The Good and Not-So Good of Solar Batteries

You get to keep the excess energy that is generated by your solar panels in periods of high sunlight. Which can be used when the weather changes (like becoming overcast) or into the evening as the sky darkens. One of our clients has 10kWh of battery and during the summer months this was enough to last through the night, meaning no draw from the grid to their property at all some days.

The great thing about batteries is that you can manage them during period of low and high demand. Taking advantage of off-peak pricing structures from energy providers. The batteries can be discharged during certain hours, and even charged too.

Our clients often take advantage of low overnight tariffs and charging the battery from the grid, especially in the winter. That means you are buying from the grid at a reduced price, but using it a peak-times. 

Solar arrays need a little bit of energy to work, which means they don’t generate electricity, even on the brightest of days, when we have a power-cut. However, a battery that has stored some electricity during the day can be used as back-up. This is great for areas where powercuts are common, and can be set up either by way of a socket to feed from the battery or to supply a circuit in the home.

The grid infrastructure was never designed for input from our homes, the flow was one-way. Export limits can be put on solar arrays in certain places where it has high capacity, even more so when arrays are installed in areas where a lot of solar already exists. 

Using batteries means we are helping to support the grid, making it more stable, by not exporting large amounts particularly on those high sunlight summer days.

Straight in with the biggie. Ranging on average from £1,000 – £2,500 for a 5kW they have a high initial cost outlay, and so take sometime before the cost is recuperated through the energy savings they make. Domestic batteries are still relatively new if you look at solar installed across the world, and new technology always comes with higher cost.

Like all batteries, solar batteries have a limited lifespan and will start to degrade over time. Most come with 10 year warranty, but as the technology is new, there isn’t much evidence of how much longer that they will continue to work after this.

There are efficiency losses during charging and discharging, and most batteries will discharge to 5-7% of their actual capacity and stop. This is to protect the lifetime of the battery, similar to electric cars, discharging them completely makes them less efficient.

That means a 5kW battery is truly only giving you 4.8kw – 4.9kW.

However, Myenergi batteries work a little differently again, you can read more about them and why we recommend this UK manufacturer here – ARTICLE : Why Should I Invest In Myenergi Products

Batteries work in cells, these cells fill up one by one until the battery is fully charged. As the battery gets used, sometimes these cells can get ‘stuck’. When this happens it can reduce the amount of energy they can store and cause alarms to appear on the solar array. In order to keep the battery healthy during its lifespan, periodic checks are recommended, together with force charge and discharge cycles to clean any blockages. All relatively straightforward, but comparing to the solar array that needs very little maintenance, it is a consideration.