Solar options for home in 2022

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#3307069 8-Nov-2024 20:06

JimmyH:

Is there any recent modelling on the economics of solar. I have looked at installing it several times over the last 6-7 years, but every time I built a spreadsheet the numbers didn't work. And they were a long way off working, not just a little bit. Particularly given:

We are generally out during the day on weekdays, so likely wouldn't be around to use much of the power as it's being generated.
Our heating and hot water are mains gas, which limits the use we can make of power - and replacing those with electric currently isn't on the radar, it would cost a fortune, and given any reasonable cost of capital the payback period would be "never".
The rates for selling to the grid seem unreasonable. I know that power companies are trying to make a profit, and it would be silly to expect them to buy from me at the same rate they sell to me. But the purchase rates seem to be unreasonably out of line with both sell prices and spot market prices.
Battery prices seem uneconomic - and NZ battery prices seem to be much higher that householders pay in the US.
Or is my information out of date, and is it time to take another look at a solar fit-out?

i would add that odds are gas prices will go way up in coming years. power is always going up as it is. there is a lot of new battery tech coming out. a lot of grid storage systems happening. so good chance prices will continue to fall.

i think in the next year or so we should get a clearer idea of whats happening with nz gas situation and the advances in tech.

KiwiSurfer

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#3307073 8-Nov-2024 20:21

fastbike:

I also know some folk who have skipped the solar part and gone straight to an AC battery which they charge using free power available on some plans e.g 9pm to midnight with Contact. Not sure how that would work out, you might need 3 phase to pull enough power out to cover the other 21 hours. Also those plans are too good to be true so are likely to be altered which would be a pain if they were an integral part of your payback calcs.

Most TOU plans compensate for the free/cheaper power in off-peak hours by making the kWh rate more expensive in the peak hours (and some also increase the daily charge as well). Agree they will be altered if people start abusing them. Retailers they will optimise the off-peak and peak pricing split to ensure they still make a reasonable profit off customers. So if there is a big increase in the off-peak usage they could look at either reducing the off-peak period, add restrictions, increase peak prices, etc to bring profitability back.

Source: Recently did a big analysis of my energy usage against a lot of different retailer's plans to work out the best bang for my non-solar buck.

HarmLessSolutions

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#3307078 8-Nov-2024 20:50

Jase2985:

JimmyH:

Is there any recent modelling on the economics of solar. I have looked at installing it several times over the last 6-7 years, but every time I built a spreadsheet the numbers didn't work. And they were a long way off working, not just a little bit. Particularly given:

We are generally out during the day on weekdays, so likely wouldn't be around to use much of the power as it's being generated.
Our heating and hot water are mains gas, which limits the use we can make of power - and replacing those with electric currently isn't on the radar, it would cost a fortune, and given any reasonable cost of capital the payback period would be "never".
The rates for selling to the grid seem unreasonable. I know that power companies are trying to make a profit, and it would be silly to expect them to buy from me at the same rate they sell to me. But the purchase rates seem to be unreasonably out of line with both sell prices and spot market prices.
Battery prices seem uneconomic - and NZ battery prices seem to be much higher that householders pay in the US.
Or is my information out of date, and is it time to take another look at a solar fit-out?

Batteries still dont make sense for most.

Sell back rates depending on provider are actually pretty good, most are 12-17c, you just have to watch the import rates as thats where they will make their money from you.

As you have mains gas and are unlikely to change solar really isnt for you until gas prices get up there. You really need as much as you can on solar, to either use directly or be able to shift the usage.

Our installer advised us that a battery wasn't viable with our use model and 15 months on that advice was accurate. We WFH so can manage consumption including charging 2 EVs to maximise self consumption which is at ~63% overall to date.

Octopus's 17c FIT vs 18c night rate also makes the grid a cheap backup for nighttime EV charging and minimises the economic benefit of battery storage.

https://www.harmlesssolutions.co.nz/

dukezoid

74 posts

Master Geek
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#3307114 9-Nov-2024 08:43

HarmLessSolutions:
dukezoid:

Speaking of diversion, anyone checked out the Ali offerings?

e.g. 3.6kW 'PVmate' https://www.aliexpress.com/item/1005004829132599.html

Seems like it's built to a budget. From the 3 star review "Works but only drives from 600W and often loses the WIFI connection with in plus a refreshment every 8 seconds and things happen in 8 seconds. In the clear I advise against."

