Are solar batteries worth it?

If you’ve already installed solar panels, then you’re probably wondering, are solar batteries worth it? Solar panels have been increasing in popularity, largely due to the money households save on their energy bills. It’s estimated that around 970,000 households in the UK now have solar panels installed – reducing their reliance on the grid. 

With the rise in energy costs and the new price cap set for October 2022 to April 2023, electricity costs have grown by 19%. So, you might now be wondering how to monetise your solar panels installation – one way to do that is to install solar batteries. 

Solar batteries essentially store the excess energy generated from your solar panels, instead of letting it go back to the National Grid. This energy can then be used to power your home during times of the day when your solar panels don’t generate enough electricity, or be sold back to the grid – more on that later. 

So, are solar batteries worth it, and what are the pros and cons?

Solar batteries can help reduce your dependence on electricity from the grid, but are they worth the investment? (Image credit: Adobe)

The average solar battery will cost you around £4,000, and when added to your solar panels installation cost, it can become a pricey investment. However, if we take a look at the long-term benefits of solar batteries, there are definitely some advantages and saving potentials for your household.  

Solar batteries reduce your dependency on the National Grid electricity you use and enable you to store the energy that your solar panels generate. They also enable you to use the electricity that you’ve generated during cloudy days or even at nighttime; this can save you further costs on your energy bills.

When discussing whether solar batteries are worth it, cost is most certainly a deciding factor. Currently, solar batteries cost anywhere between £1,800 and over £9,000. The reason for such an expansive price range is it all depends on the capacity of your solar batteries, chemical composite and the battery’s life cycle. 

When solar panels were first introduced they were fairly expensive but as they become more widespread, their price will become more affordable. This is also expected to happen with solar batteries, but like with any new technology, it takes some time for the prices to become more affordable.

Discover how much a solar battery would cost for your system by answering a few quick questions

Solar batteries can store any excess power generated by your solar panels to be used when the sun isn’t shining. (Image credit: Adobe)

There’s two types of chemical materials that are most commonly used for solar batteries – lithium-ion and lead-acid. But, what’s the difference between them, and which one is most cost effective and has the longest lifespan?

If we compare the two types of batteries using the same storage capacity of 4kWh, lithium-ion batteries have a preliminary cost of around £4,000, whilst lead-acid batteries only cost around £2,000. 

Although the initial cost of lithium-ion batteries is double the cost of lead-acid batteries, they work out to be the most cost effective if you consider their long-term usage and higher cycle life, according to Swell Energy. As such, lithium-ion solar batteries have proven to be more cost effective than their lead-acid counterparts.

So, what makes lithium-ion batteries the most cost effective if their preliminary cost is so high? The life cycle is the deciding factor when it comes to choosing between lithium-ion and lead-acid batteries. 

When comparing the two batteries with a 4kWh storage capacity, the differences are very noticeable. Lithium-ion batteries typically have a life cycle (complete charge/discharge cycles) of 4,000, compared to lead-acid’s 1,800 life cycle – lithium-ion batteries most certainly come out on top. The more life cycles that a solar battery has, the longer time it can perform at an efficient rate. A longer lifespan of your solar batteries also means there will be fewer future replacement costs.  

The storage capacity of your solar battery reflects how much energy your battery can store. The Depth of Discharge (DoD), or usable capacity, refers to the amount you can use. 

So, if we compare lithium-ion’s DoD which comes in at 90% and lead-acid’s DoD is only 50% – lithium-ion batteries are more cost effective. A larger capacity means the battery can store more energy, and this results in a higher preliminary cost. This is a deciding factor when it comes to picking your solar batteries; the higher the storage capacity you have, the more energy you have to store and use. The below chart details why lithium-ion batteries work out cheaper in the long-term.

Are solar batteries worth it, if you need to replace them in the future? You can figure out the lifespan of your solar battery by considering its life cycle. As previously mentioned, lithium-ion batteries with a 4kWh storage capacity have around 4,000 life cycles. 

Solar panels typically have around a 20 to 30-year lifespan, and when you compare that to just a five to 15-year lifespan for solar batteries, it’s almost guaranteed that you’ll need to replace them. So, you should be mindful of this when deciding whether solar batteries are worth it – know that there will be future costs involved that you need to weigh up.

