Hi John;
Who has the space to have these platforms moving
around all over the yard or roof?
Tracked PV systems don't really take up much more roof
area than fixed panels for the same energy throughput
per day.
Remember, you have less of those expensive PV panels.
Use the space for stationary panels and get more.
If the same space is properly covered with a tracked
array the energy output would be about the same.
However there would be a substantial savings in initial
costs.
30% - 40% doesn't stand up in most practical/actual testing.
Do you have any references to this?
This is often what one would get in the November to
February portion of the year. However, in the May to
August the increase is more like 100%.
Of course there a bunch of factors and one needs to
study the NREL data set to see what your location can
do.
OK, tracking on a roof is not as good as a system that
can turn more than 180 degrees which the roof mount
can't do.
It can spread your peak charge out over a longer period
though if you can't take the shorter "surge"
I rarely here anyone state this important factor. To go
further, the spreading of power generation increases the
likelihood that the power would be consumed directly by
the user. This avoids the efficiency loss of passing the
energy through ones batteries.
I realize this thread has been about PV. But thermal
collectors also have an increase. Especially those low
efficiency flat plate collectors.
These flat plate collectors only reach their best
efficiency when the sun is normal to them. They have
two loss mechanisms.
1. The cosine loss. (This is the same loss that PV has.)
2. Concentration loss. Concentration factor is 1X when
the sun is strait on. Stasis temperature and operating
temperature define the efficiency. When the sun is off
axis the effective concentration factor is less than 1X.
Causing stasis temperature to be lower while operating
temperature is the same the efficiency must be less.
Cooler yet. The concentration factor could be higher than
1x. Maybe 2X or 3X. This substantially increases system
efficiency over the flat plate version. Especially in colder
weather conditions.
I would state this differently.
I would say the increase can be as LOW as 30% to 40%.
Duane
--
Home of the $35 Solar Tracker Receiver
http://www.redrok.com/electron.htm#led3X [*]
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