Battery Storage

What do home batteries do?

Batteries store excess solar energy generated during the day to power your home at night. Batteries can also charge off cheap rates of electricity in order to run your property when electricity is most expensive.

Is battery storage worth it?

Sometimes it makes more sense to sell excess solar energy back to the grid rather than storing it in a home battery. We can model your property and compare solar installations with and without batteries. In general, we have found that properties with medium to high energy usage can benefit from batteries, especially when coupled with a variable electricity tariff like Octopus Go (which has a cheap, night tariff).

Do batteries work off grid or when the grid goes down?

Some of the batteries listed below work when the grid goes down and can function for long periods off grid. For instance the Giv Energy AOI and Tesla Powerwall 3.

Why use Seven Hills Solar?

We supply and install top-of-the-line battery brands like Giv Energy, Tesla Powerwall, Victron, and SolarEdge backed by our expert installation and support.

How much is a home battery system?

Typical home battery installations cost from £2,500 to £9,000. The price depends on:

· The amount of battery storage you go for. This is the energy the batteries can store, measured in kWh. Sometimes the more expensive batteries are cheaper per kWh of storage.

· The speed the batteries can charge and discharge. The is the power of the battery inverters and is measured in kW. These typically range from 2 kW to 11kW.

· The functionality of the battery system such as the ability to power your house when there is a power cut. More sophisticated battery systems can run your entire house off grid while the solar panels continue to top up the battery0 for longer grid outages.

· Better battery brands have good usability, UK support, intuitive monitoring apps and integration with variable energy tariffs.

How much VAT do I pay on a home battery?

Currently batteries are rated at 0% VAT until 2027.

What are the best batteries for homes and residential properties?

We’d recommend the following brands and battery types.

Best value battery system: The Giv Energy Hybrid System

The Giv Energy Hybrid or AC coupled 5.12 kWh battery system costs from £2,800 installed.

Giv Energy are a UK based company and have been developing battery systems especially for the UK market for a number of years now.

The solar and battery inverters are combined into a hybrid system. This saves on components and is also an efficient way to store energy with minimal conversions losses between DC and AC electricity.

If you already have solar that’s ok, we can still fit an AC coupled version which works well.

There is an option for running a small back-up supply off this system, but it won’t run your whole house off grid. For this reason, we can fit a back-up socket outlet which works if the grid goes down.

Best Value Whole House Back-up System: The Giv Energy All In One (AIO) System

The Giv Energy All in One 13.5 kWh battery system with back-up gateway cost from £6,800 installed.

This battery is the big brother of the system mentioned above. With its own 6 kW, integrated battery inverter, it can be installed with any solar array.

The Giv Energy Back-up gateway isolates you from the grid if it detects a power outage. This way the powerful battery inverter is able to run your house while keeping engineers who maybe working on the power lines outside your house safe.

The solar keeps generating in back-up conditions in order to keep the battery topped up for longer grid outages.

Premium Battery Storage: Tesla Powerwall 3

Tesla Powerwall 3, 13.5 kWh battery system with back-up costs from £7,800 installed.

Powerwall 3 offers whole home back-up like the the Giv Energy AIO system above but with a few extra benefits.

Powerwall 3 has the option of DC coupling a suitable solar array straight into the battery. This means that you may not need a separate solar inverter.

Powerwall 3 has a massive 11 kW discharge rate meaning that it will easily run all the appliances in a typical house (even a 7 kW car charger)!

This huge power output can be tweaked down if requested by the District Network Operator (DNO) which is a very handy feature for such a large battery.

What Batteries are best for three phase properties?

If you have a house with a three phase electricity supply or a small, three phase commercial property, Tesla Powerwall 3 is a good option. You can install one or multiple Powerwalls and Tesla software manages the power over the phases. There is a great video explaining how this is achieved here.

What is the best battery for three phase back-up?

Victron offer a great system for single and three phase batteries which also provide UPS grade back-up and full off grid capabilities.

Is it worth fitting a battery without solar panels?

You can charge most battery systems (including all the ones mentioned above) on a cheap, night tariff and use that power in the day.

For instance, Octopus Go night tariffs are currently 8.5p per kWh vs a day tariff of 26p per kWh. That’s a difference of 17.5 p per kWh.

Assuming one of the 13.5 kWh batteries, we can then work out the annual savings presuming you manage a full battery cycle every day:

17.5p per kWh x 13.5 kWh battery capacity x 365 days x 0.9 for round trip efficiency losses = £776 savings per year.

Presuming energy process stay the same, the battery would pay for its self in roughly 10 years.

Things to consider: 1) If your roof is suitable, getting solar may be a better investment than a battery on its own. 2) Do you consistently use at least 13.5 kWh of electricity each day? If not, then the returns will be slower. 3) On the plus side, energy prices may increase, leading to faster returns on investment.