Solar panels: the essential guide

Solar panels are the future – here's what you need to know before installing yours

solar panels on a roof

Solar panels are one of the most environmentally-friendly ways to power your home. The renewable energy sector is the future of UK energy, but you need to do your research before deciding whether this is the best energy solution for you. Read our advice to find our how much solar panels cost, how much you can save, and whether they're right for your long-term future goals.

  • In the meantime, discover our dedicated energy comparison page, complete with a handy tool to see if you could benefit from switching suppliers

Choosing the right type of solar panel for your property

There are three main systems available for domestic micro generation. One generates electricty (solar PV), one is used for heating and hot water (solar thermal), then you can get a hybrid of the two (solar PV-T):

1. Solar PV – Photovoltaic panel

photovoltaic solar panels on a red tile roof house

This type of solar panel captures the sun’s energy using photovoltaic cells, then converts it into electricity which can be used around the house for powering appliances and lighting. PV is currently the most common type of solar panel in the UK, with nearly half a million homes having had them installed. The panels are most commonly fitted onto pitched roofs.

Costs and saving

Installing a domestic 4kWp solar PV system costs around £5,000 to £8,000. These systems can generate approximately the amount of electricity that an average household uses in a year — around 3,800 kilowatt hours.

A PV solar panel should last 25 years, but parts may need replacing during this time. Your installer should advise you on maintenance and how to check your system is functioning properly; however, the panels generally need little attention.

‘Rent a roof’ deals

Some companies offer to install solar PV panels for free on a ‘rent a roof’ basis, meaning the installer owns the system and claims the FiT, plus any income from energy exported back to the grid. The advantage for the homeowner is that they obtain free energy when the system generates, without having to invest in the initial outlay costs. However, be aware of the implications that renting your roof out may have on your mortgage (with some leases for solar panels being as long as 25 years, it could affect remortgaging or selling on).

2. Solar thermal

solar thermal tube panels on a black tiled roof house

Using roof-mounted panels to heat water, a solar thermal system can provide an average three-bedroom semi-detached home with around a third of its hot water demands. A complication of the systems is that they need direct sunlight to work, so north-facing roofs are unsuitable.

You’ll still need a boiler, immersion heater or heat pump to make the water hotter, and provide hot water when solar energy isn’t available, such as on overcast days. 

Costs and savings

The typical cost of installing a solar thermal system is around £3,000 to £5,000. The Green Deal has helped many UK homeowners finance this initial outlay, and the RHI (Renewable Heat Incentive) can also provide some financial help.

Homeowners may be eligible to receive payments for the heat generated from their solar water heating system through RHI; for example, an average four-person household could receive a £330 RHI payment per year.

Savings from solar thermal panels are moderate — the system can provide most of a household’s hot water in the summer, but much less in winter.

  • The Energy Saving Trust calculates that homeowners should typically see a saving of £60–£70 each year on their water-heating bill.
  • The systems will also cut your carbon emissions by between 230kg and 510kg of CO2 a year for a typical installation.
  • Maintenance costs are low and most solar water heating systems come with a 5–10-year warranty.

Choosing a suitable location for solar panels

solar-panels-cost-benefits

Before investing in a solar PV (photo voltaic) system, consider your home’s location and how much sun it benefits from during the day, which will ultimately affect the amount of energy you can generate, and the financial benefits received. Location is key in working out the amount of available sunlight that hits your solar panels and converts to usable energy. If the panels are not facing south or angled towards the sun’s elevation, the amount of energy produced will inevitably be lower. For example, panels in southern Scotland might generate around 15 per cent less than an equivalent system in southern England, where levels of sunlight may be more prolonged. Think about the surrounding area, too. If your panels are fitted just to the north of a large tree or building, they’ll be shaded at certain times of the day or year, and this will dramatically reduce output, potential income and savings.

Do I need planning permission?

In many cases, installing solar panels falls under permitted development rights, with no need to apply for planning permission. However, you’ll need to check which limits and conditions apply to you.

Planning permission may be required if you live in a Conservation Area and the roof faces the highway, or if your home is listed. See planningportal.co.uk for more details.

Financial incentives for solar panels: do they still exist?

Sadly, financial incentives for installing solar panels and exporting solar energy ended on 31 March 2019; if you got your solar panels before this, you'll still get your payments. 

Selling energy back: how it works in 2020

Under the new rules, if you wish to export energy, you'll no longer be selling it to the grid, but to your energy provider. There's no fixed price, and not all suppliers have buy-back energy schemes in place, although the green energy sector is leading here (Octopus is one supplier who are already buying back solar energy from their customers) , The other thing required if you want to eventually make a profit from selling renewable energy is that expect it to take 20+ years, so exporting electricity is only worth it if you're planning on staying at your property for the long term. 

