Photovoltaic (PV) Solar Panels

Welcome to a series of four short video clips designed to show what you can do in your home to produce electricity and/or hot water for your use.

The information and views provided are based on actual use by Chew Magna residents who have installed these technologies and have been using them for years.  This means you are getting actual operational experience and not just marketing views from the equipment supplier!

Some of the issues raised will be specific to the location and not associated directly with the technology and these will be highlighted.

The range of renewable technologies covered are:

  • Photovoltaic (PV) with battery storage;
  • Air source heat pump (ASHP);
  • Ground source heat pump (GSHP);
  • Solar thermal hot water (STHW):

The suitability for your situation will depend on a number of factors, including house construction, location and financial aspects.  Remember that while each technology has a payback tariff that provides an income, there is an upfront capital installation cost that may not suit your particular circumstances.

In this video we take a brief look at photovoltaic (PV) solar panels.


  • Electricity generation using solar photovoltaic (PV) arrays or PV tiles is a popular technology, able to installed almost anywhere.  In this video we look at PV panels and a battery storage system.
  • PV panels are made from silicon and supplied as panels, typically 1m wide by 1.6 – 1.9m long, with the smaller panel producing about 250 Watts (W) output and the larger panel about 350W.  
  • Panels are placed in rows to produce the total output required, which for a house is typically between 2-3 kilo Watts (kW).  The two photos show panels being installed on a roof and the final completed PV array.
  • The silicon photovoltaic semiconductor cells covert sunlight into a DC electrical current, which is then converted by an inverter into AC, either for use in your home or for export to the electricity grid.  Placed on your roof, or on the ground, all the panels need is direct access to the sun and no shading from trees or buildings next door.
  • Depending on the type of PV cell system, you can end up with a greatly reduced output when the panels are in shade.  Unless you have optimizers fitted to each panel the output of the PV system could be reduced to near zero when only one or more panels are in shade.
  • Surplus electricity not used in the home is exported to the power grid, for which you can get payment under the Smart Export Guarantee scheme if you register with an electricity provider.  Tariffs vary with the provider and are between 1.5-5.5p/kWh ( ).
  • Comparing PV panels and PV tiles, PV tiles can be useful for getting around tough building regulations as well as for retaining the original appearance of a building.  The price of solar tiles used to be much higher than it is now and they are becoming more price-competitive and popular as time goes on.
  • PV roof tiles are generally considered less effective than PV panels, simply because they are not suitable for every kind of roof design and as they are built into the roofing material there is no possibility for the tile to be turned/ re-oriented after installation.
  • , showing clearly the fourfold variation in monthly output between winter and summer.
  • Trees do grow, so bear that in mind when you site your system, especially if your neighbour has trees!  The panels are largely self-cleaning but you get them washed each year by our ‘friendly’ window cleaner to maximise the potential output.
  • Unless you also have a battery system, to maximise electricity use in the home use high demand appliances such as washing machines, dishwashers or tumble dryers when the sun is shining.  There is clearly less choice if you use an electric cooker/oven in the evenings but if you can bake or cook during the day, then you could save much of the electricity required. 
    • PROS:
    • easy to install in most locations, roof or ground mounted;
    • low/no maintenance requirements;
    • fitting optimizers mitigates the problem of greatly reduced output due to shading;
    • reduces your carbon footprint
  • CONS:
    • check location and orientation of your roof/ground mounted array to avoid shading;
    • a 3.5kW system is about £4,800;
    • inverter typically last 10-12 years, needing replacing during the lifetime of a PV system, at £500-£1,000.


  • At various times of the year the output of your PV system will exceed what you can use and the surplus is exported to the grid.  Currently any surplus exported to the grid under the Smart Export Guarantee scheme earns between 2-5.6p/kWh.  However, if you have a storage battery installed you could save imported electricity at +25p/kWh, depending on your provider.  
  • Li-ion battery storage units are the most common and work like a car battery, being charged by the PV panels and storing electricity for later use.  A typical domestic storage battery is sized at 4-8kWh.  Domestic battery packs are available from a number of providers and the Powervault unit below is an example of one battery provider.
  • The battery can be located in most places around your home but not in an external garage due to the cold.  There is a cooling fan that makes some noise, so locating the unit needs consideration.  The battery lifetime is estimated at about 10 years, so over the 25-year lifetime of a PV system it will need replacing at least once.
  • The unit charges when surplus electricity is available and provides electricity in your home when either the PV panels are no longer generating in the evening, or if you have a high load during the day, before electricity is drawn from the power grid.
  • The ability to charge fully is determined by the time of year and size of PV panel system.  From example, using a 3.2kW PV system with a 4kW storage battery, from about mid-January on a sunny day charging could reach +40%, while on sunny days in late February/early March charging could reach 100%.  Full charging is then expected until about early Sept., again dependent on cloud cover, when thereafter PV output will decline and battery charge decrease to zero/near zero on short, cloudy winter days.
  • A number of websites provide further information on battery systems and costs etc., such as, and
  • The Pros and Cons of a Li-ion battery storage system are:
    • PROS:
    • easy to install in most locations;
    • Li-ion solar batteries outperform others when it comes to storing energy.  They are more efficient, charge faster, require no maintenance and last substantially longer;
    • provides electricity for later use;
    • can reduce your energy costs;
    • reduces your carbon footprint.
  • CONS:
    • check the proposed location for noise issues during charging/discharging operations;
    • typical cost of 3-4kWh battery is £3,500-£5,000;
    • battery lifetime is about 10 years, so will need replacing at least once.
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