Hi,

so, here's how I understand things:
1) evacuated tube collectors (ETC) maintain efficiency at higher inlet temperatures;
2) flat plate collectors (FPC) are more efficient at low inlet temperatures;
3) ETC are more expensive than FPC by both per joule and per sq_m.

what's to stop us trying to optimise using the benefits of both in a mixed system?

I'm thinking: 6-8sq_m of FPC in series with ~2sq_m of ETC.

Is there any technical constraint that would prevent this being viable? (apparently the MCS certificate can't handle it but that's bureaucracy, eh?)

best wishes - Jeremy