Anyone else had this happen

[Bessy765]

We have a 6kWh (16) panel system with a Solax 5kW Hybrid Inverter and 2 x 5.8 kW batteries. When the batteries get down to 10% the system shuts down (this during darkness) as this time of the years the batteries don’t get enough to go all night. as it gets light the batterie start adding power to the system as well as the incoming mains. When the batteries get down to 6% they system then starts to charge the batteries from the mains.
I appreciate that what goes into the batteries will come out again as stored energy, it just seems this is inefficient as you will not get out all of what you put in and we appear to end up using slightly more than if this did not happen. Just wondered if this is a problem, have been trying to get through to Solax for some time by phone and email but as yet no response.

 

[mitzimad]

batteries are usually measured in ah so im not sure how big your batteries actually are to comment also you dont mention what your running every night you say the batteries start to charge from the mains if you have mains power your batteries should never run out

 

[Bessy765]

This is a domestic system, The batteries are 5.8kWh, each during daylight hours they are charged by my 6kWh solar panel array. Yes we have mains power to the house and at this time of year not enough from the panels will cover daily use. So as of just now 21:00 the batteries are down to 10% the supply from them stops and the house is then supplied by Scottish power through the mains supply. But my query is why as daylight begins the batteries will again start to provide power through the inverter. If the batteries get then down to 6% they then start to take power from the grid to charge them. Not had the system in for long so still learning. But it seems an inefficient way of using power.

 

[rwg]

Hi,

we have the Solax batteries too. The batteries do go down very slowly below 10%, and if it is anything like ours it will charge at 400W from the mains when it thinks they have got too low. It's not good for the batteries to get too low, so topping them up will help ensure they last.

If you have a Solax inverter with emergency power output and you put it in 'backup' mode rather than 'self use' mode, the batteries go down faster, dropping 1% every 3 hours or so. This is because in 'backup' mode it never goes fully to sleep (since it couldn't provide emergency power if it was completely asleep) and I assume it takes its standby power from the batteries rather than the grid so it can still be alive if the grid goes out.

How quickly is your power level dropping? When I was running our inverter in 'self use' mode, the drop was really slow - only 1% overnight maximum, often no drop, although the nights were shorter back then in the summer!

It's worth knowing that you certainly don't get back all the power that goes into the batteries. There are losses at various stages, including the charging, in the battery itself and also when the power comes back out and converts back to AC. What you get back out might be between 75% and 90% of what goes in, depending on the rate of charge/discharge.

cheers,

Robin

 

[Bessy765]

Hi Robin, thank you for your input, what had thrown me is during the evening depending on how much is harvested during the day as soon as the batteries get down to 10% the output stops, then as the sun comes up the batteries start to give out power running as low as 6%. Then when it gets to 6% they start getting charged by the incoming mains. Why it just doesn’t just stay turn off at 10% then. When the panels get to a certain level start up again.

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[rwg]

Ah, ok, that's a bit different to what I was thinking then. Our solax inverter is battery only (we have a separate solar system on the original FIT tariff that we cannot change without losing the FIT status).

I guess the theory is that once the sun comes up it will quickly be able to top up the charge, so it's OK to drop a bit below 10%. Of course in the winter the solar panels don't really get going very fast in the morning, particularly if you have shading from trees or nearby buildings.

You may be able to tweak the settings to stop this from happening - there are loads of settings on the inverters that can be changed through the Solax Cloud app or via the inverter screen. Unfortunately the documentation is very sparse about what all the settings actually do, so you have to guess based on the name and a bit of trial and error. I would suggest writing down the original values before changing anything. I don't think I am giving away any secrets by saying that the default passcode to access the advanced settings is '6868', since you can find that within about 60 seconds of web searching anyway.

If I was looking for a way to stop the discharge below 10% in your setup, I would look through the settings to see if I could find any that looked battery related that had a current value of either 5% or 6%. You would probably find a 'minimum state of charge' setting of 10% too somewhere - that controls the first cut off that you see at 9pm or so.

cheers,

Robin

 

[Bessy765]

Today we ran out of power whilst it was just still light but the 10% lockout happened. True about info I don't think the installers were very clued up on how to program it either. Trouble is I loose a couple or more units wasting energy to re charge back up to 10% when if it just stopped at 10% till there was enough daylight to start charging from 10%. Thank you for your input much appreciated

 

[Bessy765]

If on my inverter plate it reads max AC output/input power 3680 va is this rated at 3 kWh >

 

[Raul]

The inverter is capable of a output/input of 3680va apparent power. If a load applied to that of power factor 1 then that’s 3680w of power consumed. The 3kwh means energy, wrong terminology for power. Energy it’s power over time. A load of 1kw over 3hrs amount to 3kwh. Or a load of 3kw over a hr, same 3kwh of energy is used.

