Before purchasing any equipment you need to know what appliances you intend to use and for how long, this will help in assessing the size of the solar panels required. There are various terms used when describing power consumption, here we will explain what they mean in easy to follow stages.
How much power do you need?
All appliances have a power rating of VA or Watts (VA also means Watts) this refers to the amount of energy consumption the appliance uses over a one hour period. Watts are normally used because it is a universal indicator for 12v and 240v appliances.This rating can be found either on the appliance or by looking at the technical section of the manual.
Example:
A 20w low energy light bulb would consume 20 watts per hour or 40w in 2 hours
A typical LCD TV consumes approx 110 watts per hour or 220 watts in 2 hours
To use the above light bulb and TV for 2 hours per day we would need a solar panel system capable of providing a total of 260 watts hours of power (260wh).
You can use the above guide to calculate your power requirements per day.
Selecting the solar panel
All of our solar panels are shown in watts (IE: 10w, 20w etc) this refers to the maximum amount of power the solar panel produces in one hour of sunshine. The amount of hours of sunshine can vary depending on where the panel is located and the time of the year, winter / Summer etc. A typical solar panel will provide around 70% to 80% of it's stated power so, when calculating how much power you need it is advisable to add 25% to your needs.
The above example shows that 260 watts of power is needed, therefore you would need to purchase a solar panel kit which could produce approx 325 Watts of power (260w + 25%).
To calculate the maximum power a solar panel can produce, firstly select the size of solar panel then multiply it by the amount of sunshine hours you would expect.
A typical 60w Solar panel in 6 hours of sunlight at maximum power will produce 360 Watts (60w x 6), this would be sufficent for our needs.
Please note that the term sunshine hours does not neccessarily refer to direct sunlight, our solar panels will continue to generate electricity even on cloudy days.
Batteries
The type of battery used is very important, all batteries are made up of 2v cells, the types sold on this site are 12v batteries consisting of 6 x 2v cells.
The capacity of batteries is measured in Amp Hours (IE: 26ah) to calculate the capacity multiply the AH by the battery voltage. In this case it would be 26ah x 12v = 312 watts.
This means that the battery could supply 312 watts of power for one hour or 156 watts over 2 hours. It is also worth considering the amount of power you may use during sunshine hours. If no power is required during the daytime then the battery will need to store the whole amount for nightime use.
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