Solar Choice
In April last year, we got 7.8kW of solar with a SolarEdge inverter, including consumption monitoring. In November, we got a 9.3kWh LG Chem battery. From this experience, we have learned a lot from the benefits of solar and independently, batteries, and think there is a lot you should do prior to making the leap into batteries. Here are 5 steps I think households should take before getting a battery:
1 – Add as much solar as you can
It is important to remember that batteries do not produce electricity, just store and shift it. On the other hand, solar produces electricity. The electricity can be used to power your household, and export to the grid. While many complain that feed-in-tariffs (10-15 c/kWh) are much less than what you pay for electricity (25-35 c/kWh), they still present a good return for your excess solar. Just on feed-in-tariffs alone, once can expect 8-12% ROI (annual savings/revenue divided by cost of solar installation).
We used to pay around $1,600 per year for electricity. With solar, we were earning around $110 per month in feed-in-tariffs, more than covering the cost of our remaining grid electricity usage, resulting in running at around $700 per year profit. With current high feed-in-tariffs, it is a good time to go big on your solar now to payback a good portion of your system in the next few years.
Feed in tariff credits
This could even mean getting 10kW of solar or more.
2 – Consumption Monitoring
It is important to have a good idea of how much solar you are producing, how much electricity your house is using and when, and how much solar you are using directly (ie. self consumption). Prior to getting a battery, we had shifted loads like hot water heat pump, dish washer and washing machine into solar production times to maximise our solar production. This saw us being 65% solar supplied! And only using 2-4 kWh per day from the grid.
So we knew that getting a 9.3kWh battery was a bit overkill for what we needed. But at least we knew. Without consumption monitoring, we wouldn’t have been in tune with our electricity demand and solar production to become 65% solar supplied, and would not have known what size battery we needed or if we needed one at all.
3 – Hot Water
Like many shire households, we used to have a resistive element hot water tank for out hot water. It was on a controlled load, and produced hot water overnight. We found that it was using 8 kWh per day. This was around half of our daily electricity use!
We now have a hot water heat pump. This is efficient and uses 2 kWh per day on average. When we got solar, we moved our heat pump production for overnight, to come on at 1pm each day. For watching our consumption monitoring, it is powered by solar for pretty much all of the year.
Photo: Heat pump (in blue) operating from 1pm
Basically, we are using solar to make our hot water in the middle of the day, then using the hot water when needed. It is effectively an 8 kWh battery. A new hot water heat pump and tank costs between $2,500 and $4,500 installed, much cheaper than a Tesla Powerwall or LG.
Other than a heat pump, you could also use a timer to make your hot water system to make hot water during the day, or use a PV Diverter to power your hot water with solar (around $1,000).
4 – LED Lighting
We use lights predominantly at night. If you get a battery, it is wasteful to use up the battery capacity using inefficient lighting. It may mean that you get a bigger (more expensive) battery, or you leave less battery capacity available for back up or other purposes. Efficient lighting like LEDs can use 80-90% less than older lighting technologies.
5 – Electrify and be efficient
It is now possible to meet all your household energy demands efficiently using electricity. This may mean a heat pump for hot water, electric induction stove tops and ovens and efficient reverse cycled air conditioning for heating in winter. This means no more gas bill, and in particular, now more gas connection fixed fees. This saving on gas bills can help your payback on a battery. And even more, you can reach 100% solar supplied!
Rather than investing in a huge or multiple batteries, see what efficiency improvements can be made around heating, cooking and other uses, and see through your consumption monitoring what best battery may suit.
If would like to find out more about how to go all electric efficiently, the My Efficient Electric Home Facebook Group is a great place to get info, hear from others and ask questions.
This article is by Jonathan Prendergast, founder of the volunteer-run Sutherland Shire Community Energy initiative (and website) Sunny Shire. He also contributes to My Efficient Electric Home Facebook group – a popular and active forum for Australians seeking to improve energy use in their homes. It was reproduced here, via Solar Choice, with his permission.
This post was published on June 20, 2018 12:42 pm
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View Comments
The energy efficiency discussion was traditionally a key part of every responsible solar sale. Now there are much bigger fish to fry with it!
