Futures Forum: New battery technology to change the energy infrastructure
Here's a very helpful discussion thread from YouGen, the on-line renewables-user community:
Could new batteries take you off grid? | YouGen Blog | YouGen, Renewable Energy Made Easy
Another black box has come along with equal promise:
Can a £2,500 'solar box' power your house at night?
They cost £2,500 and are the size of a dishwasher. Can these new 'solar blackboxes' really stockpile free power?
9:22AM BST 06 May 2015
167 Comments
It's the holy grail of home owners who have invested in solar panels – the ability to store power for use when the sun isn't shining.
A growing number of households, thought to number in the few thousands, are using hi-tech blackboxes that store up solar energy to use at night.
Currently, solar panels create "free" electricity as it is being generated, but if home owners need power at night, the energy is drawn from the National Grid and bought from their energy supplier as usual.
Used in conjunction with efficient solar panels the new devices could cut bills by 60pc, manufacturers claim.
But experts are more sceptical. Some have dismissed the gadgets as "overpriced and oversold", because savings are cancelled out by the £2,500 outlay of buying and installing one of the blackboxes, as well as regularly replacing internal batteries.
How does it work?
The boxes are the size of a dishwasher and designed to go in the kitchen, like the one pictured below, and silently charge up during sunny spells, monitoring whether electricity is flowing in or out of the house. The box itself contains a set of rechargeable batteries.
As soon as solar panels stop bringing in power, they flip to "discharging mode" and begin to power appliances in the home.
This means the "base level" of consumption in a home – the ongoing use of a modem, for example, or a set-top box – is always powered from solar energy rather than from the grid.
In theory, the device cancels out the cost of running small gadgets and appliances – that push up energy bills constantly sapping power.
The hungriest gadget is a wireless router, costing £21.92 a year while on standby, according to energy firm Ecotricity. Other costly devices include a desktop PC left on standby (£3.65), keeping a mobile phone charger plugged in (£2.44) as well as an electric toothbrush charger (£1.22) and a child's night light (73p).
The Powervault fits alongside your kitchen appliances and switches to "discharge" mode if you need extra energy
Even during the day, if you need a burst of energy to power an oven or kettle, for example, the device flips to "discharge" mode.
Joe Warren from start-up, Powervault, the only British firm to manufacture blackboxes, said: "They perform best if you have large solar panels that generate plenty of electricity, but you're not at home during the day to use it."
Surplus energy would otherwise be exported back to the grid.
Just 25 homes have a Powervault box installed although Mr Warren said the technology was in its "early stages". The firm recently gained £750,000 investment in a "crowdfunding" fundraiser to build more units.
How much can you save?
A household will save 50pc on energy bills by using solar panels but could save 60pc if they also use a battery system, according to Powervault's calculations.
But the cost of the blackbox could quickly cancel out these savings.
The units themselves typically last 15 years and the internal battery has to be replaced every five years, at a cost of £500. Including the capital outlay, that means your annual cost over 15 years is £233.
But having a shower or putting the kettle on could rapidly drain the batteries, experts warn, meaning they will need replacing more quickly.
Battery prices could fall in the future, as costs have already fallen by 40pc in the last year, according to figures from Renewable Economy, an energy-efficiency research centre based in Australia.
The income home owners earn from solar panels, known as the "feed-in-tariff", will be unaffected by the boxes. Currently, householders are paid money for every "kilowatt hour" of electricity their solar panels produce.
They earn 13.39p per kWh for all solar energy generated, and 50pc of this gets an added 4.89p per kWh. This is because you are assumed to use half of the electricity you generate and export the other half to the National Grid. The exported electricity gets a 4.89p "bonus" payment.
Installing solar panels in southern England, for example, typically saves £135 a year in energy bills alongside an income of £600 a year in feed-in-tariff and export tariff payments.
Scottish households save slightly less – £110 a year on energy bills and an income of £500, according to the Energy Saving Trust. You can work out the income from solar panels in your home with an online calculator.
The solar blackbox could, in theory, improve on the energy bill saving of £110-£135. It won't increase solar panel income or improve electricity generation.
Solar panels currently save up to £135 a year in energy bills, on top of 'feed-in-tariff' payments
The verdict
People will still rely on the grid – the blackboxes simply don't store enough to power high-consumption appliances, said Chris Rudge, a solar energy expert at YouGen, an online community for home owners with renewable devices.
Powering an electric shower, induction hob or hot tub, for example, would run the batteries flat in a minute or two. He said: "The battery unit is there to keep low wattage domestic appliances running, like lights and the television."
Costs are falling as big companies join the market, including Bosch, the home appliance maker.
Last week the US electric carmaker, Tesla, announced it would be making batteries that can power homes.
The new wall-mounted energy battery, costing $3,000 (£1,954), will be available in US homes from the summer. The company hopes it will "change the entire energy infrastructure of the world."
Foreign firms have been selling battery storage devices for the past two years, and these can be fitted in homes in Britain.
Mr Rudge said: "Some are good, a few look very doubtful!"
They mostly cater for people in cities or towns who simply need to store power to use at night. "This will save them buying in power when they get back from work," Mr Rudge said.
The £4,700 "Sunny Boy" box, for example, is manufactured by German-based company SMA and claims to cut energy bills by 52pc. This is compared to households which use solar panels on their own.
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