Your Roof Making sense of solar 2 Your Roof Making sense of solar 3 Your Roof Making sense of solar 4 Your Roof Making sense of solar 5 Your Roof Making sense of solar 6 Your Roof Making sense of solar 7 Your Roof Making sense of solar 8 Your Roof Making sense of solar 9 Your Roof Making sense of solar 10 Your Roof Making sense of solar 11 Your Roof Making sense of solar 12 Your Roof Making sense of solar 13 Your Roof Making sense of solar 14

Your Roof

. Making sense of solar

Solar thermal

.Q & A

IS MY ROOF SUITABLE FOR SOLAR THERMAL?
WHAT ACCREDITATIONS WILL MY INSTALLER NEED?
WHAT KIND OF SOLAR THERMAL IS AVAILABLE?
WHAT SUPPORT IS AVAILABLE FOR HOMES THAT WANT TO INSTALL SOLAR THERMAL?
WHAT DO I NEED TO DO TO BE ELIGIBLE FOR THE RHI?
WHAT MIGHT A SOLAR THERMAL SYSTEM COST ME?
WHAT IMPACT WILL A SOLAR THERMAL SYSTEM HAVE ON MY ENERGY BILL?
IS SOLAR THERMAL ELIGIBLE UNDER THE GREEN DEAL?
WHAT IMPACT WILL SOLAR THERMAL HAVE ON MY CO2 EMISSIONS?
ISN’T IT TOO COLD AND WET IN THE UK FOR SOLAR THERMAL?
HOW BIG SHOULD MY SOLAR THERMAL SYSTEM BE?
CAN SOLAR THERMAL BE USED INSTEAD OF TRADITIONAL HEATING?
CAN SOLAR THERMAL WORK WITH A COMBI BOILER?
HOW LONG WILL MY SOLAR THERMAL SYSTEM LAST?
DOES SOLAR THERMAL REQUIRE MAINTENANCE?

CAN YOU RECOMMEND WHICH PRODUCTS AND INSTALLERS ARE BEST?

WHAT COMMON INSTALLATION MISTAKES DO PEOPLE MAKE WHEN IT COMES TO SOLAR THERMAL, BOTH IN TERMS OF INSTALLATION AND USE?

WHAT ARE THE BENEFITS AND DISADVANTAGES OF INSTALLING A COMBINED SOLAR PVT SYSTEM?

HOW DOES SOLAR THERMAL WORK IN CONJUNCTION WITH OTHER SYSTEMS (EG BOILER, HEAT PUMP, UNDERFLOOR HEATING, ETC)?

WHAT SHOULD HOMEOWNERS DO TO MAKE THE MOST OF SOLAR THERMAL TECHNOLOGY?

OTHER THAN THE PANELS, WHAT SOLAR THERMAL SYSTEM ELEMENTS ARE NEEDED AND HOW MUCH SPACE WILL THEY REQUIRE?

IS MY ROOF SUITABLE FOR SOLAR THERMAL?
The orientation of your roof, the slope of your roof and any shading are vital factors in deciding whether solar thermal is a good choice for your home regardless of the type of panel you are interested in. Maximium energy is collected by a system tilted 35 degrees from horizontal.

We would never recommend a solar collector facing north. However, many people are surprised to learn that there is not a great deal of difference on the total energy collected over a given year for all other directions. This is especially true for panels on a roof tilted at around 35 degrees, where the difference in performance between facing east or west, and facing due south, is only around 12%. It is important to be aware that if the output of the collector is reduced on an east or west orientation the collector area should be increased accordingly to ensure hot water needs can be met.

WHAT ACCREDITATIONS WILL MY INSTALLER NEED?
The Microgeneration Certification Scheme (MCS) is an independent scheme that certifies products and installers to a professional set of standards. To qualify for Government grants both the product and the installer need to meet MCS standards.
Your installer should also be a member of the REAL Consumer Code.

WHAT KIND OF SOLAR THERMAL IS AVAILABLE?
There are 2 key types of solar thermal collector:
1/ Flat plate collectors. These are based on a thin heat absorber sheet, usually copper, backed by a tubing system to carry fluids. They are relatively thin, highly insulated and encased in glass. They are cost effective, with a range of mounting options and can reach efficiencies of 75-80%. They can be fitted on top of existing roof tiles, or in new-build or roof replacements where they can be integrated into roof tiles themselves.
flat plate
2/ Evacuated tube collectors. A vacuum between glass tubing provides extremely efficient insulation and evactuated tubes can reach very high temperatures. There are two different categories of evacuated tube (direct flow and heat pipe). Both are similar in appearance but work in different ways. Heat pipe evacuated tubes can only be installed vertically but direct flow tubes can be installed vertically or horizontally.
evacuated tubes

WHAT SUPPORT IS AVAILABLE FOR HOMES THAT WANT TO INSTALL SOLAR THERMAL?
Solar thermal is supported under the Renewable Heat Incentive.  The current situation is slightly complicated but we’ll make it as simple as possible. The RHI is based on the same principle as the Feed-In Tariff. It pays a premium price for every unit of heat your system generates. The RHI is in operation for solar thermal systems up to 200kW in size. However the RHI will not be available until summer 2014 for domestic solar thermal systems.

To try to encourage the domestic market ahead of summer 2014, from last July up to 25,000 solar thermal installations will be supported by the Government’s RHI Premium Payment scheme. This pays £600 towards the cost of purchasing a solar thermal system now, but it requires that you undertake a Green Deal Assessment (which costs around £100).

Homes taking up the RHI Premium Payment scheme should then be eligible for the RHI solar thermal tariff when it goes live, as will anybody else who has had eligible equipment installed from July 2009. Eligible equipment is under consultation but you can be confident that standard solar thermal systems will be eligible. In domestic systems the Tariff will be ‘deemed’ – that means an estimate will be made of the output of your system based on typical domestic use and the number of people living in your home. The RHI will pay a minimum of 19.2p/kWh for 7 years, with payment rising with RPI. However, the total level of support you will get from the RHI will depend on the number of people living in your home. The logic of this is that while everyone can enjoy the same space heating, the more people living in your home the more hot water you will use. See the Financial Incentives section for more details on the RHI and the STA’s estimates of the financial returns for homes of different occupancy levels.

You will not need to meter your solar thermal system. In order to be eligible for these incentives, the installer and product must be MCS registered.

WHAT DO I NEED TO DO TO BE ELIGIBLE FOR THE RHI?
To be eligible for the Renewable Heat Incentive your property needs to have undertaken a Green Deal assessment and to meet Green Deal criteria. i.e. your loft must be lagged to at least 250mm and any cavity walls must be filled. Note this is different to eligibility for FITs for solar power. You must also use MSC certified equipment and installers.

WHAT MIGHT A SOLAR THERMAL SYSTEM COST ME?
The cost of systems varies, but the average installed cost across the UK currently is £4200. This is for a system made up of a 4m2 collector area, a dual-coil hot water cylinder of around 200-250 litres, a controller and pipework etc.

Please note that average system cost is only indicative. Costs can vary significantly depending on your hot water delivery system.

Reseach by the Solar Trade Association shows that if the solar thermal market increased by

WHAT IMPACT WILL A SOLAR THERMAL SYSTEM HAVE ON MY ENERGY BILL?
The RHI payments for domestic systems are not yet finalised. However, the consultation mooted a Tariff of 19-21pkWh.

On average water heating makes up 20-30% of total domestic gas bills. Normally you would expect to save between 30-70% of your annual water heating costs with a solar thermal system. If the occupant carefully follows the installer’s advice, higher savings can be obtained.

IS SOLAR THERMAL ELIGIBLE UNDER THE GREEN DEAL?
Solar thermal Green Deal TBA

WHAT IMPACT WILL SOLAR THERMAL HAVE ON MY CO2 EMISSIONS?
A breakdown of annual CO2 emissions from a semi-detached house which is constructed to the current Building Regulation Standards Approval document shows that space heating and water heating combined account for over half of domestic CO2 emissions. STA assessment coming.

ISN’T IT TOO COLD AND WET IN THE UK FOR SOLAR THERMAL?
Solar collectors can work even if it’s freezing cold. All they need is daylight and we get enough of that even on a cloudy day. An antifreeze solution circulates around the loop of an indirect solar thermal system protecting it from sub-zero temperatures.

The UK receives 60% of the solar energy received at the equator. Each square meter of the UK receives ample energy to operate an efficient solar panel system as long as the collectors are sized according to the required output.

HOW BIG SHOULD MY SOLAR THERMAL SYSTEM BE?
The collector size you’ll need depends on a number of factors; estimated hot water usage; how large a contribution you want to annual hot water load; geographical location; incination of the roof and type of collector.
For domestic solar hot water systems it has been found that installing 1m2 of flat plate collector, or 3/4m2 evacuated tubes per person will give satisfactory results. Heat loss through the system will be larger the smaller the collector is, therefore it is unusual to install a collector of less than 2.5m2 in the UK.
So it is important to beware of underestimating the size of the collector needed, as any cost savings may be outweighed by reduced performance if a system is too small.

CAN SOLAR THERMAL BE USED INSTEAD OF TRADITIONAL HEATING?
In order to ensure proper efficiency of your water heating system a solar thermal system must be used in conjunction with a traditional gas or electric heating system.

CAN SOLAR THERMAL WORK WITH A COMBI BOILER?
This depends on the type of combi-boiler you have. If your boiler is certified to accept pre-heated water then the solar thermal system can be installed in a cold line feed. However, many combi boilers cannot accept preheated water, so it is not advised to install solar thermal with such boilers. For more information on this type of installation it would be advisable to contact a local installer.

HOW LONG WILL MY SOLAR THERMAL SYSTEM LAST?
Solar thermal usually has a life expectancy greater than 20 years, and they are usually supplied wtih a manufacturer’s warranty of 10 years.

DOES SOLAR THERMAL REQUIRE MAINTENANCE?
Neglible maintenance is needed. The fluid circulating in the system should be topped up or even drained and replaced every 5 years or so. However, an annual assessment of the solar thermal system is recommended to help maintain efficiency levels and to help avoid potential longterm problems. This could happen alongside your annual boiler service.

CAN YOU RECOMMEND WHICH PRODUCTS AND INSTALLERS ARE BEST?
No, it is not our role to recommend certain products, installers and companies. Please see the resources section for independent sources of advice. You can search the Renewable Energy Consumer Code and the Microgeneration Certification Scheme websites for installers. You can also search the Solar Trade Association database, as all our members have to be certified by both schemes.

WHAT COMMON INSTALLATION MISTAKES DO PEOPLE MAKE WHEN IT COMES TO SOLAR THERMAL, BOTH IN TERMS OF INSTALLATION AND USE?

Common installation mistakes can include incorrectly specified components (such as pumps, valves and joints) that aren’t rated for the temperatures and pressures that can be present in a solar circuit. Lack of insulation (or use of low temperature insulation which then melts) on pipes is also a common mistake. Undersizing the hot water cylinder is often also an issue which limits system performance.

WHAT ARE THE BENEFITS AND DISADVANTAGES OF INSTALLING A COMBINED SOLAR PVT SYSTEM?

PVT systems are yet to be proven so not really possible to say. There is an inherent mismatch between the two technologies in that ideally PV needs to operate at a lower temperature than solar thermal systems need to operate at to be effective.

HOW DOES SOLAR THERMAL WORK IN CONJUNCTION WITH OTHER SYSTEMS (EG BOILER, HEAT PUMP, UNDERFLOOR HEATING, ETC)?

They should work automatically together. A conventional solar thermal system heats the water in a hot water cylinder. The boiler’s input should be thermostatically controlled so if the water in the cylinder is below the desired target temperature then the boiler simply tops up the solar. If the solar has heated the cylinder to or beyond the target temperature then the boiler won’t have anything to do. Either way the boiler hasn’t to work as hard and fuel is saved. Integration with heat pumps is similar. Integration with underfloor heating is a little too complex to quickly describe and is better with a diagrammatic explanation.

WHAT SHOULD HOMEOWNERS DO TO MAKE THE MOST OF SOLAR THERMAL TECHNOLOGY?

Ideally use most of the hot water in an evening and morning so the hot water cylinder is cool at the start of the day. That way the solar thermal system has a lot of “space” to add it’s free solar heat.

OTHER THAN THE PANELS, WHAT SOLAR THERMAL SYSTEM ELEMENTS ARE NEEDED AND HOW MUCH SPACE WILL THEY REQUIRE?

Mainly a hot water cylinder that should ideally be a little larger than what many people already have in an airing cupboard. It is possible to add solar thermal to a combination boiler (I.e. No hot water cylinder) and there are cylinders designed to supply solar pre-heated water to the inlet of combination boilers. If necessary some of these products can be located in the loft space. Other components, pumps, valves pipes etc take up very little space and will go in the loft or airing cupboard quite easily.

 

Over 100GW
of solar power has been installed globally
- equivalent to around
11 nuclear power stations running full time.
independent
expert advice
to help you make
the smart choice
who we are
your
roof
. calculator
What not
to do
catch the
sun music video