Discussion: the possibilities and challenges of battery storage

We have a Q&A with Immersa here on the Bulb Community tomorrow. Immersa provides secure, sustainable and affordable energy through the use of eco-friendly renewable energy systems and battery storage.

Following our discussion about electric vehicles, where we highlighted some potential issues, this article from CNBC looks further into the possibilities and challenges of battery storage. Some interesting takeaways:

  • ‘Over the last decade a surge in lithium-ion battery production has led to an 85% decline in prices, making electric vehicles and energy storage commercially viable for the first time in history.’

  • ‘Government incentives and falling solar and wind costs are …. accelerating the viability of energy storage.’

  • ‘Batteries hold the key to transitioning to a renewable-fueled world. Solar and wind are playing a greater role in power generation, but without effective energy storage techniques, natural gas and coal are needed for times when the sun isn’t shining or the wind isn’t howling. And so large scale storage is instrumental if society is to shift away from a world dependent on fossil-fuel.’

If you have any thoughts about how batteries will fit into the future of renewable energy, we’d love to discuss below - definitely some food for thought ahead of the Immersa Q&A tomorrow.

A few years ago I was thinking about getting myself a couple of solar panels and hooking them up to a battery bank then using an inverter to convert battery power to mains power. I am curious to know how big a battery I would need to supply say 5 kWh a day.

Hey @Smart_fitter,

I’ve asked the experts for any insight on your question! You can check if they reply on this thread here: Battery Storage Q&A with the Experts


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You’ll need more than ‘a couple of solar panels’ to generate 5kWh per day. Depending on where you are a ‘standard’ PV install of about 3.5kWp (12 to 16 panels) generates a daily average of about 10kWh, averaged over a year, in the middle UK. In December and January it will generate much, much less than this and during the summer months can easily generate over 30kWh/day. So to average 5kWh you’ll need about 6 or 8 panels facing south. To generate 5kWh throughout the year, allowing for a few dark days, you might need 30 or 40 panels, rough estimate. It’s not usually viable to try to get 100% of your consumption from PV. The size of battery is dependent on a lot of factors including: how much electricity do you need through the night; how long do you want to run from the battery if there’s no sun for a few days; what peak discharge rate do you need; how deeply do you want to cycle the battery; how much do you want to pay for it? And lastly, unless you’re planning an off-grid system you will need a solar inverter / battery charger fully specified for mains network connection. All that said, I’m a great fan of PV systems. Over the winter I really notice just how much our PV system contributes to our electricity (non) usage as soon as the sun comes up again in February! I would love to fit a battery but it just doesn’t make economic sense yet. Much cheaper is to fit a solar diverter which monitors the mains feed current to your house (for a grid connected system) and diverts any excess generation into a hot water tank. This makes the majority of our hot water usage from February to November.

There are lots of panels now readily available that surpass 350W per panel, and a few that are rated over 400W (eg the Canadian Solar HiKu panel at 410W). So with the space for 12-16 panels, I’d certainly hope to do quite a bit better than 3.5kWp if I was installing a system today.

Thanks! I think I’ll stick to paying for my electric :joy:

Hi Steve,
You’re absolutely right. What I was trying to say was that Smart-fitter would need more than ‘a couple’ of panels to get 5kWh per day averaged through the year. I’d definitely encourage anyone to get a PV system, so long as their expectations are realistic for whatever situation they’re in. Thanks for the note about the HiKu panels. They do have a higher output than many other panels but that’s in part because they’re a bit bigger, at just over 2.1m x 1m, than most of the 300 - 330W panels, but a very impressive specification. It’s great to see how the efficiency of PV keeps going up and the cost keeps going down. I have 12 panels which almost completely cover my garage roof and although the angle isn’t ideal and we live in Scotland they still supply about half our annual consumption and most of our hot water through a relatively inexpensive diverter.