NOTE: The usage hours above assume you have had adequate sunshine to fully charge your battery, or your battery has had a full solar re-charge because you have not used it recently.
FURTHER CALCULATION & GUIDANCE NOTES
You may find that in order to full charge larger capacity batteries, especially during the winter months, that you need to design your system with more solar power wattage input, in some cases a multi solar panel array maybe needed.
BATTERY AH TO KWHR CALCULATION NOTES
In some systems, 12 volt batteries will be connected in series (end to end) to create a higher final voltage which may be needed to suit the type of inverter used. For example, two 12 volt batteries in series will provide 24 Volts, or 8 x 6v batteries in series will provide 48V
In the above 12v Battery example, if two 12 volt batteries rated at 100 Amp Hours were connected in series, while the voltage would increase to 24 Volts, the Amp Hours would remain the same. Therefore, whilst batteries in series add the total voltage together giving a higher voltage output, the total Ah capacity of the batteries is not added together in the same way.
An example of why this happens can be seen when comparing batteries wired in series and parallel. For example, 2 x 100Ah batteries in series would give a 24v output at 100Ah = 2.64Kwh OR 2 x 100Ah batteries in parallel would give a 12v output at 220Ah = 2.64Kwh. Battery KWh storage is indicated above below the battery capacity user input box.
A battery solar charge controller will be needed in most circumstances to control the output voltage from the solar panel (usually 18-22 volts) and ensure steady charge to the battery. Our charge controllers also have a 12v output and a 5v USB output.
TYPES OF SOLAR ELECTRICITY STORAGE BATTERY
The natural cost effective choice is to use a deep cycle lead acid battery but please be aware of their limitations as below. Battery limitations may mean it could be better to oversize the battery for you required usage to reduce the depth of discharge and in turn prolong battery life
|Depth of Discharge||Deep Cycle Battery|
||1000 and more cycles
Other types of specialist solar power storage lead acid batteries are available which can last for over 2000 deep discharge cycles. These often have specially coated and thicker heavy duty positive plates within the battery.
Lead acid car batteries or similar should not be used for solar electricity storage purposes as they are not suitable for deep discharging due to their thin lead plate construction.
You may wish to use an inverter with your battery in order to convert the output voltage to power 240V AC appliances. Note that whilst inverters are very useful, they do only have an efficiency of around 90% meaning that 10% of your battery storage will be an inefficiency loss. Alternatively, you may wish to consider using 12V DC input lighting and appliances which would not suffer the invert losses.