What are solar panels?

Solar panel electricity systems, also known as photovoltaics (PV), capture the sun’s energy using photovoltaic cells.

These cells don’t need direct sunlight to work – they can still generate some electricity on a cloudy day.

The cells convert the sunlight into electricity, which can be used to run household appliances and lighting.

The benefits of solar electricity

  • Cut your electricity bills. Sunlight is free, so once you’ve paid for the initial installation, your electricity costs will be reduced.
  • Get paid for the electricity you generate. The UK government’s Feed-in Tariff scheme pays you for the electricity you generate, even if you use it.
  • Sell electricity back to the grid. You will also receive another payment for the electricity you export through the Feed-in Tariff scheme.
  • Cut your carbon footprint. Solar electricity is green renewable energy and doesn’t release any harmful carbon dioxide or other pollutants.
  • A typical home PV system could save around 1.2 to 1.7 tonnes of carbon per year.

How do PV cells work?

PV cells are made from layers of semi-conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers. The stronger the sunshine, the more electricity is produced. Groups of cells are mounted together in panels or modules that can either be mounted on your roof or on the ground.

The power of a PV cell is measured in kilowatts peak (kWp). That’s the rate at which it generates energy at peak performance in full direct sunlight during the summer.

PV cells come in a variety of shapes and sizes. Most PV systems are made up of panels that fit on top of an existing roof.

The electricity these panels generate has to be converted to be used in your property and that needs an inverter which is always part of the package sold by suppliers but which has a life-span of around 10 years so over the 20-years of the Feed-In-Tariff you will need to replace this element at least once – potentially more depending on the quality you pay for.

Solar panels - PV in this instance with a small solar thermal top left

Solar Thermal – water heating

These systems use free heat from the sun to warm domestic hot water for washrooms, swimming pools, pre-heat of boiler feed water – wherever you need hot water.

A conventional boiler or immersion heater can be used to make the water hotter, or to provide hot water when solar energy is unavailable.

  • Hot water throughout the year – the system works all year round but here in Scotland you’ll almost certainly need to heat the water further (boiler / immersion heater) in winter.
  • Reduced energy bills – sunlight is free, so once you’ve paid for the initial installation your hot water costs will be reduced.
  • Lower carbon footprint – solar hot water is a green, renewable heating system and can reduce your carbon dioxide emissions.

How do solar water heating systems work?

Solar water heating systems use solar panels (collectors) fitted to your roof which harness heat from the sun and use it to heat water stored in a tank.

There are two types of solar water heating panels:

  1. Evacuated tubes
  2. Flat plate collectors

Is Solar right for your property?

  • Do you have a sunny place to put the panels?  You’ll need around 5m2 roof space facing East to West through South which receives direct sunlight for the main part of the day. The panels don’t have to be mounted on a roof however. They can be fixed to a frame on a flat roof or hang from a wall.
  • Do you have space for a larger, or an extra, hot water cylinder? If a dedicated solar cylinder is not already installed then you will usually need to replace the existing cylinder, or add a dedicated cylinder with a solar heating coil.
  • Is your current boiler compatible with solar water heating? Most conventional boiler and hot water cylinder systems are compatible with solar water heating. If your boiler is a combination boiler (combi) and you don’t currently have a hot water tank, a solar hot water system may not be compatible.

A competent accredited installer will be able to assess your home and help you choose the best setup to meet your needs.

Solar panels - solar thermal in this instance