Sigenergy - My solar journey

[Brumby]

Well... I have taken the plunge into solar - and that has been into the Sigenergy architecture.

What am I looking to install...?
30 465W Aiko ABC panels, filling a second storey gabled roof on both north and south facing sides.
30 TIGO optimisers as I have a shading issue which progressively increases from early afternoon
30kW Sigenergy 3 phase inverter
48kWh Sigenstor battery
Sigenergy gateway

Target installation and commissioning is prior 30th April, 2026 - because of the battery rebate changes.

Yes, the inverter is a beast and the battery is maxed out.  This is deliberate for several reasons:
1. Over engineering is in my blood     
2. The Sigenstor battery is one of the few that will fit the capacity I seek in the space I have available
3. The battery rebate plunges on the 1st May for big batteries.
4. In the short term, I will be looking at trying my hand at the energy trading game through a provider like Amber.  If I have an opportunity to export at $20 per kWh for 10 minutes, I want to pump out all I can.     Yes, I know this isn't a high probability event, but being ready gives one options.  (I have had more than one opinion which feels this only has 2-3 years before this becomes less worthwhile.  We will see.)
5. In the longer term, there are planned expansions of energy needs of the household, which a higher capacity system will be able to handle.
6. I want to address future needs as much as I am able and only incur expenses once, avoiding having to revisit equipment choices as much as possible.

I know I am opening myself up for the critics, but that is inevitable for sharing.  Nevertheless, I am interested in opinions.

PS.  I have passed on a link to this thread to Sigenergy.

[Marco]

There's a company which trades on the imbalance market for battery storage here, my sister is letting them install a battery. ROI is pretty impressive but I doubt that will last more than a year, who knows though maybe market inefficiency persists. But at least the heatpump can stay running in case of power failure, it's monoblock and not filled with glycol.

Are there no similar schemes in Australia? Requires central control over part of the battery capacity, but the imbalance market is more profitable than spot.

[Siwastaja]

There's a company which trades on the imbalance market for battery storage here, my sister is letting them install a battery. ROI is pretty impressive but I doubt that will last more than a year, who knows though maybe market inefficiency persists. But at least the heatpump can stay running in case of power failure, it's monoblock and not filled with glycol.

They all crash. We also do this, our market also crashed. We are in a good position as a balance service provider because we really did not promise anything and quite the opposite were probably the most honest about it on the market - but our resellers are taking the shitstorm. FCR market is down to 1/10 price level of the best days in Finland, just what happened in Sweden a year or two earlier.

Look for something similar to what we try to be - a long-term energy optimization partner, which can always create some value for the battery (e.g., what we do is, that is savings from spot price electricity contracts, and looking into peak shaving when peak power fees enter the game), instead of selling the one great big thing (e.g., Frequency Containment Reserve), and then fail colossally when the price level crashes.

[Marco]

They all crash.

It's a two year contract, with dynamic pricing consistent with the rest of the market and the cost of the battery/install is very interesting. I guess there's a very small chance they try to scam her on the electricity contract in the second year, but I doubt that.

If the balance market arbitrage disappears, she got the battery system for a good price. No harm done.

Dunno at what stage of the boom/bust Australia is though.

[Siwastaja]

If the balance market arbitrage disappears, she got the battery system for a good price. No harm done.

Yes. Two things to look at:
1) Decent price for the battery - compare to similar kWh, kW ratings doing google searches. Don't believe pre-calculated payback times.
2) Generic battery/inverter - not some provider-specific special hardware. This way, a different controller (EMS) can be swapped in later.

Like, we support handful of inverters and do smart spot price self-use optimization + grid balancing as a combined optimization. If we go bust, our box can be removed and another box installed. Just like at least 2MW of our customer base is those who bought from a "well known" "market leader" who never was able to deliver anything that works and is qualified, so after listening to empty promises for half a year, they pulled out those boxes and installed ours. Inverter+battery remains untouched and is the most valuable part of the system.

