Solar thermal panels/tubes are designed to produce around 50% - 70% of an average homes hot water usage over the year. In this respect they are a great addition to most properties and also qualify for the renewable heat incentive (RHI). In the summer it is possible they can provide all of your hot water requirements and in the winter months they will produce approximately 20%. Hot water is needed on a daily basis and therefore will always be a cost but what solar power will do is give you a reduced rate of expenditure. Energy suppliers can hike their prices but the sun’s energy doesn't cost a penny!