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How to Size Solar Battery for an Efficient System

January 16, 2023

Learn how solar batteries can save you money by partnering with PES Solar. Call 800-650-6519.

How many solar batteries do you need to power your home 24 hours per day? Without the right calculations, you could spend too much on batteries you don’t need. Knowing how to size solar battery banks can help optimize your renewable energy system. 

Below, our solar energy technicians explain how you can improve your power efficiency. After reading, partner with a trusted company to learn more about the basics of solar batteries.

Why Is It Important to Size Your Battery Bank Correctly?

Solar battery installations are expensive and require routine upkeep. Unfortunately, many homeowners do not invest in the correct amount of batteries to maintain energy efficiency. Correctly planning your battery bank helps you save time and money by reducing your dependency on a local power grid.

Key Sizing Factors to Consider

Most manufacturers measure battery storage capacities by kilowatts per hour (kWh) or amp hours. These measurements help determine how much energy a battery can hold and produce when your solar array is inactive.

For example, an average 10 kWh battery may provide around ten hours of power to an appliance that consumes 1 kWh. Still, some factors can cause these numbers to fluctuate.

Every battery comes with a depth of discharge (DoD) rating. This measurement indicates how much energy the unit discharges per cycle relative to its overall battery capacity. For example, a 10 kWh battery with a DoD of 80% roughly provides 8 kWh storage.

Sudden temperature changes may also reduce your battery’s efficiency by a small percentage.

Calculating Solar Battery Bank Size

Knowing how to size solar battery banks doesn’t have to be challenging.

Start by calculating how much power your home consumes daily. If you aren’t sure, an energy bill should give you a good idea of how much kWh your home consumes every month. Divide that number by 30 (days in a month) and then multiply it by 1,000 to convert the sum into Watt-hours.

Now, determine how many days of power you want your home to consume off the grid. For example, suppose you want your 8 kWh batteries (accounting for the DoD) to supply 10 kWh a day for three days:

  • 10 kWh x 3 days = 30 kWh (desired power for three days)
  • 30 kWh power / 8 kWh battery = 3.75 batteries needed

Note: Remember that your solar panels will still consume energy daily unless obstructed by snow or debris. Even if you want to be completely energy dependent, you may only need to calculate a few days worth of power.

Learn More From Trusted Solar Panel Technicians

For some, keeping up with the math when planning a battery bank can be difficult. Fortunately, you don’t need to complete the process alone. At PES Solar, we help homeowners optimize their energy efficiency with world-class solar arrays and support.

Continue exploring our blogs to learn the importance of investing in better batteries for solar energy storage.

Learn how to size solar battery banks with PES Solar in Orlando, FL, by calling 800-650-6519.