I summarize it as Maximize PV, then 5 load-shaving steps AND BATTERY ELECTRIC VEHICLE, then size batteries to support both household and vehicle charging.
Considering the inefficiency of an internal combustion engine in a car or truck (or bus), plus the direct and externalized (health, climate disruption, water, soil and air pollution) costs of fossil fuels, using the sun to power your car is 3 to 7 times more valuable per kilowatt-hour than using it to power your home or business. That can mean 1 to 2 year payback times from savings.
Once this is widely understood, the Renew Economy team will be convincing people to go fully electric 5 times faster than before, and Australia can move the 2050 schedule up to 2030, starting without help from the feds, and then using the excitement to win the next elections.
Households with more than one vehicle can replace the one that never leaves town with a battery EV of modest range. Do it now. There are a couple of iMiEVs for under $15K here: https://www.carsales.com.au/cars/electric-fueltype/?sortby=~Price&offset=0&setype=sort&area=Stock&vertical=car&WT.z_srchsrcx=makemodel
Exactly. People talk about charging station locations, and charge speeds, and vehicle range as big issues. If you are a two-car household with your own off street parking, none of these are going to be an issue for you. We could get significant electric vehicle take-up if people knew these things.
And if you get a second hand Leaf or i-MieV the upfront cost is sorted as well, but the availability of these cars is going to be the limiting factor.
Yes. I have an ordinary power point in the carport where I park our household's two cars. One is an ex-demo iMiEV we got almost 5 years ago. The other is a Holden Volt plug-in series hybrid we got second-hand early this year. The latter is the car we take for trips out of town because it has petrol range extension. Both cars have sufficient battery range for all local trips. All energy for our local driving is supplied by charging at 10A from that ordinary power point.
I agree with all points except with the step of "... size batteries to support both household and vehicle charging ..."
Batteries are a waste of money (this will change over time). There are better things to do with $30k for 3 Powerwalls or similar and it is cheaper to use the night tariff for charging the electric car.
And at the moment batteries behind the meter do nothing positive for the environment as long as you can feed all excess solar energy back into the grid. (max 10kW per phase in NSW)
Jo, I totally agree with you that "There are better things to do with $30k for 3 Powerwalls or similar"
If the Powerwalls are 11 kWh each, that would be $30k / 33 kWh, or AU$909 per kWh. The average global price, per Bloomberg, appears to be about US$209 per kWh, so you are at a severe disadvantage price-wise, probably largely due to federal energy policies.
My statement, "... size batteries to support both household and vehicle charging .." is based on prices of US$150/kWh, going down to US$100/kWh by 2022 at the latest. At Australian electricity prices, it might very well be worth doing at US$209/kWh.
Mark I concur. Once batteries at these low prices are available in Australia it will be a totally different ball game. But we are not there yet.
Once this happens, the grid operators and electricity retailers need to think of something to avoid mass defection from the grid. I am thinking of things like paying for auxiliary services like grid stabilisation. Standing charges even if you do not use the grid, could however be another (unwelcome) outcome.
Thank you for this article.
I would like to add that in contrast to the five points mentioned in the article, batteries are NOT renewable energy NOR negergy (avoided use of energy).
So also from the environmental perspective it is better to spend money on the above five points first.
Yep!
I agree Jo.
I didnt' want to be overly dismissive of household batteries. It does depend where your region is up to on the renewable energy transition however I think.
In NSW for example, where it is 80% black coal, we need to direct our $ into solar generation.
In somewhere like South Australia, which will be almost 70% renewable in a couple of years, there is a good case to suggest having a battery supports the environment by reducing morning and evening peaks which currently are served by gas and charging batteries through use of renewables via the grid or rooftop solar.
With concepts like Reposit and Virttual Power Plants, household batteries may solve future problems (and have good returns for battery owners) as we reach very high levels of renewable energy penetrations.
Thanks and agreed. We just have to make sure that household battery services will be paid for according to their value to the grid.
And as you said we need aggregators like Reposit and Virttual Power Plants to allow that to happen.