If you are considering investing in a solar photovoltaic system for your home then you may want a rough idea of costs before getting quotes. We will take a look at a typical UK domestic installation to work out how much it is going to cost.

This information will not be relevant for hobbyist and those looking to set up their own PV system at home. These DIY systems tend to be what is called off grid and are not wired into the homes mains electricity. Instead we are looking at the cost of the solar panels themselves, the wiring and inverter as well as the mounts used to affix the panels to your roof.

Before you even consider looking for prices you should have gotten a site survey or at least done your own research. You will need to see whether or not your roof is suitable for solar. Not all homes are so let us take a look at the main factors that will affect the performance of your panels.

Solar photovoltaic panels turn light into electrical energy so the more light they get the more electricity they will produce. In the northern hemisphere you will need a South facing roof, the farther off South your roof is facing the less efficient the panels will be.

Although they can produce electricity on cloudy days the lower the light levels the poorer their performance. It is a good idea to check for any potential shading, are there trees overshadowing your roof? Are there any other tall structures that may cast shadows over your roof? Shadows reduce the panels performance so you may want to check at different times of the day to see if any shadows appear.

Most homes will have enough space on their roof to accommodate the amount of panels needed for a typical installation starts at around nine square metres. The more space that you have the larger the array you can have which in turn produces more of your electrical requirements.

In the UK solar panels cost in the region of £4,000 per kilowatt but this can double depending on the technology and size of the installation. The cost per kilowatt reduces the larger the array as you essentially only need to pay for the extra panels.

A standard size is about 2.2kWp (kilowatt peak) which during the Summer will usually provide most if not all of your daytime electricity requirements. You will still need to buy in electricity from your supplier at night.

Your panels should be guaranteed for 25 years but can continue to work for many years after the guarantee expires. There are many solar panels that are still producing energy after 40 years. You should be aware that after about 20 years the performance of the panels will drop to about 80 percent of their peak performance. Newer types of panel may perform better.

There are new technologies that are improving performance, reducing cost and increasing longevity all the time. This is one of the reason costs can vary so much between installers. You can ask your installer what types of panel are going to be installed which will enable you to research them online.