Well, happy anniversary to us and our rooftop solar array and battery storage. The 5kW of solar (LG) and two Enphase battery storage systems were installed 12 months ago, along with a solar hot water system.
Welcome to our lives as electricity load defectors. Not grid defectors (yet), but load defectors – part of a still small percentage of homes with solar (20 per cent) and a tiny fraction with battery storage – all looking to meet some of their own electricity needs.
This cohort be small now, but it is already significant, and it is rapidly growing. In time, perhaps by the early 2040s, half of all electricity demand will be served by homes like ours, as well as businesses and community projects. Network and market operators understand this, and welcome it.
Here’s some of the key details from our story: Until the installation of our solar system just over a year ago, the average draw from the grid of our house in the previous six months we had been there (late summer, autumn and winter) was around 18kWh/day.
Our total use – thanks to the installation of the solar hot water system (from Apricus) and the junking of the old and inefficient “kettle” that previously heated the water – has fallen to 13.7kWh/day over the full year.
But our average draw from the grid has fallen to just 5kWh a day – thanks to the fact that most of our supply now comes from rooftop solar, and some of that is put in two very small boxes (battery storage) for use in the evening, or during the day if the solar output goes down.
(In summer our average use from the grid is less than 2kWh a day, though it depends on how many people are staying and how much we are using the electric oven. We have pool pumps, our tank water is also delivered by pumps, and we have air-con, although we don’t use it all that much).
That data should make us very happy people, and it does.
It’s nice to have solar power most of our electricity needs throughout the day, and for the storage to look after the lights, the fridge, the water pumps and the other stuff for much of the evening. Effectively, we have gone 66 per cent renewable, and more than 100 per cent in daylight hours.
The surprising thing about these two Enphase batteries – although their maximum combined output is just 550watts/hour, is that they can look after most appliances, except for the electric oven and the rare times (twice) we had the air-con after dark, or when we have all the lights on for a party, and/or we have visitors, which is often.
Mostly, the batteries last till between 10pm and 12pm, although they often go into the early morning and (if we’d been out the night before), until dawn.
In fact, when we are not there, the house may not draw from the grid at all over a 24 hour period. (see graph above, from our Solar Analytics monitoring device. Note the blue line which shows the power is delivered by the battery).
It’s negative $31.56, probably thanks to the fact we have gotten a good feed in tariff (12c/kWh and now 16c/kWh) from our local retailer, Enova.
So, while most people have been hit by yet another 20 per cent rise in electricity bills, ours has fallen from around $2,500 a year to just $560 a year.
And that bill we do pay is made up entirely of network charges. In this region, northern NSW, that amounts to $1.60 a day. That’s about $560 a year that we can’t dodge.
To put it another way, it costs us an extra 30c/kWh of imported electricity just to use the grid – that’s a total charge of more than 60c/kWh for grid power. The network still hits the retailer for the energy we export, which is why we don’t get anywhere near the “retail” rate for our solar power, even though it’s going next door.
At those network prices, accusations of being a “freeloader” on the network are hard to stomach. No, we don’t fit into the prevailing models of the utilities, but that’s their problem. Worse, it’s a problem for low income and low usage households – such as retirees – who are similarly afflicted with outrageous charges.
Unless those network prices moderate, and if battery storage prices continue to fall as predicted, then we will have an economic incentive to install enough batteries to cut the wires – particularly if the generation mix from the grid has not improved.
That’s not something we would necessarily want to do. Our belief is that it is better to stay on the grid and be involved in energy trading, using our battery to provide network benefits, and all the other benefits of sharing electricity. We’d be happy to sell our output to low income housing at a discount of what we now sell to the retailer.
But not if the networks continue to load up costs, refuse to take write downs for past over investment, and don’t recognise the benefits of distributed generation. Properly used, solar and storage can save networks, and other consumers money.
Just look to Horizon and what they are doing, the Exmouth Golf Club is one example, but consumers and communities do not need to go off-grid, they can make do with a “thin” wire, by using their own solar and storage.
So, how did everything perform?
The LG panels have done pretty well. They are not ideally placed, because the roof structure meant we had to go east-west, and the neighbours gum trees cause shading that affects just under 10 per cent of the output.
Still, despite those limitations, they have still managed a “capacity factor” of around 17 per cent, or just over 20kWh a day.
The Enphase batteries have also gone well, without a hitch. It’s surprising how much they can do and we can see the argument for a modular system – just add more when you need it.
Right now, we can’t see the point of a bigger battery storage system like a Powerwall 2, because we could simply not make enough use of it. Maybe if we went off grid though, but then we’d likely need two of them, although I haven’t done the numbers on that.
