Solar power system technical discussion only

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neb

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#306750 18-Aug-2023 12:03

Starting a new thread for this to collect technical discussions into one place for future reference rather than spread across more than a dozen "which system should I get" threads from the last two years, this isn't for any "which system should I get" questions but to provide a single location for a long-term record of technical issues with solar systems that people have encountered.

One thing I encountered after the first day with the Enphase system active is the way export works. If you set the system up to maximise self-consumption/minimise grid draw, and this is for ESS systems in general and not just Enphase, it'll export power from your batteries to compensate for grid draw. In other words if you've got your oven wired to a grid-only circuit, not on the ESS, then running the oven and drawing 3kW for that from the grid will export 3kW from the batteries/ESS to the grid to achieve a net zero grid draw. This means that running a grid-only circuit will still result in your batteries being drained even though the circuit isn't on the ESS.

While this makes sense when you think about it, the behaviour came as quite a surprise, not helped by the poor way the Enphase app displays the flows which showed a direct flow from the batteries to the ESS circuit which wasn't actually drawing the power.

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#3117534 18-Aug-2023 12:15

I thought this thread was about the planets and now I am disappointed

wellygary

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#3117539 18-Aug-2023 12:21

BlargHonk:

I thought this thread was about the planets and now I am disappointed

Pluto for Eva :)

neb

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#3117541 18-Aug-2023 12:22

BlargHonk:
I thought this thread was about the planets and now I am disappointed

What do you mean, the title is "Solar power system technical discussion" and always has been. Does your mind often play tricks on you like this?

Talkiet

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#3117542 18-Aug-2023 12:35

I bought a Huawei Sun2000 inverter and about 6.5kw of panels. It works fine however it seems impossible to extract data from it directly for reporting. I can use the Huawei portal, and many people post that they think the modbus over TCP can be made to work, but the nearest I have got is dumping the modbus RTU and seeing that data is actually flowing - but it's not in a recognised format.

Kinda sucks that no-one (including authorised installers and support) knows how the systems work beyond getting them installed and delivering power.

If anyone out there DOES have a Sun2000 inverter and is able to locally extract any data from it - please speak up. (I have almost certainly seen any pages you're going to link :-( )

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

neb

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#3117544 18-Aug-2023 12:40

Another point I noticed last night, if you're on one of the free-power plans and using it to recharge your batteries then you should try and limit the current draw to something less than the maximum possible. I was getting undervolt alarms because the continuous 5.5kW draw was pulling the grid down well below the point I'd set for alerting. Since there's 3 hours you don't need to charge everything all at once but can spread it out a bit.

BlargHonk

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#3117551 18-Aug-2023 12:55

neb:
BlargHonk:

I thought this thread was about the planets and now I am disappointed

What do you mean, the title is "Solar power system technical discussion" and always has been. Does your mind often play tricks on you like this?

I went to school at the Derek Zoolander Center for Children Who Can't Read Good

neb

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#3117603 18-Aug-2023 13:08

For people who missed the first half hour or so of the thread's life, the subject line was originally missing the "power" bit, I edited it later to make the title unambiguous.

Quic Broadband

Move to New Zealand's best fibre broadband service (affiliate link). Free setup code: R587125ERQ6VE. Note that to use Quic Broadband you must be comfortable with configuring your own router.

Shindig

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#3117611 18-Aug-2023 13:33

Too infinity... and beyoo

Oh, yeah Solar electricity generation.

Lets start with a list of the go to bits of hardware, for a 'dream' setup?

The little things make the biggest difference.

eonsim

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#3117790 18-Aug-2023 19:28

Talkiet:

I bought a Huawei Sun2000 inverter and about 6.5kw of panels. It works fine however it seems impossible to extract data from it directly for reporting. I can use the Huawei portal, and many people post that they think the modbus over TCP can be made to work, but the nearest I have got is dumping the modbus RTU and seeing that data is actually flowing - but it's not in a recognised format.

Kinda sucks that no-one (including authorised installers and support) knows how the systems work beyond getting them installed and delivering power.

