(→‎Collectors: pool itself)
(acromondomch)
caletorolic4
'''Solar Thermal''' systems use Solar energy to provide heat (as opposed to Solar Photovoltaic systems which generate electricity).
===Pump Power Reduction===
System running cost depends on pump power, as this is the one ongoing non-free energy input. Designing to minimise pump power can reduce run cost to trivial levels, whereas an inefficient design with a 500w pump can cost £100 a year to run. (example 10p/kWh, 8 hours a day pumping, 8 months per year use.)
===Potential Returns===
The amount of energy used to heat water is quite limited for domestic uses, so the energy return for [[Domestic Hot Water|hot water]] systems is inevitably limited, and is in most cases below £100 per year. Much more energy is used for space heating, so greater returns are possible with a warm air system.
The amount of energy used to heat water is quite limited for domestic uses, so the energy return for [[Domestic Hot Water|hot water]] systems is inevitably limited, and is in most cases below Â£100 per year. Much more energy is used for space heating, so greater returns are possible with a warm air system.
==Return on Investment==
===ROI===
'''ROI''', or Return On Investment, is the money a solar system saves in one year as a percentage of system cost. As an example, an £800 system saving £80 a year on heating costs would give 10% ROI, and this system would take 10 years to pay back its cost if interest were disregarded. IRL it would take a good deal longer due to interest.
'''ROI''', or Return On Investment, is the money a solar system saves in one year as a percentage of system cost. As an example, an Â£800 system saving Â£80 a year on heating costs would give 10% ROI, and this system would take 10 years to pay back its cost if interest were disregarded. IRL it would take a good deal longer due to interest.