[nctnico]

Well... I have taken the plunge into solar - and that has been into the Sigenergy architecture.

What am I looking to install...?
30 465W Aiko ABC panels, filling a second storey gabled roof on both north and south facing sides.
30 TIGO optimisers as I have a shading issue which progressively increases from early afternoon

I'd investigate whether the TIGO optimisers can be used on all panels. And it might not be worth it because shading makes you lose generating capacity anyway; adding the TIGO units does not prevent that. There are also big differences between inverters being able to handle shading well or not. If you use a better inverter which can deal with shading properly, you don't need the TIGO units. The less electronics on the roof, the better. Another good option may be to divide the solar panel install into groups (strings) of panels which have no shading and groups which have some shading and put each on a seperate MPPT. Maybe even have multiple inverters instead of a single big one.

In my solar panel install I have two groups. One group gets some shading in the fall due to a tree in front of the house, the other always has full sunlight.

[Brumby]

I'd investigate whether the TIGO optimisers can be used on all panels. And it might not be worth it ......

I've made a deeper dive into the question and have encountered one aspect I hadn't considered: Control interaction between how optimisers target operating parameters and how the Sigenergy MPPT logic works.  You have two different processes thinking they are taking care of business and there is no formal coordination which can deliver some sub-optimal situations.

Further, by using panels which have the all back contact construction, shading impact is reduced in both magnitude and timewise response.

The question of optimisers has become less compelling.

[Brumby]

The decision has been made to not run with optimisers.  Reasons:

1. The all back contact construction of the Aiko panels I'm getting handles shading better, especially with the nature of my shading
2. Panels are divided up into 4 strings which addresses basic optimisation
3. ROI.  The anticipated benefit isn't stacking up against the cost.
4. Looking to find room for two more panels
5. Put some of the money into higher power panels
6. Eliminates string control issues.
7. Less overall installation cost
8. No electronics on the roof - increased reliability

There's a part of me that will wonder if optimisers would have been a good move, but I'll see how things go.

[Brumby]

Well, I have Solar now!

32 490W Aiko ABC panels in 4 strings of 8: East and west strings on the north face and the same on the south face.
30kW Sigenergy 3 phase inverter
48kWh Sigenstor battery
Sigenergy gateway

Installed last Tuesday and started generating a bit of power straight away.

It was late that afternoon.  The sky was heavily overcast - you could not tell where the sun was, but the clouds had some brightness.  My effort to put panels on the south has shown promise.  At the initial switch on - all four strings were generating the exact same amount of power: 450W, so that's 1.8kW on a miserable day.

It's only been a few days, but my solar generation chart shows indications of the general trend envelope - but with huge chunks taken out of it, commensurate with the weather patterns.  Nevertheless, I did catch one moment when the instantaneous power output from the panels was 15.1kW.  This surprised me as I did not expect to get that close to the nominal 15.68kW rating of the panels, especially in such less than ideal weather.


I am now in "self consumption" mode, running the house and charging the battery when solar is available and using the battery when solar isn't around.  With that, I can say that I have yet to draw 1kWh from the grid since installation (but I have pumped 20-30kWh per day into the grid, once the battery reached 100% for the first time)

That's a good start, but I am now in search of data.  The members of the household have developed a cost derived "energy cautious" behaviour which results in restricted use of appliances - but now I want to see how those appliances impact the energy scene.  My wife is reluctant to run the A/C because of cost fears learned over the years, but I told her we could have run it for 10 hours from the energy we exported to the grid that day.  The fact that temperatures are relatively mild right now means we don't really think about such comforts.

It is a whole different scene now.  It is going to take time to get accustomed to the energy freedom we now have - but also to tread carefully as we learn.....


My aspiration for energy trading is looking promising with the system I now have - but the abovementioned need for data is paramount in making wise decisions about allocations in the energy budget.

[woodchips]

Looks good, but in the UK seeing the sun is usually tricky.

Questions, if you don't mind please.

Total cost, total subsidies?

How many volts is the battery store? Maximum charge and discharge current?

