Solar system with Safe T Cut keeps tripping

[Crossy]

Yeah, those really tiny ants like electric fields for some reason, and crushed ones are a pretty good insulator when they get inside switches.

 

[Muhendis]

29 minutes ago, Crossy said:

Yeah, those really tiny ants like electric fields for some reason, and crushed ones are a pretty good insulator when they get inside switches.

 

I have an inverter fridge which was disabled by them. They found a way into the electronics and onto the main circuit board.

There's a high voltage mains area and a low voltage DC area on this board connected by optocouplers ............... and ants.

 

The ants must have been resistive conductors for some time because the heat of them conducting was enough to burn the board between the high voltage AC track and a low voltage DC track.

 

There was a fair bit of charcoal left behind as well as a load of pretty useless electronic components.

 

I called in the fridge repair man who was quite surprised by the amount of damage done. He had seen it before but on a lesser scale.

He was also a lecturer at the local tech. college teaching students how to repair domestic appliances and he wanted the dead board as an example to show to his students.

 

My thoughts were "if that's what ants can do, what will happen if the uncles ever get in".

[sometimewoodworker]

7 hours ago, Crossy said:

Yeah, those really tiny ants like electric fields for some reason, and crushed ones are a pretty good insulator when they get inside switches.

 

That is why all my outside electrical boxes and lights have ant powder added

[pedritosan]

On 8/6/2023 at 1:24 PM, Crossy said:

Yes, pressing Test should turn everything off ???? 

 

You could try turning off the breakers for the outside kit and see if that makes any difference when it rains. Does the Safe-T-Cut trip out again if you reset it?

 

Did you get a price for the Huawei battery packs? A couple of other members are looking for them and the $$$ being asked is frightening. Sadly, being high-voltage battery packs 3rd party units are like rocking-horse droppings ???? 

Sorry for my late response...I wasn't notified of new messages for some reason. Yes, the battery was expensive. It is only 5KWH and costs 50,000 (including installation). I am told the advantage of the Huawei system is that you can add batteries to your half-depleted system in 5 years and the system automatically adjusts, maximizing the remaining life of your existing battery. However, at 5KWH, it almost always lasts us all night if there are no guests in the house. The house is teak, poorly insulated, and we do not have heat pump AC systems. So, one guest will deplete the battery in a night. 

 

I turned off the breakers on the outside kit as suggested and the power did not go off. Apparently, it shut down the solar to the inverter, but did not impact the battery.

 

After resetting the Safe-T-Cut, it seems to no longer trip out. Why is that? Such a mystery what you all do! 

 

 

[pedritosan]

Fortunately, I have a giant gecko next to the box, so no ants.

[sometimewoodworker]

1 minute ago, pedritosan said:

I am told the advantage of the Huawei system is that you can add batteries to your half-depleted system in 5 years and the system automatically adjusts, maximizing the remaining life of your existing battery.

That is a wonderful idea but regrettably it is pie in the sky.

Batteries degrade over time and adding additional batteries to a degraded battery bank will significantly reduce its performance. This is why you should always keep battery sets together for best economy.

[Muhendis]

1 hour ago, sometimewoodworker said:

That is a wonderful idea but regrettably it is pie in the sky.

Batteries degrade over time and adding additional batteries to a degraded battery bank will significantly reduce its performance. This is why you should always keep battery sets together for best economy.

As the man said.

Adding strong new batteries to weaker old ones will deplete the new batteries quicker.

 

If you are interested to extend the life of your batteries then keep them in a moderately cool place (25C is perfect but they should be ok at 30C) and arrange for your depth of discharge to be as little as possible. 30% would give an extremely long life but for lithium chemistries, 40 to 50% should give you many years of power.

[Dan O]

On 8/6/2023 at 12:05 AM, pedritosan said:

Thank you so much for your help!

 

@Dan There are no old ground wires as the electrical system is new. I had to ask for each and every ground to be installed by an electrician that I hired.

 

@Crossy. Yes I'm worried, too. Here are some pictures...

 

@CarlYai...it would be much appreciated!

 

 

I must not have been clear on my comment, sorry for that. Check to see if you have a connection from a neutral line that is run to a ground in the earth, not to an existing ground wire. That is a common way many thai "electricians" wired houses without ground wires in the circuits and it can play havoc when upgrading to a proper panel. It may not be your problem and as crossy said have a proper inspection done of the whole system

[sometimewoodworker]

13 hours ago, Muhendis said:

If you are interested to extend the life of your batteries then keep them in a moderately cool place (25C is perfect but they should be ok at 30C) and arrange for your depth of discharge to be as little as possible. 30% would give an extremely long life but for lithium chemistries, 40 to 50% should give you many years of power.

Again a wonderful idea on temperatures but incorrect 

at 30C the battery service life is about 50% of the maximum. At 25C it is around 30% less than at 20C

Quote

Valve Regulated Lead-Acid (VRLA) batteries have a rated design life capacity based on an optimum operating temperature of 20-25°C.

