Battery Storage Knowledge Bank

Battery Storage Benefits: Domestic (<50kWh)

Quick links

Residential solar storage: Tesla Powerwall

Save up to 60% on your electricity bill - buy cheap, use peak! And, if you have solar PV... Generate over 70% of your electricity on site using residential solar storage.

Time of use optimisation – buy cheap, use peak!

With the advent of smart metering, time of use tariffs are coming into their own. The traditional Economy 7 tariff has now been extended to full time-of-day tariff differentiation.

As batteries start to become more commonplace, it is anticipated that not only will there be time-of-day import tariffs, but there will also be time-of-day export tariffs, with those in a position to export during the winter peak times (4-7pm) having the potential to earn comparatively high tariffs from export.

The time-of-day import tariff from Bulb profiles as follows (during summer time):

Bulb smart tariff

See the local rates on the Bulb smart tariff.

For a consumer on a flat 22.36p per kWh tariff, there is an opportunity to save around 10p per kWh (compared to their current tariff) by ‘buying cheap’ at night and ‘using peak’ in the day.

If the system is used with a solar system as well, then further savings are available from on-site usage of the solar electricity. If these savings are conservatively valued at 5p per kWh, then with a 2,400kWh on site usage benefit, the total battery savings will be around £450 – £500 per annum.

And that’s before the anticipated rise in electricity prices is factored in as we all start to drive electric cars… or any future peak time export revenue earning opportunities are factored in.

Increase self-generation to >70%

A well designed residential solar storage system should provide >70% of annual electricity requirement, with grid top up required online in November to March.

The less you rely on the National Grid for your electricity, the more you protect yourself from rising prices.

PV and battery usage

Use your spare solar electricity – it’s free!

In the UK, hundreds of thousands of domestic and small commercial solar systems have been installed. Having paid to install the system the best way to maximise the system's potential is to use as much of the electricity generated by the system on site, rather than exporting it to the grid. 

PV systems of all sizes need to be monitored using a smart meter or export meter to receive payment of the electricity exported to the grid. The rate of fixed or variable pay for export is set by the electricity supplier under the Smart Export Guarantee (SEG) scheme. The rate is likely to be in the region of 15p/kWh and given that domestic tariffs are typically 22.36p per kWh it makes sense to use as much electricity on site as possible. 

The likely economic gain from a residential solar storage system is analysed in detail in the economics of storage.

Emergency power supply / backup

Spare capacity within the National Grid has now fallen as low as 1.2%. In November 2015, the National Grid actually had to pay major factories to down tools and cut demand between 4pm and 8pm. The risk of blackouts is increasing; as this risk increases, it makes sense for householders and businesses to start looking at installing backup power supplies.

Reduction in carbon footprint

It always makes sense to use electricity at the point of generation, thus minimising transmission losses. Furthermore in a world where electricity is increasingly in demand, there is environmental and social value in storing energy on site for later use, particularly if such use is at times of peak demand across the grid.

For more information, call us on 0118 951 4490 or download our free guide to energy storage:

Download now