Upgrading new home distribution board, and considering Solar

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MrMe

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#317827 19-Nov-2024 14:08

We are getting a sparky around to quote upgrading our distribution board, for our 1970's era home.

A goal of doing this is to introduce RCD's.

In the medium-term we also want to look at getting solar. I am starting to learn that there is a Big world of solar options and variations. Wowee 😄

A wild early guess is that we would get a decent benefit from solar; from daytime use, charging our electric car, and perhaps hot water heating - and we would not pursue a system with battery storage. Expect to get more clarity on our needs and engage with installers at a latter point.

My question now is:

is there anything that is worth knowing about solar installs now - while we have a sparky upgrading our distro box - or is this work and a future solar install fairly separate matters?

Thanks !

Jase2985

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#3310626 19-Nov-2024 14:12

Make sure you have quite a few spare slots on a DIN rail for circuit breakers, smart meters etc for the solar system. Consider how the solar components will be installed, ie how close and what they need to communicate with the inverter.

RobDickinson

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#3310627 19-Nov-2024 14:16

Def have spare space.

For water heating best is a diverter that takes excess solar you are not using and switches that from export to water heating, these are a bit pricy tho. Another option is a timer added to your board so it only heats during solar hours. thats a lot cheaper.

Dingbatt

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#3310632 19-Nov-2024 14:37

In addition to all the sage advice above, ensure there is adequate space for cable runs up into the ceiling, and if appropriate, down the wall to the underfloor.

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BlargHonk

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#3310634 19-Nov-2024 14:39

RobDickinson:

Def have spare space.

For water heating best is a diverter that takes excess solar you are not using and switches that from export to water heating, these are a bit pricy tho. Another option is a timer added to your board so it only heats during solar hours. thats a lot cheaper.

Adding a timer to your HWC Circuit is great if you switch to one of the three hours free power plans (i.e. Contact or similar) then you can get most of your hot water for free!

tripper1000

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#3310639 19-Nov-2024 14:42

Also think about how the future wires will be routed to the new switchboard.

Locating it in a visible location such as a hall-way can make this tougher/slower/more expensive in future.

Locating it in a utility space, or backing on to a cupboard/wardrobe can make future wires faster/easier/cheaper to install.

Also putting in a conduit from the crawl space/ceiling space to the switch board can be helpful.

If you have a rough idea where solar inverters are going to be located, you can even add the extra wires during switchboard upgrade to expedite future installation.

neb

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#3310653 19-Nov-2024 15:00

Adding to the chorus above, consider the worst-case scenario for RCDs, MCBs, etc that you'll need, then get an enclosure that will take at least twice that number. You can never have too much room in there, but you'll always have too little if you don't seriously overprovision from the start. And that's not just "I need a few extra MCBs for solar", once you go down that path you'll start adding energy meters, Shelly's (ugh), CTs, and all manner of other stuff that you never actually planned for but that just sort of came up over time.

neb

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#3310654 19-Nov-2024 15:01

Dingbatt:

In addition to all the sage advice above, ensure there is adequate space for cable runs up into the ceiling, and if appropriate, down the wall to the underfloor.

Oh, and run at least two lots of Cat5 in for whatever control electronics you'll inevitably be adding at some point.

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neb

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#3310657 19-Nov-2024 15:03

RobDickinson: For water heating best is a diverter that takes excess solar you are not using and switches that from export to water heating, these are a bit pricy tho. Another option is a timer added to your board so it only heats during solar hours. thats a lot cheaper.

Another option, which is what we have, is to use HA to connect the HWC when you're exporting excess solar and/or on free power if you're on one of those plans. Costs a fraction of what a diverter does and it doesn't rely on the diverter trying to guess what's going on.

richms

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#3310662 19-Nov-2024 15:16

Switching it on and off means that you have to have enough solar to cover the full load of the element. Whereas the diverters I looked at would dim the element down to keep the import to a minimal amount.

When I looked at it, needed a cable run from the CT at the supply to the diverter as the wireless ones didnt update fast enough. This may have improved now as I dont have enough solar to bother with a diverter as Im lucky to export 10 kWh per month.

Richard rich.ms

neb

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#3310668 19-Nov-2024 15:39

Ah, in my case there's batteries as well so the binary control was more ensuring the HWC didn't start draining the batteries at 3am.

muppet

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#3310670 19-Nov-2024 15:43

I wouldn't bother going Solar, I don't understand the obsession with it.

It's going to be next to useless when the Sun burns out.

chimera

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#3310674 19-Nov-2024 15:51

As others have said, make plenty of space down the wall and under your house so Solar installer can feed wires later

Solar brain dump...