What is the idle current of the inverter? This seems the problem, figures I have seen say anything upto 5% even with no load, and 30kW is quite something.

Is all the power cabling in copper or aluminium? Significant cost difference.

In the UK heating is far more important than cooling, might have a week of aircon weather, but there is 7 months of heating. It is always the autumn and spring where the problem rises, chilly, not cold, but some kW heating still needed. I have bought, secondhand, several air source heat pumps to try to cover this heat load but have been universally disappointed, a supposed 5kW isn't anything like a 5kW electric heater. The exception is a swimming pool heater, 11kW, and that really does pump out some heat, manages 60C outlet temperature easily, does take 14A at 240V though. Would need a large inverter, and batteries that can cope with that current draw, not cheap?

Thanks

[tszaboo]

There's a company which trades on the imbalance market for battery storage here, my sister is letting them install a battery. ROI is pretty impressive but I doubt that will last more than a year, who knows though maybe market inefficiency persists. But at least the heatpump can stay running in case of power failure, it's monoblock and not filled with glycol.

Are there no similar schemes in Australia? Requires central control over part of the battery capacity, but the imbalance market is more profitable than spot.

Yeah unfortunately I don't believe in the long term possibilities of such schemes. Because as an end customer, we are taxed on the electricity both ways, when we buy and when we sell. Companies will have a better taxation, and with that they will take the entirety of the market, because they can arbiter on 1 cent while you can on 10 cents.
As it happens again, taxes screws with the people, and help the rich get richer.

[Siwastaja]

There's a company which trades on the imbalance market for battery storage here, my sister is letting them install a battery. ROI is pretty impressive but I doubt that will last more than a year, who knows though maybe market inefficiency persists. But at least the heatpump can stay running in case of power failure, it's monoblock and not filled with glycol.

Are there no similar schemes in Australia? Requires central control over part of the battery capacity, but the imbalance market is more profitable than spot.

Yeah unfortunately I don't believe in the long term possibilities of such schemes. Because as an end customer, we are taxed on the electricity both ways, when we buy and when we sell. Companies will have a better taxation, and with that they will take the entirety of the market, because they can arbiter on 1 cent while you can on 10 cents.
As it happens again, taxes screws with the people, and help the rich get richer.

End customers have one advantage over large grid-connected energy storage facilities though - they have own consumption which enables doing things behind the meter, which is nearly impossible to tax. So for households, arbitrage means buy at low price, self-use at high price - sell only in special exceptions. Storage-only facilities do not have this option. Their taxes and grid fees are minimized, but even that is more than zero. For households, self-use is free of penalties.

Commercial/industrial (i.e., energy storage solutions for those who use electricity: offices, factories etc)  is in the best position. They possibly combine the advantages of both: lower taxation, better contracts, and self-use.

[Brumby]

Installation on 17th March with power generation commencing at 15:25.  At sunset today, 8th April, total generation to date has reached the first MWh - 1.00989 MWh to be exact.

This has been across a few sunny days, punctuated by cloud and several mediocre days.  Typical Autumn weather for Sydney.  Operating in self-consumption mode at the moment, after the first two days of catch-up, the battery has been charged to 100% from the solar every day but one.  No power has been drawn from the grid other than the minimal amount required to maintain grid connectivity.

The heat pump HWS typically pulls 1.0-1.5 kWh on most days, with around 2kWh on the days it runs a weekly sterilisation cycle.

At this time, excess generation has been simply exported to the grid - without any consideration of export tariffs.  (We are still operating under the electricity plan that was in place before the solar installation.)  Please don't lecture about wasted opportunity - this is just a period of becoming familiar with household usage and system performance.  [Update] The existing tariff offers 4 cents per kWh, which is somewhat unexciting, but at least we know the provider is tracking exports.

It is clear that, as useful as my solar panels are, to maximise revenue from energy trading, I will need to look at judiciously timed importing of energy to charge my battery for resale at profit.

