How to Buy Solar Panels

With the advent of Feed-in Tariffs and next year’s Renewable Heat Incentive, solar energy features on many a self-builder’s ‘must-have’ list. But how can you be sure you are buying the right panels? Happily the rules are simple and if you follow the below tips, you should end up with a system to be proud of.

Solar Photovoltaics (PV)

Solar PV systems produce electricity. There are two main panel types: monocrystalline and polycrystalline. ‘Mono’ are more efficient – and more expensive – and often a bit smaller than equivalent ‘poly’ systems. Poly can be up to 20% cheaper – and for larger roofs may, therefore, be more financially attractive for some – but will produce less electricity than an equivalent rated mono system.

A typical domestic system of 4kWp may cost up to £20,000 — a big outlay, so it’s essential to ensure you are choosing the right product and installer. Here’s some tips to ensure you don’t end up disappointed:

• Check the supplier: do they have a good record? Take up references, speak to their former clients and check out the work.

• Use only MCS-accredited suppliers and equipment. The MCS scheme is run by the Government and both the equipment and installer must be accredited for the system to qualify for Feed-in Tariffs. See homebuilding.co.uk/green for details of the scheme.

• Check out the price. Most reputable suppliers are coming in under £5,000/kWp for systems from 2kWp to 4kWp. Much more than that should ring alarm bells.

• Do your homework on Feed-in Tariffs — do not rely on the supplier to explain it all to you. Check that the amount you will get back justifies your investment.

• Use only brand name panels. With manufacturers like Sharp, Schüco, Kyocera, Solar Century and Romag, you know it will be a quality product that will last for decades.

Solar Thermal

Solar thermal systems produce hot water. There are two principal types: evacuated tube and flat plate. Evacuated tubes tend to be more efficient, especially when the roof is not directly south-facing, but are more expensive. Flat plate can be mounted in the roof (rather than on top of the roof covering) and are therefore good for new builds.

A typical domestic system will be 4m2 to 6m2, depending on the size of the property, and produce around 2,000kWh per year with a potential income of around £360 per year under the forthcoming Renewable Heat Incentive. A typical domestic system will cost £4,500 to £5,500 (including installation and hot water cylinder) with a payback period of some 10-11 years.

The rules for buying solar thermal are largely the same as for PV. But solar thermal is likely to be working in conjunction with another system (i.e. a boiler or heat pump). The installer has to be capable of making the systems work together in harmony.

Expert Tips

Ploughcraft, manufacturer of the Solar-Log, Britain’s first solar PV log system, offers its top tips for choosing a solar panel installer (01484 723344)

• Make sure you choose a company that employs all its own roofers and electricians. This will ensure that your installation is of the very highest quality.

• Ask to see the installer’s qualifications — many companies are using unqualified staff.

• Ask what roofing experience the installer has — many solar companies have no roofing expertise at all and this is a crucial skill. It’s a bonus if they have an NVQ in solar roofing with heritage experience.

• Choose a company which has hundreds of installations under its belt and that is happy to provide customer testimonials.

• Ask who guarantees the workmanship and ensure it is underwritten in case the company goes bust. Reputable companies offer a solar care insurance warranty for ten years.

• Ask who is going to check the structural integrity. It is not unusual for installers to miss the fact that the solar panels may overload the roof structure.

Solar success story

Michael and Sue Anson, from Brinsley, have installed both PV and thermal solar panels, and are delighted with the result.

As part of a wider process of making their bungalow more energy efficient (which included adding extra insulation and triple glazing), the Ansons installed PV panels from MG Renewables (0844 800 3454), largely to take advantage of the Feed-in Tariff scheme, and solar thermal to provide hot water. During three months of last summer, they produced 1,492 units of electricity, which earned them over £600 and cut their bills dramatically, and they received a refund of over £300 from their gas supplier from the solar thermal panels. “Our panels have been performing better than predicted. It’s great to know we can provide for ourselves whilst saving money,” says Sue.

Installation Issues

Richard Swords, MD of PV supplier Greenenviro Energy Systems (0800 064 6014), explains the installation process.

Residential installations rarely take longer than two days, and the panels can be fitted on virtually any type of roof — it’s the roof’s condition that matters. It has to support the panels and their roof anchors and rails; if the structure is too weak, the installation can’t go ahead.

The best time to install the panels is when your property is being built or re-roofed, as the rafters are exposed and it also gives you the opportunity to have recessed panels, for a flush fit. Keeping the roof watertight is critical, so disruption to the tiles and felt is kept to an absolute minimum. Some tiles will need to be removed, so that the roof anchors can be screwed to the rafters at specific intervals, and are then replaced. The position of the roof anchors is important: if they are inaccurately placed, the rails, which sit on top of the tiles, will not be parallel and the panels will look uneven.

In the case of PV, the wiring is connected to an inverter, via a watertight hole in the flashing, which converts the direct current from the panels to alternating current. In the case of thermal, copper piping is connected to a backplate and carries heat transfer fluid down to the cylinder’s heat exchanger.

Notes

PV & Thermal? Hybrid systems of thermal and PV are now available (PVT). Basically, the thermal collector removes heat from the PV module as a byproduct of the electricity.

Rent-a-Panel:Some companies offer to mount solar PV to your roof and give you ‘free’ electricity in return. While you might save £48* a year on a 4kW array, the company will make around £1,320 under FiTs.

*Note: A saving of £48 is likely the worst case scenario however the max one could expect to save, something in the region of £480, would require a system of more than 9kWp, needing around 90 sq m of roof area and costing about £36,000. In my estimation that is not the typical domestic installation.