Low budget, local solar

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nic.wise

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#316287 2-Oct-2024 14:31

I was wanting to play around with Solar (being we can't get a proper install on the roof)

Talking to a friend in germany, they can set it up so they have up to 800W, with panels + battery + controller, and it goes into their wall plug.

So:

Panels (4, 2 pairs) -> battery (2, one for each pair of panels) -> grid-tied controller/inverter/cut-off-at-800W thing -> wall plug -> house

Anyone know what the logistics of this is in NZ? Obviously, can't go over the plug rating (10A, which is what, 2200W?) but for the same 800W....

thinking about recreating that setup. Charge the battery during the day, discharge into the house at night to offset lights, leaf etc. If it's >800W used, it'll pull from the grid as per normal

Crazy?

Nic Wise - fastchicken.co.nz

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#3290097 2-Oct-2024 14:47

1) 800W is a measure of instant load, not a storage measure,

2) Batteries are Expensive,

A battery that will let you draw 800W for an Hour or 200W for 4 hours (Basically 1Kwh) will run you a about $1000 (ball park)

CYaBro

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#3290099 2-Oct-2024 15:01

No different doing that with a small system to a big roof install.

Would still need to go through all the proper stages and certifications since you'd be connecting it to your house and the grid.
And would need to be installed by an electrician.

Perhaps a better way would be to go for a small off-grid system, that's what I did on our shed.
Couple of 300W panels (72V max) into a controller which is also connected to a 24V LifePO4 battery (Approx 3kWh) and 2000W inverter.
Inverter has a standard 3-pin socket on it for 230V stuff.
That system runs lights in the shed, 3 wifi access points and a small switch, cctv camera and charges our batteries for power tools.
Also runs a water blaster when we need it out there.

Opinions are my own and not the views of my employer.

nic.wise

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#3290100 2-Oct-2024 15:02

yup, the person I was talking to has 2x 1600W batteries. I expect this to be in that kinda range.

Maybe I should have said "not low budget, more less-official-installed" or something. I expect, if we want to try this out, that we'll be out a good $2500-$4000. 1-4 500W panels, 1-2 batteries, a controller, wire, possibly some contstruction to house it.

If it works, our property is better setup for a vertical wind turbine... which is about $1000 off aliexpress, tho that was just my first search

Nic Wise - fastchicken.co.nz

nic.wise

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#3290101 2-Oct-2024 15:04

CYaBro:

No different doing that with a small system to a big roof install.

Would still need to go through all the proper stages and certifications since you'd be connecting it to your house and the grid.
And would need to be installed by an electrician.

Perhaps a better way would be to go for a small off-grid system, that's what I did on our shed.
Couple of 300W panels (72V max) into a controller which is also connected to a 24V LifePO4 battery (Approx 3kWh) and 2000W inverter.
Inverter has a standard 3-pin socket on it for 230V stuff.

Yeah, that might be a better first step, and kinda what I was originally thinking (and we can charge our ebikes off it, for eg). I hadn't realised that, outside of the legal parts, you can _just plug it into a wall socket_ and the house will draw the power.... had a mental block around "its just one circuit, after all"

Nic Wise - fastchicken.co.nz

nic.wise

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#3290102 2-Oct-2024 15:05

BTW, the reason why I can't just call a solar provider and get it installed:

Overhanging trees to the north
South Facing roof slope
Did I mention trees, which I can't cut down? :( (also don't wanna cut down, but if I did, I can't)

Without that, I'd just get a pro to do it. Hence thinking "what we can do to see how much we get from some panels and a battery"

Nic Wise - fastchicken.co.nz

SomeoneSomewhere

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#3290107 2-Oct-2024 15:26

There's two fundamental options for solar:

Fully independent; separate from the general electrical grid. As long as the panel voltage is ELV (<120VDC) and there's no fixed mains wiring (i.e. just a socket on the inverter), I believe you can totally DIY this in NZ with no electrician, inspection, or permission.
- This really needs a battery to work
- This is a pretty common setup for campervans, sheds etc. You could theoretically put it on your house and maybe add a battery charger and run small loads, but you can't do anything that could possibly feed back into the grid. You would have a separate socket that would be independent from the rest of the house electrics, and solar would only supply that socket, not offset anything else.
Grid tie: the panels push energy back into the grid. In NZ, by regulation, this must be done with an approved inverter, hardwired (no plug/socket), with the permission of the lines company, and certified by an electrician and inspected by an inspector.

