Review: a month with a Solargrow solar system
In October last year, we had a “once in a lifetime weather event” - some larger-than-tennis-ball hailstones, which went through this area with quite some force. A few hit our solar panels: the above is what happens when a large hailstorm hits a glass solar panel. Ouch.
The insurance company’s people came, looked at our roof, and decided that it all needed replacing: not just the solar panels, but the roof itself. In March or April, the neighborhood started to buzz with the eager sounds of roof replacements, and by May it was our turn to have the roof replaced. We used the insurer’s company for this, a company called Ambrose Construct, and they were very good - a good project manager, and good communication all the way through.
They would have replaced the solar as well for us, with a like-for-like replacement. Our system was almost ten years old, and was capable on a good day of producing almost 5kW. But, a few things had changed - not least, ten years ago we didn’t have an electric car.
So, I got the insurance money, and put a bit more in for an upgrade. The replaced roof came with more space for solar panels (a water heater having been removed), and my instructions to the solar people were “as many solar panels as we can fit please, and whatever size battery you think we should have, here is a graph of what we’re using”.
That, it turms out, is 28 panels on our roof, capable, theoretically, of producing 13.3kW. (They’re Trina Vertex S+ TSM-475 panels). A Sungrow SBH 20kW battery. A Sungrow SH10.0RS hybrid inverter. And a Sungrow 7kW AC-22E EV charger. Total installed cost, if we were buying this fresh, was (AUD) $27,500: that price includes some government subsidies for a home battery. We used Essential Energy Solutions (and I think if you tell them I sent you, you get some money or something).
After a month or so… how’s it all working?
The plan for savings
We were spending (AUD) $188.48 per month on electricity use. (That’s not our electricity bill - just the electricity we were using. There’s a daily charge on top of that, and other things which won’t change.)
To be fair, $188.48 was already quite low. We have a good deal using OVO Energy, which gives us three free hours of electricity between 11am-2pm; and because I have an EV and they think I’ll use lots more electricity because of it, a low overnight rate of just 8c/kWh. (The rest of the time, we spend 32.8c/kWh on electricity, and a standard “peak demand” fee which is something to do with the maximum amount of electricity we used in one half-hour during 4pm-9pm, multiplied up by some random figure, I don’t know, it’s Queensland, they do things odd here). OVO don’t offer this plan any more, I don’t think, but use my referral code here and you can save at least $120 on your first year’s bill, and I’ll save too!
The three free hours of electricity between 11am-2pm was quite unusual when I signed up; but is becoming a standard feature for all electricity providers in Australia. I think the federal government has told them to do it, since it looks like a good deal and might get them re-elected or something. In reality, everyone’s solar panels, including mine, are doing lots of generation at that time, so the wholesale price of electricity at this time is very low, so nobody really loses out.
I was timing a LOT of things to only go on during the free period, or overnight for the cheap rate. It was quite fiddly to do all this, but I’d got it so that the majority of energy use was happening in these times. I’ve no doubt that had I not, our bill would have been rather higher.
My new plan? To use the thee free hours of electricity as a solar top-up, to charge the home battery. As well as the car battery, maybe.
The software
The software is, as with all these things, “OK”.
Actually, it’s a bit bewildering. Thankfully, Solargrow gives you both an app, which is fine, and also a website, which is better.
This graphic shows the middle of a sunny winter’s day. The battery is already 100% charged; and the house was only taking 1.4kW. So, the 6.3kW being made by the solar panels is being split - 4.9kW back into the grid (for which I will earn 2c/kWh, which is nothing), and the rest to power whatever’s going on in the house.
The website is kind of fine. It has a steep learning curve. I’ve understood enough of it, but I doubt that it’ll be used to its best abilities by, you know, people not like me.
Anyway, I worked out where to tell it to charge the battery between 11am and 2pm; and also the priorities it should give various things.
And here’s a typical day.
Actually, it’s today. It’s been an overcast, quite miserable day today. Not much sun at all, so the panels have been quite low. A few spots of drizzle, which is unusual for Queensland in my experience (either it’s glorious and sunny, or it’s pelting it down with rain with a force unavailable to Californian shower heads).
Not entirely built for the colour-blind… the light blue less than zero is the battery charging. You can see that it started charging at about 7am.
At 11am, all hell breaks loose. The darker blue is power from the grid - we’d not taken any until 11am. Because electricity is now free, my system is using it to charge the battery and power the house. You can see the battery - the dark green line - full up to 100% by about 1.30pm. A lot of things in the house are timed to go on during 11am-2pm, including today the bread machine, the dryer, and the dishwasher.
The battery charging plan works!