If anyone out there DOES have a Sun2000 inverter and is able to locally extract any data from it - please speak up. (I have almost certainly seen any pages you're going to link :-( )

Cheers - N

I take it you've tried the Home Assistant integration in Hacs that claims to get data from Huawei SUN2000 inverters?

neb

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#3117794 18-Aug-2023 19:40

neb: One thing I encountered after the first day with the Enphase system active is the way export works. If you set the system up to maximise self-consumption/minimise grid draw, and this is for ESS systems in general and not just Enphase, it'll export power from your batteries to compensate for grid draw. In other words if you've got your oven wired to a grid-only circuit, not on the ESS, then running the oven and drawing 3kW for that from the grid will export 3kW from the batteries/ESS to the grid to achieve a net zero grid draw. This means that running a grid-only circuit will still result in your batteries being drained even though the circuit isn't on the ESS.

Looking at the Enphase docs these are really, really misleading on the matter, stating repeatedly that "battery power is not exported to the grid", which is a bit like arguing that you didn't kill the guy, it was the bullet fired from the gun you were holding that killed him. Can someone confirm that their ESS, Enphase or not, does this? I'd like to make sure that's the case before I open a ticket with Enphase, because it completely negates any benefit to moving high-draw loads off the ESS.

Talkiet

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#3117802 18-Aug-2023 19:53

eonsim:

Talkiet:

I bought a Huawei Sun2000 inverter and about 6.5kw of panels. It works fine however it seems impossible to extract data from it directly for reporting. I can use the Huawei portal, and many people post that they think the modbus over TCP can be made to work, but the nearest I have got is dumping the modbus RTU and seeing that data is actually flowing - but it's not in a recognised format.

Kinda sucks that no-one (including authorised installers and support) knows how the systems work beyond getting them installed and delivering power.

If anyone out there DOES have a Sun2000 inverter and is able to locally extract any data from it - please speak up. (I have almost certainly seen any pages you're going to link :-( )

Cheers - N

I take it you've tried the Home Assistant integration in Hacs that claims to get data from Huawei SUN2000 inverters?

My HA install is not a supported type. I remain convinced HomeAssistant is a cruel joke in breaking changes and split platforms engineered by some Linux gurus that have decided Linux based systems were getting a BIT TOO EASY to use.

There's also an option to scrape the site, but unless your installer knows what they are doing, it won't be setup right and can't be changed by an end user.

I've even gone as far as getting one of these ( https://www.aliexpress.com/item/4001114113365.html?spm=a2g0o.order_list.order_list_main.48.16781802sjVs2U ) but it fails to recognise the modbus packets (again because the inverter setup is both witchcraft and a continuously moving target that Huawei change from version to version) - I can get it to spit out text, but short of rewriting a parser for it there's little useful info.

Cheers - N

https://www.aliexpress.com/item/4001114113365.html?spm=a2g0o.order_list.order_list_main.48.16781802sjVs2U

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

Talkiet

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#3117803 18-Aug-2023 19:56

This is the one option I haven't tried yet, but after several options that should have worked have all been sunk by changing software, bad setup, installers without knowledge of anything beyond the huawei ecosystem and faulty documentation - I'm only going to try something that someone else in NZ has managed to get working. I've sunk way too many hours into a farcically broken ecosystem.

https://github.com/jesusrop/esphome_huawei_sun2000

Cheers - Nhttps://github.com/jesusrop/esphome_huawei_sun2000

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

neb

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#3117806 18-Aug-2023 20:09

Talkiet:
it fails to recognise the modbus packets (again because the inverter setup is both witchcraft and a continuously moving target that Huawei change from version to version) - I can get it to spit out text, but short of rewriting a parser for it there's little useful info.

This is only a starting point, but have you tried using a modbus scanner to see what you can retrieve from the Huawei? Had to do something similar once and used that and libmodbus on an embedded Linux system to read out the data.

