The Energy Saving Trust has published the results of a solar water heating trial. There are some interesting findings which I’ve excerpted here:
Summary of key findings
1. Solar water heating systems have the potential to work well in the UK and the Republic of Ireland when installed properly and controlled adequately by the user.
2. From the properties we trialled, well-installed and properly used systems provided around 60 per cent of a household’s hot water. The trial also found examples where systems were not properly configured or used, and where the contribution from solar was as low as 9 per cent. The median across all systems was 39 per cent.
3. Householders in the trial were happy with their solar water heating systems: 84 per cent were “satisfied” with their system, and over 50 per cent were “very satisfied”.
4. In the field trial, there was little difference between the total solar energy yield of those installations that used flat-plate solar collectors and those that used evacuated-tube solar collectors.
5. The trial found that the way householders use their solar water heating system is critical in achieving the best results from solar water heating systems. Better advice to users on how to control their solar water heating systems (in terms of volume of hot water use, timing of back-up heating and hot water use, and temperatures required) is essential.
6. Where mains electricity provided power to the pumps and controllers of systems in the trial, the amount of energy used was generally small compared with the overall heat delivered.
7. We observed insufficient insulation installed on some hot water storage cylinders and pipes. This significantly reduced the proportion of hot water their solar water heating systems provided.
8. Industry standards should be reviewed to ensure they reflect the findings of the trial and the need for better advice to customers.
9. Solar water heating systems can achieve savings on energy bills. Based on the results of the trial, typical savings from a well-installed and properly used system are £55/year when replacing gas and £80/year when replacing electric immersion heating; however, savings will vary from user to user.
10. A well-installed and properly used solar water heating system is likely to provide carbon savings. The typical savings are 230kg/year when replacing gas and 510kg/year when replacing electric immersion heating.
If you’re thinking of going for solar water heating then it’s worth checking out the report. EST also published a similar report on their heat pump trials a while back.
Renewable heat sources are expected to be supported by the Renewable Heat Incentive (which will be similar to the Feed In Tariff for electricity generating microgen) but there have been many delays to its launch and it is currently uncertain exactly when it might come into effect.