Solar options for home in 2022.

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212 posts

Master Geek

#3282069 14-Sep-2024 11:40

HarmLessSolutions:

@fastbike, I'd be looking at more solar friendly supply plans if I were you.

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Another export option is Meridian's solar plan @17c FIT, if they're still accepting 5 year contacts in order to access this.

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Thanks for the help. I've just plugged in the figures Meridian offered me two weeks ago (with the option of a five year lock in). 30.3 cents peak, 18.14 cents off peak. 17 cents export. Also their daily rate is $100 less per year.

This model shows a saving of $3008 ! And that is with no changes on my side. Given the off peak cost and export and very close they is probably little to be gained from shift some of the night loads onto day.

Also I don't have a car so have no ability to use the excess for transport. Also our space heating is heat pump so that is impacted by the night rate (we have a thermally massive house so tend to run the heat pump overnight using the cheaper rates. Having said this the heat pump will be less efficient when outside temps are below 5 degrees so I could look at modelling theses settings too).

Otautahi Christchurch

fastbike

212 posts

Master Geek

#3282284 15-Sep-2024 12:28

fastbike:

This model shows a saving of $3008 ! And that is with no changes on my side. Given the off peak cost and export and very close they is probably little to be gained from shift some of the night loads onto day.

Whoops. I was using the comparison between being on Meridian, without solar vs with a solar installation.

I've now spent a couple of hours refining my model to better account for the differences between the reference site and my own planned installation. The Niwa SolarView tool is really useful here as you can factor in how my site will perform each month compared to the reference site: allowing for orientation, tilt and capacity it ranges from 1.83 in December to 1.34 in June. My initial modelling assumed a constant factor of 1.8 so was too optimistic.

The revised model shows staying with Contact and no installing solar - as the baseline - costing a total of $3,200 p.a.

Scenario A - staying with Contact and installing my PV system would give an annual cost of $1,450, saving $1,750 p.a.. Assuming a system cost of $15k this gives payback in 8.5 years

Scenario B - moving to Meridian (with their 5 year contract locking in rates, breakable after 2 years with no penalty) would give annual costs of $524, saving $2,676 p.a. with payback after 5.6 years

There is also another variant to add to these scenarios, that involves installing an additional 8 panels on a standalone garage with a small separate grid tied inverter.
This increases savings for A to $2,001 p.a. and for B to $3,182. Assuming an incremental cost of $5k this pushes the payback out a few months but gives a better return in the long run and I'm being very conservative with the incremental installation costs as most of the fixed costs such as a new meter, inspection, travel/overheads etc are already covered.

I've done some more research and now have an option to purchase a full pallet of Trina Vertex S 440W panels at a bargain price (requires the full pallet of 36) so this may be the preferred direction. I will discuss with the installer on Friday as he is way more flexible than one of the sales/marketing outfits.

At this stage I'm going to give the battery a miss as my initial modelling shows the battery would take in excess of ten years to pay back. I can review this after I've had the system installed for a couple of years and have more real time data to play with.And hopefully by then battery and BMS tech has moved on again so costs could be lower (or is that wishful thinking).

I may still get a hybrid inverter but would need to think about the battery coupling (AC does not need the hybrid, just an intelligent battery management system). DC coupling is a little more complicated because some are LV but the current quick ramps up if you want any decent power out them (e.g 51.2V at 7kW is 150A), HV batteries seem to operate at around 15-25A with the voltage being specified to match the required power (e.g. 7kW at 15A is 460V dc). Maybe DC batteries are not such a good idea ?

Otautahi Christchurch

LightbulbNeil

57 posts

Master Geek

#3282385 15-Sep-2024 18:38

Have you looked at different panels , like the industrial sized ones? We went with 30 industrial panels and got a better coverage than the smaller sized panels.

Ours are the 500w DC arrangement. A battery for us is a way off. Currently with the 5 year deal with Meridian and in Hamilton. It was cheaper to go with 3phase and 15kw of panels and with Meridian for us. But everyone situation is different, so one solution does not meet every ones needs. Our outlay was effectively 8.5 years of power based on September 23 prices. The larger system is going to pay itself off in 6yrs 3 months or so. We had days in winter where it only generated 7.2kwh July 17,2024. We used 30kwh that day, which is the average for July. I think that from memory the pallet of panels was either 32 or 34 panels.

It's interesting seeing different ways of looking at a Solar system. Some look at it from what would my money do else where, and in that case would not install solar at all. We looked at it from the point of view of reducing our outgoings when we retire. Have factored in a replacement inverter for 10 years time. The cash return each year, if saved will pay for the inverter.

fastbike

212 posts

Master Geek

#3282413 15-Sep-2024 23:07

LightbulbNeil:

Have you looked at different panels , like the industrial sized ones? We went with 30 industrial panels and got a better coverage than the smaller sized panels.

The roof has its own challenges. Realistically, we have about 4700mm vertical and about 13600 horizontal. There is also a large Velux window smack bang in the centre. It is also a curved mono pitch on a 12.7m radius with an angle of 26 at the base and 10 at the ridge. The redeeming features are it faces north at 346 degrees, has no real shade apart from very late in the afternoon. It also has a great structure that can be fastened into almost anywhere (avoiding 400mm at the edges). So the best layout is 1762x1134 panels laid in landscape, 4 rows up and seven panels across (with the two centre most removed for the window).

I have been offered 440W Trina Vertex S panels at $152 each if I collect from local depot (in multiples of 36). This is $0.35 / watt !
Can you recommend a better value point ?