And the numbers for the solar hot water are good too. We had to have the booster on a couple of times over a few weeks in late autumn, when it got cloudy and rainy, but haven’t used it at all for the last four months – but then it hasn’t rained either and the region has enjoyed above average solar hours per day.
Giles Parkinson is founder and editor of One Step Off The Grid, and also edits and founded Renew Economy and The Driven. He has been a journalist for 35 years and is a former business and deputy editor of the Australian Financial Review.
This post was published on October 4, 2017 10:50 am
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View Comments
this is you personally Giles?
Yep
well done; as a dyed in the wool environmentalist, who owns no property (went with previous wives), it is not economically sound to outlay funds - to conduct qualitative and quantitative methodologies - on someone else's house.
I designed and built my first energy efficient house in 1983/4 (2 wife got that one), using aspect (orientation), design and a mix of building components to have a home reliant on as little imported energy as possible.
For more than 30 years, I have tried to sway local and state government to incorporate energy efficiency in house design and written to federal government, but it's like talking to a very thick high embodied energy structure.
Wrote a booklet on 'energy efficient house design' (2002), bagging the BCA's 'energy rating system and finally vindication on ABC 7.30 Report April 26 2011 ... but still no changes wtf.
I am in the solar industry, responsible for marketing and installation of systems, but very leery of the 'batteries are the future', given the 'Kia warranty'.
Many people have solar but don't get the return (Qld just went to 10.6 cents feed-in and until about a month ago, Ergon Energy capped feed-in to 3kW systems, so zero export devices add additional - non-beneficial to Consumers - cost.
I have a puny website and will add your story (if that's OK), to http://www.est-red.com
Regards,
Daniel
Bravo!
Of course it would be best to stay on the grid and ensure that some of your excess production is used by your laggard neighbours who don't yet have solar gear. This would be simply the best use of the grid we already have.
But the reality of the situation is that nothing will change until the grid faces unbearable pressure from losing customers altogether. It's the wrong thing in the long run, but in the short run all of us who can disconnect altogether ought to do so. Gleefully!
Agree with all the above my LG panels plus Tesla storage make me seriously want to consider pulling the plug but I would rather share my considerable excess Kwh with the others until they catch up! The old socialist in me wont lie down.
Gold-dust. Precise, succinct and informative.
Hi Giles!
Great to see your Apricus is working well for you! Question about your Enphase batteries to further improve the economics. Initially I was the same thinking 270watts is not enough to really make a difference.. and the small storage would be too small to make a real dint for an aussie family...
Question I have for you: Are you / have you considered / is it possible to be discharging batteries in the evening and re-charging off-peak rates for use in the morning?? Looking at the Enphase Battery Specs - they give you 10 year warranty or 7300 cycles.
Effectively, cycling twice a day is going to give you 4.8kWh of storage and allowing you to "load shift" your morning load to off-peak times. I haven't personally set up an enphase system like this yet... Happy to be corrected by others if this is not possible / allowed?
Don't think it is allowed, but if it is pretty pointless with Enphase, as they take so long to discharge, would be running into solar time. As it turns out, we use out Enphase to capacity pretty much each day, and on many days do more than 1 cycle, because it discharges during day if solar output down and load is up, and then charges back up again.
Hi Brendan - I'm in Sydney and have a Powerwall v1 with Reposit hardware attached, which incorporates the ability to do tariff arbitrage (charge off-peak) when required if the house is on TOU.
It is not often used for us, with 6kWh usable getting us through the night quite often. My house sits on about 140W usage between 11PM and 7AM as I've got timers taking out the "vampire power" of devices on standby during that time.
While I wouldn't be hard-setting a system to cycle twice per day, another benefit of any battery system is covering solar intermittency e.g. on cloudy days, so I get an occasional day where the battery cycles 1.5 times.
It will be interesting to see the effect on lifetime performance. I have a blog on all this if you're interested.
Hello Giles,
Congrats on the first 12 months with Solar and Batteries. Just coming up to a year myself - but totally off the grid as the connection fee (or lack there of), made the business case for batteries even more compelling. Dropped my town supply gas connection at the same time which also added to the ROI, moving to LPG instead.
Unlike others - I don't share the same socialist feelings as regards feeding excess power back into the grid - that is unless they want to pay the connection fee on top the feed in tariff! If they do, sure - you can have the excess solar power and even some stored energy, but when the price is right!
Cheers
A Grid Defector
Roger, How do you cope with long spells of cloudy wet weather?
Or do you have a small gen set for those situations?
David, I am lucky enough to live on the south side of Brisbane, so multiple rainy days do not happen often, maybe 2-3 times in the past 10 months. I have 13kWh of LG Chem battery storage with 5kw of solar. I can keep me going for 2 days at a stretch. I started off with 6.5 and added a second two months ago. Most days the batteries are charged up by 10.30am.
