What is Solar Photovoltaic (PV)?
More commonly known as Solar PV, these panels are designed to produce clean, renewable electricity from the sun to power your home.
It’s also possible to sell the electricity your system generates to Guernsey Electricity to supply the island with even more renewable electricity.
As well as meeting your immediate electricity needs such as lighting, heating and power, PV systems are also used to charge battery systems and electric vehicles (EV’s). Batteries can help your solar energy go further as you can store what you don’t use to be used at night for example.
How does Solar PV work?
Solar PV link solar cells together in a panel which convert sunlight into electricity using photovoltaic materials such as silicon.
These solar cells produce a Direct Current (DC) electricity which flows from the panels into your solar inverter. This converts the DC electricity into the Alternating Current (AC) needed for your home.
Some people also install SMART systems that monitor both the amount of electricity you’re generating and consuming and combine this with a battery charging system to store the surplus power.
In the near future, Guernsey Electricity will be restructuring and rebalance their tariffs.
This means the standing charge will be increasing and the cost per unit of electricity will be decreasing.
The fixed element of a customer’s bill, currently known as the standing charge (or connection fee), represents the cost of being connected to the network. Being connected to the network provides you a secure supply should you need a top up and also the ability to sell your excess electricity.
The real cost of being connected to the network includes:
- electricity cables and infrastructure
- investment and maintenance of electricity assets
- fixed overheads to maintain the power station as back-up supply
Design layout and direction
Your installer will survey your property and design a system that takes into account:
- Roof size you will need a roof large enough for a minimum of four panels
- Direction solar PV panels that face south generate the most electricity over the year. However, panels that are both east and west-facing can provide more balanced generation throughout the day by making the most of the morning and evening sunlight.
- Shade trees, chimneys and dormer windows may cast a shadow on your roof and this should be considered in your design. If shading cannot be reduced during the design phase, a DC power optimised inverter or microinverters can help reduce shading on one or two panels from impacting your entire system
- Solar array angle solar PV panels generate the most electricity when positioned with a 35 to 40 degree angle.
- Roof material this will influence the design of the roof mounting system used to fix the panels to your roof, for example a pitched slate roof will have different needs compared to a bitumen felt flat roof.
Below are some indicative prices and your installer will provide a specific cost according to the final design.
|Available roof area||System size||No. of panels||Sq. m||Approx system cost||Approx annual output|
These estimate prices do not include scaffolding costs and any associated roof/building works.
Annual service and regular cleaning will make sure they are always generating as much power as they can for your home.
Every property and every solar PV system is different, and it is important that you discuss the anticipated return on capital with your preferred installer.
To help recoup the PV installation cost faster, it may be worth considering property insulation which will reduce heat loss and electricity bills.
Improving the energy efficiency of your property is one of the most effective ways of reducing your energy bills. The power generated from your solar PV will go much further if the appliances in your home – such as LED lightbulbs and energy-efficient washing machines – demand less energy from them.
You will need a roof large enough to fit at least 4 panels to make it worthwhile. As panels are usually 1.7 metre by 1 metre, you will need at least 7 square metres (sqm)of unobstructed roof space after allowing a space of at least 400-500mm around the borders of the roof
In Guernsey, south-facing roofs usually generate the most electricity.
However, having panels on both the east and west-facing roof space can provide more balanced generation throughout the day by catching both morning and evening sunlight.
Objects like trees, chimneys and dormer windows may cast a shadow on your roof during some parts of the day. This should be considered during the design phase and panels should be positioned away from extreme shading.
If this is not possible, a DC-power optimised inverter or microinverters can help reduce the impact of shade over one or two panels from impacting your entire system
Solar panels generate most electricity on roofs with a 35 to 40 degree angle. If you have a flat roof, it’s worth considering a specific mounting system for flat roofs at 10 degree pitch to make sure you’re getting the most from your solar PV system.
Home battery storage systems can be an excellent option for homeowners who want to store solar energy for use when their system is unable to generate enough electricity for their needs, such as during the night.
Solar PV can generate electricity on both sunny and cloudy days. As more power will be generated during the sunnier days, many people choose to store any excess energy generated in a home battery systems.