So we've had our solar panels for just over a year now. How has it gone? Any
regrets? Would we do it again?
The graphs still look good
The black line is our average pre-solar power bills for the six years to 2021;
the red lines are our post-solar power bills for 2022 and 2023. Solar was
fitted in mid-February 2022.
Our very best month was November when our power bill was... $1.92. Pre-solar
it would have been over $230.
We've saved over $2,000 this year in power bills. That sounds like a lot,
but break-even (including interest on the debt, too) is still out in
2029. That's only 8 years out of a 25 year warranty lifespan, and even 25 years later the panels should be only minimally degraded (say 10% or so).
Hot water timer - Sinotimer was the quality you'd expect for $26 ...
Much of the savings is still in making the most of Contact's free electricity
from 9pm to midnight, and having the hot water cylinder come on only at this time.
It keeps piping hot on that schedule no problem at all.
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A typical partly cloudy day.
Timers come on during the solar
generation time
The Hot water cylinder kicks in at 9:05pm when
power is free
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It was all good until November when it failed. And it failed off. So no hot
water for us.
Damian the sparky came and unwired it, and we were back to switching the HWC
on manually at 9pm when Alexa told us to, and off again when we blearily got
up.
... But the EuroTech timer is great
So we went to plan B which was the $218
Schneider bluetooth timer kit
from Eurotech.
It's fantastic, and pays itself off in a couple of months. It works via
Bluetooth off a phone app which makes setup nice and easy and I have far more
confidence in getting more than just a few months out of it. You can put it onto the internet to control your HWC remotely with a 'Wiser Zwave Hub' but that's $500, so only worth it if you go all-in on home automation and put similar IoT controls on all your plugs and lights.
The only issue was installation. The timer unit is physically quite large
(deep) in ways that the hot water cylinder's external mounting box is not.
After trying various ways to make it fit I settled on stacking two mounting
boxes on top of each other. It actually worked tidily and well, with long
screws thoroughly securing both boxes to the wall.
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Anticlimactic looking for the effort that went into it
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Looking for emergency power during a power cut
Oct 2023: According to everybody, if you want emergency power during a power cut you must have a battery hooked into your system. Without a battery, the solar power automatically cuts when the grid power goes down. This is because without a battery sink, the solar panels will liven the grid and make working on it highly dangerous.
However - my sister in law has just had solar installed by eSolar with a great workaround. Her system has a 'magic plug socket' that comes directly out of the inverter and bypasses the meter.
During a power cut, she can plug essential items such as her freezer and phone charger into that plug socket, and it will provide 240V and as many amps as the panels are generating. Neat!
Looking for simple static batteries
It would still be nice to have some battery storage. We usually generate far more than we can use during the day (for 8c /kWh credit) and then use power in morning and evening that we pay 30c /kWh for. It wouldn't take much storage - say 6-8 kWh - to cover off those few hours of usage and use hardly any grid electricity - apart from that free power at night that I'm so obsessed with!
Aug 2023: there seems to be more options now. mysolarquotes have a pretty good writeup and some initial options there. The usual solar-provider suspects all seem to have smaller cheaper batteries available. I might have to revisit this, even if it's so I can write another blog post!
I am on the fence about the ROI still. An EV with vehicle-to-home capability would be ideal, because you're buying a car that happens to be a battery too, but the large outlay would probably take decades to pay off at the meagre returns you'd earn. Even with the 73% margin we pay on export vs import power, the grid is probably a better value "battery" than what we could buy.
What could change this in the future is storage batteries made from old EVs. Either modern crashed ones where the battery will effectively last forever - or old Leaf batteries that are too degraded to use in a car anymore. This degradation isn't a problem for home storage - you just get more of them! - and home use has a much lower draw and recharge rate than a car so the batteries will have a quiet retirement and should last okay.
EVs Enhanced in Christchurch operates a great "cascade" where they fit their own new batteries and high capacity used batteries to Leaf owners who want the best range they can get, then take those batteries and sell them cheap to Leaf owners with almost unuseable batteries; then what happens to the oldest batteries? They are looking for other companies to reuse them and manufacture static storage batteries.
They pointed me at https://www.b3batteries.co.nz/ who they are talking to - they have a 'coming soon' website but let's see what happens there. I'm pretty keen for the right price.
