Solar batteries: their benefits & capacity

Solar battery storage is a separate add-on to solar panel installation, designed to help you get the most out of the electricity you generate. These batteries allow you to save any excess power so it doesn’t automatically get sent back to the grid, but is instead ready to be used when you need it. Whether during bad weather or as the sun sets, you can use this energy instead of staying reliant on the ongoing generation of energy from your solar array.

Let’s delve into the key benefits of solar batteries and any extra details that’ll help you make this decision easier.

Are solar batteries worth it?

There are several benefits to investing in a solar battery alongside your solar panels.

• Potentially reduce your energy costs: By storing and using energy you’ve generated, the less you have to buy from the grid.

• Energy independence: Avoid energy price spikes and become more self-sufficient.

• Earn money: Depending on the system you opt for, you can sell excess energy back to the grid, allowing you to earn an income.

Types of solar batteries

There are several types of solar batteries available, each with its own features and benefits. Here’s a look at each of them:

Inverter compatibility

While a solar battery can be retrofitted to your solar panel system, it must be compatible with your inverter. An inverter is the device that converts the direct current (DC) that’s stored in a solar battery, converting it into alternating current (AC). Once in AC, the energy is then used to power household appliances or is directed back to the grid. Here are the two different types of inverters you can get:

• Hybrid Inverters: These are designed to work seamlessly with both solar panels and battery storage. You’ll want a DC-coupled battery when choosing a hybrid inverter.

• String Inverters: These are a lot less common, and only really used if a customer is certain they won’t want batteries in future.

Our all-in-one systems

At Wickes Solar, we’ll also be providing all-in-one systems; a singular device that combines a solar inverter, solar battery, EV DC charger and an energy management system. From leading brands such as the Tesla Powerwall 3, Sigenergy Sigenstor and the Fox EVO, these combination systems are the answer to efficiently producing, storing and using solar energy.

What’s the capacity of a solar battery?

The capacity of a battery is measured in kilowatt hours (kWh), just as you see on your electricity bill, and it indicates the amount of power a battery can store and discharge. The way batteries work is by storing electrical energy as chemical energy within a very delicately balanced collection of materials, including electrolytes and negatively charged semiconductors, along with their positive counterparts.

Power comes from the inverter, and is absorbed by the battery as ‘potential energy’, so when an appliance draws current from the battery, a reaction creates the electricity again and the appliance bursts into life. The amount of material inside the batteries and the mixing of materials is what gives you the capacity.

Please note, the capacity written on the side of the battery is not always the capacity you’ll have to use, as discharging a battery to 0% can create a short circuit and cause damage, therefore impacting capacity.

What are the best solar battery brands?

When selecting a solar battery for your home, it's important to explore the different brands available to ensure you select the right solution for your solar system. Here are some of our recommendations:

• Fox ESS: These batteries offer exponential efficiency performance, and a durable and versatile outdoor design. Their modular scalability also allows for storage expansion as your solar system grows.

• Duracell: A trusted household name, Duracell solar batteries offer the fastest charge/discharge for easy use of stored energy. The powerful, AI-powered monitoring app and integrated smart energy management system are designed to give you more control over your power.

• Tesla: The highest power output, Tesla’s batteries have an integrated inverter which offers up to 11 kW output without the need for extra components. They’re the perfect choice if you already own products under the Tesla umbrella through the seamless Tesla app integration, and their flexibility makes your solar system highly scalable.

How to choose the right solar battery capacity for my home

You’ll first need to consider your energy needs to understand the capacity that’ll work best for your home. Look at your average daily electricity usage, decide whether you could benefit from backup for essential areas or your entire home. Once you’ve made these decisions, next you’ll want to define your budget and the size of your solar system.

Depth of discharge

This metric alludes to the previous one, as it’s the amount of power you can draw from the solar battery before the battery management systems stop you. For reference, most batteries come with a depth of charge of around 94–96%, but some modern batteries will allow 100%.

If they can discharge to 100%, the battery management will step in to protect the battery when it gets this low, causing it to recharge by pulling power from your solar set-up or the grid.

Many older batteries only come with 6000 charge cycles; however, modern brands, such as Duracell, go up to 8,000 cycles. Therefore, if you’re charging and discharging once a day, your battery would last approximately 21 years.

Operating temperature

Heat is a particularly important factor in the efficiency and longevity of a battery, with higher temperatures causing problems for the chemicals inside. While different types of batteries can stand various kinds of extreme temperatures, here in the UK, most batteries installed in solar systems are lithium-ion.

Lithium-ion batteries can function between minus 20 and plus 60 Celsius, but they’re best kept at plus 10 to plus 30 Celsius.

Solar battery performance in extreme weather conditions

One thing we often get asked is how solar batteries still perform when the UK is met with extreme weather. If temperatures become seriously hot or go from cold to hot consistently, your battery’s lifespan could be impacted. On the other hand, very low temperatures can reduce capacity and charging efficiency. However, most battery systems have built-in thermal management to protect the battery and keep it safe and working optimally.

Whether replacing your solar battery storage or getting all the details before you invest in solar energy, the team at Wickes Solar are always on hand to offer their expertise. Get in touch for our finance options, no-obligation quotes or for more advice on solar batteries.