For every 10°C constant increase in temperature above this recommendation, it is generally accepted that battery service life will halve (reduce by 50%).

[Crossy]

It's worth noting that our OP has LiFePO4 batteries.

 

 

[Muhendis]

18 minutes ago, Crossy said:

It's worth noting that our OP has LiFePO4 batteries.

 

 

Yes I know. That's why I used those temperature figures.

Onetimewoodworkers figures are for FLA batteries.

My lead carbon batteries are in the same temperature range as LiFePO4's.

[pedritosan]

On 8/9/2023 at 4:58 AM, Crossy said:

 

Nominally 450V DC which places them firmly in the "not really DIY" area.

 

Huawei 5kWh unit 162,000 Baht!

 

https://www.solartech-center.com/product/1006/huawei-battery-powermodule-luna2000-5k

 

By contrast an off-brand 48V, 5kWh pack is around 60,000 Baht and if you DIY around half that.

 

 

 

Apologies if I got the cost wrong. My adopted daughter was doing the translation and took notes on the different components of the solar system, so the price I have must be wrong. 

 

I was originally planning on going with Sean at Eyekandi Solar Chiang Mai. He wanted to install an Alpha Smile inverter/battery with the same solar panels. Given that he is a Farang and seemed very nice, I was highly inclined to go that way. However, Llana Solar was going to install a Huawei system at a lower price. Against my better judgment, I went with Llana Solar because the reviews of the Huawei system indicate that it is very reliable, because Eyekandi could not do an install for some time, and, at any rate, the cost was lower.

 

Eyekandi wanted to do a DC-coupled system, which has advantages with the Thai power grid. But I read that the battery wears down faster over time (this is logical), and that each expansion has to be 10KwH. I'm also very paranoid about a battery fire (something that is probably a bigger problem with a poor install than an off-brand system).

 

Mine is AC coupled, meaning it is drawing a small amount from the grid unless the power is cut. The AC is converted to DC and then converted back to AC. I really do not know which is the better choice. I also don't know anything about electrical or solar systems, so I was flying in the dark with the help of ChatGPT.

 

As I understand it (again, qualified statements), Sean was going to put a whole house surge protector in front of the unit. The Huawei system does not need that as it offers surge protection built into the inverter. The only part of the system that is grounded is *after* the inverter (the circuit breaker box between the solar system and the house breaker).

 

I'm not sure whether that is the right way to do it. Llana Solar was obviously not an expert at this. Hopefully, it will all be OK.

 

Are those 60,000 baht batteries safe?

[pedritosan]

On 8/11/2023 at 8:36 PM, Muhendis said:

As the man said.

Adding strong new batteries to weaker old ones will deplete the new batteries quicker.

 

If you are interested to extend the life of your batteries then keep them in a moderately cool place (25C is perfect but they should be ok at 30C) and arrange for your depth of discharge to be as little as possible. 30% would give an extremely long life but for lithium chemistries, 40 to 50% should give you many years of power.

Huawei claims that their system equalizes when new batteries are added, such that the new battery is not unduly stressed. So, by their claims, if a new battery is added a few years in, you essentially are just upgrading the system without any undue stress.

[sometimewoodworker]

4 hours ago, pedritosan said:

Huawei claims that their system equalizes when new batteries are added, such that the new battery is not unduly stressed. So, by their claims, if a new battery is added a few years in, you essentially are just upgrading the system without any undue stress.

That demonstrates the difference between marketing speak a the physics of batteries and their degradation over time.

The claim that is being made is solid bovine waste. Or is rather/very economical with the truth.

They don’t tell you that while a new battery/s may not stress the system you are going to loose a significant amount of the lifespan of the new battery/s.

[pedritosan]

11 hours ago, sometimewoodworker said:

That demonstrates the difference between marketing speak a the physics of batteries and their degradation over time.

The claim that is being made is solid bovine waste. Or is rather/very economical with the truth.

They don’t tell you that while a new battery/s may not stress the system you are going to loose a significant amount of the lifespan of the new battery/s.

They claim it works like a solar optimizer, running an algorithm to distribute discharge equally across the new and old batteries. Huawei certainly has serious engineering capabilities. Whether and what they dedicate to the solar division is not clear, but their campus is damn impressive. Here is the info on the battery. https://www.abshop.in.th/wp-content/uploads/2023/07/LUNA2000-5-15-S0.pdf

[Muhendis]

10 minutes ago, pedritosan said:

They claim it works like a solar optimizer, running an algorithm to distribute discharge equally across the new and old batteries. Huawei certainly has serious engineering capabilities. Whether and what they dedicate to the solar division is not clear, but their campus is damn impressive. Here is the info on the battery. https://www.abshop.in.th/wp-content/uploads/2023/07/LUNA2000-5-15-S0.pdf

The way to protect new batteries from old has to be to isolate them from each other using diodes or MOS FETs or some other electronic device I guess.

Charging would present the same problems in reverse so I would put my meagre pension on MOS FET's switched between charge and discharge.