The number of solar panels batteries you need will depend on the size of your system, your power usage and what you want to achieve with your battery.

The solar battery you will most likely need is a 14kWh which comes as a single unit. It is by far the most popular size and suits solar systems 5 – 6.6kW in size. This will be sufficient power to run your home while the sun is not shining.

If you want to go off-grid, you will need a 4 – 5 times bigger battery to account for cloudy and rainy days where power harvested from panels is reduced.

How long do solar batteries last?

Between 5 and 15 years.

The lifespan of solar batteries is affected by some factors. These factors include the type of battery, care, and maintenance.

A solar battery well maintained will last longer. Maintenance is mostly on Lead-acid batteries that have you regularly clean terminals of any corrosion, avoid overcharging, among other maintenance procedures. Proper maintenance will extend its lifespan.

The type of battery is the next factor that affects the lifespan of a battery. In this case, you will find Lithium Batteries to have the longest lifespan followed by Saltwater batteries then Lead Acid batteries.

Lithium batteries- 10 to 15 years

Saltwater batteries- 8 to 10 years

Lead Acid batteries – 5 to 7 years.

Do I need a solar battery?

Solar batteries are not needed if you are using a solar feed-in tariff. You will need one or the other, as trying to run a house on solar panels alone will not work.

The reason is most households use 70% of their power at night. As solar panels generate 100% of their power throughout the day, there will be a large discrepancy between when power is produced and when it is used.

You will need to either store energy for later use in batteries or get credits fro your local energy retailer and draw on the energy later.

Sizing your solar battery system

Sizing your solar battery system is the process through which you calculate the size of batteries you require for the storage of power on your system. Through this, you are able to compare your power requirements with your solar panels and days of power storage and come up with the right battery capacity required.

The process of sizing your solar battery system is affected by the amount of consumption at your home, the number of days you would like to store your energy, and the type of batteries you get.

You have to make sure you have enough batteries for your energy needs and the type of batteries that can be charged by your solar panels.

STEP 1

The first step is calculating the total energy consumption at your home. If you already have a system installed, you can skip stepping 2.

You will need to look at your power bill and work out the average power used by your home daily. If it is a monthly bill, take the kiloWatt hours and divide by 30 to get a single-day usage.

STEP 2

The second step is calculating the best battery size for that energy.

Let’s say, for example, you have a daily usage of 20kWh on average. This is great for a 5kWh solar system that produces that amount of power each day.

Because we use 60-70% of our power at night, we need to store 70% of the power the system produces for later use.

20kW X .07 = 14kW

For this example, a standard size 14.4kWh battery like the Tesla Powerwall 2 or the SonnanBattery will do the job.