Solar Battery Storage

A solar battery is a rechargeable battery which stores  electricity generated by solar PV panels in a battery so that it can be used at a later time. When solar panels are generating more electricity than is being used at that time, it is sent to the battery rather than the grid.

When a home is using more power than is being generated by solar, the battery discharges to meet the demand.

With many solar brands now offering integrated solutions for solar panels, inverters, and battery storage system products, they are becoming increasingly popular as a way to make use of surplus electricity instead of letting it go to waste and monitor your energy usage.

The size of battery which would be suitable for you depends on your electricity consumption, along with the number of panels in your solar PV system and its power output.

Ideally, you would like to have a battery system that can handle all of your evening energy consumption, when your solar panels are no longer producing energy.

The average household in Ireland used 3,177kWh of electricity in 2022, which averages out at 8.7kWh per day (Source).

Buying a battery with a storage capacity which exceeds your daily consumption would be pointless. Ideally your solar panels should be supplying most of your electricity in the day, and the battery takes over for the evening time consumption.

There are multiple technical factors to take into consider when picking a solar battery beyond just its capacity. The battery material, lifespan, storage capacity, depth of discharge, and efficiency can vary greatly between brands and models.

Many of these considerations may also factor into the cost of the battery storage system.

As spoken about above, the choice of technology for your battery system is an important factor in its performance and cost. The newer Lithium-Ion batteries are more compact and efficient, but cost more, whereas Lead-Acid batteries are less costly, but older technology.

This refers to how much of a battery’s total capacity is used up before it is recharged. Having a deeper depth-of-discharge typically results in a battery with a shorter lifespan. If your battery states that it has an 80% DoD, then you should keep it above 20% capacity before recharging.

Solar batteries are not 100% efficient when it comes to transferring and storing the energy generated by your solar panels. The higher the efficiency of your battery, the less electricity that is lost in transition.

The electricity produced by a solar panel and that which is stored in a battery is in the form of Direct Current (DC). The electricity used in your house, however, is Alternating Current (AC).

This means that the electricity created by a solar panel cannot be directly used in our homes and must be first converted to AC electricity. This is done by the inverter.

If installing a battery along with solar panels there then becomes a technical question of where the battery should be placed.

AC Coupling

The solar electricity goes first to the fusebox of the home grid and is converted to AC. This must then be converted back to DC before it can be stored in the battery.

DC Coupling

The battery is located between the solar panels and the fusebox, meaning that DC electricity from the panels is stored directly without needing to be converted.

There are many companies manufacturing solar batteries of different scale and technical quality, and it’s important to choose the brand and model that most closely fits your needs.

Some of the more well known brands of solar battery manufacturer include:

These different companies offer a wide range of products each, batteries of different sizes, with state of the art monitoring systems, AC or DC systems, and the ability to use multiple batteries in sync.

Whether solar batteries is right for you depends on multiple factors related to how much electricity you use around the home, the price of electricity, the cost of the system, and more.

With the cost of installing a solar battery, if your surplus electricity is being used for another purpose, it bears thinking about whether the investment is worthwhile.

If you have a power diverter installed to send your excess electricity to the immersion, that means less power which can go to the battery storage.

Since 2022, Ireland also now allows homeowners to sell electricity from solar panels back to the grid. This means that excess electricity being generated by your solar panels can either go to battery storage for later use, or you can be paid for it by your utility provider.

This can potentially help increase the return on investment of your solar PV system, and shorten the length of time before it has paid for itself.

The feed-in tariff, the rate paid for excess electricity, is set by your utility company, and is generally significantly less than what it costs you to buy electricity. So having a battery to alleviate the need to purchase electricity from the grid can be a better investment.