Battery Storage

Why Do You Need a Solar Battery Storage System?

Pairing solar batteries with solar arrays is a relatively new practice, but an effective one. You can benefit from solar battery storage in 4 key ways:

  1. Store energy for later use
  2. Significantly lower your energy costs
  3. Earn money by selling stored energy to the grid
  4. Become independent from the grid

Firstly, a solar battery stores the energy generated during sunlight hours and makes it readily available for use during non-production hours, such as at night or on cloudy days, essentially enabling your home to run on 100% renewable solar energy around the clock, as long as electricity demand does not exceed the supply that the battery can provide.

In addition, solar battery backup power can lower your energy costs significantly. By charging the solar battery during off-peak hours and discharging it during peak hours, you can avoid paying a lot for electricity from your utility company. The savings from this can serve towards reducing your battery system costs.

What’s more, you can earn money by selling the energy stored in your solar battery back to the electrical grid when electricity prices are at their highest—if your utility allows net metering.

Finally, by adding a solar panel battery to your solar system, you can choose to be independent from the national grid at any time, thereby ensuring energy security for your household. Naturally, the how many solar panels you need to install for this will vary depending on your energy demands and budget.

When Is It Ideal to Install One?

A solar battery storage system is best used in combination with a solar PV array. Lucky, if you already have an existing array, it is a relatively simple task to add a solar battery into the mix. And if you have neither, the two systems can be bought in tandem to make your home run entirely on renewable energy.

The two technologies complement each other to bring down your storage system costs by making your solar panel array vastly more efficient. If you have been considering going green, there is no better time to start taking advantage of the money you can save on your monthly electricity bill.

Solar battery storage systems offer a variety of types of batteries for you to choose from, along with many advantages, like more eco-friendly efficiency, longer lifespan, and easier installation.

How Much Do Solar Batteries Cost?

Currently, the costs typically range between £1,200 and £6,000 depending on the capacity, chemical composite of battery, and its life cycle.

Solar battery costs are in a similar situation like when the technology for photovoltaic systems were new. As the adoption of solar battery storage systems becomes more widespread, their price will naturally follow the same declining trend as solar panel costs.

Lithium-ion solar batteries are the most mainstream and cost-effective batteries of all kinds.

Lithium-ion and lead-acid are two chemical materials that you can most commonly find in batteries used for solar panel systems. Despite the higher estimated price, lithium-ion batteries still enjoy a bigger market share thanks to their longer lifespan and higher usable capacity.

Battery Material

Different materials have different impacts on the discharge rate and the lifespan of the product. For example, lithium-ion batteries can discharge 70%-90% of the total amount of storage while lead-acid can only discharge around 50%. And lithium-ion batteries have at least double the lifespan of lead-acid batteries. Higher discharge rate and longer lifespan will typically results in higher prices.


Storage capacity refers to the total amount of energy your solar battery can store, and usable capacity means the amount one can use, which is usually calculated by depth of discharge (DoD).

The amount of storage capacity and usable capacity, measured in kilowatt hours (kWh), directly influences how much your solar battery storage system will cost. Larger capacity means it can store more energy and support a larger area, thus, it will result in a higher price.


The life cycle is an important indicator of a solar battery storage system’s lifespan. The more cycles a solar battery can provide, the longer time it can perform normally. Considering the lifespan of solar panels is around 25 years, replacing a new solar battery may add up to the future costs.


Installation cost of solar battery storage systems varies slightly based on the size and may be covered by some brands. Generally speaking, it is more economical to set up your solar battery system while installing solar panels.

How to Lower Your Costs

Even though the solar battery storage system cost may not be moderate, you can still find some ways to save money. There are currently solar panel funding opportunities in the UK.

Through the Smart Export Guarantee (SEG) you can earn money for exporting stored electricity back to the grid. Export tariffs vary with each energy supplier, but a good tariff is between 4-6p/kWh.

Prior to the SEG, the Feed-in Tariff (FIT) was in effect. The FIT rewarded homeowners for using renewable energy such as solar, as well as for exporting electricity to the grid. The FIT ended in 2019, and no new applications are processed. Those that are currently registered under the FIT will continue to receive payments until the end of their agreements.

Types of Solar Batteries

  • RV/ Marine Solar batteries– Marine solar batteries are suitable for smaller systems and are used for boats and by people who own RV’s. In addition, these types of solar batteries work best when no other form of electricity can be produced, due to their lower capacity for continuous service.
  • Flooded type– Flooded type batteries are lead acid batteries which have caps for adding water. These types of batteries are not very expensive to buy and have a good life span compared to the Marine solar batteries. It is recommended that flooded type batteries be used outdoors, as they emit gas when charged. If however, these are installed inside, then it is strongly recommended that a venting system should be used to vent out gases, which can be explosive and toxic.
  • Gel– As opposed to the flooded type, sealed gel batteries have no vents and do not release gases. Because of this, venting is not important and these batteries can be used indoors without any risks The advantage of this is that the battery will have a more constant temperature indoors, leading to an increase in the maintenance, and therefore performing better than the flooded type.
  • Absorbed Glass Mat batteries (AGM)– A glass mat is used between the plates to hold the electrolyte. These type of batteries are leak proof which means that they do not release gas when charging. In addition to this, Glass Mat batteries also have a superior performance, making them the best types of batteries. They have all the advantages of the sealed gel types but are of higher quality. Other advantages include the fact that they maintain voltage better, they self-discharge slower and finally they last longer. Of course, their superiority does mean that they are the most expensive out of the four types.
What Is the Lifespan of a Solar Battery?

The average lifespan of a solar battery storage system is around 5 to 7.5 years for lead-acid and 11-15 years for lithium-ion batteries. However, all batteries are vulnerable if they are over-discharged or exposed to extreme weather.

Depth of Discharge (DoD)

Depth of Discharge (DoD) means how much you can use the battery before recharging it. Just as it may be harmful for your phone’s battery to have only 2% remaining, the same goes for a solar battery storage system.

If you use up 100% of its charge or exceed its DoD limit before recharging it, the lifespan will be shortened significantly. For example, if you buy a solar battery storage system that has a capacity of 5 kW energy storage and 80% DoD, remember to charge it before using up the entire 4 kW in order to extend the life of the battery.

Compared with lead-acid batteries, lithium-ion batteries can handle a larger range of temperature changes and feature a higher tolerance level if discharged improperly. These advantages lead to lithium-ion batteries gaining a larger market share.