Other cautions would be Wifi frequency compatibility in NZ, powered by battery so ongoing monitoring to ensure that it's going, dodgy display (5 star review) and built integrity.

Paladin by contrast is NZ made, built to last with great support and wired connection to CT clamp on mains. Also microsecond mains monitoring so virtually no lag in chasing export levels.

Thanks for your thoughts. Indeed, wireless CT does seem imprudent.

Good to support local!

The toss up between HWC diversion (~$1K), dedicated PV to DC HWC element (~$1.5 - 2.5K, if DIY) or just going whole-hog with a battery ($$-$$$) is an interesting one.

RobDickinson

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#3307461 10-Nov-2024 11:55

Jase2985:

Batteries still dont make sense for most.

Quite possibly but you can pry my PW3 out of my cold dead hands.

fastbike

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#3307465 10-Nov-2024 12:01

thewabbit:

There are also these options from a company called IAMMETER

https://www.iammeter.com/newsshow/blog-scr485-20240613
https://www.iammeter.com/products/wifi-power-controller

A shame the mains connections are not properly shielded and terminated with strain relief etc. With that heat sink you'll not be wanting to mount into a closed distribution board.

I use their DIN rail mounted power meters which are solid affordable pieces of kit.

https://store.iammeter.com/wem3080t-150a

Otautahi Christchurch

eonsim

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#3307507 10-Nov-2024 14:16

JimmyH:

Is there any recent modelling on the economics of solar. I have looked at installing it several times over the last 6-7 years, but every time I built a spreadsheet the numbers didn't work. And they were a long way off working, not just a little bit. Particularly given:

We are generally out during the day on weekdays, so likely wouldn't be around to use much of the power as it's being generated.
Our heating and hot water are mains gas, which limits the use we can make of power - and replacing those with electric currently isn't on the radar, it would cost a fortune, and given any reasonable cost of capital the payback period would be "never".
The rates for selling to the grid seem unreasonable. I know that power companies are trying to make a profit, and it would be silly to expect them to buy from me at the same rate they sell to me. But the purchase rates seem to be unreasonably out of line with both sell prices and spot market prices.
Battery prices seem uneconomic - and NZ battery prices seem to be much higher that householders pay in the US.
Or is my information out of date, and is it time to take another look at a solar fit-out?

This is relatively recent and seems reasonable based on what I've looked through https://www.rewiring.nz/electric-homes-report they argue it cheaper now to go with a full electric household (including car and heating) than any mix of gas, petrol and electricity.

Jase2985

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#3307554 10-Nov-2024 17:41

eonsim:

This is relatively recent and seems reasonable based on what I've looked through https://www.rewiring.nz/electric-homes-report they argue it cheaper now to go with a full electric household (including car and heating) than any mix of gas, petrol and electricity.

While that may be the case the payback period to get there is rather long. its 7-10 years for solar even before you start changing HWC stove top heating etc.

HarmLessSolutions

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#3307562 10-Nov-2024 18:00

Jase2985:

eonsim:

This is relatively recent and seems reasonable based on what I've looked through https://www.rewiring.nz/electric-homes-report they argue it cheaper now to go with a full electric household (including car and heating) than any mix of gas, petrol and electricity.

While that may be the case the payback period to get there is rather long. its 7-10 years for solar even before you start changing HWC stove top heating etc.

The details are well laid out in their reports including the best scenario for replacement of existing appliances, vehicles, etc in the "When Should I Upgrade" section in this document.

Everyone's situation will be different so it is up to them to purchase/upgrade/replace when it makes best economic sense. As for 7-10 year payback that is essentially paying your electricity bills forward for that future duration, and as electricity supply prices keep increasing so do the gains from electrifying and so the payback period shortens. In the meantime NZ is saving foreign expenditure on fossil fuels.

https://www.harmlesssolutions.co.nz/

LightbulbNeil

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#3307694 11-Nov-2024 11:52

If we were not selling so much excess in summer, in winter we could do with more generating capacity. Wehas bottle gas hot water. A recent exercise showed that electric hot water would cost us more and would reduce the cash return each yesr. We are currently looking at 6yrs 3months for the payback of our system. When retired in 6 to 7 yesrs time, our power and hot wster will be free. It will be replaced with higher rates bills.

