A special version of my southern reflector “WinterSun” range which is horizontally pivoting so that it serves as an adjustable angle reflector in winter (roughly mid September to mid April) and an adjustable angle photovoltaic panel in summer (roughly from mid September to mid April) – the turning times being weather dependent.
The reflector is calculated at 47% efficiency (radiant external input > radiant internal output) for ~ 6 months with a 27% efficiency of electrical production facing south = nom.14W x 5hrs x 180 days = 12.6 kWh.
With the PVs facing north an output of ~20% = 51W (= nominal 65W x 5 hrs x 180 days = 58.5 kWh = total output of 72.5kWh pa = aver. 20W/day output. – not a great deal but it helps to run my computer and PV efficiencies are improving all the time.
With today’s high efficiency panels that output could be increased and using thin film (TF) panels the cost could be reduced and the whole panel made lighter in weight. Re-design is under way but difficulty in obtaining suitable TF panels is a problem. (2015).
One interesting fact I have discovered is that the PVs seem to be most efficient when at a flatter angle than prevailing recommendations – judged by the ammeter output alongside the panels An angle of 25-30º seems to give the best electrical output.
I haven’t had time to record the figures however – its on my TO DO LIST.
PS Since writing the above I have installed more PVs on the workshop roof – see p 21
See also my paper “ Southern domestic reflectors – capturing unused solar radiation”
cited by Google using key words – cheerfulness, sunlight, inside rooms
Read at the ANZ Solar Energy Society conference at ANU 2006.