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My SMA + Polarium + Solar Whole-Home Power Installation (12.015kWp, 12kW, 22kW, 700Ah)

afro-solar

New Member
Joined
Mar 18, 2023
Messages
52
Location
Johannesburg, South Africa
I did this installation in 2020, in the middle of lockdown, when prices were good and equipment was available :).

The setup is:

1. 27x 445W LONGi solar panels (12.015kWp).
2. 2x SMA Sunny Boy AV-41 PV inverters connected in parallel (12kW).
3. 9x solar panels per string.
4. 2x strings on the 1st PV inverter + 1x string on the 2nd PV inverter.
5. 2x SMA Sunny Island 8.0H-13 battery inverters (12kW nominal, 22kW peak).
6. Sunny Island inverters connected in parallel, in off-grid mode.
7. Utility grid connected to Sunny Island inverters as a "generator" source.
8. 1x SMA Data Manager.
9. All systems connected via 100Mbps Ethernet LAN (no wi-fi).
10. Voltage sensor to prevent dirty utility grid.
11. Zero grid feed-in.
12. 7x 48V 100Ah Polarium LFP batteries (33.6kWh)
13. 2x CarbonTRACK energy usage monitoring (disabled).
14. 1x SMA Energy Meter.
15. EnergyMeter iOS app using MODBUS communication.
16. SMA Energy app.
17. Polarium app.
 

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Very nice!
Since it has been in operation for two years, can you comment on how your system is doing? Has the 12kW of PV been able to produce what you need in Jan-March when I understand fog/cloudy weather can be common in Johannesburg?
For a year I had a 38kWh battery pack paired with 7kW of PV and found the battery was too small.
Wondering if your 12kW PV charges up the batteries to 100% early each day, with lots of spare PV available?
If you did it all over again today, with the knowledge you have gained operating the system for two years, would you design anything differently ?
 
Very nice!
Since it has been in operation for two years, can you comment on how your system is doing?

The system is performing very well. The inverters have been very reliable (not a single problem), as has the battery and solar panels.

I do have some experiences with the battery I'd like to share, though...

The first issue is because I am using a battery designed primarily for telco's, access to firmware updates is terrible. I have to use a lot of back doors to get information on this, but to be fair, even without a battery firmware update in nearly 3 years, it just keeps going.

The second issue on the battery is the interface between the BMS and the inverter. Polarium have two interfaces for this. The older one is called the IC-B (Incell Connect Bridge), and the current one is called the SII (SMA Inverter Interface). I had massive problems with the SII where the contactor gets extremely hot (even though it's rated for 500A), and fries the unit.

With the SII, you cannot link the battery to an SMA inverter if you don't have one, as it provides both electrical and electronic connectivity between the battery and the inverter. The IC-B is just pure electronics, translating the battery's BMS data into information SMA can understand. With the IC-B, you use an external fuse, which is a more reliable system.

The default shipping code on the IC-B allows you to only have 60 seconds worth of Bluetooth access to the battery's BMS. When I asked Polarium about this, they could not understand why anyone would want to monitor the battery for more than 60 seconds. At any rate, they agreed to fix it with a code update of the IC-B, so now it is possible to view the BMS data for as long as you want.

They promised to go back and review the design of the SII. That was back in 2020. To be honest, I don't really care. The IC-B and a regular fuse is just so reliable, I'd rather not change it for what, at the time, was unproven tech.

The third issue with the Polarium battery is that it does not come with a pre-charge resistor built in. So I had to construct my own resistor which I wired permanently across the fuse terminals. That way, if I ever needed to switch off the inverter, I can use that resistor to pre-charge its capacitors in order to turn it back on without tripping the battery.

The other thing I have had to manage is heat in the garage where I have them installed, and I used fans for that. But I just added an extractor to help force warm air out, and that has lowered the space's temperature by another 5 degrees-C. I did consider using inverter-based air conditioning units which would draw less than 700W of power, but the costs did not make sense... and cheaper air conditioners use way more power, in the 1.5kW - 2kW range.

Has the 12kW of PV been able to produce what you need in Jan-March when I understand fog/cloudy weather can be common in Johannesburg?

