SOLAR PANELS
Monocrystalline/Polycrystalline
Solar Modules Solar modules provide some of the highest
power density available in the market. They range from
12 Watts to 160 Watts and yield higher current output
by 10-17% at operating battery voltage. Ideal for battery
charging applications and in stand-alone systems such
as rural electrification, lighting, telecommunications,
water pumping etc. Supplied and installed in Africa
for over 20 years our solar modules have withstood the
test of time in some of the toughest working conditions
providing much needed free electricity to schools, hospitals,
aid project, settlements and missions.
Determining Number of Solar Panels Needed
I. First, reduce your load!
The first thing you need to do (if you haven't already)
is look at ways to reduce your household electrical
needs. Big wasteful energy consumers are electric water
heaters, stoves and heating systems. If possible, these
systems should be converted to gas power - anything
besides electrical. Usually the expense of changing
out these systems is less than the added expense of
having a solar/wind energy system to power these large
electrical energy consumers.

Other obvious things you can do to significantly reduce
your energy needs is to convert all incandescent lighting
to full-spectrum fluorescent lighting. Again, the added
expense of these lighting systems is easily compensated
by the reduction in the cost of your needed solar/wind
energy system.
Next you need to design as system that will meet your
electrical needs. For the sake of simplicity, we're
going to go over the basic steps you would take to design
a solar electric system for a home that's occupied all
year around (as opposed to a summer cabin, for instance).
The difference being that a home that would be occupied
all year round needs to be designed to produce enough
energy during the low-sunlight times of the year.
II. Determine the number of solar panels you
will need
1) Calculate your electrical load. Determine the number
of watt*hours your location will use on a daily basis.
For an entire home, this will take some busy work. You
need to determine:
What appliances you are going to power.
How many Watts does each appliance consume?
On average, how many hours do you use this appliance
per day? (Don't forget to include those things that
you use on a weekly or monthly basis, like a vacuum
sweeper or a blender).
Calculate your average daily watt*hour usage for your
entire home. That is, multiply the watts of the appliance
time the average number of hours used per day.

2) Determine the equivalent number of full-sun hours
for your location for the month with the least amount
of sunlight (typically December or January).
3) Divide your load calculation from step 1 by the
number of full-sun hours from step 2. This is will tell
you the number of Watts of solar panels you will need
to provide you enough electricity in the lowest sun-light
months.

4) Compensate for system inefficiencies. Every part
of a solar powered system has some inefficiencies in
it. The rule of thumb is if you are going to use an
inverter (to produce AC) your total system inefficiency
will be 30%. For systems that will be using the DC voltage
directly from the battery bank, the inefficiency factor
is 20%. So, to compensate for inefficiencies multiply
your answer to step 3 by 1.3 (or 1.2, if there's no
inverter). This answer is the number of watts of solar
panels you will need to provide enough electricity for
your loads.
5) Finally, to determine how many solar panels you
will need, take your answer from step 4 and divide it
by the rated power output (watts) of the solar panel
that you have chosen.
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