The Energy Saving Trust did a survery on a large number of UK and Republic of Ireland solar hot water systems.
- There were 54 flat-plate systems in the trial.
- There were 34 evacuated-tube systems in the trial.
- There was no difference in the annual solar energy yield observed between solar installations using flat-plate solar collectors and those using evacuated-tube solar collectors. This may be because although evacuated-tube collectors have higher insulation, flat-plate solar collectors generally have a larger working area as a proportion of the collector size.
Distribution of the surveyed / trial locations:
So for Silver Spray in Cornwall, should get better results as more sunshine:
The solar energy input to the hot water cylinder is at a maximum in summer, with back-up heating providing more energy in the winter months.
It’s key to set the backup (non solar) heating system to run so that the solar heating can be most effective and the house occupants have hot water when desired.
How to improve the performance of a solar water heating system:
- Using boiler timers and/or solar controllers to ensure that water is only heated by the back-up heating sources after the water has been heated to the maximum extent possible by the sun.
- Timing of back-up heating and hot water use. Systems
provided more energy when the back-up heating was
used just before the main hot water use or at the end of
the day. This provides a better opportunity for the solar
collector to heat the water rather than using the back-up.
- Having an adequately sized dedicated solar volume (that is, a portion that can only be heated by the solar water heating system). Where a dedicated solar volume is not used (for example in systems that do not require the existing cylinder to be changed), the timing of back-up heating has a particularly important impact on performance.
- Insulation is a vital part of this, as systems with poorly insulated storage cylinders can suffer from inadequate hot water provision in the mornings.
- Well installed and properly used systems can provide around 60% of the years hot water.
- Across the whole trial, the proportion of domestic hot water energy provided by solar power ranged between 9 per cent and 98 per cent (with a median of 39 per cent).
- Plenty of other findings, see the report.
Customer / Consumer Advice
What to expect from your installer:
- All MCS installers should be able to provide a detailed breakdown of the specification and costs of their proposed system. They should:
- Complete a technical survey.
- Explain how they calculated the size of the system to be appropriate for your hot water usage.
- Provide an estimate of how much heat will be produced by any proposed system.
- Supply clear, easy-to-understand and detailed information and advice on how best to use the system and operating instructions.
- Explain how the system will be installed and if there will be any disruption to your property.
- Install and set controls and settings to ensure you get the most out of your solar water heating system.
- Provide clear and easy-to-understand information on product and workmanship warranties.