Solar Energy

PV Panels
A PV panel is made up of a number of modules, and each module is made up of cells of silicon wafers, where each cell can generate electricity from sunlight, even diffuse sunlight. The top of the panel is usually glazed and the rear fitted with an antistatic material. They are then usually fitted to frames which are fixed onto roofs. The maximum output of a solar cell is described as peak watt (Wp).

There are different types of PV panel, and also hybrids of various types.

• Monocrystalline: has a single continuous silicon crystal lattice structure. These have a higher efficiency (turn more sunlight into electricity) but are more expensive.
• Polycrystalline: consists of small grains of monocrystalline silicon.
• Thin film: this still uses silicon cells but is thinner, lighter, and more flexible.
• Amorphous Silicon: this can also be applied as a thin film but is less efficient.

The panels generate the electricity as direct current. This is then fed to an inverter, which changes it to alternating current, before it goes into your consumer unit. There will also be a generation meter installed so that you can see how much electricity is being generated.

PV technology has been adapted to create solar tiles, currently in the shape of a block of tiles, to fit in better with the look of a roof; thin film PV can be applied to glazing, e.g. for conservatories , and even adapted to work on fabric. These permutations are still being developed to improve their efficiency and are generally more expensive than the PV panels.

Solar Hot Water
A solar thermal panel comes in two types:

• Flat Plate: this is a slim, rectangular box with a glazed top and black, heat absorbent interior with a metal plate covering copper tubing through which liquid passes. The sun heats the plate which heats the liquid.
• Evacuated Tubes: similar size but the tubes are more exposed and incorporate a strip of copper to absorb more heat. They also contain a vacuum around a copper pipe through which the liquid flows, and have an inner coating which makes the tubes act like a mirror. It traps as much of the solar energy as possible to pass into the liquid. Evacuated tubes are more efficient than flat plate panels.

There are also two types of solar thermal systems:

• Direct: this is where the liquid passing through the flat plate is the liquid that will come out of your taps.
• Indirect: This is where the heating system is a ‘closed loop’, and the heat is passed to your hot water tank through a heat exchanger. With these systems, it means that the liquid in the tubes can be made more resistant to freezing.

1. What kind of maintenance do solar panels need?
Hardly any. They may get dusty or guanoed, but should then get cleaned by rainfall eventually.

2. What kind of maintenance does my PV system need?
The panels should last for around 25 years, but it is likely that during that time the inverter, which takes the direct current from the panels and converts it to alternating current, will need replacing once.

3. What kind of maintenance does my solar thermal system need?
The panels should last for around 25 years. Most systems also require a pump to push the liquids around, and this may need replacing every ten years or so. If you have an indirect system, where there is an anti-freeze component to the liquid passing through the solar thermal panel, you may need to check it every year or so in case it needs topping up.

4. What do I need to consider when getting a quote / finding an installer?
When you have decided what technology would suit your situation, and want to get a quote, please remember this:

• Get at least three quotes
• Locally-based installers are likely to provide a better level of service
• Check how much experience the installer has with the technology.
• Panels come in different sizes. This means that the number of panels that could be fitted to your roof may vary dependent on the make and model of the panels.

When the installer arrives to give you a quote, ask for the efficiency of the panel (given as a percentage, and may be somewhere from 10% – 16% ) and for a quote that would show the difference in price and in energy generated between the different types of panel on offer.

Also ask what the installer will do to help you register your system for either the Feed in Tariff (if PV), or for the Renewable Heat premium Payment and for the Renewable Heat Incentive if solar thermal.

The quote from the installer shouldn’t just show what you’d expect from the system in perfect conditions, it should show what to expect from your conditions. It should be in writing and you should have at least 14 days to make a decision.

There should be no hard sales techniques employed. If the representative of the installer makes you feel uneasy then ask them to leave. If you feel that they’ve been pressurising you, please make a complaint. It will help protect future customers from bad practices.

PV Panels

The cost of PV panels is coming down rapidly and is approaching £2000 per 1000Wp (watts at peak production) installed capacity, so if 10 – 12 panels were providing say 2.5 kWp (kilowatts at peak production), it would cost around £5,000 – £6,000 to install.

There are no grants for PV panels, and since the Feed In Tariff rate dropped, it is more difficult to find the rent-a-roof options where someone else pays for the installation, you get the free electricity, but they get the Feed In Tariff payment. The Feed in Tariff, effective since July 2009, currently pays 14.90p per kWh until 01/10/2013, for a domestic system producing less than 4kWp which meets the energy efficiency criteria.

Solar Hot Water

Solar Hot Water has always been much less expensive than PV panels. 4m2 of installed panels is likely to cost around £3,000.

Also, unlike PV, there is available a contribution towards the installation cost of £600, in the form of a voucher, subject to meeting certain insulation prerequisites, and having a Green Deal Assessment carried out. This is known as the Renewable Heat Premium Payment which is available until the Renewable Heat Incentive (RHI) comes into effect in Spring 2014 for any solar thermal panels installed since July 2009 where it is expected the RHI will pay 19.2p per kWh of renewable energy generated.

Cut your energy bills in half with Solar PV Panels

If you are at home on a sunny day, then the electricity you will be using, (through putting the kettle on, playing a computer game, DIY with power tools etc) will be being generated by your panels, so you won’t be buying electricity from the National Grid. This will save you lots of money.

Also, for all of the electricity you generate, whether you use it or not, you will be paid a tariff (Feed In Tariff) at a rate which will be tax-free and index-linked for 25 years.

On top of that, for all the electricity you export to the Grid you will also receive a payment. Win win win!

Combining Solar Energy with Heat Pumps for FREE Heating & Electricity

Heat Pumps, which harvest energy from the air, water or the ground and upgrade it for space heating and hot water use, are powered by electricity, so are the perfect renewable energy partner for Solar Photovoltaic Panels (PV) as any free energy generated through solar power can be used to heat your home. With careful use a heat pump and solar PV system in your home could mean an end to heating and electricity bills.

FREE Hot Water for half the year with Solar Thermal

This is a simple technology which will provide you with free hot water, typically from April to October. This will save you money, because you won’t have had to use either bought electricity or gas to heat that water.

Also, for the heat you generate, you could receive a tax-free index-linked payment from the Renewable Heat Incentive every quarter for 20 years…

The Renewable Heat Incentive (RHI)

The Renewable Heat Incentive is a new Government-backed measure being introduced to make it worth your while to produce renewable heat. You earn a fixed income for every kilowatt hour of heat you produce. This is likely to be used in your own property, but if you are lucky enough to be connected to a heat network you might be able to get an additional payment for ‘exporting’ surplus heat.

The launch of the Renewable Heat Incentive (RHI) has now been further delayed until Spring 2014. However, the tariffs have been published.

Eligible applicants will receive:

• at least 19.2 p/kWh for solar thermal
• 18.8p/kWh for ground source heat pumps
• 12.2p/kWh for biomass boilers
• 7.3p/kWh for air source heat pumps

Good Energy’s Renewable Heat Incentive

Green energy suppliers Good Energy have their own Renewable Heat Incentive called HotROCs which rewards customers who are generating heat or hot water from renewable sources.