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Solar
Water Panel Calculator
How many
solar panels should I install?
Solar panels
can supplement other sources of heat to reduce your overall heating
costs and lower your contribution to greenhouse gas. While it
is theoretically possible to design a system that could provide
all your heating needs, it may not be economically practical because
of the need to install large amounts of thermal storage for those
times when the sun does not shine.
In northern
climates we receive the least hours of sun when we need it the
most. If we design for these conditions we will end up with heat
we don’t know what to do with in the spring and fall. The
following will assist you in estimating how many panels you should
start with. This is based on our experience in testing our systems.
Let’s
assume you want to heat your workshop. How many panels should
you use?
The quantity
of heat loss is a function of the building area, the temperature
difference between indoor and outdoor and the resistance value
R of the insulation and wall material. Other factors might include
leakage and windows. We will try to keep it simple.
The WSE heat
loss calculator below will help you determine how many panels
you should install. This is an approximate value only.
Insert R value.
If you are not sure of this, assume 12 for 4 inch walls or 20
for 6 inch walls if it is well insulated.
Insert the
dimensions of your building. Choose feet or metres.
Insert desired
temperature difference. This is the number of degrees above ambient
that you would like to achieve in the building. Choose C or F.
Insert number
of hours of daily sunshine for your area. You can obtain average
numbers from the weather office or you can just take a guess.
We suggest using a number that reflects operation in October-November
or February-March instead of December-January.
For those
of you engineer types out there who are busy checking my calculations,
please note that I have included an arbitrary correction factor
for air leakage.
To arrive
at some design heat loss, we must correct for the hours of sun.
This will mean that the temperature will overshoot the design
conditions when the sun is shining and fall below design conditions
when it is not. This fluctuation can be reduced by installing
thermal storage if desired. If you happen to have in-floor heating
and a concrete floor, the thermal storage is already there.
It is recommended
that you install solar panels that will provide about 50% of design
loss to start with. Remember that it is very simple to add more
panels in the future.
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