Photovoltaic (PV for short) is the industry name for what is more commonly known as solar power. A photovoltaic (or solar) array consists of multiple photovoltaic modules which are linked together in order to convert solar irradiation (sunlight) into usable electricity. Most people refer to them by their more common name of “solar panels” - but they should not be confused with Solar Thermal panels or tubes, which only create hot water.

There are 6 key factors that influence this:

1) Location – Where your house is located will determine both the intensity and number of hours of sunshine your roof will receive. This is known as “solar irradiation”.

2) Orientation – Your roof orientation has a big impact on the number of hours of direct sunlight it receives. A roof facing South will yield the best overall performance, but installations facing anywhere to the South-East and South-West are also feasible. Installations using panels facing East and West are also possible. North-facing installations are not recommended.

3) Roof Pitch – You can’t change the pitch of your roof, but the optimum angle for achieving the maximum yield from your solar installation is between 30° and 40°, depending on your location.

4) Shade - Any shade will reduce the overall performance of a solar array. Whilst shading cannot always be avoided, the solar panels should not be shaded between 10am and 4pm. Your installer should assess the estimated impact of obstacles like chimneys, aerials, satellite dishes, dormer windows etc in their survey.

5) Size of Your Roof – Quite simply, the number of solar panels you have installed will determine how much electricity you can generate.

6) Product Choice – Solar panels are not that different to many other products like a TV or mobile phone, where we decide how much we want to pay in return for the number and quality of features we want. Different brands of solar panel will generate different amounts of electricity, plus panels and the inverters will vary in how efficient they are in converting the daylight that hits the panels into electricity for your home.

Solar panel installations are given a power rating in kilowatts peak (kWp). This is the maximum amount of electrical power which they will generate in standard test conditions.

The total amount of electrical energy the solar installation generates in a year is measured in kilowatt hours (kWh). This will depend on the system’s orientation, shading and location, as well as the size of the system (in kWp) that you have installed.

The amount of electricity your solar installation generates annually in kilowatt hours, is not the same as the saving you can expect to see on your electricity bill, as you may not have the opportunity to use all of it. To maximise your savings from using the free electricity, you need to use it during daylight hours when your solar array is generating power.

The electricity you do not use gets exported back to the grid, unless you have batteries.

Yes. When your solar installation is not generating enough electricity to meet your needs, you will still buy electricity from your supplier at the standard rate shown on your bill. By having solar power, you will of course enjoy a lower annual electricity bill.

Solar power arrays do not require direct sunlight and they generate electricity even on cloudy days. Typically in December, a system will generate 25% of the energy it yields in July. It will of course not generate any power at night – no daylight means no electricity is generated.

Solar panels are approx 1.65 square meters and an average 4 kWp installation will cover around 25 square meters.

This will vary depending on your installation size and type of property, but an average 4 kW system (16 x 250W panels) takes 2-3 days to correctly install.


The two main components are the solar panel and the inverter.

Panels vary based on the maximum amount of electricity they are capable of generating and how efficient they are at converting sunlight into electricity. The inverter converts the direct current (DC) produced by solar panels in alternating current (AC) which is suitable to be used in your premises. Different makes of inverter will be more efficient at doing this than others.

The make you choose of both panel and inverter will therefore have a direct impact on the amount of free electricity that will flow into your home.

All the products supplied by Rexel come with the reassurance of warranties; have been fully tested and are of quality manufacture to give you peace of mind. Whilst warranty periods vary depending on the manufacturer, solar panels typically last for 25 years, so you can fit and forget your installation for some considerable time!


Panels require little or no maintenance. However, to ensure your panels continue to generate the maximum electricity possible, we recommend they are professionally cleaned every 1-2 years as a minimum. If you are in a location that has dusty atmosphere (near a factory for example) or have a high incidence of bird droppings, then you may need them cleaned more often. Attempting to clean panels yourself with unsuitable products could damage your panels.

You will be able to view the amount of energy being generated via your inverter and/or an approved generation meter, or an energy monitor. Your inverter will normally have a display or web portal where you can see its status.