Solar Battery Cost Guide

Welcome to Quotation Check and our guide to home solar battery prices.

We’ve researched the cost to buy and fully install a home battery with connections to the national grid and existing solar panels.

Explore our guide below where we explain:

• The key benefits of solar batteries and how they work.
• How much it really costs to get a Tesla Powerwall or a Powervault 3 installed.
• Information for those wishing to charge an electric car.
• Battery life expectancy and degradation.
• How long they can power your home in the event of a power cut.

Key Benefits

Solar panels are a great way to reduce electricity bills and protect the environment from the harmful effects of emissions. They do have one major drawback though; the energy created must be used instantly as solar panels don’t have any in-built storage capacity.

Sure, you can export excess electricity into the grid. However, the government recently scrapped “feed-in” tariffs and there’s currently no set amount a provider must pay per unit fed into their grid from a new customer.

If you spend most of your time during the day at home, then solar panels can significantly reduce your bills. Those who are away at work during the day and only use electricity in the evening may, however, only see a moderate reduction.

This is where solar batteries can really make a difference.

These storage devices are small enough to be fitted inside a porch cupboard and powerful enough to provide electricity to your fridge, TV, Wifi router and a few other essentials for several days. Used in the evening or during the night, they can completely remove your dependency on the grid until the next day when the solar panels recharge the battery.

There is another benefit; if you use up your stored electricity and there’s not enough power from your panels to recharge the battery, it will try to charge from the grid at off-peak times so you can then use cheap electricity rather than costly peak-time power.

Cost to Install a Tesla Powerwall Battery

Tesla is one of the most popular manufacturers of solar home batteries and their Powerwall product is the industry leader.

One Powerwall can hold 13.5kWh of power which is enough to keep a typical house going through the evening and night. When the sun rises, the Powerwall then switches to charge mode and any power from the solar panels that isn’t being used will divert to the Powerwall.

Here’s how much we were told one Powerwall would cost to install:

Want to Charge Your Electric Car From a Solar Battery? Read This First…

One of the key selling points for many people is the idea that they can charge their electric cars with power from their solar panels.

The theory is simple; charge the home battery from sunlight during the day and in the evening, use the electricity to power the home and charge the car.

With petrol prices so high in the UK, this sounds like the perfect solution for the environment-conscious consumer who wants to save money too.

There’s just one problem; the Tesla Powerwall provides 13.5kWh of usable energy while a Tesla 3 car has a 75kWh battery. Put bluntly; you won’t get anywhere near a full charge, not even if you dedicate all the power from the Powerwall to the car battery.

Sure, with just one Powerwall, you can fully charge a car with a smaller battery such as a Toyota Prius (4.4kWh battery) or half charge a Nissan Leaf (30kWh), but with most of the power from a single battery being used in the home, you won’t have much left to charge a car for moderate or heavy use.

Whether you’ll have enough power left in a single battery to charge your car sufficiently will depend on:

• How many miles you do.
• How much of the stored electricity in the Powerwall you use in the evening.
• If your car is at home during the day or not as solar panels can charge the car once the Powerwall is full.
• The weather.
• The size and generating capacity of your solar panels.

Tesla actually recommends two Powerwall batteries for EV owners, and the cost of an extra Powerwall is around £9000.

To calculate whether you can save money by charging your car from a Powerwall, consider:

• Your power consumption at home, especially in the evening and at other times when the solar panels aren’t generating much power.
• The generating power of your solar panels.
• Your mileage and how much you would pay per mile to charge the car off the grid.
• When you can charge the car (if it’s in the evening or night time then you’ll only have a limited amount of power in the Powerwall)

Cost to Install Another Brand of Solar Battery (Powervault)

We also sourced quotes for the installation of a Powervault 3 from EDF Energy and also from a local registered electrician that specialised in home battery installations.

The figure below is the average price for a fully installed 8kWh battery which is quite a bit smaller than the 13.5 kWh Tesla Powerwall.

If you would like to find a registered installer, you can start by contacting Powervault.

Life Expectancy and Degradation 

The life expectancy of a Powerwall battery and most other similar products will depend on how many charge/discharge cycles it has completed. For example, if it’s only used as a backup in power cuts, it should last decades.

If the Powerwall is used daily, it should last 15 – 20 years but may experience degradation, which will reduce its ability to hold power.

Tesla offers a 10-year warranty with its Powerwall and guarantees that its charging capacity will not be below 80% at 10 years of age.

As for how the battery will perform after 10 years, nobody really knows.

How Long Can a Powerwall Battery Power a Home?

If a property suffers a power cut, a Powerwall battery can supply enough power to last about a day provided only the essentials are switched on; a TV, laptop, fridge/freezer, wifi router and some lighting for example.

If power-hungry appliances are switched on, then the Powerwall can be depleted in a matter of hours. Appliances to avoid during a power cut are anything that produces heat; kettles, electric ovens, hairdryers and heaters etc.

In theory, a Powerwall can power a home indefinitely provided that:

• Energy usage is below the storage capacity of the battery.
• You don’t demand more than 7kW peak or 5kW continuous.
• The solar panels have enough generating capacity to fully charge the battery.
• The weather is favourable.

Can Storage Batteries Be Used Without Solar Panels?

Yes, most batteries can be charged from the grid and then discharged as required by the home.

Some users charge their batteries during the night when electricity is cheaper and use it during the day and evening rather than using costly peak-time grid power.

If you intend to do this, either with or without solar panels, speak to your energy provider about the best tariff for you.

Can I Earn Money by Feeding in Excess Power to the Grid?

Feed-in tariffs were a great way for homeowners to sell excess power from their solar panels to the grid. The money earnt was usually deducted from their energy bill or paid cash.

The government has now cancelled feed-in tariffs for new customers and replaced it with the Smart Export Guarantee.

Energy providers with more than 150,000 customers must now offer at least one tariff where they pay owners of solar panels money per unit fed into the grid. Unfortunately, the government has stated that they must pay “more than zero” but haven’t set a minimum price above this.

As the financial incentive for selling power to the grid has all but evaporated, more and more people are looking at storage batteries such as the Powerwall and Powervault.

By installing a home battery you can still save a lot of money and do your bit for the environment. If you can fully charge or even partially charge an electric vehicle, the savings potential rises considerably.

Solar Battery FAQs

Below you’ll find answers to common solar battery questions: