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Best Batteries For Solar Power Storage

What Size Solar Battery Do You Need

Calculating the necessary battery size in a solar power system can be a challenging task. The selection of a solar battery size for a solar panel system will dictate the capacity for capturing and storing solar energy.


As battery technology advances and the demand for renewable energy solutions grows, there is a considerable interest in developing solar energy storage solutions. It has resulted in the increasing availability of solar batteries, allowing those already utilizing solar panels to take advantage of this technology.


This article will discuss the process of determining the appropriate battery size for a solar energy system.

Selecting the Right Battery Size

What is your goal?

Many individuals opt to purchase a battery to reduce the grid electricity they utilize, resulting in potential cost savings. Some may want a battery to provide a backup power supply, while others may wish to use solar energy to power their home.


Maximizing cost savings by completely eliminating the need to purchase electricity from the grid is not typically the most cost-effective option. However, in certain circumstances, it may be beneficial to purchase electricity from the grid.

Electricity consumption

The average Australian household consumes 16kWh of electricity daily. A typical domestic consumer may utilize one-third of this energy (5.33 kWh) during daylight hours when solar panels are operational.

If you were to use a battery to power your electricity purchase from the grid, you would need a battery with a capacity of at least 10kWh.

Available funds

If you’re in need of a battery storage solution for your electricity usage and have a budget of less than $10,000, you may find the selection of options to be somewhat limited. Solar batteries typically cost about $1,000 per kWh, so a 10kWh battery would equate to an estimated expenditure of $10,000.

If you are a low-energy user, you could get a small battery of less than 5kWh to serve your needs.

Size of the existing or proposed solar panel array.

The method of determining the appropriate battery size differs depending on whether the buyer already has solar panels or is purchasing a new solar and battery system.


How to calculate battery size

The battery sizing requirements vary depending on whether you are procuring a new solar panel and battery system or if you already possess solar panels.


If you already have a 5kW system or are looking for one, you may need a battery with a capacity of 10kWh to 13.5 kWh. The appropriate battery size depends on your daily electricity consumption and purchase objectives.


  • The battery bank capacity, expressed in kilowatt-hours (kWh), is equal to the amount of energy consumed daily in kWh, multiplied by the number of days of desired autonomy, divided by one minus the state of charge (SOC).


  • The battery bank size calculation is by multiplying 1.9 and 3, then dividing by the difference of 1 and 0.5, resulting in a total of 11.4 kWh.


  • The amp-hour rating is done by multiplying the energy storage capacity in kilowatt-hours by 1000, then dividing the result by the battery voltage in volts.


  • The 24 Volt system requires a capacity of 475 Amp-hours, equivalent to 1000 x 11.4 / 24.

What Factors Impact The Solar Battery Size

Electricity loads

A battery will deplete its charge when a load draws current from it. As the load draws more current, the battery discharges faster.

Your individual needs

Rooftop solar systems are great, but combining them with solar batteries is even better. 


It would be best if you also considered the following factors when selecting a solar battery:


  • Your location and climate.
  • Your solar rooftop system’s energy production. 
  • Consumption of energy: How much energy you consume each day. 
  • What’s on your budget and what’s important to you

Types of Batteries for Solar Power

Sealed lead acid batteries

Lead acid batteries are rechargeable batteries that utilize chemical reactions between lead, water, and sulfuric acid to store electrical energy. This technology is well over a century and a half old, yet it remains widely popular due to its reliability, durability, and affordability.

Shallow cycle batteries

A type of battery that features plates of small surface area and is not tolerant of multiple deep discharge cycles.

Deep cycle batteries

Photovoltaic solar panels generate electricity when exposed to sunlight. To ensure self-sufficiency, off-grid and grid-connected PV systems rely on a single battery or a set of interconnected Deep Cycle Batteries (known as a “battery bank”) to store the generated solar energy.


Photovoltaics harness energy from daylight to power deep-cycle batteries during nighttime or overcast days. Storage batteries are integral to any off-grid or grid-connected alternative energy system, as they help to regulate the DC voltage.

Frequently Asked Questions

Are solar batteries worth the extra cost?

Absolutely. The installation of a battery as part of a home solar system is highly beneficial as it ensures continued power supply in the event of an outage and reduces the need to draw electricity from the grid.
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