SteveXNZ

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#3117900 19-Aug-2023 08:43

Technical issues to watch out for – particularly 3-phase systems

I have an AlphaESS Smile T10 10kW 3-phase system with 16kWh battery storage. I’m very happy with it, but there are a few things I wish I’d known while configuring it.

While a 10kW system, it’s limited to 3.3kW per phase. This isn’t usually a problem, particularly if loads are evenly distributed over the phases, but it does have a couple of consequences.

While configuring my essential feeds (those circuits supplied in the event of a grid outage) I happily included the fridge in my scullery. But when that circuit is shared with the toaster, jug and coffee maker and the 3.3kW is exceeded at breakfast time, a soft breaker trips, and it takes a few minutes for a reset. I’ve since moved that circuit off the essential feed and will manually protect the fridge if I’m home.

When programmed to minimise grid draw, the system powers the house from the battery. If more than 3.3kW is required on one phase it tops up from the grid, and “pays back” from the battery on the other two phases. Net power is zero, but the system is simultaneously importing and exporting (single phase solar on a 3-phase supply will exhibit the same behaviour at times).

So what’s the consequence of this? Nothing practically, until the power bill arrives. “Net metering” says my 3-phase meter must independently record import and export – no problems with that. But what doesn’t happen is “net billing”. I’m on Electric Kiwi’s Movemaster plan which applies differential time of day tariffs. If I use zero net energy over say the 7am-9am peak I should pay $0. Not so fast! I’m actually paying 40c/unit for what I’m importing, and receiving a 14c/unit credit for what I’m exporting! This makes no sense at either the transformer/utilities level or EK’s spot market level. I have an on-going dispute with them and have asked them to justify their billing practice and make it clear on their website.

My final technical concern is the extraction of meaningful stats from either my power meter or AlphaCloud (which is where my solar stats end up), to be displayed in consolidated form via a web interface or mobile app. I’m not a conspiracy theorist, but it seems that electricity retailers, metering companies and solar suppliers are doing their damnedest to deny consumers access to raw import and export data, with phase-splits in my case. You want to beg for a csv file of incomplete half-hourly data? Maybe. You want access to an API so you can use the stats for appliance switching from your smart home system? Good luck with that! What about the modbus interface? How does that work? Good luck getting meaningful info on that. Bring intelligent EV charging into the equation and things get harder still. As we respond to climate change in an increasingly electrified world the lack of architecture, standards, and efficiency tools has me worried. Choose your system with the integration capability you need, and which will hopefully evolve with future standards.

SomeoneSomewhere

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#3117908 19-Aug-2023 09:30

neb:
neb: One thing I encountered after the first day with the Enphase system active is the way export works. If you set the system up to maximise self-consumption/minimise grid draw, and this is for ESS systems in general and not just Enphase, it'll export power from your batteries to compensate for grid draw. In other words if you've got your oven wired to a grid-only circuit, not on the ESS, then running the oven and drawing 3kW for that from the grid will export 3kW from the batteries/ESS to the grid to achieve a net zero grid draw. This means that running a grid-only circuit will still result in your batteries being drained even though the circuit isn't on the ESS.
Looking at the Enphase docs these are really, really misleading on the matter, stating repeatedly that "battery power is not exported to the grid", which is a bit like arguing that you didn't kill the guy, it was the bullet fired from the gun you were holding that killed him. Can someone confirm that their ESS, Enphase or not, does this? I'd like to make sure that's the case before I open a ticket with Enphase, because it completely negates any benefit to moving high-draw loads off the ESS.

Not being familiar with these systems, what you'll tend to find is that the system aims to zero out power flow through a point - that point being where the measuring current transformer (CT) is clamped around a cable.

If that CT is around the incoming mains, then that's the only current it can measure, and it will zero out all power flow into/out of the house.

If that CT is around a specific bundle of circuits, then only those circuits are compensated for.

If there's a disconnector so that the system can run islanded on battery power alone, then the CT may need to be located where that disconnect is.

When you say 'ESS', are you referring to energy storage systems, or essential supply (i.e. circuits kept live in a power outage)?

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