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Installing a battery bank for a grid-connected home? Smaller is probably better

by Solar Choice Staff on 11 August, 2016

in Batteries & Energy Storage

If you are in a grid-connected home and want to get batteries for your rooftop solar system, you’re probably wondering how much capacity to have installed. Although the ultimate answer comes down to your personal preferences and goals, what about if you’re primarily after a good return on your investment? In this article we’ve endeavoured to answer the question, ‘What size battery bank makes the most sense for a grid-connected solar home?’ The short answer is ‘a small battery bank’.

When batteries make sense

Although solar PV systems are quite affordable on their own, batteries are still pricey. For pretty much any battery product with a 10-year warranty, you’re looking to pay in the range of $2,000 per every kilowatt-hour (kWh) of capacity installed. These costs are likely to fall sharply in the coming years (especially for lithium batteries), but this looks like it will remain true for at least the rest of 2016.

Let’s say you’re dead set on having batteries installed in your home as soon as possible, but in addition to the many other reasons a battery bank might already be attractive, you also want to make sure it’s a solid investment? Fortunately, there are a few scenarios in which a battery bank already ticks both of these boxes; in the case of a typical grid-connected solar system, the key is keeping it small. Read the full article →


Manuel 29 September, 2016 at 7:57 am

Hi there,

Great article, wish I’d found it earlier!

There are some errors in your calcs/graphs that I’d just like to point out:
– sample day energy flow doesn’t show the last slice (hour 23-24h)
– daily energy balance double counts the battery consumption. While the battery supplies load it doesn’t generate, so its contribution to the load shouldn’t be added to total consumption. This should increase the self-sufficiency that you’re reporting, so it should be good news.

Thanks again for the great illustration of battery use.

Solar Choice Staff 29 September, 2016 at 1:46 pm

Thanks for the comments, Manuel – I’ll pass this on to SunWiz, who are the ones that created the PVSell software that I used to create those graphs.

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