Solar options for home in 2022

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499 posts

Ultimate Geek
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#3418037 23-Sep-2025 17:59

Stu1:

HarmLessSolutions:

This video was posted on the NZsolar subreddit. Some good solid simply explained advice that mirrors our installer's advice for us to not bother with batteries, due to our consumption management and use model.

Good vid , the excel sheet would be great to play around with

Lots of very generalised assumptions in the video from the tariffs (TOU not mentioned), to the split of consumption winter vs summer etc.

You really want to download a previous year's worth of your own consumption data and then model what your own roof will produce so you can see if you are importing/exporting at each time period.

And only then plug in the tariffs. I had access to generation data at 15 minute resolution for a site close by, and had consumption data for our own house at 5 min resolution so could build a detailed model and compared 5 different retailers before chosing Meridian who were offering 5 year plans - I think they will now offer 3 years.

I'd also echo the advice to go for additional panels given how cheap they are.

Also don't skimp on the inverter output - think about how you use power. Our inveter allows us to run two ovens and the heatpump simultaneously - a great bonus in winter.

Otautahi Christchurch

HarmLessSolutions

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Uber Geek
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#3418064 23-Sep-2025 18:24

fastbike:

HarmLessSolutions:

This video was posted on the NZsolar subreddit. Some good solid simply explained advice that mirrors our installer's advice for us to not bother with batteries, due to our consumption management and use model.

Lots of very generalised assumptions in the video from the tariffs (TOU not mentioned), to the split of consumption winter vs summer etc.

You really want to download a previous year's worth of your own consumption data and then model what your own roof will produce so you can see if you are importing/exporting at each time period.

And only then plug in the tariffs. I had access to generation data at 15 minute resolution for a site close by, and had consumption data for our own house at 5 min resolution so could build a detailed model and compared 5 different retailers before chosing Meridian who were offering 5 year plans - I think they will now offer 3 years.

I'd also echo the advice to go for additional panels given how cheap they are.

Also don't skimp on the inverter output - think about how you use power. Our inveter allows us to run two ovens and the heatpump simultaneously - a great bonus in winter.

A simple presentation as I said and though it may fall short of pulling in the extra details you've mentioned it is great entry level advice and streets ahead of what the likes of Powerswitch have on offer.

I also assume that this is intended as a sort of flyer for Equity Solar Brokers who obviously have the skills to provide more focused advice, probably as a paid service. I haven't yet had time to look through their other Youtube offerings but there looks to be more detail available there.

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

CrashAndBurn

693 posts

Ultimate Geek
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#3418070 23-Sep-2025 18:44

HarmLessSolutions:

Price seems about right though overpanelling is recommended to maximise generation day length and performance in poor weather.

Worth checking what fixing they're using on your tile roof. Our installer uses a special Tin Tile bracket that requires lifting the tiles, fixing direct to the batten and then the bracket has a profile that zigzags out between the tiles. This avoids drilling through the tile which would compromise your tile roof warranty but it adds a bit of expense to the installation. A lot of installers don't bother with the extra expense of doing this in order to win on price.

They will be using solar brackets made by Gerard which is what our roof is made of.

LightbulbNeil

73 posts

Master Geek
+1 received by user: 21

#3418085 23-Sep-2025 19:42

An interesting video with the solar broker. Currently a battery would save us about $850 per year, but cost for the compatible Telsa power wall on 1 phase is just under 18k installed. We have 3phse Fronius inverter and is the older type, where it would need 3 batteries to have all 3 phases on a battery backup. It would need a few things changed to the same phase as the battery to be used at night. In winter we use more power at night time than we do in the day time. In the summer, we use more in the daylight hours than we use at night. The west facing array does make a big difference when running a dryer at night etc after 5pm getting the washing dry. We have not tried the time delay of washing in the early hours of the morning and then running the dryer on a delayed start, but is something that we should be looking into, as we do have an effective 4kw east array as well.

If things change significantly with the solar buyback schemes etc, then we may well end up with a new inverter and a largish battery to get us through the winter. For us, batteries would need to be about 1/3 of current prices for it to be worth while for our circumstances. So get a 3phase inverter that can run all 3 phases off the 1 battery supply.

In 3 years time our Meridian contract comes back up for renewal , so will look a lot more into the current technology in 3 years time.

Neil

fastbike

499 posts

Ultimate Geek
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#3418093 23-Sep-2025 20:25

LightbulbNeil:

An interesting video with the solar broker. Currently a battery would save us about $850 per year, but cost for the compatible Telsa power wall on 1 phase is just under 18k installed. We have 3phse Fronius inverter and is the older type, where it would need 3 batteries to have all 3 phases on a battery backup. It would need a few things changed to the same phase as the battery to be used at night. In winter we use more power at night time than we do in the day time. In the summer, we use more in the daylight hours than we use at night. The west facing array does make a big difference when running a dryer at night etc after 5pm getting the washing dry. We have not tried the time delay of washing in the early hours of the morning and then running the dryer on a delayed start, but is something that we should be looking into, as we do have an effective 4kw east array as well.

