The much vaunted, long awaited, highly anticipated, often delayed Renewable Heat Incentive is finally with us, and brings yet more surprises.

The probable tariffs were announced some time ago and the industry was pleasantly surprised to see that solar thermal technology (that producing hot water rather than electricity) was to attract a rate of 19.2p/kWh, a good deal higher than anticipated. But then, a week before the scheme officially launched, the eligibility rules were published by the Department of Energy and Climate Change (DECC) and revealed that the sole eligible use for solar thermal technology (flat plate or evacuated tube) is for producing domestic hot water. Ineligible uses are swimming pools, space heating and anything other than domestic hot water.

DECC confirmed that domestic hot water means water coming out of a tap or other outlet and that the solar thermal system must be connected solely to that outlet system. Further clarification confirmed that any solar thermal system connected to a thermal store or other hot water storage cylinder that supplies both domestic hot water and space heating would be ineligible and unable to claim RHI.

This means that the vast majority of solar thermal system so far installed, and yet to be installed, will not be eligible for the tariff. Put simply, using a thermal store is the best, most efficient and effective way of using a solar thermal array, which is why they have one.

Reading between the lines, it seems that this rule is a mistake. It is not clear if it comes from a misunderstanding of the way solar thermal system work, is simply poor drafting or the government’s attempt to discourage the use of solar thermal (at its higher tariff) from being used as the sole heat source. The rule goes against everything the RHI scheme is intended to do and the buzz in the industry is that this mistake will be rectified, although probably not before January 2015. As a consequence those people that have invested in a solar thermal system are left not knowing if they will get an RHI tariff or not for at least 9 months.

The government’s history in terms of the RHI scheme is not great and it would be a leap of faith to assume that all will be well come January 2015. People planning on installing a system will be taking a gamble and this eligibility rule has to be a body blow to the solar thermal industry, the only truly zero carbon heating technology.

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