While October - March tends to be our summer period in Johannesburg, where we see the most rain (especially, as you say, between January - March), it is still the best period for solar yield throughout the year. We are blessed with clear-sky winters, and the lower ambient temperatures are great for solar panel and inverter efficiency, but with the sun being so low in the sky, the actual sun hours from which you can make power are far fewer. So even though our summers are rainy, it's still the best time of year to make power. Not so much in Cape Town, as their winters are generally stormy most of the season. And Durban is too far east to have any real solar irradiation compared to the western parts of the country. Johannesburg is not a tropical region, so our rainy summers are not a huge issue as, say, South East Asia.

For a year I had a 38kWh battery pack paired with 7kW of PV and found the battery was too small.

38kWh of battery is a lot of power. Do you mean it was too small in terms of the amount of energy you would make per day from solar so you can have somewhere to dump it, or in terms of your use requirements?

Wondering if your 12kW PV charges up the batteries to 100% early each day, with lots of spare PV available?

It does do, I haven't had any trouble with that at all. Between charging the battery and running the home, I make about 40kWh of solar energy per day.

I do have one issue where the battery will not charge beyond 53.1V, and it claims that to be 100% SoC, with a cell voltage of 3.55V. I have spoken to SMA and Polarium about this, and it seems that the issue is the BMS having firmware that backs charging off at 53.1V. The battery is designed to call 100% SoC at 54.75V, so I'm working with them to get a firmware update so we can unlock that.

If you did it all over again today, with the knowledge you have gained operating the system for two years, would you design anything differently ?

Well, I would use larger solar panels now; in the 580W - 675W range, so as to maximize early-morning, late-evening and cloudy-day solar yield. I would also find some space to have either an east- or west-facing string, to catch sunrise or sunset.

I would use a more commonly-sold battery (EG4, BYD, Dyness, Renogy, Ark Battery, e.t.c.), because even though Polarium's batteries perform excellently, they are not really a retail vendor (their customer base tends to be telco's or large industry). So getting access to them for support on technical questions is a real minefield. It would have ended in tears if their product was not solid, and I was unable to reach them at the same time. These more common batteries also ship with built-in pre-charge resistors, so that would be useful (to be fair, I don't know whether Polarium now support pre-charge resistors in their latest batteries, but I have asked the question... let's see how long they take to respond).

Other than that, I'd still choose SMA for the inverters. There are two things I like from Victron that SMA don't do, which is in-built grid voltage sensing, as well as in-built Earth-Neutral Bonding. But even if I've had to do these two things externally with SMA, I would still choose SMA over Victron. Low Frequency inverters don't excite me :).

And I would definitely maintain discrete inverters still, i.e., PV inverter + battery inverter as separate systems. I'm not particularly sold on all-in-one hybrid inverters, unless the application is very very small. And anyway, I prefer AC-coupled systems.

Thanks for your feedback, and questions. Most appreciated!
 
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Thanks for the very detailed reply!
I find it very informative to see what others have done, and then what they learned over a couple years of operations.
Yes, my comment about battery size vs PV-array size, was realative to available PV collection during a day: ie a 12kW PV system will quickly recharge a battery bank of 30-40kWh perhaps missing out on some available late afternoon sun when the batteries are full and there is no-where for the excess energy to go. In my set up - like yours - I have gone to 10kW PV for effectively the same reason, to make better solar collection on cloudy /poor days.
I have not see these Polarium batteries before, are they a local product?
 
Yes, my comment about battery size vs PV-array size, was realative to available PV collection during a day: ie a 12kW PV system will quickly recharge a battery bank of 30-40kWh perhaps missing out on some available late afternoon sun when the batteries are full and there is no-where for the excess energy to go.

Exactly.

I oversized the system so that I could get as much yield during cloudy/rainy days. I just run out of roof space, unfortunately. But I am also lucky to have a flat roof, so I have more space than most people.

Actually, I've worked out that the perfect day for me would be ultra-white clouds between 6AM - 9AM, clear skies from 9AM - 3PM, and ultra-white clouds from 3PM - 6PM.

