Solar stored

Issue 32 Words: Andrew Reddaway

Tesla’s dramatic entry into the household energy storage market has shaken up the solar industry, but what effect could it have at the local level? The ATA’s energy analyst Andrew Reddaway says the situation is particularly interesting for those embarking on new builds.

Australian householders are taking up solar at a rapid rate. While we may be lagging on large-scale installations and political will, around 15 per cent of Australian households now have rooftop PV. The vast majority of these systems are grid-connected, and so potentially well-placed to take advantage of developing hybrid options.

For grid-connected users, any excess electricity generated is exported to the grid, with the shortfall (for example when the sun isn’t shining), imported from the grid. A solar system with batteries for non-sunny times allows you to store the excess generation for use later on, getting around the sunlight and peak demand mismatch. The obvious benefit is electricity bill savings, due to the current low feed-in-tariff rates for recent solar installations. Some battery systems also allow you to run lights and appliances during a grid blackout.

Batteries also make it possible to disconnect from the electricity grid entirely. However, with no support from the grid a much larger and more expensive battery system would be needed. An off-grid system must be sized to meet the worst-case scenario, typically a cloudy winter week. Off-grid systems are most advantageous for new rural developments where the electricity company would charge a high cost for connection. Of course, the other benefit is eliminating electricity bills entirely! [Ed note: See the ATA’s Off grid homes eBook for tips and case studies.]

Grid-connected battery storage is not yet compelling on a purely economic basis. However, Tesla’s new Powerwall battery (expected to be available later this year) has set a new price benchmark that we expect competitors to match.

Indeed there is a rapidly expanding range of options which make use of lithium-based technology, considered superior by some for its high efficiency, high cycle life and light weight. Lithium chemistries are also favoured by conventional electronics companies who see a market in home energy storage. The familiarity of the battery technology, being used for almost all modern portable electronic devices, and its light weight for reduced shipping costs, makes it particularly attractive. LG Chem has rushed to release its own competitive version, similar in size, shape and capacity to the Powerwall, while Schneider Electric, Positronic, Bosch, Off-Grid Energy and Samsung have similar offerings. However, where weight and size are not a problem, such as systems mounted in utility rooms and garages or dedicated sheds, thereare also some excellent lead-acid battery based storage options available, including Selectronic’s MyGrid (with a lithium version due out later this year), or the Hy-Tech hybrid system from Going Solar.

The ATA’s research has shown that based on these trends, residential batteries could be financially appealing for many within the next few years.


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Cover of Issue 32
You can read more about Solar stored in Issue 32 of Sanctuary magazine.

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Composting toilets can save up to 60,000 litres of water a year for an average home.

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