I wonder if anyone out there has experience of installing and running such a system. Essentially I am looking for all the components - so direction there would be most appreciated. Cheers
Summary of System Control
1) PV panel (1) drives primary circuit pump (3) The primary circuit is a water/glycol mix to prevent freezing PV electricity output is proportional to sun intensity. If correctly matched and sized, the pump provides correct flow rate for the given insolation and switches itself of at night
2) The primary circuit transfers heat from a collector (2) to the solar water cylinder (5). The collector will probably be an evacuated tube design The cylinder is an unvented twin coil design
3) The store provides pre-heated water to the combi boiler’s (7) DHW inlet The boiler must be abler to change burn rate from a low or zero value to 100%
4) Should the solar water exceed (say) 60 Deg C a thermostat will divert cold mains water to a mixing valve upstream of the taps to prevent scalding. Thermostatically controlled mixing valve with temperature offset needed here.
5) If the solar cylinder temperature (Tstore)is higher than the return flow from the radiators – measured by (Tret) the 3 way valve (
diverts the flow through the second coil and on to the central heating inlet at the combi Thermostatically controlled diverting valve needed here.
Required Safety Features 6) If the primary circuit pump fails under insolation water temp will rise possibly to superheated steam (200 deg C quoted). Donot have a solution for this yet
7) If the solar water cylinder temp rises to (say) 70 Deg C the CH pump is energized to pump water round the radiators. Programmable stat controller with user defined offset (hysteresis).