I am, however looking into wholesale pricing to get a feel for trends and price spike behaviour.  I've only just begun in this endeavour - and it is rather interesting.  I can see AI, properly trained and resourced, as being very useful.  Nevertheless, I need to find my feet before delegating control of my energy.

[Brumby]

Questions, if you don't mind please.

Total cost,

Not for public disclosure.

total subsidies?

Solar panels: $3,888.00
Battery: $14,148.00

How many volts is the battery store? Maximum charge and discharge current?

Haven't looked up the specifics, but the maximum battery discharge is less than 30kW for my stack.

What is the idle current of the inverter? This seems the problem, figures I have seen say anything upto 5% even with no load, and 30kW is quite something.

No figures available.  There are reports of total system overhead being of the order of 500W, but I don't believe that figure is accurate.  There is some heating around the inverter, but there's no way it's that much.

Is all the power cabling in copper or aluminium? Significant cost difference.

Don't know.  Didn't ask.

In the UK heating is far more important than cooling, might have a week of aircon weather, but there is 7 months of heating. It is always the autumn and spring where the problem rises, chilly, not cold, but some kW heating still needed. I have bought, secondhand, several air source heat pumps to try to cover this heat load but have been universally disappointed, a supposed 5kW isn't anything like a 5kW electric heater. The exception is a swimming pool heater, 11kW, and that really does pump out some heat, manages 60C outlet temperature easily, does take 14A at 240V though. Would need a large inverter, and batteries that can cope with that current draw, not cheap?

Sydney and the UK have rather different weather challenges.

[Brumby]

Solar newbie here...

Today was the closest to a clear sky over my panels that I have encountered so far - so I would like to record the solar generation chart.  Total 54.16 kWh.



The trailing edge appears relatively clean, which suggests to me that my concerns about afternoon shading were not borne out in practice.  If I am incorrect on this, I am keen to be corrected.

[Brumby]

Still running in self-consumption mode - because I'm looking at getting data before venturing into the unknown. 

Part of the problem is getting members of the household to relax a little and un-learn their decades of experience with power usage and bill shock.  Now we are getting into the colder months there is an uptick in heating through a combination of reverse cycle A/C (heat pump) and resistive heaters.  The power usage shows very clearly on the charting available through the App - and I am getting to know when the A/C is turned on, even when I'm nowhere near the house.  This will provide some reference when we get into the new household heat pump project (more money!)

What I have observed is that having the south facing solar panels has been a very good decision.  Certainly the north facing ones generate significantly more power in full sun, but when the skies are gloomy, rainy or otherwise compromised, the difference between north and south facing panels can be minimal.  Take today for example - showers and cloud all day:



Power generation was woeful, but the south panels basically doubled that woeful amount - which has eased the risk of depleting the battery.

FYI, Since the 17th March, I have not taken any energy from the grid - other than that which is necessary for grid connectivity.  I have exported a bit of power, but at 4 cents per kWh (legacy tariff), it's not going to set me up for retirement.

[Brumby]

We had a bit of sun this morning then broken cloud.

This shows the sort of result one would expect coming into Winter:  (Can you pick the north facing strings?)



This brought the battery up to 94.7% SOC.  There was no exporting, but I'm happy with that.

Tomorrow is forecast to be similar to today - sunny in the morning and some cloud in the afternoon.  I expect the battery will easily reach 100%.  I might even make 20 cents for exported power. 

[Brumby]

Well, it had to happen at some point...

Last night, after a couple of cold days where A/C heating featured notably, combined with less than ideal weather, at a time just after the evening peak, the crunch came.  The battery SOC hit 10%, which is the minimum level that has been set and we then started importing from the grid for the first time in 100 days and 6 hours.

We have several more days of rain forecast, so solar generation will be down - but with the cloud cover, temperatures are not likely to be low enough to warrant much in the way of heating.  As such, it will be interesting to see how the balance of generation versus usage will go - and how much grid power will be imported.

This is one reason why you don't go completely off grid.

Moving to an energy trading setup is getting closer.