Our gas is 550$ a year including bottle rentle for 2 to 3 adults hot water califont.

The smaller solar system we were initially looking at would be a 10 to 11 year payback and we would still have some electricity charges in winter.

Neil

HarmLessSolutions

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#3307698 11-Nov-2024 12:33

LightbulbNeil: If we were not selling so much excess in summer, in winter we could do with more generating capacity. Wehas bottle gas hot water. A recent exercise showed that electric hot water would cost us more and would reduce the cash return each yesr. We are currently looking at 6yrs 3months for the payback of our system. When retired in 6 to 7 yesrs time, our power and hot wster will be free. It will be replaced with higher rates bills.

Our gas is 550$ a year including bottle rentle for 2 to 3 adults hot water califont.

The smaller solar system we were initially looking at would be a 10 to 11 year payback and we would still have some electricity charges in winter.

Neil

If you're referring to thermal solar panels along the lines of a SolarHart system I'd strongly advise against it. The economics of them don't stack up against PV these days.

The much better HW system is a conventional HWC of a decent capacity that is heated from your PV by way of a diverter. This set-up is often referred to as a 'poor man's battery' as you're essentially storing access generation in the form of heat so just boosting the amount of your generation you're self consuming. A diverter is typically around the $1,000 mark plus installation and from our experience it is the single best component in our solar set-up. Apart from the very rare occasion where a 'forced' grid import is required to address <40 degree temperature for safety reasons we have totally heated our home's water from only solar since it was installed ~3 years ago.

https://www.harmlesssolutions.co.nz/

Jase2985

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#3307770 11-Nov-2024 15:29

LightbulbNeil: If we were not selling so much excess in summer, in winter we could do with more generating capacity. Wehas bottle gas hot water. A recent exercise showed that electric hot water would cost us more and would reduce the cash return each yesr. We are currently looking at 6yrs 3months for the payback of our system. When retired in 6 to 7 yesrs time, our power and hot wster will be free. It will be replaced with higher rates bills.

Our gas is 550$ a year including bottle rentle for 2 to 3 adults hot water califont.

The smaller solar system we were initially looking at would be a 10 to 11 year payback and we would still have some electricity charges in winter.

Neil

$550 is an awful lot of night rate electricity, about 4,500kWh on our current plan, or approximately 13kWh per day, so 4.33h of heating on a 3kW element you would be able to heat about 260L from 15deg c to 60deg c or an awful lot of hot water use.

We are a family of 4 with 2 kids and a wife who has 2-3 baths a week and we would be lucky if we used 3h or power on hot water a day.

networkn

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#3307847 11-Nov-2024 20:11

Perhaps my expectations are out of whack, but I ended up filling out a form and providing information and being promised 3 quotes, but all of them want a qualifying meeting of between 30-90 minutes etc.

Seems OTT. I want to understand what we would need to cover our current power requirements + 15%, on a system that can be expanded, and optional battery.

I asked them if they can just email the list of questions, and I'll fill them out when I have time. Nope.

Jase2985

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#3307855 11-Nov-2024 20:48

Most want to speak to you to get an idea of what you want out of solar, how you use power etc etc, it is much easier to do it like that than to do it over a form. I got a couple of quotes with no meetings, but the one i had a meeting with is the one i ended up going with. he just seemed to understand what i wanted more than the generic quotes that were fired my way via email.

timbosan

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#3307871 11-Nov-2024 21:51

networkn:

Perhaps my expectations are out of whack, but I ended up filling out a form and providing information and being promised 3 quotes, but all of them want a qualifying meeting of between 30-90 minutes etc.

Seems OTT. I want to understand what we would need to cover our current power requirements + 15%, on a system that can be expanded, and optional battery.

I asked them if they can just email the list of questions, and I'll fill them out when I have time. Nope.

I went down this route recently as well, looking for a better deal than the original Harrisons quote (who are excellent to deal with, just expensive). I didn't proceed with any, I found them quite pushy.

In the end the only place I got a quote from (all I supplied was a photo of the roof) was MicroMall. They gave me options for a full install, partial (still needs a Sparky), and either a battery or just panels. Very quick replies. They are currently top of my list.

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