is the difference between solar thermal and solar photovoltaic?
Currently, there is a big confusion between
photovoltaic cell generates electricity. It faces south, it must be inclined
at 35 degrees to maximize production across the year.
In France it is systematically integrated into the roof
(the tiles are removed) because the purchasing price is much more interesting
vs a non integrated solution. This integration is the only source of defects
related to PV.
temperature collector is used to heat a house and/or to produce domestic
hot water, it must be inclined generally at 60 / 70 ° (can even be
installed vertically), so it can provide part of the winter heating and
DHW during the summer months without causing overheating. In order to maximize
the heat production, the collector must be strongly inclined to collect
the sun ray, as the winter sun is low. Here, we are not looking for the
maximum yearly production but rather the best fit between heat production
and the needs. Obviously producing Domestic Hot Water for camp site in
summer, would need to maximize summer production, i.e. the collector
should not be inclined too much as the summer sun is very high.
Is it true that the ultimate
flat plate collectors are better than evacuated tubes?
Under normal household use, a flat collector average yield
is actually better than average evacuated tube collector (calculated against
the overall surface). See detailed study here
We often hear that solar heating
is not possible with dissipation in radiators, what is it?
This is absolutely false, if you read the proposed study
on the above link, you understand it is key the collectors work at low
temperatures (low delta T). Obviously make solar heating in a thick concrete
floor (20/25 cm) capable of storing a large amount of energy is very efficient.
We are going to illustrate this by comparing a simple solar DHW, a house
heating with radiator and a direct floor heating.
take the best collector tested by the CSTB, the French Testing organization.
It is a Tinox coated collector: the top line in light blue. At an outside
temperature of 0 ° , the delta T will be equal to the collector temperature.
Direct Floor heating require a temperature of 30/35 °
C: yield is then around 60%.
In case of radiator require temperature is 45/50 °
C: yield is around 55%
Case of DHW, temperature is 65/70 ° C: yield is around
45% see even worse if one wants to raise the water at 80 ° C
Conclusion, one cannot promote solar DHW and at the same
time says that solar heating with radiators is not performing!
How much training does it take to
become a good solar installer?
The solar installer is a carpenter, a plumber, an electrician
with knowledge in automation and industrial IT. From our standpoint, we
need a serious training to acquire these skills, in France the BTS level
that seems most appropriate.