Cannot recommend the Redback Inverter and LG-Chem Batteries highly enough - very good power management and the batteries charge quickly with the overall limiting factor of the max discharge at around 4.5kWh. That is perhaps the limiting factor.
Cyclone Debbie was the closet I have come to running out - however a few breaks in the cloud got me through.
One last comment - I seem to use 15-20% more power on average off the grid than when connected! Go figure! On the gen set - ah no, sort of defeats the purpose.
Have a lot of information if interested.
Roger, Many thanks for the feedback - I am a big believer in hands-on experience!
I live on the coast in Port Macquarie area and put 4kW of PV on the roof 18 months ago.
Two mistakes: A) should have installed 5kW of PV and B) should have angled the panels for more winter performance rather than summer performance as I export cheap power in summer and buy expensive power in winter.
It is also clear to me that I need battery storage to optimise my PV usage and that is my next project. Also, if I can go off-grid it would certainly help the RoI.
I would certainly appreciate any info that you can send me that you see as relevant from your experience. My email is david.hall49@outlook.com
David, Why go off-grid? Add more panels like I did and work out how much power you use over night, size your battery for that.
The aim of the game is to export enough solar to cover not only daily usage, but enough to cover service charge costs, plus charge the batteries.
Our household for the month of September exported 749.2KWh @ 12.5cents/KWh=$93.65, but after SAC of $33.71, we made a PROFIT of $61.85!
Note! We didn't import anymore than 1KWh. If something happens to the system, we have the grid as back up.
Yeah, we could go off-grid and I designed the system to be able to cut the cord if needed, but as you can clearly see it won't pay to do so.
Solarguy, Thanks for this it is good to know and I will look into this option. I think that to go over 5kW of installed PV I may have to change to a 3 phase system(?).
Dave, You can over size an array + 33% above max inverter AC output. So, 5kw inverter, array 6.65kw. These are CEC rules that the CER follow and will only allow that amount extra to claim STC's. If you go over that amount you can't claim STC's at all.
That may be all you need for all I know. If not then 3phase is in order to go higher.
Solarguy
You are 100% correct - being able to size the system as you have done is perfect. The Grid is there and is a good backup as you say, but every case is different and there is no one rule.
In my case (15x310 panels - 4.6kw) - it is unlikely that I would generate enough excess solar power to cover the cost of the connection + SAC considering that the FIT was 6 cents when I installed the system. At 11 cents it is marginal.
I am more than happy to sell any excess power back to the grid and draw nothing from it, but the Network provider needs to cover the connection + SAC costs as they are getting the benefit - not me! Now that works for me but not for others. Again there is no one rule fits all.
There is however no denying the fact that with the current price of power, alternatives are cheaper today and they are only goint o get cheaper tomorrow. If Oil was $150 per barrel and we were paying $2.75 per litre for petrol or diesel, changing to EV's would be economical too, but at $1.35 per litre, it is economically very marginal!
15% more power use is from conversion losses.
What was the cost of installing the system and how long do you think (at the present rate) it will take to pay them off?
Mates rates, so very quickly! But at normal prices, less than 5 years for the solar, probably around 8 years for the solar plus storage. But i haven't crunched the numbers exactly on that.
What are normal battery + install prices today, there?
Hello Giles and congratulations. I have had rooftop solar for years and batteries are the next step. I have been thinking about Enphase but wasn't sure about their effectiveness. Your experience seems to be all positive even with your modest beginning of 2 battery units. Can you give some insight into how hard , or not, is it to add more batteries after the initial install. Would be it be less costly ( per unit) to install 'big' initially rather than install 'small' initially and then add more later.
It would be fairly easy, just the installation costs - essentially the installer's time. Not sure it would be any cheaper, but by growing it you can avoid over-investments, which seems to me to be the biggest risk in on-grid battery storage
Thanks for the advice.
This is a great place to discuss these matters. As is My Efficient Electric Home on facebook. Feel free to join in with our 2,000 members. And keep reading One Step Off the Grid and Renew Economy! Link to the facebook group here: https://www.facebook.com/groups/996387660405677/
"Worse, it’s a problem for low income and low usage households – such as
retirees – who are similarly afflicted with outrageous charges."
This is a point that I would like to see advocates for the less fortunate press home.
People should be rewarded for using less, not penalised.
Giles, you say "maximum combined output is just 550watts/hour". I've never seen the unit watts/hour. What does it mean? The only units I know are power (watts) and energy (watt hours).
It's an error, he meant 550watts, which is the rate of power delivery from the battery. If they delivered 550W for an hour then the energy delivered would be 550Wh. watts/hr is a meaningless term, since a watt is a joule per second, adding 'per hour' to that makes no sense in this context.
I'm sure Giles made a typo, watts/hr, rather than watt/hr.