Home Battery Storage: A Real-World Case Study from Ashwell

Battery storage of electricity, either from self-generated electricity or to take advantage of off-peak tariffs, is increasing in popularity.  To help understand how a battery installation might work for you here is a case study from an Ashwell village resident with some suggestions for requirements for a battery installation and their experience using their installation:

To get the best out of a Storage Battery you need to have one or ideally both of the following:

• PV (Photo Voltaic) roof panels

• A dual rate or flexible electricity tariff which allows you to charge the battery when electricity prices are low, and use the battery when prices are high (typically at 4pm – 8pm).

What size of battery do you need?

• Look at your weekly or monthly electricity usage in kWhs (Kilowatt hours) across the year

• Ideally you need a battery capacity that:

  • Either matches the amount of electricity you use during peak hours (4pm – 8pm), or

  • The amount that you use during an average Summer week (May – September)

Our situation

We have an all – electric house including:

• PV (Photo Voltaic) roof panels

• Air source heat pump (for heating & hot water)

• Solar water heating panels (which really only contribute during the Summer)

• An EV (Electric Vehicle) charging point

• Our electricity tariff is Octopus Agile which is linked to the market price of electricity for every 30 minutes (day & night). For us it is the cheapest tariff with typical prices per kWh ranging from 15p per hour (night time or off peak) to 50p per hour (peak 4pm – 8pm). But in certain weather conditions we are actually paid to use electricity! 

  
  

In Summer we use about 80 – 100 kWhs per week, peaking in winter to up to 400 kWhs per week.

Our experience

In December 2025 we added a 20kWh capacity Storage Battery linked to our PV panels and our EV charger. We bought this through an Electrician who is an authorised installer of the EV charger we had previously installed. However, there are alternatives and some Electricity Suppliers (like Octopus) will also install Storage Batteries and /or PV panels.

We adjust when the battery charges from the Electricity Grid to when the cost is generally below 15p per kWh. Depending on the tariff you choose you can either leave the programming of your charger up to the Electricity Supplier or you can do it yourself on a daily, weekly or monthly basis. 

In Winter we have found that we need to charge the battery for two periods each day to cope with the amount of electricity being used by the heat pump. But this largely keeps our average cost of electricity to about 15p per kWh.

During sunny summer weather our PV panels are charging the battery as much as is required, so we are not using any electricity from the Grid.

Our results

Will we get a payback on the investment in the Storage Battery? This is not certain and there are some variables outside our control.  For example, it depends on:

• How long the battery lasts. That should be 10 – 15 years.

• The average price of electricity changes during that time.

What we do know is that we would be paying more for our electricity if we didn’t have the battery. So it’s reducing our current cost of living, which was one of the goals. It is also further reducing our carbon footprint (once the battery has been manufactured!).