If you’re going to have a solar powered electrical system you’ll want to know how big you have to build it. In order to do this you need to take into consideration the storage capacity required,the maximum discharge rate, the maximum charge rate,and the minimum temperature the batteries will be stored at. The capacity rate will determine the size of the battery.
The temperature where the batteries are stored is a critical factor because the batteries performance is affected significantly. At 40 degrees the battery will be at 75% capacity and at 0 degrees it will be at 50% capacity. A battery that isn’t affected by this is the Concorde PVX. This battery is acclimated to withstand temperature indifferences. If you need to store your batteries outside is recommended that you use a sealed gel type battery. Be sure to insulate your storage area well even if you have batteries that temperature resistant.
First you will need to add up all the wattage hours used in your house. To do this all you have to do is look at the wattage rating on your appliances and multiply it by the hours of use each day. If there isn’t a wattage rating just use the amps rating and multiply it by 120 volts,that will give you the watts. ( amps x volts = watts) Side note you won’t be able to power large wattage appliances because it will drain your battery bank too fast so anything over 1500 watts should not be included in your configuration.
Then you add all the appliances wattage hours together. Remember this is for each day of use separately. Then multiply it by 3 because if your power is out for three days you’ll need to determine what size you need for that length of time.
To find battery capacity multiply daily watt hours usage by 2 that way you will use only 50% of the battery capacity.To determine the size of the battery bank in hours you will divide the total watt hours by whatever size battery system you’re using 12,24,48 volts
For instance if you have 25200 watt hours take that 25,200/12volts=2100 amp hours then divide that by whatever your batteries amp hour rating is and you’ll get how many batteries you’ll need to use to have enough energy to run your appliances comfortably if you didn’t have 3 days of power or three days of no charging your batteries.
For example your house uses 25,200 watt hours of power and you use 12 volt batteries in your battery bank so you divide 25,200/12 =2100 amp hours then divide that by the batteries amp hour rating. which in this case is 105 amp hours for the 12 volt system you’re using. This comes out to 20 batteries in your battery bank. This number will vary on the size of your battery.
If you need to store the batteries a considerable distance from your power box you will need to hook them up in series so you will have more voltage.It is more efficient to do this because you will lose amps through the power cable than if you have them hooked up in parallel. To hook the batteries in series you connect positive to neg and neg to positive.
To hook the batteries in parallel you hook them up positive to positive. and neg to neg. This will increase your amperage to increase your batteries capacity. This will allow you keep your batteries closer to your power box. And will give you more battery usage.
You can wire your batteries in series to increase your battery amperes capacity If you would like to know more about having a battery storage system check out my other article about what batteries you should use for your solar powered system.
Now you know how many batteries you’ll want to have in your solar powered system. In my next article we’ll discuss what kind of battery is the best for you. 12 volt 20ah lithium battery