Your batteries are doing exactly what they been set to do. You have to get the manuals read and try other settings, like priority, Soc threshold etc.

 

[autorouter]

batteries are usually measured in ah so im not sure how big your batteries actually are

Amp-hours is a measure of the charge capacity, not the energy capacity. Because practically all motorhome batteries are 12V, the amp-hours is usually used to compare batteries and battery bank capacities, as you say.

To find the energy capacity you need to know how much energy each amp-hour of charge has, and the voltage will tell you that. '12 Volts' means each amp-hour has an energy of 12 watt-hours. So a 12V battery with a charge capacity of 100Ah has an energy capacity of 100 x 12 = 1200 watt-hours, that is 1.2 kWh.

If you want to compare batteries of different voltages, like 3.6V laptop batteries or 48V storage batteries, it's easier to use the kilowatt-hours rather than be asking what voltage the amp-hours of the battery refers to. The energy capacity doesn't depend on the battery voltage.

Having said that, if you try to buy one of those small phone-charging battery power packs, they tell you the amp-hour capacity (eg 10000mAh) without telling you the voltage, because they are all about 3.6V.

So you can work out that one of those 5.8kWh batteries is the equivalent of 5800/12 = 483 Ah at 12 volts.

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[MisterB]

It def seems to be a conflict between what your inverter is set at and what your battery BMS is set at.

The reality is that whoever installed the system might be competent with 'electrics' but possibly not the components and set up of a home battery system.
I think this is only going to get worse as more and more competent electricians are pulled into the home battery installation market, seduced by the big bucks on offer!

 

[autorouter]

We have a 6kWh (16) panel system with a Solax 5kW Hybrid Inverter and 2 x 5.8 kW batteries. When the batteries get down to 10% the system shuts down (this during darkness) as this time of the years the batteries don’t get enough to go all night. as it gets light the batterie start adding power to the system as well as the incoming mains. When the batteries get down to 6% they system then starts to charge the batteries from the mains.

I think the charging that kicks in at 6% is some kind of override that is meant to avoid damage to the batteries and protect your investment. I'm sure you would prefer to use a couple of kWh rather than risk damage due to excessively low discharge level.

But as you say it should never get to that state anyway. As rwg says, on many inverters you can choose the level of 'backup' reserve and the 'self-use' level. For example if you think there's a risk of a power cut, you could set the backup to 50%. Then there is always some power if the power gets cut, for freezer, medical devices etc. Also if you know there is going to be a power cut (they might be advertised on a rota basis for example) you could set the backup to 100% to be best prepared for it.

The way things are going nowadays, I think it would be a good idea to become more familiar with your settings, maybe there is a phone app you can download. Some of the older inverters can take a bluetooth or wifi dongle to make it easier.

 

[rwg]

Yep, I have set my system to 50% minium level for the winter. Even on a sunny day like today we will not fill the remaining 50% from the solar panels from November through to February, so no wastage abd we have about 5kWh in reserve in case of a power cut.

Having thought about the original poster's issue a bit more, I wouldn't worry too much about it. If it takes 1kwh to charge up from the mains from 6% to 10% then you have to balance that against the fact that you got 75 or 80% of that amount of electricity out of the batteries as they discharged from 10% down to 6% in the first place. You are only out of pocket by the losses in the system, not the whole amount.


A bit of educated guesswork here... I suspect the activation in the morning when the panels come online is supposed to help catch all the power available generated from the panels. However, if the panels take a long time to start producing decent amounts of power (perhaps due to shade on them when the sun is low), the battery may get down to the 6% limit before the panels get going enough to charge.


Cheers, Robin

 

[Bessy765]

Thank you for all your inputs, yes there is a lack of explanations as stated as more get involved the expertise gets less.
having worked out some of the settings the min soc was set at 10% but at first when trying to raise it to 20% it said settings failed, the setting for charge from grid was also reading disabled but it was still doing it. So I tried entering the disable charge from Grid got the message setting success, so tried the min soc set to 20% got the message success so put it back to 10% see what happens in the morning. No sensible instructions came with it.

 

[autorouter]

the setting for charge from grid was also reading disabled but it was still doing it.

That's probably referring to the 'normal' charging from the grid, which you might not want to happen. Unless you're on one of those tarifs where you get cheaper power at off-peak times. The 6% is probably some kind of 'emergency' override to prevent battery damage by discharging too low. It should never be necessary in normal circumstances.

Maybe set the minimum SOC to 20% and see what happens, it might not dip to 6% in that case.