Otautahi Christchurch

fastbike

212 posts

Master Geek

#3282414 15-Sep-2024 23:12

LightbulbNeil:

It's interesting seeing different ways of looking at a Solar system. Some look at it from what would my money do else where, and in that case would not install solar at all. We looked at it from the point of view of reducing our outgoings when we retire. Have factored in a replacement inverter for 10 years time. The cash return each year, if saved will pay for the inverter.

That's a good perspective. I'd also add in the fact that we are displacing coal and gas, as hydro can act as the battery in NZ for the peak periods. (There are two problems to be solved in NZ power system: peak capacity, and the dry year problem.)

From a personal economic pov, the payback period is just over 5 years, so that is close to 20% return on investment. None of my other investments pay anything like this - and it is tax free, and after the capital is repaid there is likely to be another 15 years of savings !

Otautahi Christchurch

wongtop

563 posts

Ultimate Geek

#3282496 16-Sep-2024 09:50

Just be aware if you are thinking of going big that last time I checked, Meridian had something like a 10 kW size limit to be eligible for their 17c solar plan.

billgates

4705 posts

Uber Geek

Trusted

#3282504 16-Sep-2024 10:03

Meridian does not checks the PV array size limit atleast if you switch from another electricity provider like in our case. We were 15kW PV when we switched from Genesis to Meridian. Meridian never asked about the size of the PV array.

Do whatever you want to do man.

HarmLessSolutions

969 posts

Ultimate Geek

Subscriber

#3282507 16-Sep-2024 10:12

Meridian's T&Cs does have a 10kW maximum on their distributed generation customers. I wouldn't be surprised if customers transferring from other suppliers could manage to slip past Meridian's checks and balances but probably wise to consider putting a throttling method in place in the case of being caught out further down the line. Of course if your self consumption is constant enough to keep your export below the 10kW cap this won't be problematic in terms of economic viability.

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

fastbike

212 posts

Master Geek

#3282509 16-Sep-2024 10:25

HarmLessSolutions:

Meridian's T&Cs does have a 10kW maximum on their distributed generation customers. I wouldn't be surprised if customers transferring from other suppliers could manage to slip past Meridian's checks and balances but probably wise to consider putting a throttling method in place in the case of being caught out further down the line. Of course if your self consumption is constant enough to keep your export below the 10kW cap this won't be problematic in terms of economic viability.

Yes, my modelling shows that max export is always less than 10kW. Interestingly the lines company (Orion) have a limit of 5kW per phase. I have a 3 phase connection so can connect up to 15kW without asking for an exemption.

https://www.oriongroup.co.nz/connections/solar-or-diesel-generation

Export Limit
The maximum export phase imbalance shall not exceed
5kW. That is, for a single phase installation the export to
the network shall not exceed 5kW. For two phase
installations, the export to the network will be limited to
10kW evenly spread across the two phases. For a three
phase system, the maximum export difference between
any phase shall not exceed 5kW.

Otautahi Christchurch

MikeFly

148 posts

Master Geek

#3283152 17-Sep-2024 13:30

fastbike:

I have been offered 440W Trina Vertex S panels at $152 each if I collect from local depot (in multiples of 36). This is $0.35 / watt !
Can you recommend a better value point ?

@fastbike

Thats a great price, is it inc GST?

LightbulbNeil

57 posts

Master Geek

#3283206 17-Sep-2024 14:02

A larger system is very beneficial in winter.
That's a good price for the panels it seems to me.
Going 3phase is also a good move in my view.
We went 3phase on the house build becuse used machinery with 3phase can sometimes be had for a bargain. It can also lower your peak current draw as well for when that pricing model comes into NZ.

fastbike

212 posts

Master Geek

#3283212 17-Sep-2024 14:29

MikeFly:

Thats a great price, is it inc GST?

Yes $132 excl GST. But you have to buy in multiples of 36 and have some way of handling a ~800kg pallet. They will forklift it onto your transport.

Otautahi Christchurch

dantheperson

174 posts

Master Geek

#3283213 17-Sep-2024 14:29

Simlar prices at trade depot, 33 cents/watt. But you can buy just one panel, don't need a pallet load.

https://tradedepot.co.nz/450w-bifacial-mono-n-solar-panel-all-black/

fastbike

212 posts

Master Geek

#3283215 17-Sep-2024 14:32

LightbulbNeil: A larger system is very beneficial in winter.
That's a good price for the panels it seems to me.

Yes, I was thinking it was pretty sharp.

LightbulbNeil:Going 3phase is also a good move in my view.
We went 3phase on the house build becuse used machinery with 3phase can sometimes be had for a bargain. It can also lower your peak current draw as well for when that pricing model comes into NZ.

I was lucky that my wife's Dad talked me into getting a three phase connection when we built 20 years ago as I wanted a small workshop and he recommended 3 phase machinery.
Apart from a slightly more complicated main distribution board (it has 3 bus bars and sets of breakers) I would highly recommend it for any new "all electric" build.

Otautahi Christchurch

fastbike

212 posts

Master Geek

#3283217 17-Sep-2024 14:36

dantheperson:

Simlar prices at trade depot, 33 cents/watt. But you can buy just one panel, don't need a pallet load.

https://tradedepot.co.nz/450w-bifacial-mono-n-solar-panel-all-black/

Looks a nice price, none available outside of Akld though. And I'm not familiar with the brand, ERA ?

Also the Voc seems a bit lower so current is on the high side.

Edited to comment on electrical spec

Otautahi Christchurch

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