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Solar panels, or photovoltaics (PV), capture the sun’s energy and convert it into electricity to use in your home. Installing solar panels lets you use free, renewable, and clean energy to power your home and appliances. Plus any extra electricity can be sold to the grid or stored for later use. 

How do solar panels work?

1. When the sun shines on a solar panel, solar energy is absorbed by individual PV cells. These cells are made of layers of semiconducting material – mostly silicon. 
2. The PV cells produce an electrical charge as they become energised by the sun. The stronger the sunshine, the more electricity generated. Cells don’t need direct sunlight to work and can even work on cloudy days.
   1. Solar panels absorb energy from the light spectrum visible to us and wavelengths that can pass through clouds which means electricity is still generated on cloudy days. 
3. The electrical charge creates a direct current (DC) of electricity.
4. The direct current passes through a solar inverter to turn it into alternating current (AC) electricity. You need AC electricity to run your household appliances. 

Benefits of solar panels 

• Reduce your electricity bills – as sunlight is free, your electricity costs will be reduced. 
• Cut your carbon footprint and emissions – solar energy is a clean, renewable energy source. A typical solar panel system could save one tonne of carbon per year
• Sell extra energy to the grid – you can export electricity you can’t use yourself and get paid for it. See the Smart Export Guarantee. 

Installing solar panels 

Energy saving trust has a solar panel calculator which will help you work out if your home could benefit from solar PV. It will take around 10 minutes to complete, and will tell you how much it may cost to install a solar panel system, how much money and carbon you could save by changing to solar PV, and how much money you could get from selling electricity to the grid. 

For a detached bungalow in Lamlash with a south facing roof with no obstructions, , with one person living in the home and at home for half the day, with electric storage heaters the calculator above recommends a solar panel system of 4.5 kWp (typically 12 panels) 

They could save £620/year (calculated January 2025) based on the following assumptions:

• Electricity generated – 3700 kWh of low carbon electricity
• Solar energy used – 18% of 3700 kWh
• Savings on their electricity bill – £160
• Solar electricity exported – 82% of 3700 kWh
• Export payments – £460*
• Environmental impact – estimated carbon savings of 830kg per year

*export payments are based on average electricity prices as of July 2024

The estimated installation cost would be £7100 and the panels could pay for themselves after 11 years. 

The cost of installing solar panels also depends on: 

• The size of the system.
• Any difficulty accessing your roof.
• Whether you choose panels or tiles and whether you choose to integrate them into the building.
• If you need to renew or strengthen the roof covering.

When it comes to installing solar panels, your installer must be MCS registered (a completion MCS certificate is required by energy suppliers in order to qualify for the Smart Export Guarantee feed in tariff) and in turn that also means they have insurance cover so that if there are any faults i.e. a roof leak within two years on installation your claim will be addresses even if the installer has ceased trading. 

Combining solar panels with other renewable technologies

Solar panels on their own offer lower electricity bills and clean energy. But they are at their optimum when combined with other renewable technologies i.e. heat pumps and battery storage.

Solar panels and Smart Meters

Whilst a smart meter is not a requirement of solar panels, they complement each other well and without a smart meter you won’t be able to benefit from smart meter exclusive tarfiss and they are necessary for the Smart Export Guarantee and Feed in Tariff schemes. These schemes help you offset excess energy to the grid, which can help you offset your energy bill considerably. 

Smart meters are reliant on signal, and although mobile data and WAN networks are improving, some areas in Arran have poor, or no signal and can cause issues in facilitating the calculation of credit from the feed in tariffs.  

Solar panels and battery storage

Instead of selling surplus energy to the grid or relying on fossil fuels, an energy storage battery you can save your solar energy to use when your panels aren’t generating energy. By installing a battery this reduces your need to import and pay for electricity from the grid during peak times. As we all know Arran can be cloudy, but by storing up unused solar energy in batteries this will allow you to stop cloud watching!

Battery storage tends to cost around £5000 to £8000. 

Solar panels and heat pumps

A heat pump is a low carbon heating system that is powered by electricity. By using solar panels to power the heat pump you can lower your electricity and heating bills.

Solar panels, batteries and time of use tariffs

Most people aren’t home during the day to use the energy their solar panels generate. When this energy isn’t used, it’s sent back to the grid.

If you work from home, you’ll naturally use some of the energy. If you’re out, you can set timers on appliances to make use of it.

You typically earn around 12p per unit for unused energy through the Smart Export Guarantee. However, since buying electricity usually costs more than double that, it’s more cost-effective to use the energy yourself.

Time-of-Use Tariffs

Some energy providers offer time-of-use tariffs, where electricity costs less outside of peak hours. With a battery and such a tariff, you can:

• Store excess solar energy during the day.
• Use stored energy during expensive peak times.
• Sell stored energy at peak rates on innovative tariffs.

For more information on energy tariffs please see here.

Solar Thermal Heating or Solar Water Heating

Solar thermal heating or solar water heating use energy from the sun to warm water for storage in a hot water cylinder or thermal store. Since solar energy availability changes throughout the year, these systems cannot provide all your hot water needs year-round. A boiler or immersion heater is usually needed to supplement the heating.

