the grid unless you set up timers to run your appliances during the day. However, if you’re at home during the day then you can get best use of the power to run appliances such as dishwasher, tumble dryer washing machine and oven etc.
Orientation of your roof: An unshaded south-facing roof will generate the maximum amount of solar power in a day, but east and west-facing roofs can also work well – particularly as mornings and evening are often the times of peak electricity use.
Hot water: If you have a hot water cylinder with an immersion heater then you can install a solar diverter that will send surplus energy to heat hot water for about 9-10 months per year.
Quality: You also need to keep in mind that there are a lot of solar panels on the market with varying quality and warranties. It’s a bit like buying a car. You could go for a cheap basic model such as a Dacia or something posher like a BMW or Mercedes. The cheapest may not be the best as they are less efficient and won’t produce the same amount of kWh over their 25 plus year lifespan. Most of the costs are fixed regardless of the brand of panels. Labour, scaffolding, fixings etc. take up the biggest part of the cost. The actual cost of the panel & inverter is a smaller part of the equation so it can be worthwhile upgrading for a small extra cost.
Getting a grant: If you have a low household income or are on certain benefits you may be able to get a grant to cover the cost of your panels. Check out our Guide to Home Energy Grants.
Finding an installer: For suggestions on local installers, check out our page on Getting Professional Help.
Solar Together Scheme: this is a group buying scheme backed by West Sussex County Council that offers benefits of economies of scale and strength in numbers. Find out more here.
GreenMatch have published a series of helpful YouTube videos on: