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Solar Thermal Hot Water System

solar thermal hot water system

Solar thermal hot water systems are a very green and (once the installation costs are paid) very cheap alternative to electricity or gas for producing hot water for the home. It doesn't matter whether it is a hot or cold day, the technology works just as well.

They cannot supply all of the hot water a typical UK home would need, especially in winter, and so in terms of pure cost effectiveness have not previously been a valid option in the UK. However, with the introduction of the Renewable Heat Incentive (RHI) anticipated in April 2011, under which those who use the technology will be paid per kWh of heat produced, it has become a potentially valuable, safe investment.

Is My Property Suitable for a Solar Thermal Hot Water System?

Solar thermal hot water systems can be installed at most properties. Ideally you'll need a south facing roof on which to install the panels so that they receive the maximum sunlight throughout the day. Alternatively if you have an east and west facing roof you could install two panels, one on each side, though obviously this would increase installation costs. If you are only able to install panels on a north facing roof then it is unlikely that they will produce enough heat to be worth installing.

You'll need to install a dedicated solar cylinder within your home as a replacement for, or in addition to, the existing tank. The new cylinder will be larger and you must make sure you have space. Finally, your current boiler (which you will still need) will have to be compatible with the solar thermal hot water system. Most are but a combi boiler with no hot water tank is one notable exception.

How Much Will a Solar Thermal Hot Water System Cost to Install?

Installation costs depend on the size of the property. For a 2/3 bedroom house it will cost around £3,000 - £5,000, rising to £5,500 - £8,000 for a 6/7 bedroom home. It may be possible to save some money by doing the installation work yourself. According to at least one installer this is possible though as with any large DIY project this should be approached with caution. Limited grants of £400 are available and you should ask your installer about this.

How Much Hot Water Will a Solar Thermal Hot Water System Produce?

Obviously predicting this cannot be an exact science but on average in the UK a system should be able to produce around 60% - 70% of a home home's total water needs across the year. Naturally the system will be more productive in summer, when it will produce around 90% than in winter, when it will produce around 30%. These numbers could be improved by taking other hot water saving measures such as washing clothes at lower temperatures and taking showers instead of baths.

With the technology as it stands a solar thermal hot water system can only supplement, and cannot replace, a traditional fuel burning boiler.

Can a Solar Thermal Hot Water System Heat My Home?

No. Space heating requires much more heat than a solar hot water system, at least in the UK, could realistically produce. A large system could possibly produce enough to heat a home in the summer, though of course this would be of little or no value. It would not be able to cope in the winter. Some other heating system would therefore need to be in place. There are a number of renewable energy options which are, or will in the near future be, covered on this site.

Is the Heat Produced by a Solar Thermal Hot Water System “Free”?

Yes, at the time of writing no one has yet worked out a way to charge for sunlight! Seriously though, once the system is installed there are no running costs and no scheduled maintenance is required so whatever energy is produced is free both in financial and CO2 terms.

Will Solar Thermal Hot Water Systems Only Produce Heat in Summer?

No, they depend only and sunlight and are not affected by the ambient temperature, though as there is much less sunlight available in winter solar thermal hot water systems will produce much less heat in winter, about 30% of a property's needs compared to 90% in summer.

Could I Get a Grant Toward the Installation Cost?

Limited grants of up to £400 were available but have been recently withdrawn. It is of course in installers' interests to be aware of what assistance is available to their customers and so you should enquire with them about this when asking for quotes.

Could I Get a Loan To Cover the Installation Cost?

There are a number of schemes being discussed but for now, if you have enough equity, you may be better to increase your current mortgage. Interest rates are very low at the moment and a mortgage, although riskier because it is secured against your property, will always be cheaper than an unsecured loan.

How Much Would I Save in Fuel Bills?

The fuel bill savings are likely to be fairly small. The Energy Saving Trust, who are independent of installers, estimate that for a three bedroom semi-detached property the annual saving would be around £50 - £85 depending what type of fuel you currently use (gas and oil are cheaper than electricity). A more significant saving could be made however in terms of maintenance costs. Most solar thermal heating systems come with a 5 - 10 year warranty and theoretically no maintenance will be required in that time. Compare this with a traditional fuel burning boiler, which may quite conceivably need to be completely replaced in that time. You will still need to your boiler but it should last longer if it doesn't need to work as hard. If you were to replace your boiler with, say, a ground source heat pump (also requiring little or no maintenance) you could save even more.

What is the Renewable Heat Incentive and How Much Could I Receive?

The renewable heat incentive (RHI) is a government incentive designed to encourage people to install microgeneration systems, such as solar thermal hot water systems, in order to reduce the amount of fossil fuels consumed and so help the UK meet its CO2 emissions targets.

Under the scheme, homeowners are paid for each kWh of renewable energy they produce. The rate varies depending on the type of technology used, with the greenest technologies receiving the highest rate. The rate for solar thermal hot water systems is 18p per kWh. This is the highest rate as it is the cleanest option. The scheme is still in the pilot stage and the details have yet to be clarified however it is envisaged that the payments will be based on estimated rather than metered use. The total amount of energy that your home should use in a year will be calculated based on size and number of occupants etc. What will not be taken into account is how well or poorly insulated, and generally energy efficient, your home is. Instead, a minimum standard will be presumed.

The “average” home uses around 6,000 kWh of heat per year to produce hot water, so if a solar thermal hot water system were to produce say 60% of that, or 3,600 kWh, this would equate to an incentive payment of £648 per annum.

A note of caution - where you retain a traditional fossil fuel burning (or electric) water/space heating system this may adversely affect the number of kWhs ascribed to your solar thermal hot water system and thus reduce the payment you can expect to receive.

The government have decided to go ahead with the renewable heat incentive and it will commence in June 2011 and in the case of solar thermal hot water systems will be paid for 20 years. Individual rates are yet to be confirmed.

Is Installing a Solar Thermal Hot Water System Cost Effective?

As mentioned above the cost of the installation for a 2/3 bedroom property would be £3,000 - £5,000. The fuel bill saving will be around £50 per annum so based on this alone, the system would take 60 - 100 years to pay for itself. Factor in the renewable heat incentive payment of as much as £650 per annum however and the capital investment could be recovered in 5 - 7 years. The incentive payment is guaranteed for 20 years so in that period up to £14,000 could be earned in fuel savings and incentive payments against an initial outlay of just £3,000 - £5,000, a good return for such a solid investment.

In addition it is worth bearing in mind that fuel prices are likely to rise at greater than the rate of inflation so the actual fuel savings should be higher.

An important note of caution is needed here however, the RHI was a Labour initiative and, although the current administration is equally (if not more depending on the Lib Dem influence) committed to meeting emissions targets, they have not confirmed whether they intend proceeding with the scheme.

UPDATE : The government have decided to go ahead with the renewable heat incentive and it will commence in June 2011.

Do I need to use a MCS installer?

Installation must be performed by a MCS accreditated installer in the case of solar panels, to benefit from the Renewable Heat Incentive (RHI). We await further information about similar requirements for other renewable energy installations.

Once the RHI does launch, most installers will able to assist with registering your system.

Do I Need Planning Permission?

In England you will not usually need planning permission, though you may if the property is in a conservation area. If it is a listed building; you will certainly need to enquire about listed buildings consent. In Scotland and Wales you would currently need to apply for planning permission though the rules are currently under review.

What Maintenance Do Solar Thermal Hot Water Systems Need?

Very little. There any not many moving parts and the safety issues that apply with gas and electrical systems do not apply so scheduled inspections are not required. The panels do need to be kept reasonably clean (though they are cleaned to an extent by rain water) and it is recommended that they are checked perhaps once a year. In addition an engineer should be asked to inspect the system every 3 - 5 years (or as directed by the installer) to ensure optimum performance.

Most solar thermal hot water systems will come with a 5 - 10 year guarantee.

How Long Do Solar Thermal Hot Water Systems Last?

The manufacturers claim that they will last for more than 25 years. This is much longer of course than a boiler would be expected to last and hopefully, in 25 years time although the RHI payments may well have come to an end the technology should, as tends to be the case with new technologies, have become much cheaper.


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