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I am limited to the 5kv output of my inverter, even when not load shedding. Is this normal?


Solar Newb

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Hi,

I spent a substantial amount of getting a solar system installed at my home.  I have a 5.5kv DEYE inverter with 6 solar panels totaling just over 3k watts.  I also have a Felicity 8.7kv felicity solar battery connected.  I understood when buying the system that I would be limited to the 5,5kv of the inverter when load shedding, but what I was not expecting, is that I am also limited to the 5.5kv when the power is on.  My electrician assured me that this is normal, but, I'm not convinced and would like a second opinion.

So, now, even with Eskom power on, I have to still watch out for what I am using and if I say have some lights on at night, cook with the oven, and put the dishwasher on... the lights trip and I have to wait about 30s for them to return, which it does automatically with the error AC_OVERLOAD.

So, my question is, is this normal? Or should I get another electrician out to take a look?

Thanks in advance...

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I thought the exact same thing when our system was installed. We were running around 24/7 ensuring that we never went over the 8kW limit of our inverter. Load shedding or no load shedding. 

The installer subsequently explained that there was an AC pass-through on the SunSynk Inverter which allows for loads of current to kind of bypass the inverter when the grid supply is on, so that one can operate the stove, pool, washing machine, etc, etc, etc and one can safely use a lot more than 8kW without it tripping.

This makes sense to me, even though I am not an electrician, and we have been operating like this for 2 months without any issue. 

So to me, what you are explaining doesn't make sense...

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On 2023/04/26 at 10:52 AM, Solar Newb said:

Hi,

I spent a substantial amount of getting a solar system installed at my home.  I have a 5.5kv DEYE inverter with 6 solar panels totaling just over 3k watts.  I also have a Felicity 8.7kv felicity solar battery connected.  I understood when buying the system that I would be limited to the 5,5kv of the inverter when load shedding, but what I was not expecting, is that I am also limited to the 5.5kv when the power is on.  My electrician assured me that this is normal, but, I'm not convinced and would like a second opinion.

So, now, even with Eskom power on, I have to still watch out for what I am using and if I say have some lights on at night, cook with the oven, and put the dishwasher on... the lights trip and I have to wait about 30s for them to return, which it does automatically with the error AC_OVERLOAD.

So, my question is, is this normal? Or should I get another electrician out to take a look?

Thanks in advance...

If your loads are correctly split and the CT correctly installed and inverter settings done correctly then you should not be having this issue.

Maybe provide a diagram or photo of your install DB board especially, then maybe we can help guide you in the right direction or at the very least give you some relevant questions to ask your installer :)

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On 2023/04/26 at 10:52 AM, Solar Newb said:

Hi,

I spent a substantial amount of getting a solar system installed at my home.  I have a 5.5kv DEYE inverter with 6 solar panels totaling just over 3k watts.  I also have a Felicity 8.7kv felicity solar battery connected.  I understood when buying the system that I would be limited to the 5,5kv of the inverter when load shedding, but what I was not expecting, is that I am also limited to the 5.5kv when the power is on.  My electrician assured me that this is normal, but, I'm not convinced and would like a second opinion.

So, now, even with Eskom power on, I have to still watch out for what I am using and if I say have some lights on at night, cook with the oven, and put the dishwasher on... the lights trip and I have to wait about 30s for them to return, which it does automatically with the error AC_OVERLOAD.

So, my question is, is this normal? Or should I get another electrician out to take a look?

Thanks in advance...

This sounds like you have all the loads connected to the essential/backed up output of the inverter. The way it's usually done is that the DB is split into essential and non-essential loads. The non-essentials are usually big drawers like the geyser and the electric stove. Those loads will not get any power when the grid is down, but they also will not count towards the kW limit on the inverter.

Even then you have to be careful. Most electric kettles, for example, pull nearly 2kW. So with a few kitchen appliances running at the same time you can easily go over the limit. My inverter is limited to 4.6kW which sounds a lot if you say it quickly ("20 amps!") and it will allow an extra 50% for 10 seconds. If I am making breakfast and I'm using the toaster, the microwave, the kettle etc then I can bring the system down - with the grid up or down - because the kitchen plugs are on the backed up (or essential) side of the DB.

What is tripping? The inverter or the battery? If I read the spec sheet correctly then your battery is rated for 80A continuous load, about 3.8kW. So it is possible that battery gives up before the inverter does.

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31 minutes ago, Bobster. said:

This sounds like you have all the loads connected to the essential/backed up output of the inverter. The way it's usually done is that the DB is split into essential and non-essential loads. The non-essentials are usually big drawers like the geyser and the electric stove. Those loads will not get any power when the grid is down, but they also will not count towards the kW limit on the inverter.

As I'm reading this, the load is tripping while on the grid. The inverter has a pass-through current of 32A, so let's say one should be able to connect up to around 7.5kW of essential loads as long as Eskom is up. But if the OP has got on an  oven and dishwasher connected to the essentials, make that 3kW plus 2kW during the heating cycle, plus whatever other loads (maybe a geyser or a kettle), it all adds up quickly.

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I hope this counts as a sub-question of the main question here. Alongside our 5kv inverter-battery set-up is a mini-DB with a switch that bypasses the inverter -- i.e., it switches to direct Eskom. When we do this (not during load shedding, of course), we don't have to worry about overloading the system by running the toaster, microwave, kettle etc  simultaneously. (And the switch happens quite seamlessly, so desktop computers and TVs keep running.) But I'm not sure whether this is good or bad for the inverter and battery. Or does it make no difference? It seems to me (as a total layman) that if there's not going to be any load shedding for a longish period (say a day or more), bypassing the inverter and battery should give them a "rest" (even though they're not actually switched off), maybe reducing wear and tear or extending battery life.  Or does switching back and forth put a strain on the battery and inverter -- or on anything else?

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