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[Bessy765]

Thank you for that I will leave it a 10% for tomorrow just to see the up it to 20%

 

[Bessy765]

Following further suggestions I reset the main SOC to 20% this has made no difference. Whilst I am not concerned about the cost of re charging the batteries it is more a case of is it working correctly. If not will it cause harm or shorten the working life of these batteries? My lithium set up in our motorhome the bms controls the discharge and cuts off at 10% although I understand that it is a slightly different set up. The company that supplied the house set up are not forth coming with and help.

 

[Bessy765]

System is now sending power back to the grid when the battery is only at 7% that cant be correct??

 

[Jimbohorlicks]

I would check with your supplier to see if you can go onto a dual tariff, system 7 or equivalent ,then you could top up your batteries during off peak hours and use them during the day when you need the extra power.

 

[rwg]

How are you seeing the figures for what it is doing? If you are using the Solax app then that only updates every 5 minutes or so - you get a snapshot of what the device was doing at the time the update happened.

The inverter can send power back to the grid for a short period. If the power being used by the house suddenly decreases then the inverter will be supplying too much power, so some will flow back to the grid. Within a few seconds it will spot the outflow of power and reduce the power it is producing, however it is possible that the 'update' to the Solax app occurred just at the moment that the power was flowing out, which would then show up in the app for about 5 minutes.

cheers,

Robin

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[Bessy765]

How are you seeing the figures for what it is doing? If you are using the Solax app then that only updates every 5 minutes or so - you get a snapshot of what the device was doing at the time the update happened.

The inverter can send power back to the grid for a short period. If the power being used by the house suddenly decreases then the inverter will be supplying too much power, so some will flow back to the grid. Within a few seconds it will spot the outflow of power and reduce the power it is producing, however it is possible that the 'update' to the Solax app occurred just at the moment that the power was flowing out, which would then show up in the app for about 5 minutes.

cheers,

Robin

Hi Robin many thanks for your reply. At the times of posting there was very little current demand, but this system seems to have a mind of its own it seems to act completely at random, as it may result in legal action I will not name the supplier of the system but the original quote was for 6.5 kWh batteries and a 5kWh inverter I have ended up with a 3kWh inverter and 5.8 kWh batteries and been overcharged by £450 and as they did not install as they original quoted I have to reapply for planning permission so out a lot of money.

 

[rwg]

For it to do what is supposed to do, the most important thing is that the inverter can monitor the flow of energy between your house and the grid. Your installer should have put in either a digital meter in your fuse box or a current clamp clipped around one of the wires from the main electricity meter.

Do you know which you have? The digital meter would look something like this. https://www.solartradesales.co.uk/Cache/Images/SDM230-MODBUS-1500x1500.jpg

If the inverter gets bad data from the digital meter or current clamp then it will likely misbehave. You can check the values it thinks it is getting on the inverter front panel. Scroll down to system status, press enter then down to meter/Ct then enter again. Negative values are energy coming in, positive going out.

If you have a current clamp and it is fitted the wrong way round then all sorts of weird stuff will happen. Similarly if it not put around the correct wire.

If you have a digital meter like the one linked above then you can use the arrows going round button on it to cycle through the readings until you get to 'W' for watts with no other letters shown. That shows the meter reading for power in or out of the property. Here, positive is drawing from the grid, negative is exporting.

Anyway, checking what you can about the inverter monitoring the energy flow might reveal something not quite right or help you understand what is going on.


Robin

 

[Bessy765]

For it to do what is supposed to do, the most important thing is that the inverter can monitor the flow of energy between your house and the grid. Your installer should have put in either a digital meter in your fuse box or a current clamp clipped around one of the wires from the main electricity meter.

Do you know which you have? The digital meter would look something like this. https://www.solartradesales.co.uk/Cache/Images/SDM230-MODBUS-1500x1500.jpg

If the inverter gets bad data from the digital meter or current clamp then it will likely misbehave. You can check the values it thinks it is getting on the inverter front panel. Scroll down to system status, press enter then down to meter/Ct then enter again. Negative values are energy coming in, positive going out.

If you have a current clamp and it is fitted the wrong way round then all sorts of weird stuff will happen. Similarly if it not put around the correct wire.

If you have a digital meter like the one linked above then you can use the arrows going round button on it to cycle through the readings until you get to 'W' for watts with no other letters shown. That shows the meter reading for power in or out of the property. Here, positive is drawing from the grid, negative is exporting.

Anyway, checking what you can about the inverter monitoring the energy flow might reveal something not quite right or help you understand what is going on.