At 2pm, the system stops taking electricity from the grid. It looks as if, because it’s been overcast today, the battery started helping the solar - it doesn’t normally do that. The battery also helped during the cooking of dinner between 5pm-6pm. We’ve hardly taken any electricity from the grid at all.
My experience of it all
I blew the fuse
Within a week, I got a worrying message - while all the power was still on in the house, the system was telling us that we had no grid power at all. Nobody else had a power cut - just us, except we didn’t have an actual power cut, because the battery was still giving the house electricity.
I ended up having to call Energex, the electricity board, and they came out almost instantly.
It turns out that all houses have a physical fuse, which is set to blow after the house reaches about 12kW (50A). No normal house should be doing that. Ours… was.
The Solargrow system was doing what it should have been - pulling as much electricity as it could, to both charge the battery, charge the car, and cover what the house was doing. But it didn’t know that it had a 12kW limit.
Anyway, it does now. It’s a setting that your installer should have set - though they weren’t to know my plan was to charge the battery from the grid. Our fuse now has a 15kW limit (63A); but the system has been told not to take more than 10kW from the grid. You’ll see it hitting that in the graph above.
The battery is almost exactly the right size
Above, you’ll see that the battery is about 40% full at the start of the day. Sometimes it’s 20%, and it’s set to stop at 10% to keep it healthy, and it hits that occasionally. But all in all, it works quite nicely.
I’m surprised, because 20kW is… well, I drive a 64kW battery about in the electric car. It could power the whole house for three times longer than the battery. But the battery is just the right size for the house, which is excellent.
Home Assistant integration hasn’t been entirely smooth
I’ve yet to properly get this integrated into Home Assistant. There are seemingly three integrations I could use: the one I’d like to use, Sungrow HASS, has an all-local mode that doesn’t pull data from the iSolar website: but I don’t, yet, see all the numbers I’m expecting. I’m helping the author to get it to work.
That said, I’m not sure what I’d use the Home Assistant integration for: the iSolarCloud application is capable enough for everything I’d like to do. The only thing that it’ll be helpful for, I suspect, is to have a backup of the data (and an easier way to see the home battery charge).
The EV Charger
The EV charger hasn’t been great so far, and the internet will tell you this too. The device is physically quite nice - it has an RFID card that you have to wave at the unit to unlock it and get it to charge (which I’ve disabled, since I can see who’s in my parking space from my camera, and I work from home).
As the internet will tell you, it falls offline quite regularly, and also goes into an error mode a fair bit: the only way to fix that is to physically take the charger out and then put it back in again. It’s just stopped charging a few times I’ve used it.
That said, it’s seemingly had two firmware updates since I got it - which I have to do manually - and it’s been much better since then. Early days.
And as this graph will show you, it’s quite intelligent.
I’ve set it to be “fast charging but self-sufficient” or something. That essentially pulls as much power from the solar that it can. The graph above was the middle of a sunny day, and my panels were making a decent amount of power. You can see it ramping up at the beginning of the day, as the sun rose in the sky, and then you can see it switching off for periods where it couldn’t get enough power from the system. Entirely as expected. By about 1.30pm, the car was recharged. The house battery still got to 100% too.
The actual savings
So, you’ll remember that we were spending $188.48 on electricity.
The first bill we had with this system setup, we spent just $35.08 on electricity.
I think that’s still higher than it’s going to be. Part of that was the “peak demand” thing, and that appeared to finger 7.30pm on Jul 31 as the peak electricity time for which it’ll work out a monthly charge. I don’t think I’d set the battery properly by that point (it was only commissioned on Jul 30). So I think the savings will be even greater: I don’t think we’re using any grid energy during the 4pm-9pm time any more.
There is a daily maximum of (from memory) 24kWh during the newer “three hours of free electricity” tariffs. I don’t have that maximum with my current plan; and I assume that I’ll have to do some fiddling to make that work. Mind, I’m not normally going near that.
After the insurance payment, in total I actually paid $12,000 for this system. So, at $150 savings a month, it will have paid for itself in just over six years. That’s clearly a pretty good thing - especially when you add the caveat that we were pretty good at shifting the electricity consumption to take advantage of our plan anyway.
That’s clearly a bargain; but if I were paying the full price for this installation, it would take fifteen years to pay itself back: and I’m not sure that’s particularly great.
Anyway, there we are!
We have a neighbour who has his own battery (or, perhaps, his own generator). When there is a power cut locally - which there is more often than you’d think - he turns on his house’s christmas lights to show off that he still has electricity.
I’m looking forward to also having electricity during a power cut. But I don’t think I’ll turn the lights on.