Power from the sun
Unfortunately only 5 - 17 percent of solar energy can be converted to useful electricity. To understand this and help in selecting the solar cells for your application it helps to understand a little about how solar works.
Types of Solar panels
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Mono Crystalline
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Poly Crystalline
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Amorphous
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1.
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Crystalline Silicon PV Module: There are 2 types of
crystalline silicon (c-Si) are used PV modules. Mono crystalline and
poly crystalline. Conversion efficiencies of crystalline pv modules
averages about 10-15%. Downside is poor effeicieny in low light
conditions and are not shadow reststant. Dust and dirt deposits reduces
efficiency considerably. |
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2.
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Amorphous Silicon PV Module: Amorphous silicon (a-Si)
PV module or thin-film silicon PV module absorbs light more effectively
than crystalline silicon PV module, so it can be made thinner. However
it's efficiency is low at between 6 - 8%. Production cost is lower.
Amorphous panels are usually twice the size of crystalline panels for
the same wattage. Because of it's higher efficiency in low light and
being shadow resistant actual power production is higher than
crystalline panels. |
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3.
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Hybrid Silicon PV Module: This combines the advantages of the above two types of panels (c-SI) and (a-SI). By surrounding mono crystalline silicon with thin layers of amorphous silicon we increase the mono crystalline panels to lower light levels and indirect light. Hybrid silicon PV module has highest conversion efficiency at around 17%. |
Which Solar Panel
For most people price is always the
single most crucial factor.
From cheapest to most expensive
1. Amorphous
2. Multi-crystalline
3. Mono-crystalline
4. Copper indium
Amorphous panels are cheaper to
manufacture and to compemsate for lower efficiency the panels are twice
the size of similar capacity multi-crystalline panels but half the
price.
If space is a problem such as on boats and caravans then
mono-crystalline panels are the way to go.
If not then amorphous panels should be the choice as the same 20 year
warranty is offered.
Advantages of Amorphous Panels
Multi Amorphous panels are reputed to
work in low light. The reason for this is clear when you consider that
the BD40 amorphous panel has peak operating voltage of 62 volts.
As voltage drops in low light it is still above 13.5 volt charging
voltage of your 12 volt battery bank.
With a multi-crystalline panel it's operating voltage is from 14 - 18
volts. If the voltage falls below 13.5 volts the battery cannot be
charged. Energy produced will be dissipated by the controller.
Amorphous panels are shadow resistant meaning that power production is
not cut-off if a shadow falls over the panel.
The glass surface is smooth. Dirt and grime forming are easily washed
off. Bird droppings will not cut-off power production.
As amorphous panels work well in indirect light it's efficiency could
be increased with reflected light.
