Harnessing the power of the RHI


Robert Burke, HETAS, encourages installers to diversify into multiple technologies to meet the shifting needs of the market

It’s difficult to talk about renewables without mentioning the RHI, but it is one of the main drivers behind the demand for biomass, solar, wind and heat pump technology. The non domestic RHI has been successful in helping commercial users to make the switch to more renewable forms of energy, and it’s hoped that the domestic version will follow suit when it’s launched sometime next year.

But rather than considering just one technology, there has been a change in attitudes to using hybrid systems for domestic users. Traditionally these have been popular in commercial installations where a specific piece of equipment is used for a certain job such as water heaters for domestic hot water, and boilers for space heating only – as opposed to one boiler doing both jobs. However, the rising price of fuel has made many consumers examine their energy costs and look for the most effective way of providing heating and hot water for their homes.

Solar thermal is the perfect partner for biomass boilers, with solar capable of producing cost effective hot water and heating during the summer backed up with the heating capacity of the biomass boiler during the winter. Together the two technologies combine to help bring down energy costs. And, with the addition of an individual room heater such as a log burning stove, households can reduce their carbon footprint and save energy at the same time.  

Solar thermal and biomass boilers can be combined using a thermal store, which can be used to supplement space heating and hot water demands. In the summer hot water (and space heating if needed) is effectively supplied free of charge from the sun’s energy. To meet the requirements of the MCS, a hybrid solar/biomass installation must use a thermal store in order to efficiently use the energy generated by both renewable sources.

Using a hybrid system with a thermal store means your customer can have mains pressure hot water without the need for a pressurised unvented system. As the mains pressure hot water is fed into the store it passes through a coil heat exchanger where the heat inside the thermal store is transferred to the mains water. A blending valve fitted at the exit of the coil brings the water to the required temperature. This type of system avoids the need for large runs of pressure relief pipe work and reduces the risk of Legionnaires ’ disease from large volumes of stored hot water.

With tariffs already confirmed for the domestic RHI now is the time to make sure you’re up to speed with training and qualifications. MCS registered installers using MCS approved products will be able to take advantage of the full funding available, which could mean householders will receive hundreds of pounds a year for using biomass boilers, solar thermal panels or heat pumps. The tariff levels for biomass boilers have been set at 12.2p/kWh, and households will be paid on a quarterly basis for seven years based on the estimated heat demand of the property. A Green Deal assessment is required, and installers must be MCS certified or equivalent.

Most biomass installations are likely to be in rural areas, and installers working in off-gas areas are being encouraged to add both solar and biomass qualifications to their skills. For more details on MCS certification, installers and products visit www.hetas.co.uk.