Battery storage in your home?
- Will Hazlerigg
- Sep 1, 2017
- 4 min read
Batteries are an energy storage solution that we get asked a lot about, and they certainly are something that is certainly very a la mode. There is a good reason for this of course and that is because they could help to bring about the next energy revolution! Their role in such a revolution comes from the potential for batteries to work together to create a “distributed grid” energy system: storing up cheap electricity generated when demand is lower - including from Solar PV or other renewable sources - then discharging the stored electricity at ‘peak’ times, when energy from the traditional grid network is expensive. Installing batteries in every home could solve the renewable energy debate of what to do when solar and wind farms produce electricity at times of no demand. The most important factor of all is that they could reduce the world’s reliance on fossil fuels. They would achieve this by allowing green energy resources to be fully utilised without the worry of the wind dropping or the sun being hidden by clouds. Viva la revolution!
To paint a picture: Imagine being close to self sufficient in terms of your energy needs. This is achieved by your solar panels are charging your home battery while you are away at work so that in the evening you can take advantage of the energy that you produced during the day. And if your solar panels produced more energy than can be used or stored, the battery will ‘sell’ your surplus over a shared energy grid, earning you money at the best rate available. In fact these smart batteries can act as your own personal energy broker, selling and buying electricity when the rates benefit you the most. So not only will you see a significant drop in your use of grid-based energy, but you will be earning money from it to. Smart!
The price of the batteries, much like the price of Solar PV, has been falling over recent years to the point at which they are now affordable for households. The price is set to fall even further if Aceleron (a clean-tech start-up), like Nissan, is right in thinking the answer lies in reusing rather than recycling car batteries. Amrit Chandan (a chemical engineer who is leading business development at Aceleron) says “car batteries can still have up to 70% of their capacity when they stop being good enough to power electric vehicles, making them perfect – when broken down, tested and repackaged – for functions such as home energy storage”. This development will no doubt greatly reduce the cost of home energy storage even further in a few years there is a large swell in the number of car batteries that need to be replaced.
Choosing the right size of battery for your home is vital. The Tesla battery for example has a very large storage capacity which most households would not use. If you have an electric vehicle (EV) then a larger battery like this will be great for you as you will be able to run your home and charge your car all with energy that you have produced. However if you don’t have an EV then you will have a lot of energy that you don’t end up using, and you will have paid more for the extra capacity you do not need.
This is why you will really need to do your research or why you should come to us, so that we can advise you on the best route to take.
Frequently asked questions:
What is the Cycle count and what does it mean?
The cycle count of a battery means how many full charge cycles you can get out of it. This is literally fully charging and draining the battery X amount of times. Tesla says that they have 10,000 charge cycles for example and give you a 10 year warranty to go with it. A standard laptop battery has a cycle count of 1,000.
What is the amount of charge a battery can hold?
This obviously depends on the size of the battery in question. The Tesla power wall 2 (10kW) charge put into layman’s terms, is said (by Tesla) to be able to store enough electricity to power lights, plug sockets and a fridge in a four-bedroom house for a whole day.
For longevity or the amount of time that you be able to run your house off the battery (power delivered over time), look to the kilowatt-hours figure: 10 kWh means 10 kilowatts delivered for an hour, 1 kilowatt for 10 hours, or 1.8 kilowatts (a 15 amp household circuit) for just under six hours. In other words, your investment (plus inverter, plus electrician, plus solar panels) gives you one 15-amp circuit running draw for a quarter of a day. Time to think about chaining together two or three Powerwalls, and doing high-drain applications (laundry, dishwasher) early in the day on sunny days.
https://www.extremetech.com/extreme/204702-what-the-tesla-powerwall-home-battery-means-inexpensive-time-shifting-for-solar-energy
If you would like to work out what size the battery you would need follow what was said in this article. “To work out what you will need we will need some starting values. First, how long do you want to run your house on a battery? I think Elon Musk (from Tesla) said one week. Got it. The next big thing is the power usage. I think a fair assumption is a constant 2000 Watt power usage. Clearly a house would need more than 2000 watts at some point in the day. However, at night you wouldn't need much power such that the average for the day could be 2000 watts. If you don't like that value, you can put your own numbers into the calculations.
If I know the power and the time, I can use the definition of power to calculate the energy stored in the battery. Having the power in Watts is fine (since a watt is a Joule per second) but I need the time in seconds.”
Source and link if you would like to go deeper into the article:
https://www.wired.com/2015/02/size-battery-need-power-house/
What are Intelligent batteries?
You can also now get ‘smart batteries’ these don’t just store solar energy – they can also store ‘economy tariff’ energy. This means you can buy your energy during the day when it’s cheaper, store it, and use it in the evening and at night instead of paying your energy supplier’s premium ‘peak-time’ rates.
What is the Cost of the batteries?
Anything from 3k and up to where the sky's the limit, as according to Mr Musk the sizing can be infinitely scaled up.
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