Lithium-ion solar batteries are more expensive initially, but they work out cheaper in the long run because they last longer. (Image credit: Adobe)

The return on investment for solar batteries depends on your household’s electricity consumption and, unfortunately, the energy price cap. 

One thing that is guaranteed when you have a solar battery is that your reliance on the grid is reduced, and your energy bills will reflect this. 

Solar batteries will need to be replaced around half-way through your solar panels’ lifespan, meaning you’ll have purchased two sets of batteries. This will cost anywhere from £5,000 to £12,000 altogether based on the cheapest solar battery costing £2,500. Based on the average three-bedroom household, it’s predicted you’ll have an annual saving of around £186 on your energy bills and that comes to a total loss of £7,000 after 25 years (the average lifespan of your solar panels).

With this being said, the average household will still make a profit on their solar panels set-up. With energy prices on the rise, storing all the electricity that you generate is profitable. 

Households in England, Wales and Scotland could benefit from a Smart Export Guarantee (SEG) tariff. The SEG allows you to sell back your renewable energy generated from your solar panels that’s then stored in solar batteries and sent back to the grid. Under this scheme, all licensed energy providers with over 150,000 domestic customers must provide at least one SEG tariff. 

The scheme does not specify how much suppliers would pay for your excess energy; this means that rates are not the best that they could be, and could fluctuate. There’s 15 different licensed companies that offer SEG rates, but which is the best tariff?

Two of the best companies for their SEG tariffs include Tesla and Octopus Energy – the two with the highest paying rates. Tesla offers 11p per kWh and Octopus Energy offers 7.5p per kWh. At first glance you might think Tesla is the best deal, but you won’t when you realise that Tesla (administered by Octopus), requires you to purchase a Powerwall 2 solar battery – coming in at an eye watering £9,000. The battery only has a 10-year warranty, therefore it would need to be replaced for an additional £9,000 about half way through your solar panels’ 20 to 30-year lifespan.

So, although Tesla’s tariff has the best rates, the initial costs added to the replacement costs completely diminishes any benefits. This also means that the average three-bedroom household would lose £4,900 over 25 years when you take into consideration the initial costs and replacement costs for the Powerwall 2 solar battery. That same three-bedroom household will make £8,600 over their solar panel’s lifespan should they opt for Octopus Energy’s 7.5p per kWh tariff.

With no extra costs involved, Octopus Energy is the best deal on the market right now. You’ll make 7.5p per kWh of energy that you send back to the grid. It should be noted that this is only available to its own customers and the rate for other households is set at 4.1p per kWh. 

You can choose any supplier for your SEG tariff – it doesn’t have to be the supplier that already provides you with electricity.

Below is what you could save based on average household sizes and the size of your solar panel set-up.

If there’s no more storage space because your solar battery is full, the renewable energy generated will simply stop being absorbed from your solar panels. Your solar panels will continue to generate energy but it will not be used or stored until there’s demand or space for it.

This is similar to if you don’t have a solar battery. You’ll lose about 50% of the power your solar panels generate. If you have no solar battery the energy generated must be used up as it’s generated because there’s nowhere for it to be stored for later use.

Are solar batteries worth it? Yes, if you can afford them. With the rise in energy prices, the less you rely on the grid, the lower your energy bills will be. However, here are a few things to consider before taking the plunge.

1. They’re a good investment if you’re trying to move off the grid entirely. If your solar battery has enough storage capacity and generates enough power, you should be able to power your household entirely on your renewable energy.
2. Currently, solar batteries have a high initial cost, and if you want to break even quickly or make a profit, this might not be the solution for you. 
3. There’s also an opportunity to make a profit on your renewable energy by choosing an SEG tariff that allows you to send energy back to the grid. This is only viable if you choose the best tariff and avoid Tesla’s costly Powerwall 2 battery. 
4. For the time being, solar batteries are a very expensive investment. The initial set up cost and replacement cost will hopefully decrease overtime, like the cost of solar panels did. Until this happens, it is most likely only an affordable option for very few.