If things change significantly with the solar buyback schemes etc, then we may well end up with a new inverter and a largish battery to get us through the winter. For us, batteries would need to be about 1/3 of current prices for it to be worth while for our circumstances. So get a 3phase inverter that can run all 3 phases off the 1 battery supply.

In 3 years time our Meridian contract comes back up for renewal , so will look a lot more into the current technology in 3 years time.

Neil

We have a 3 phase 10kW Solis inverter with 12kW of panels (facing almost due North). We have a battery that we can cycle for 24kWh keeping it well away from the fully charged/fully discharged zones so it should last a very long time.

Even with a large fully electric (except gas hob) home we only used about 100 kWh of day time power over the 3 winter months. And we do sometimes use the full 10kW capacity of the inverter in winter.

We're lucky that we found an installer that allowed me to contribute sweat equity to keep the costs much lower than a package deal. The battery went in 4 months later.

We're also lucky that we kinda lucked out in choosing the inverter / battery combo even though that was not obvious at the time we spec'd the original PV/inverter combo.

We're currently exporting a bit of power (approx 6kWh) between 7am and 9am in the morning when a sunny day is forecast so we do not pump too much back into the grid - being able to charge the battery from the "peak" of the PV output.

Otautahi Christchurch

chimera

563 posts

Ultimate Geek
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#3418228 23-Sep-2025 23:48

HarmLessSolutions:

This video was posted on the NZsolar subreddit. Some good solid simply explained advice that mirrors our installer's advice for us to not bother with batteries, due to our consumption management and use model.

Totally disagree on the battery front, no matter what system. If he's calculating ROI then he must be including the battery cost, and he's stating a battery cost of a Tesla Powerwall at $17,000 for 13kWh... so he is WAY off the money!!! I can sell you a top brand LiFePO4 16kWh (~13kWh or so usable at 80% DoD) battery for under $5k. That changes the math SIGNIFICANTLY. Batteries are great - yes for power cuts - but also for rate shifting if you are on a lower rate overnight, charge the battery then and use the battery during peak hours in the morning. Likewise charge with excess PV during the day and use battery at peak hours at night.

chimera

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#3418229 23-Sep-2025 23:55

...oh, and obviously we had this discussion via PM already :-) So the lesson is not to go with a proprietary branded inverter when installing, go for more of the GoodWe, DEYE, etc hybrid inverters. One that doesn't force you to use their brand of batteries. For eg, I've got a DEYE 8kw hybrid inverter and am WELL impressed with it. Been rock solid since day one, good price, good warranty.

MikeFly

192 posts

Master Geek
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#3418231 24-Sep-2025 03:30

LightbulbNeil:

An interesting video with the solar broker. Currently a battery would save us about $850 per year, but cost for the compatible Telsa power wall on 1 phase is just under 18k installed. We have 3phse Fronius inverter and is the older type, where it would need 3 batteries to have all 3 phases on a battery backup. It would need a few things changed to the same phase as the battery to be used at night. In winter we use more power at night time than we do in the day time. In the summer, we use more in the daylight hours than we use at night. The west facing array does make a big difference when running a dryer at night etc after 5pm getting the washing dry. We have not tried the time delay of washing in the early hours of the morning and then running the dryer on a delayed start, but is something that we should be looking into, as we do have an effective 4kw east array as well.

If things change significantly with the solar buyback schemes etc, then we may well end up with a new inverter and a largish battery to get us through the winter. For us, batteries would need to be about 1/3 of current prices for it to be worth while for our circumstances. So get a 3phase inverter that can run all 3 phases off the 1 battery supply.

In 3 years time our Meridian contract comes back up for renewal , so will look a lot more into the current technology in 3 years time.

Neil

Hi Neil, I would add to that, get a 3Phase inverter that can run unbalanced across phases. Goodwe ET series for example and I think Deye as well can do this, Sungrow (discussion here) no doubt others.

fastbike

499 posts

Ultimate Geek
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#3418233 24-Sep-2025 07:03

MikeFly:

Hi Neil, I would add to that, get a 3Phase inverter that can run unbalanced across phases. Goodwe ET series for example and I think Deye as well can do this, Sungrow (discussion here) no doubt others.

+1 for that.

We have a 10kW 3 phase Solis S6 (S6-EH3P10K-H) which allows us to run 2 ovens and the heatpump. Each phase can deliver independently up to 3.6kW. Occasionally the heat pump will draw 4kW, and only 400W is from the grid.

I'm not sure how all of this works in the background but it sure seems like magic to me (even with a strong technical/microelectronics background).
The Chinese manufacturers are the world leaders in this space with many innovations coming out of their labs.

Otautahi Christchurch

dukezoid

74 posts

Master Geek
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#3418353 24-Sep-2025 10:45

CrashAndBurn:

I just received a quote for solar below and was wondering how it compares to others. House in Drury. Single face metal tile install. Electric hot water timer included.

12 x Trina S+ 500

6kW Sigen Energy Inverter

Fully installed 13.5K

Add 8.5K for a 9kWh Sigen Battery

Is this a reasonable price?