You cannot put a grid-tie inverter on a plug here. The protection against unplugging the inverter and getting live male pins is not considered strong enough.

SomeoneSomewhere

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#3290109 2-Oct-2024 15:30

I'm not clear on why you can't go the normal route here?

A solar installer is going to tell you it's not cost-effective to put solar on a heavily shaded roof, but there's no rules saying you can't waste money. If you pay them, I'm sure many contractors will do it. There's plenty of sub-optimal solar installs.

If the shading is so bad that you'll get almost no power, this applies to both a small and a large install.

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richms

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#3290126 2-Oct-2024 16:26

Plug in grid tie inverters are actually on the prohibited item list to import, so most aliex sellers will not bother trying to send them there.

Additionally, grid tie in a portable building isn't something that will fly in a legit manner. You can do all the bluetti type boxes that supply loads that you like, but nothing that backfeeds is allowable, not even microinverters.

What would happen if you are already set up with an export meter and just happen to hook up an additional grid tie inverter isn't something that anyone has told me, Not heard of anyone being pinged for exceeding their agreed export limit with the lines company, that is assuming that you have enough additional to get there.

With DIY being so cheap and it is something I would like to see be allowed, but I doubt it will ever happen.

Richard rich.ms

pdh

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#3290129 2-Oct-2024 16:37

>There's two fundamental options for solar:

Well... I am told that a third option is quite do-able.

Solar fed to a battery - feeding an inverter - that uses the battery/solar power when it's available (and is programmed to do so) - and consumes grid power (when it needs to). The inverter is rated (and obviously wired) to isolate the grid from any locally produced (solar) or available (battery) power. The inverter feeds some portion of the house - circuits (lighting & wall plugs) that are professionally rated, wired & labelled (to prevent shock / danger). The inverter is, of course, also professionally installed by a (certified) sparkie.

My source for this information (last week), was an Auckland supplier (company's chief tech guy, EE & EWRB) who's been selling on-grid & off-grid systems for several decades. Thousands of systems.

He's both an engineer and EWRB, I'm an engineer (albeit a BMech). I believed he knows whereof he speaks.

There may well be size (kW or kWh) limits to this sort of installation. There may be different regs in different areas of the country. You will need to check this. But for Auckland area, I'm assured that it's completely & professionally acceptable.

richms

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#3290132 2-Oct-2024 16:44

pdh:

Well... I am told that a third option is quite do-able.

Solar fed to a battery - feeding an inverter - that uses the battery/solar power when it's available (and is programmed to do so) - and consumes grid power (when it needs to). The inverter is rated (and obviously wired) to isolate the grid from any locally produced (solar) or available (battery) power. The inverter feeds some portion of the house - circuits (lighting & wall plugs) that are professionally rated, wired & labelled (to prevent shock / danger). The inverter is, of course, also professionally installed by a (certified) sparkie.

My source for this information (last week), was an Auckland supplier (company's chief tech guy, EE & EWRB) who's been selling on-grid & off-grid systems for several decades. Thousands of systems.

He's both an engineer and EWRB, I'm an engineer (albeit a BMech). I believed he knows whereof he speaks.

There may well be size (kW or kWh) limits to this sort of installation. There may be different regs in different areas of the country. You will need to check this. But for Auckland area, I'm assured that it's completely & professionally acceptable.

Confirm that you can still do stuff on the DC side of that install yourself, because when I asked as soon as the inverter was part of the electrical installation of the property, the batteries and panels were as well so were not able to be DIYed and had to have someone out with the ground testing stuff to check that you had the panels earthed properly etc, whereas a bluetti type install with ELV panels was totally not their concern as they are an appliance like any other UPS.