Robin

As you can see the finesse of the installlation

 

[rwg]

Yes, that looks like a CT clamp on the brown wire. If the brown wire with the clamp on goes straight to the meter when you follow it (in the direction of the arrow on the clamp) upwards then the CT clamp is in the right place and the right way round I think.

The wiring from the clamp looks a bit iffy mind you...

If you can get to this screen on the inverter then you can test that the clamp is working as it should

This shows ours, with the power coming from the grid currently at 653 W (importing).

When the battery is flat, get to this screen, you will see (hopefully) the amount of power you are drawing from the grid as a negative number. Maybe -300W. Then turn the kettle on and go look again - it should change to maybe -2500W or even -3000W as it registers the power drawn by the kettle being imported from the grid. The value should change within a few seconds of the kettle going on and should go back again just as quickly once the kettle is turned off.

You should rarely see this number go far positive (as that would mean you are exporting power). The exceptions are

*) When the batteries are full and the solar panels are still generating
*) When the batteries are being charged at their maximum rate and the solar power exceeds this rate
*) For a few seconds at a time if the solar output or power used by the house changes - until the system regains balance
*) Small amounts (<100W) - the system may not activate the battery charger if there is only a small amount of excess power as trying to charge with 40W available might mean 30W gets used running the charger and 10W goes into the battery - not worth it.

Note that if the battery gets cold, it will not charge as fast as if it is warm, so if you get a lot of sunlight on a cold day and the battery is outside or in an unheated garage, it may not charge very fast. In fact, if the battery goes below freezing it will not charge at all, as charging below freezing can damage Lithium batteries.


cheers,

Robin

 

[Bessy765]

I will check that in the morning, thank you so much for your time it is most appreciated.four weeks on and I am still waiting for the paperwork. Not a problem at the moment as we have an existing small solar array on the roof of the house and get 60p a unit so will not be exporting the new system until the fit runs out in 11 years time.

to say the whole set up is poorly installed this is how the batteries are placed so much for a professional installation.

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[rwg]

Certainly a bit messy on the wiring front. Surely they could have managed a few clips to hold everything to the wall nice and tidy!

Our batteries are outside and have all the cables protected by corrugated plastic pipe (which is actually recommended in the Solax battery install guide).

I keep meaning to put together a bit of a shelter to keep the worst of the weather (and the leaves) off them. Expect I will get round to it by about springtime!

cheers,

Robin

 

[Bessy765]

Certainly a bit messy on the wiring front. Surely they could have managed a few clips to hold everything to the wall nice and tidy!

Our batteries are outside and have all the cables protected by corrugated plastic pipe (which is actually recommended in the Solax battery install guide).

View attachment 694310

I keep meaning to put together a bit of a shelter to keep the worst of the weather (and the leaves) off them. Expect I will get round to it by about springtime!

cheers,

Robin

Hi Robin got in touch via email with Steven Yang from Solax who has been most helpful. He has performed a software update and checked my inverter is working properly, he explained that there is a program in the inverter to prolong battery life by controlling the discharge of the battery during low temp this allows apparently loads of less than 200 w to be taken from the grid to slow the discharge, as I had queried this he nacelles it but I have asked him for the sequence to re enstate it myself.if you have a Solax inverter and need to contact him for any reason please supply your inverter serial number so he can assist. Again many thanks for your input Ted

 

[Ex-sparky.]

Thank you for all your inputs, yes there is a lack of explanations as stated as more get involved the expertise gets less.
having worked out some of the settings the min soc was set at 10% but at first when trying to raise it to 20% it said settings failed, the setting for charge from grid was also reading disabled but it was still doing it. So I tried entering the disable charge from Grid got the message setting success, so tried the min soc set to 20% got the message success so put it back to 10% see what happens in the morning. No sensible instructions came with it.

Hi I’ve got Solax a/c coupled inverter and 2x 5.8kw batteries installed, I’m on economy 7 so set my inverter on Force Time Use and charge the batteries at night on the cheap rate so start the day in winter on 100% that’s from 8am. On a good day I can get to 2am before they drop to 10% (my cheap rate starts at 1am). But even when the batteries are at 10% they won’t charge from the grid until the time I’ve set the inverter to tell them to charge it stays at 10% and pulls power from the grid to supply the house. At the time of posting this my night rate is 11p kWh and day rate 44p kWh

 

[Bessy765]

That’s a good set up, we are on a fixed deal fromScottish power at 17p per unit which runs until end of Feb then will see if there is a deal like you have.

 

[Ex-sparky.]

I’m with Scottish power, my fixed deal ended August 31, the rate I’m on is standard variable the only fixed rate they would offer me was paying £506 a month. Although the battery set up should have reduced that amount through the summer.

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