If you install eligible electricity-generating technology, including solar PV panels, you could get money back from your energy supplier by selling surplus electricity back to the grid. You will also receive a set tariff for any electricity you generate (even the energy you use yourself). In addition to FiT tariffs, harnessing solar electricity will help to cut your energy bills.

As solar electricity is a renewable energy, you’ll be reducing your home’s carbon footprint, too. The Energy Saving Trust estimates that a typical domestic solar PV system could save over a tonne of carbon dioxide per year — and more than 30 tonnes over its lifetime.

Solar photovoltaic energy is measured in units called kilowatts peak (kWp). This refers to the rate at which the PV cells generate energy when operating at peak performance — which is in direct sunlight during the summer months.

solar photovoltaic thermal panels on a modern curved sedum roof home

  • One square metre of solar PV tiles will cost around £500, excluding installation costs.
  • They tend to produce energy less efficiently than panels, generating at between 50W and 120W per square metre, whereas panels produce more than 134W for the same area.

How to boost the benefits of solar panels

There are things you can do to ensure a reasonable payback on your solar installation, says Brian Horne, energy expert at the Energy Saving Trust:

  • Get a good deal: make sure you request quotes from several installers
  • Pick a good location: Ideally, you will want a system that is angled between 30 and 50 degrees and facing between south-east and south-west. Avoid areas of shade.
  • Use more of the electricity yourself: put on the dishwasher, washing machine and tumble dryer during the day, but all at different times. You could invest in a solar diverter, which heats up a hot water cylinder when the sun shines, or a battery system to store the electricity for use in the evening. However, more research is needed on the cost benefits of these.

Is it possible to go ‘solar only’?

For people who live in isolated properties, with no realistic option for a mains connection, solar PV is one of the options for providing some level of electricity supply. You will need a substantial battery store, and most people would also opt for a diesel generator to top the system up when necessary. An off grid electricity system will never provide the consistency of supply that you get with the mains, but for some homes it is the only realistic option.

If you already have mains there is no point in even considering disconnecting. It is theoretically possible to do so, but you will spend a fortune on equipment that takes up a lot of space in exchange for a variable supply that won’t be able to run all of your existing appliances. And you won’t be helping the planet much either.

If you have the mains, use it, and if you fit enough solar panels you may generate more than you use over the year. If you want to call that ‘solar only’ then that’s up to you.

Solar panels: how can the numbers be increased?

Getting solar PV panels fitted to your roof is now cheaper and easier than it has ever been. Unfortunately, since government incentives for solar panels ended, the number of installations has dropped dramatically. The only hope is that as the renewable energy sector expands, with the 2030 renewable energy target set at 32 per cent of the market, more companies will buy solar energy from individuals/. This will help bring prices down to the point where support is no longer necessary, and solar electricity becomes competitive in its own right.

residential-solar-panels

Is solar panel cheaper than gas and electricity?

Solar power is not currently the cheapest way to generate electricity, as most of our electricity comes from large gas and coal fired power stations, which are still the most affordable. However, solar has now become low priced enough to offer a useful contribution to the national electricity supply, with only limited support to reflect the carbon dioxide savings that result, and the benefit of generating electricity close to where it is used. For the householder, solar power is unlikely to be cost effective yet without Feed-in Tariff support, but it could become affordable without support in the coming years.

How much will solar panel installation cost?

The cost of solar PV installations has come down dramatically over the past few years. Recent installations suggest a likely price of around £5,000 to £8,000 for a typical domestic installation (4 kilowatts peak output). As prices have been falling it may be possible to get a significantly lower installation quote now. However, we would advise anyone considering solar PV to get several quotes, and to check the quotes and the installers’ credentials carefully, to make sure you are getting a fair price but also a good quality installation. The cost of the panels is always a significant part of the installation cost. There are also several other pieces of equipment to pay for, including the inverter (which converts the electricity to mains voltage AC), the generation meter, the panel mounting system and the wiring. There is also the cost of paying someone to supply, install, connect and register the panels and, for most systems, the cost of scaffolding.

Do you have to pay to be connected to the grid?

Not directly, but you do have to pay to use a registered installer who will ensure that your grid connection is safe and legal, and will notify the District Network Operator once your system is connected.

Will it cost to maintain solar panels once installed?

The solar panels themselves are unlikely to need any maintenance during their expected 25 year life. If a panel fails it should be covered by the manufacturer’s warranty – check the details of this and all other guarantees before agreeing to an installation!

One piece of equipment that probably will need replacing is the inverter – this is the box of electronics that converts the solar output into 240V electricity that can be connected to your supply. The inverter is unlikely to last as long as the panels, and will not have the same length of warranty, so you should expect to have to replace it at some point during the life of the system. Expect to pay around £600 to £800.

Images: iStock (PV and Thermal), Newform Energy (PVT), Solar Slate (Tiles and Slates)

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