Why would I want battery storage?
There are a number of reasons why you would consider a battery system operating in combination with your solar PV system.
Improve ‘self-consumption’
Solar PV systems generate most of their energy during the middle of the day when the energy demand of most households is at their lowest. A typical household may have a base load of only 300W to 500W to run essential appliances, for example, fridge, freezer and a broadband router. But depending on the size of your PV system, it will produce a surplus of energy when production reaches levels of 3,000W, maybe even 4,000W. Under these conditions, the surplus energy is fed back to the grid with no added benefit to you.
The chart below provides a graphical illustration of how that looks: -
Figure 1 – Typical household consumption and solar generation
During the most productive periods of the day, the surplus energy will be exported to the grid and so you lose the benefit. As can be seen from the chart, peak demand within the household occurs first thing in the morning and most of the evening when the solar system is at its least productive.
A battery storage solution solves this problem by storing the surplus energy during the day:-
Figure 2 - Daytime battery charge cycle
The stored energy is then used to run your household demand in the evening and beyond: -
Figure 3 - Evening battery discharge cycle
Back up supply during a power cut
Although not a major problem in the UK, it is possible to provide a limited back up supply to provide power to essential devices such as a broadband router or fridge/freezer during a power outage (grid failure). This is not always possible and will depend on the system design; SolaSave Engineers can discuss your specific requirements and the options available.
Time shifting
It is also possible with some battery storage systems to ‘smooth out’ your consumption peaks by storing energy during low tariff charges and using this during peak tariffs.
Protection from energy price increases
Investing in solar and battery storage technologies is not cheap, but then, neither is buying energy from the grid!
Let’s briefly examine the financial case for investing in the technology. Suppose you invest £10K on a new solar PV system with battery storage. Looking at just the first 20 years’ worth of production from a solar system, you will generate 50 to 60MWh of energy. If you were able to utilise 80% of that energy (aided by batteries), then you will effectively be buying 48MWh of energy for £10K in today’s money. This equates to around 21p/kWh. Although this is more than today’s cost of electricity (around 15p/kWh); this will prove be a very cheap option in 10 years’ time let alone in 20 years.
BUT, there’s even more good news, you’ll also get paid the Government’s Feed-in-Tariff (FiT) at the current rate of 6.7p (combination of generation & export rate) which further reduces the cost to around 14p. And of course there’s no inflation on your PV battery system, you’ve ‘locked in’ at 14p for the next 20 years.
Figure 4 – Cost of grid electricity vs. solar battery