That sounds on the high side. Have you shopped around? Ask for itemised quote to aid compare.

Quote check:
- Trina 500s are around 180 ea so 2,160
- 6kW inverter maybe $4 ish (was quoted an 8 for 4.5K
- plus racking / wiring / CT / breakers / install 3-4K

=~11K - so 13.5 def high

AIUI they only make 5 and 8 kWh batteries, cost on an 8 is around 4.5K +gst so that seems very padded.

Installed Sig in Feb. It is good kit (touch wood).

Suggest you go for at least 10kW inverter (they do up to 12 on single phase), it’s not much more and you’ll appreciate down the track.

One can save a bit by putting up your own racking and even running conduit and wiring (not terminating, that has to be by electrician) if you find a friendly installer. Hot water timer is an easy self install, definitely get smart (wifi) not dumb! Shelly integrates with Sig or you can get a Tuya for ~$15 (I’ve installed four Tomzn 63A relays , no issues)

HarmLessSolutions

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#3418361 24-Sep-2025 11:40

chimera:

HarmLessSolutions:

This video was posted on the NZsolar subreddit. Some good solid simply explained advice that mirrors our installer's advice for us to not bother with batteries, due to our consumption management and use model.

Totally disagree on the battery front, no matter what system. If he's calculating ROI then he must be including the battery cost, and he's stating a battery cost of a Tesla Powerwall at $17,000 for 13kWh... so he is WAY off the money!!! I can sell you a top brand LiFePO4 16kWh (~13kWh or so usable at 80% DoD) battery for under $5k. That changes the math SIGNIFICANTLY. Batteries are great - yes for power cuts - but also for rate shifting if you are on a lower rate overnight, charge the battery then and use the battery during peak hours in the morning. Likewise charge with excess PV during the day and use battery at peak hours at night.

The base information behind that video is still sound and it should be remembered that it is aimed primarily at new entrants to home solar who are usually heavily reliant on their installer to stitch the various components together in a cohesive package. Equity Solar Brokers appear to work as an intermediary between customers and a stable of reputable installers so will be bound by the practices of those installers who are likely to be resistant to including components with unrecognised reliability and manufacturer support. The installer after all will be the one who carries the can if the component fails.

Also the fact remains that payback on batteries is a combination of the amount of electricity that can be shifted from immediate use to it offsetting import at the time the battery is discharged. The differential between import price and FIT at the time of use is the crucial factor and as FITs from some retailers move towards supply price the effective ROI reduces directly.

In our own case two inverters feeding onto the two phases into our property is incompatible with monitoring software parameters that are designed to European or other juristictions where this configuration wouldn't exist. Adding batteries to our situation would only add a further complication to what is already too far from the norm to enable accurate real time control of its output automatically. I therefore have adopted a hands on approach in order to maximise our self consumption, which is always going to yield the best return on investment for solar.

This video from the same source also mirrors the strategy we have adopted on our multi phase property, except we have put a separate inverter on the second phase expressly for export (no consumption).

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

chimera

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Ultimate Geek
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#3418365 24-Sep-2025 12:08

Yes the basis of the video is good. However the long and short of it is, no matter how you lay it out $17k for battery to your overall cost (vs ~$5k) ammortised over say a 10 year payback, significantly affects your ROI. That is $12000, over $1200 per year, $100 a month. That is a considerable amount of difference on a $20-$30k system.

My 2nd point is relying on installers alone to provide recommendations (and at their price point) is probably valid if you take into consideration most have zero idea on how a solar system works. Most rely on "expert" advice from the installer. But if you both understand your average power usage and educate yourself on how solar works (undertanding kw, kwh, various rates, battery requirements etc) prior to installation, then you call the shots and can save a ton of money, improving your payback. I did this with the solar installer and basically told them what I wanted, rather than them selling me something they thought I wanted. I used AA Solar and I will admit the good thing about them was they were very open to what I wanted - we discussed different options, I could "speak" solar and we settled on a solution that was both workable and cost-effective to me.

The sun don't shine at night :-)

Jase2985

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#3418492 24-Sep-2025 14:23

@dukezoid:

AIUI they only make 5 and 8 kWh batteries,

Nope their new ones are different sizings, "6kWh" and "10kWh" see the video and data sheet below

https://www.youtube.com/watch?v=bkrr4i0PruU&t=333s

https://www.sigenergy.com/uploads/en_download/1750078918261785.pdf

timmmay

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#3418494 24-Sep-2025 14:26

It made no financial sense for us to get a battery with our solar system. We pay 21c/kwh and get paid 19c/kwh for exported power. That 2c/kwh margin is what the battery would gain us, the roi on that is probably decades. The only way it would make financial sense for us to get a battery would be if the export rate drops by I don't know maybe 50% or more.

The grid is our battery.

richms

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#3418497 24-Sep-2025 14:46

timmmay:

It made no financial sense for us to get a battery with our solar system. We pay 21c/kwh and get paid 19c/kwh for exported power.

That is far from the norm, and will probably change when more people start exporting and the power becomes worthless at that time of day.

Richard rich.ms

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