Why Use Solar Power?
You can bring power to a shed, workshop or summerhouse for lighting, tools or an alarm system. You can bring power to electric gates and fences without running cables across your garden or through your home.
You can ventilate your greenhouse with an extractor fan.
You can trickle charge your car, motorhome or boat battery to keep it in peak condition and extend its life.
As for caravanning, with a Solar panel to power your TV, radio or computer, you are not tied to a 240v hook-up on a busy campsite. You really can get away from it all!
The possibilities are endless - and all without adding a penny to your electricity bill!
How to calculate your solar power requirements
There are three things to consider in order to choose a Solar panel or create a Solar system.
You need to know how much energy your battery can store and then select a Solar panel that can replenish your stock of energy in the battery in line with your pattern of use.
1: How much energy can your battery store?
Battery capacity is measured in Amp Hours (eg 17AH). You need to convert this to Watt Hours by multiplying the AH figure by the battery voltage (eg 12V).
For a 17AH, 12V battery the Watt Hours figure is 17 x 12 = 204WH
This means the battery could supply 204W for 1 hour, or 102W for 2 hours i.e. the more energy you take, the faster the battery discharges.
2: How much energy will your appliance(s) use over a period of time?
The power consumption of appliances is given in Watts (eg 21" fluorescent light, 13W). To calculate the energy you will use over time, just multiply the power consumption by the hours of use.
The 13W light fitting, on for 2 hours, will take 13 x 2 = 26WH from the battery.
Repeat this for all the appliances you wish to use, then add the results to establish total consumption.
3: How much energy can a Solar panel generate over a period of time?
The power generation rating of a Solar panel is also given in Watts (eg STP010, 10W). To calculate the energy it can supply to the battery, multiply Watts by the hours exposed to sunshine, then multiply the result by 0.85 (this factor allows for natural system losses).
For the Solar 10W panel in 4 hours* of sunshine, 10 x 4 x 0.85 = 34WH. This is the amount of energy the Solar panel can supply to the battery.
Note: Battery condition and weather conditions affect performance.
Tip: The bigger the battery, the more energy you can store so you can draw more power for longer.
Tip: Look for energy-efficient appliances (low power consumption) so the battery lasts longer.
Tip: Large panels can collect more energy in less time, but a small panel that is permanently exposed to the sun may be suitable.