Whilst payback for Solar PV is around 8-10 years, and is fairly consistent across properties, the payback for solar thermal is much more variable from house to house. Below we give you an idea of the potential payback periods for solar thermal.
The payback time of an energy-saving solution is a measure of how cost-effective it is. The payback time will be shortest if the cost of installation is low compared to the savings made each year. \ (\text {payback~time}=\frac {\text {installation~cost}} {\text {annual~savings}}\)
The amount of energy saved during a setback period depends on how far you let temperatures drift and for how long they remain in that setting. The more you let your home temperature drift – and the longer you let this drift occur – the more money you’ll save.
With a SEG payment of 4p/kWh, the payback period is 12 years. If the SEG payment increases to 15p/kWh, the payback period would increase to 19 years – arguably longer than the battery’s lifespan – as the relative benefit of not having a battery has increased.
Most of the components are covered under a warranty of at least 5 years, some are 20 years. If there’s a failure that ends up costing me then I’ll have to re-assess the payback timeframe I will be ignoring panel degradation.