Solar options for home in 2022

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#3449072 2-Jan-2026 17:51

insane:

Sorry @tweake, I got a lot of respect for all the help you've provided on GZ over the years, but we're heading into the imagination game here.

If rapid refueling was so critical we should then expect huge numbers of ICE drivers to have large petrol/diesel storage at home to avoid the service station (a.k.a fast charger)

yes thats true, but no one makes their own petrol at home let alone cheaper than a gas station and we typically have multiple gas stations in every town. i'm just pointing out this option actually exists, charging speeds are getting insanely faster and human nature being what it is, there will be more demand for it.

how someone wants to use that or not use it, is up to them. its simply an option.

fastbike

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#3449073 2-Jan-2026 17:59

tweake:

yes thats true, but no one makes their own petrol at home let alone cheaper than a gas station and we typically have multiple gas stations in every town. i'm just pointing out this option actually exists, charging speeds are getting insanely faster and human nature being what it is, there will be more demand for it.

how someone wants to use that or not use it, is up to them. its simply an option.

You seem to be conflating apples with some other vegetable.

I have 68kWh of home battery storage. I also have a car that can just squeeze in 60kWh if it was dead flat and I needed it fully charged.

However I am unusual and my use cases are unusual - I cannot see a large market for an expensive home energy storage system, and an expensive EV, and a very expensive system to connect them together. Battery prices are already very low and the rapid increase in capacity/$ we saw in the last 15 years is flattening out.

Sure there will some for whom $$ is not an issue - they are after convenience. Sales figures for the new car market in NZ do not lead to the type of systems you are advocating.

Otautahi Christchurch

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#3449157 3-Jan-2026 12:23

fastbike:

.....We ended up with 27 panels on the roof. We had looked at Fronius but ended up with Solis as they had 4 independent PV inputs - the roof layout required 3 which most could not support....

This is an interesting comment.

I'd need to split my panels over multiple roof faces too. Per the below. Does this imply I need to support more than two too?

HarmLessSolutions

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#3449161 3-Jan-2026 12:51

@insane That plan view needs an indication of where north is to get best answers to your question.

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kangaroo13

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#3449162 3-Jan-2026 12:52

insane:

fastbike:

.....We ended up with 27 panels on the roof. We had looked at Fronius but ended up with Solis as they had 4 independent PV inputs - the roof layout required 3 which most could not support....

This is an interesting comment.

I'd need to split my panels over multiple roof faces too. Per the below. Does this imply I need to support more than two too?

In principle, because you have two faces with NNW aspect, these two faces could be on the same string (I'm assuming N is straight up in your photo). If they are all pointing in the one direction with similar sun exposure, they can be put on the same string, regardless of whether they are on one face or multiple faces. However, it looks like you have some shading on your most northern face, and so you could be advised to have 3 strings (or prune the trees, or use optimisers). The principle here is that with a string inverter, traditionally the performance of each panel is derated to the performance of the worst performing panel in the string.

The derating to the worst performing panel is mitigated to some degree in modern panels with built-in bypass diodes (and can be further so using optimisers) - i.e. if you only had option of a 2 string inverter, it would probably work out OK, but you're probably better off looking into 3 string inverters and getting some expert advice on this.

You also want to be careful with constant shading from your satellite dish. Check out a recent YouTube video from Joonulup electrical on this topic (https://www.youtube.com/watch?v=rW0lvKdqLJM). Can the sat dish be removed, or relocated to a southern facing roof face?

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#3449216 3-Jan-2026 13:44

HarmLessSolutions:

@insane That plan view needs an indication of where north is to get best answers to your question.

North is straight up, and in summer the roof gets full sun from 8:30ish, but in winter there's shading on the East end of it until around 11am (neighbours have massive trees that we've pruned once before). Harrison's and Zen both suggested some Tygo optimisers, but that was before I thought about adding panels on the West face to get late afternoon sun and prolong the generation duration, so if that was in play they might have suggested different inverters

The West face is a two story drop, so I imagine that's extra fall protection or scaffolding so perhaps why that was not suggested originally.

Both satellite dishes can and will go when the roof is replaced, I've never used them - came with the house.

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#3449218 3-Jan-2026 13:59

I wonder why noone makes triangular shaped panels to better fit roof shapes like this.

Richard rich.ms

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#3449219 3-Jan-2026 14:04

insane:

HarmLessSolutions:

@insane That plan view needs an indication of where north is to get best answers to your question.

North is straight up, and in summer the roof gets full sun from 8:30ish, but in winter there's shading on the East end of it until around 11am (neighbours have massive trees that we've pruned once before). Harrison's and Zen both suggested some Tygo optimisers, but that was before I thought about adding panels on the West face to get late afternoon sun and prolong the generation duration, so if that was in play they might have suggested different inverters

The West face is a two story drop, so I imagine that's extra fall protection or scaffolding so perhaps why that was not suggested originally.

I'd be thinking twice about whether the expense and effort of putting panels on a WSW facing (30 degree sloping?) roof is justified. They're not going to see much sun for a good part of the year.

You're aiming for close to 10 kW of panels as I understand it. I would think the roof pitches coloured yellow would be able to accommodate that much capacity?