Larger solar water arrays can contribute slightly to home heating, but they generally provide less than 10% of the required heat, making it less practical.

Most solar water heating systems are designed primarily to supply hot water for bathing, showering, and hot taps.

How do solar hot water heating systems work?

Solar water heating systems use solar collectors, such as panels or tubes, to capture energy from the sun. These collectors convert the infrared portion of sunlight into heat. A mixture of water and glycol inside the collectors circulates through a circuit, transferring the heat to a hot water cylinder.

There are two main types of solar water heating collectors:

• Evacuated tubes –  A series of glass tubes installed on roof tiles.
• Flat plate collectors –  Mounted on roof tiles or integrated into the roof.

Benefits of solar water heating 

• Hot water throughout the year – as the system works all year round, it should be able to provide around 90% of an average household’s requirements in the summer, dropping to 25% in the winter. You will need to heat the remaining percentage of water further with an immersion heater or other fuel source, especially in the winter.
• Reduced energy bills – as sunlight is free, your hot water costs will be reduced.
• Lower your carbon footprint – Solar water heating is a renewable heating system and will help you reduce your carbon emissions. 

Is a solar water heater right for me? 

To determine if solar water heating is suitable for your home, consider the following:

1. Sunny location for panels –  You’ll need about 5 square meters of south-facing roof space (or east-to-west facing) that gets direct sunlight. Panels can also be mounted on flat roofs, walls, or the ground.
   
2. Space for a larger hot water cylinder – Solar systems require a cylinder with a coil connected to the solar collectors. If you don’t have a suitable cylinder, it may need replacing or adding to your current system.
   
3. Boiler compatibility – Conventional boilers and systems with hot water cylinders are often compatible.
   
4. Planning permission – Most installations don’t require planning permission, but listed buildings or homes in conservation areas may have restrictions. It is good practice to check with the planning office.

Commonly asked questions

Do I have enough space? 

Typically the average solar panel system is around 3.5 kilowatt peak (kWp). The kWp is the maximum amount of power the system can generate in ideal conditions. Typically this would cover between 10 to 20m^2.  of roof surface, and could consist of six to 12 panels. Individual panels tend to be around 2mt tall and 1mt wide. 

It’s important to remember to take into consideration not only your current electricity consumption as well as your future consumption i.e. you may have a fossil fuel powered car/van now but in the future you may have an electric car/van.

Does my roof face the right way? 

An unshaded south facing roof is ideal for maximum performance. East and West facing roofs still work, but we recommend you seek professional advice as they will be able to advise on the optimal tilt and orientation of your panels based on your roof pitch. 

Typically an east or west facing roof will produce 15-20% less energy. 

Could my panels be affected by shade? 

Nearby buildings, trees or chimneys could affect and have a negative impact on your system. Finding an unshaded spot is best, but we understand that sometimes shading is unavoidable. Some solar PV systems can minimise the impact of shading by using an optimiser. Solar optimisers help improve the overall performance of your system, so if one panel is shaded, it doesn’t impact how much electricity the other panels can generate. However, if your roof doesn’t have shading, having an optimiser won’t help you generate more electricity but you will be able to monitor your systems performance. 

Can I install panels on a flat roof? 

Yes,  however normally panels on a flat roof would be tilted up to help maximise their energy productions. 

Sometimes it may be necessary to renew or strengthen your roof structure, as sometimes panels need to be weighted down therefore the roof needs to be strong enough to deal with the added weight – a professional will be able to advise you on this. 

Can I install panels in my garden? 

Yes, you can install panels in your garden on a suitable frame. Make sure they are away from anything that may cause shade like nearby trees or buildings, and they should be as south facing as possible. 

A great advantage to installing panels in a garden is it’s much easier to keep them clean, however you would need to be more careful about rodents and other physical damage. You may need planning permission for this – please seek advice from the local planning authority.

Can I install panels on my shed or garage? 

Yes, although it’s important to make sure the building roof is strong enough to take the added weight of the panels – a professional will be able to advise you on this. 

If the building doesn’t have its own electricity supply already then this should be factored in when looking at the total cost. 

How long do they last? 

Solar panels should last for 25 years or more. If you have a solar inverter (the device that converts DC to AC), you need to replace this after around 12 years. Most inverters have warranties of 5 five years as a minimum, which you can often extend to 15 years however you may find that a 15 year warranty costs almost as much as a replacement inverter. 

How do you maintain a solar panel system? 

Solar panels don’t require much maintenance. Keeping nearby trees well trimmed to minimise shading would be the most important. 

In Arran and the rest of the UK, the rain will keep your panels clean if they are tilted at 15 degrees or more. However you may still need your panels cleaned occasionally. 

Your installer should leave details of any maintenance checks that you should make to ensure everything is working properly. 

How do I get solar panels? 

Whilst we cannot make recommendations directly, you can find a list of accredited providers who have provided services to Arran here. You may be eligible for funding, a grant or loan if solar panels are taken as part of a ‘bigger package’ i.e. you install insulation, and an air source heat pump as well as solar at the same time. You can see our list of current funding, grants and loan information here.

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