The super white clouds in the early morning and late afternoon are more effective at solar generation than clear skies with sunlight coming in at the wrong angle.

In my set up - like yours - I have gone to 10kW PV for effectively the same reason, to make better solar collection on cloudy /poor days.
I have not see these Polarium batteries before, are they a local product?

Polarium are a Swedish brand:

https://polarium.com/

They were previously known as Incell. They cut their teeth in designing batteries for telco's, specifically mobile network operators, who needed off-grid or backup power solutions at cell sites. I ended up with them because the SMA partner I used for my inverters was also pushing those batteries. They were reasonably priced, and at the time, we mainly had Pylontech in South Africa, whose 4.8kWh battery was pricier than the Polarium one. Of course, there are many more battery brands here now, so the choice is good.

One issue I ran into using Polarium in an AC-coupled system was that they tuned their BMS with such sensitivity that the demands of an AC-coupled system required a firmware update that relaxed some of their thresholds at which the BMS disconnected the battery due to an over-current. That is because mobile network deployments tend to be an all-DC system, which have smoother power requirements than in AC systems, particularly where the grid comes and goes. But that was all sorted out when they realized their batteries had been deployed in an AC-coupled system, and just updated their settings to match.

And yeah, I just heard back from Polarium on the pre-charge resistor. They still do not support it in their current range of batteries. No clue on if it's going to be on the roadmap. It's not a show-stopper, but in 2023, you expect a car to come with wheel screw cover removers as standard :).
 
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Have come across the Polarium battery for the very first time how do they connect with the Chinese inverters on an off grid setup ? Where can i get the connect bridge?
 
I did this installation in 2020, in the middle of lockdown, when prices were good and equipment was available :).

The setup is:

1. 27x 445W LONGi solar panels (12.015kWp).
2. 2x SMA Sunny Boy AV-41 PV inverters connected in parallel (12kW).
3. 9x solar panels per string.
4. 2x strings on the 1st PV inverter + 1x string on the 2nd PV inverter.
5. 2x SMA Sunny Island 8.0H-13 battery inverters (12kW nominal, 22kW peak).
6. Sunny Island inverters connected in parallel, in off-grid mode.
7. Utility grid connected to Sunny Island inverters as a "generator" source.
8. 1x SMA Data Manager.
9. All systems connected via 100Mbps Ethernet LAN (no wi-fi).
10. Voltage sensor to prevent dirty utility grid.
11. Zero grid feed-in.
12. 7x 48V 100Ah Polarium LFP batteries (33.6kWh)
13. 2x CarbonTRACK energy usage monitoring (disabled).
14. 1x SMA Energy Meter.
15. EnergyMeter iOS app using MODBUS communication.
16. SMA Energy app.
17. Polarium app.
This is nice and was wondering how i can get hold of a connect bridge for Polarium battery. I have some Polarium batteries and a Sunsynk 12kw inverter but can get them to communicate.
 
Very nice!
Since it has been in operation for two years, can you comment on how your system is doing? Has the 12kW of PV been able to produce what you need in Jan-March when I understand fog/cloudy weather can be common in Johannesburg?
For a year I had a 38kWh battery pack paired with 7kW of PV and found the battery was too small.
Wondering if your 12kW PV charges up the batteries to 100% early each day, with lots of spare PV available?
If you did it all over again today, with the knowledge you have gained operating the system for two years, would you design anything differentl
 
Hi very encouraging kindly assist where can I get the connect bridge and which inverter did you use?
 
Hi @afro-solar that is an awesome setup. Can you please advise what your grid monitoring parameters are set to on the Sunny Boy? Is it set specific to your grid operator/region or do you have it set to off grid mode?

And what is the benefit of connecting utility grid to Sunny Island as generator source as you mentioned you are an AC coupled setup so the Sunny Boy would,be connected to your utility grid and Sunny Boy would be Co nected to.your AC Input 1 on Sunny Island to complete AC coupling so SI can throttle/frequency shift SB as required?

I would not have thought your grid operator will like to be connected directly into the Sunny Island as generator input?

Thanks
 
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