Richard rich.ms

wellygary

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#3290137 2-Oct-2024 17:00

"The inverter feeds some portion of the house -"

And there is your boondoggle, to connect to the house wiring you need either a permanent connection - which drags your entire setup into "requires compiance" world,

OR, you backfeed the circuit via an outlet, - this can only be done with an illegal "suicide cord"- which means the set up will fail any certification requirement..

You cannot homebrew/DIY on to a regular mains connected circuit

SomeoneSomewhere

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#3290139 2-Oct-2024 17:04

pdh:

>There's two fundamental options for solar:

Well... I am told that a third option is quite do-able.

Solar fed to a battery - feeding an inverter - that uses the battery/solar power when it's available (and is programmed to do so) - and consumes grid power (when it needs to). The inverter is rated (and obviously wired) to isolate the grid from any locally produced (solar) or available (battery) power. The inverter feeds some portion of the house - circuits (lighting & wall plugs) that are professionally rated, wired & labelled (to prevent shock / danger). The inverter is, of course, also professionally installed by a (certified) sparkie.

My source for this information (last week), was an Auckland supplier (company's chief tech guy, EE & EWRB) who's been selling on-grid & off-grid systems for several decades. Thousands of systems.

He's both an engineer and EWRB, I'm an engineer (albeit a BMech). I believed he knows whereof he speaks.

There may well be size (kW or kWh) limits to this sort of installation. There may be different regs in different areas of the country. You will need to check this. But for Auckland area, I'm assured that it's completely & professionally acceptable.

That's option 1 with add-a-battery-charger; the battery charger is just part of the inverter.

My understanding is that regulations are not super clear on whether the ELV parts (battery, panels) are prescribed work or not. Many will err on the side of caution. You shouldn't need a separate inspector because it's not mains synchronous generation.

Part of the issue is that your inverter now needs to be sized for the full load able to be connected to it (likely at least a 16A circuit, so 4kW plus any allowances for starting large loads). A grid tie inverter only needs to be sized for the actual panels with no need for overload capability.

SomeoneSomewhere

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#3290141 2-Oct-2024 17:07

wellygary:

"The inverter feeds some portion of the house -"

And there is your boondoggle, to connect to the house wiring you need either a permanent connection - which drags your entire setup into "requires compiance" world,

OR, you backfeed the circuit via an outlet, - this can only be done with an illegal "suicide cord"- which means the set up will fail any certification requirement..

You cannot homebrew/DIY on to a regular mains connected circuit

OP seems to have accepted that the charger-inverter would need to be installed by a qualified sparkie, in a manner similar to a hardwired UPS. It doesn't strictly need a separate inspection/ROI, although I would argue that the complexity and hazards are actually higher than with a compliant grid-tie inverter.

The question is whether the ELV side is prescribed work.

nic.wise

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#3290150 2-Oct-2024 17:43

SomeoneSomewhere:

You cannot put a grid-tie inverter on a plug here. The protection against unplugging the inverter and getting live male pins is not considered strong enough.

Very good point. It'd be one of those patented death plugs...

Nic Wise - fastchicken.co.nz

nic.wise

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#3290151 2-Oct-2024 17:45

SomeoneSomewhere:

I'm not clear on why you can't go the normal route here?

A solar installer is going to tell you it's not cost-effective to put solar on a heavily shaded roof, but there's no rules saying you can't waste money. If you pay them, I'm sure many contractors will do it. There's plenty of sub-optimal solar installs.

If the shading is so bad that you'll get almost no power, this applies to both a small and a large install.

We have some other places around the property which might work at a much smaller scale, but we'd likely want to pack the panels away over winter, for eg.

But yeah, we could throw money at it. we have a LOT of roof space (60SQM, give or take, all flat) which can see the sky... and in summer (and a lot of winter, TBF) they get a fair bit of direct sun.

Might need to get a new quote/estimate, given that panels are now so cheap. Last time was a good 5+ years ago

Nic Wise - fastchicken.co.nz

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