For me personally, I wouldn't have bothered with solar UNLESS going hybrid and including a battery (based on my needs)

Batteries continue to drop in price, the cost for LifePO4 is pretty cheap now. I just paid 29c per watt hour (NZ$3500 for 12KwH usable)

Many plans have varying tarrifs, peak, off peak (3/4 peak cost) and night (1/2 peak cost) - obviously varies a bit depending on power company, but roughly speaking. Peak sun hours typically 10am - 2pm, right when you're in off peak. Sure it shines 7am - 7pm, but kWh production is a bell curve.

Consider rate shifting, use solar to charge battery and configure inverter 'time of use' settings to use battery in peak times to minimise grid costs.

Another option is I think Meridian offer a plan where rates are a bit higher, but you get 4 hours free power a day - plan that around charging a battery and EV (say early morning before sun shines but load is also higher when people get ready for work) then balance PV and battery for the remainder

Recharge battery overnight if needed at night rates (1/2 the cost of peak) depending on your plan

Consider low vs high user (low user = higher energy rate, lower daily charge, high user = lower energy rate, higher daily charge) - this can be a kicker for those with solar that are stuck between the two, coz high user at $2.70 odd a day suddenly there's $80 a month cost before you even start.

There is an endless supply of information - false information, factual information, peoples opinions (clearly my own included lol) and systems to consider, so do your own research and spreadsheet your own requirements out.

kotuku4

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#3310977 20-Nov-2024 15:05

I have an older install 4.9 kw 20 panels (2018) and I think it works just fine without a battery for my use case.

There were no issues running duct and cable from the solar inverter to meter board. Initially installed a timer for hot water.

Yes I would prefer to have a battery, but can't see that it would pay back during the warranty or expected life span of the battery.

I had to replace the water cylinder and went for the biggest I could fit 270 litre and installed a paladin solar diverter.

I had installed more insulation in ceilings and retro fit double glazing before solar install.

All energy use is electric, total power budget is $100 per month, 3 bedroom home, 3-5 occupant's.

I would prefer to put some money into an EV.

YMMV

chimera

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#3311043 20-Nov-2024 16:49

kotuku4: I have an older install 4.9 kw 20 panels (2018) and I think it works just fine without a battery for my use case.

Yes I would prefer to have a battery, but can't see that it would pay back during the warranty or expected life span of the battery.

I suspect, because at the time a battery wouldn't have made economical sense due to cost.

Not sure how long ago you put your system in, but LiFePO4 is definitely worth considering now.

Let's see how well my math works out here, please correct me if I'm wrong...

The cost for 30KwH LiFePO4 battery (24KwH usable at 80% depth of discharge) for me was $7,000.

The suggested lifespan is 4000 cycles (at 1 cycle per day that's 4000 / 365 days = 11 years) However let's assume the battery will cycle more than once a day (more probable) and for ease of math let's say they last 7 years instead (so a cost of $1000 p.a. for batteries)

My power cost average over a year is about $400 per month or $4800 per year (yes I'm a heavy user, about 60kWh per day) Over 7 years that's $33,600.

Assume a conservative ~22c per kWh saving (when using battery) x 24kWh usable battery = $5.28 saved every cycle. At 4000 cycles x $5.28 is $21,120. Less the $7k cost of the batteries in the first place is about $14k savings over 7 years.

HOWEVER, that does assume the batteries are always getting charged using solar PV (free) which in reality isn't the case. So... if you can rate shift instead using the inverters "time of use" settings (eg: charge batteries using night rate which is generally 50% cheaper than peak rate) to then use batteries during peak times, and let's say half of the time we're charging from grid at night (50% of peak cost) and charging using solar (free) the other half of the time, then we're really saving half that $14k difference. So give or take a $7k savings over 7 years or $1k per year. Basically the cost of the batteries in the first place.

For me this is all helped further by home automation (home assistant) where I have control over WHEN I power things; basically to utilise PV or battery where possible during peak hours and PV or night rate for charging battery.

Added bonus is blackouts. I have my switchboard split with automatic EPS so if there is a power cut, the batteries will supply power to the lights and wall sockets (non-critical loads like the spa pool, pool pump, pool heat pump etc are on a different circuit)

Of course, this is all theoretical. It does also mean you will likely need to size your PV slightly larger - to cover your day load plus charge batteries. However solar installs are getting cheaper every year too (cost me about $21k for 8.5kW PV plus a hybrid inverter and EPS installed) There many variables involved. But then conversely energy prices are increasing annually also, not decreasing.

Generally speaking, even if a worse case scenario above there is still some wiggle room to get pay back or really really worst case I'm breaking even and getting the other benefits of having a battery

kotuku4

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#3311083 20-Nov-2024 18:13

Sorry my install was March 2013.
So in my case spending less $100 per month, mostly fixed and lines charges.
Adding a $7000 battery and upgrading to a new inverter with BMS, will save maybe $50 per month? Perhaps 15 year pay back?
Arghhh no...not working in my case.