A guide to solar energy

With many consumers on the hunt for ways to save energy, live more sustainably and save money, solar energy is a natural solution. The sun is a renewable power source, one which can be used to provide electricity and hot water within the home. Here’s a look at the ins and outs of solar panels.

What is solar energy?

Solar harnesses energy from sunlight. Solar cells convert light into electricity with the use of semi-conductive cells and silicon. Panels are placed on a property’s roof, soaking in light and triggering the electrons to generate energy. A circuit is created with the addition of metal contacts. The electricity generated by this type of circuit is DC, which must be converted to AC via an inverter. Direct sunlight isn’t necessary, which makes solar panels an option even in areas prone to grey weather like the UK.

Over the last decade, there have been developments in solar technology to store solar power within storage batteries, which is useful for darker days with reduced sunlight.

Types of solar energy panels

There are two main types of solar energy panels to choose from: photovoltaic (PV) panels and solar thermal (water heating) systems. Both types of panels are fitted to the roof and look quite similar at first glance, but they are used for quite different purposes.

Solar photovoltaic panels

Solar PV panels are formed from solar cells with layers of silicon crystal, which have been treated with a conducting material. When daylight hits the top layer of the panel, excited electrons move and create electricity. This can then be used either for your household’s energy needs or exported to the national grid system.

If you’re interested in installing this type of system, here are a few factors to consider.

• There are several types of PV solar cells on the market, which can vary in terms of efficiency and cost.
• Hybrid systems are the most efficient, combining silicon with crystalline cells.
• There are also solar slates or tiles, which are installed in an overlapping pattern to resemble roof tiles. This allows them to blend into the existing aesthetic of your home, but solar tile systems can easily cost twice as much as a PV panel system.
• You should also consider whether or not your home is suitable for installation.
• Solar PV panels work best on south-facing roofs in the UK, though they can also be installed on east or west-facing properties at slightly reduced efficiency levels.
• Roofs will ideally have a 30-40 degree pitch.
• You’ll need loft space for the system’s inverter.
• Your roof must be strong enough to support these panels.

Solar thermal panels

The second type of solar energy is solar water heating or thermal panels. These can be used on their own or alongside solar PV, as the rooftop systems are fairly compact. You can choose from evacuated tubes or flat plate panels. Evacuated tube systems are slightly more efficient, taking up less space while generating an equal volume of hot water as flat plates.

Installation requirements are similar for both PV and solar thermal panels.

• To install a solar water heating system, look for products certified by the Microgeneration Certification Scheme.
• You’ll also need to find a certified professional to handle the installation.

Are there incentives to solar energy?

In addition to the satisfaction of generating your own power, solar energy panels offer potential financial rewards. The government’s Feed-in Tariff scheme (FIT) rewards solar energy-producing households with cash payments. There is also the Renewable Heat Incentive (RHI), which offers a financial incentive for using solar thermal energy to heat your home and hot water.

What type of solar is compatible with my boiler?

Most hot water cylinder systems and regular boilers are compatible with solar water heating. Some combination boiler systems are incompatible, however. Solar energy is collected by the panels during the daytime, but a household’s hot water usage is greater in the mornings and evenings. This means that when the water is heated up by solar panels during daylight hours, it needs to be stored for later use in a hot water cylinder. Some combi boiler systems can use preheated water and are thus compatible with solar energy. You can check with your manufacturer to see if yours accepts preheated water, and to what degree.

Do I need planning permission?

In most cases, you do not need planning permission to install solar panels. A change in legislation in 2008 deemed solar panels to be ‘permitted developments’ in the majority of situations. They should be fitted to blend in with the property and area as much as possible. Care should be taken during installation, with panels not protruding past the roof’s surface more than 200mm or above the property’s highest point. A Building Control inspector may need to visit your property prior to installation.

Occasionally, permission from the relevant local authority is required if your property is:

• In a conservation area
• A listed building
• In a world heritage site
• To feature multiple standalone units

Using a certified installation company ensures that your panels will fall in line with all relevant regulations.