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#3449220 3-Jan-2026 14:18

HarmLessSolutions:

insane:

HarmLessSolutions:

@insane That plan view needs an indication of where north is to get best answers to your question.

North is straight up, and in summer the roof gets full sun from 8:30ish, but in winter there's shading on the East end of it until around 11am (neighbours have massive trees that we've pruned once before). Harrison's and Zen both suggested some Tygo optimisers, but that was before I thought about adding panels on the West face to get late afternoon sun and prolong the generation duration, so if that was in play they might have suggested different inverters

The West face is a two story drop, so I imagine that's extra fall protection or scaffolding so perhaps why that was not suggested originally.

I'd be thinking twice about whether the expense and effort of putting panels on a WSW facing (30 degree sloping?) roof is justified. They're not going to see much sun for a good part of the year.

You're aiming for close to 10 kW of panels as I understand it. I would think the roof pitches coloured yellow would be able to accommodate that much capacity?

The WSW (#4) gets plenty of sun from what I've seen, it's also completely unobstructed. The ridgeline between #4 and #3 shades part of #1 and #3 in the late afternoon, although by then the sun is weaker.

Having #1 and #2 together makes sense if the shading can be managed or avoided through optimisers or placement.

Yeah 10k of PV sounds optimal, but my main mission is 5kw of generation for the longest hours possible. Unless it makes more sense to get a battery to fill in the non peak periods.

The yellow arrow is the direction the sun moves through the day.

Jase2985

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#3449266 3-Jan-2026 14:31

HarmLessSolutions:

I'd be thinking twice about whether the expense and effort of putting panels on a WSW facing (30 degree sloping?) roof is justified. They're not going to see much sun for a good part of the year.

Yea. i would kind of agree. your house looks to be the mirror image of ours with respect to the east-west roof layouts.

Below in the images our East array (8x 440w panels) is at 117 degrees and the West array (16x 440w panels) is at 297 degrees, and the below images show how well they produce. East is the green line in the images, West is the light blue and the total is the dark blue.

Noting that the East panels are 1/3 of the total size of the system, i would struggle to think they are making more than about 1/5-1/6th of the total generated power. Your house it not very optimal for solar with its orientation and with the shading. those roofs dont look that big either.

Any idea of the size from the gutter to the peak and the width you could fit panels onto?

June 2025, peak of 950w on east array, 3.8kw on the west array

December 2025, peak of 2.7kw on east array, 5.6kw on the west array

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#3449268 3-Jan-2026 15:04

At the risk of stating the obvious it is worth noting that the sun rises and falls much further north in the winter than in the summer. In other words those WSW panels on @insane's roof will be seeing sunlight coming from the WNW at best later in the day in winter and at a very flat angle to the horizon. The result be be very low generating potential for that roof face.

The reason PV panels are best placed to face N with a slope of ~40 degrees is because that is perpendicular to where the sun is at midday on the equinox in NZ. Your location's latitude will give you a more accurate angle than that. Summer it's higher; winter it's lower so flatter panels are better optimised for summer and steeper panels for winter.

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

fastbike

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#3449315 3-Jan-2026 15:39

insane:

This is an interesting comment.

I'd need to split my panels over multiple roof faces too. Per the below. Does this imply I need to support more than two too?

All of our panels face almost true north but the roof has a convex curve so the tilt varies from approx 25 at the lower side to 12 degrees at the apex. We used three of the inputs to decouple the different slopes.

The other thing is to watch the max allowed voltage - both of the inverter input and the regs. I'm not sure if the revised standard has been gazetted but we were only allowed up to 600VC DC.

Otautahi Christchurch

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#3449321 3-Jan-2026 16:31

Jase2985:

....

Any idea of the size from the gutter to the peak and the width you could fit panels onto?

Using my eyes and a protractor it appears that #1 is circa 3.8m , and #3 & #4 was 2.6m. The pitch is quite low, guessing around 20°-25°

Are all panels the same size?

Jase2985

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#3449331 3-Jan-2026 17:36

insane:

Are all panels the same size?

No. they vary in size, generally about 1.8x1.2m though for residential stuff.

Knowing your total area on each roof would be beneficial as it will give you an idea of how many panels you can fit on what faces, I would be using the WNW one as the last one to have panels as the ROI on them is much lower.

fastbike

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#3449332 3-Jan-2026 17:48

insane:

The blue shaded area is facing approximately the same orientation as my garage (14 degrees south of due west). We have 14 panels in two rows, the lower row are approx 20 degrees slope the upper are about 15 degrees. We fitted microinverters due to shading (not sure I would use them again). The panels are 440W , the inverters are 380W.

That part of the system was commissioned exactly one year ago. They have delivered 6.5 MWh over those 365 days, pretty much all has been exported at 17 cents. Here's the panel by panel summary for the whole year.

Here is June 2025

Here is Dec 2025

So as others have said the winter contribution is low - we also have some tall trees due West of the garage so that clips lat afternoon performance for spring and autumn.

The Niwa SolarView tool is great for visualising the monthly differences too.

Otautahi Christchurch

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