HI everyone.

Please bear with me on this, fairly new to the whole solar and backup thing.

I have included images of all the inverter specs, the battery specs and also the WatchPower settings for reference.

Just after lockdown, we purchased this Mecer 3KVa inverter. It has 200AH of back (So they say...) from the 2 included 24V 100AH Lithium batteries.

So due to all the constant outages we have in our area lately, we decided to put up 2 LARGE solar panels. This was done 1st of April this year.

The panels we put in are 2 x TigerNeo 72HL4-BDV 585W solar panels on the roof facing east... It was summer! Yes, I know...

This is all working perfectly, but now a few little issues I have with this whole setup.

Unfortunately, this WatchPower software is all that you can apparently use with this inverter, unless you spend copious amounts on money for that Solar Assistant software. Not happening from my wallet unfortunately...

I have this software installed and running on a little Pi that I had spare here with Windows 10 on so I can remote into it and see what's going on.

I have just taken a screen shot of it which is below and this winter sun is just not the greatest right now.

The settings are the big thing.

Are we just extremely limited to what this inverter can do or how can I set it to keep the batteries as close to full as possible, especially in winter?

Reason is that 90% of the time when the power cuts, it will be late afternoon or at night and the batteries are just never full and then the system cuts off because of that!

It's so annoying and yes, this has been the case for the past 4 outages we had over the past 3 weeks. Then the sun just isn't enough to keep things running the next day and charge the battery...

So (sorry for the long story...) my questions...

1) is there anything I maybe need to tweak in the settings there to get better performance from the batteries?

2) How do I know what voltage the inverter cuts off at and what should it be and how do I set it?

3) Any other free alternatives to this WatchPower software?

Thanks in advance for the help.🙏

Layman's 2c, use at own risk, or get advice. Some points to consider all the same.

You've got an inverter with a 1200W PWM charge controller. In Winter that's just not quite enough to keep the battery charged. On average, touch and go, under the best of conditions in Winter, it's just-just sort of okay, but most of the time not, and if you're intending to run daytime loads from it as well, then you just don't have enough power generation capability. On top of that your setup is likely not optimal to begin with.

I'm assuming that your 2 x panels are connected in parallel, or it would have exceeded the inverter's max VOC and caused a failure. If this is not already in parallel, you really should change it over to parallel. But your panel's Vmp isn't ideally matched to the inverter. Better would have been to use a panel like the Canadian Solar HiKU6 CS6W405MS panel (x3), because the Vmp spec is better aligned with the battery charging Voltage. Unfortunately you've got a 25% loss of efficiency with the current panel right out the gate.

You could lower the discharge cut-off Voltage to 20V (spec as per the battery), ie. discharge it deeper than the inverter is doing now. And then I think you should change from SBU mode to utility mode, ie. just keep the battery and panels on-hand as a loadshedding solution, without trying to power the whole house from it permanently.

You'd have to do a more drastic upgrade, like changing to a 24V MPPT-controlled inverter, and adding maybe another two panels, before you can start thinking of running daytime base load and then still charging the battery by day for draining at night.

Thanks for this. Yes, panels were all installed to spec by the solar specialists. They also recommended we go with those 2 panels due to the space on the roof. Limited there unfortunately.

But I see the battery spec or sticker says it can go down to cut-off at 20V, but how do I know if the inverter is cutting of at 21 or 22V?
I have a feeling the inverter is shutting off around 24V.
Maybe a safety net or something that the GeeWiz guys reconfigure in the inverter?

Can this be checked and changed somehow?

43 minutes ago, GreenFields said:

Layman's 2c, use at own risk, or get advice. Some points to consider all the same.

You've got an inverter with a 1200W PWM charge controller. In Winter that's just not quite enough to keep the battery charged. On average, touch and go, under the best of conditions in Winter, it's just-just sort of okay, but most of the time not, and if you're intending to run daytime loads from it as well, then you just don't have enough power generation capability. On top of that your setup is likely not optimal to begin with.

I'm assuming that your 2 x panels are connected in parallel, or it would have exceeded the inverter's max VOC and caused a failure. If this is not already in parallel, you really should change it over to parallel. But your panel's Vmp isn't ideally matched to the inverter. Better would have been to use a panel like the Canadian Solar HiKU6 CS6W405MS panel (x3), because the Vmp spec is better aligned with the battery charging Voltage. Unfortunately you've got a 25% loss of efficiency with the current panel right out the gate.

You could lower the discharge cut-off Voltage to 20V (spec as per the battery), ie. discharge it deeper than the inverter is doing now. And then I think you should change from SBU mode to utility mode, ie. just keep the battery and panels on-hand as a loadshedding solution, without trying to power the whole house from it permanently.

You'd have to do a more drastic upgrade, like changing to a 24V MPPT-controlled inverter, and adding maybe another two panels, before you can start thinking of running daytime base load and then still charging the battery by day for draining at night.

He is limited by space it seems. He could have added a 3rd panel to that inverter but he is now limited by the space.

Sounds like his inverter is set to cut off too low. And he also needs to manage expectations. If running a large TV and a few other things those batteries just wont last at night.

23 minutes ago, Deanos said:

Thanks for this. Yes, panels were all installed to spec by the solar specialists. They also recommended we go with those 2 panels due to the space on the roof. Limited there unfortunately.

But I see the battery spec or sticker says it can go down to cut-off at 20V, but how do I know if the inverter is cutting of at 21 or 22V?
I have a feeling the inverter is shutting off around 24V.
Maybe a safety net or something that the GeeWiz guys reconfigure in the inverter?

Can this be checked and changed somehow?

You can check any setting by a long press of the enter button on the unit. Use the up and down buttons to get to the desired setting. Setting 29 is to get the DC cut out voltage level. Use up and down buttons to change the setting and the enter will save the setting displayed.

@GreenFields the APP settings show 26.6V from panels so luckily the 2 panels are connected in parallel but that makes the system not very efficient as you alerted to.

Edited 5 hours ago5 hr by Scorp007

1 hour ago, Deanos said:

Thanks for this. Yes, panels were all installed to spec by the solar specialists. They also recommended we go with those 2 panels due to the space on the roof. Limited there unfortunately.

Can you please elaborate on your roof size and layout - it is quite strange to hear of any roof that can only accommodate two solar panels... Don't you also have a roof facing west (or a carport of something facing north...) where you can install another two panels?

Also, you mention that you have two 100Ah lithium batteries installed. Lithium batteries don't like to be drained deeply, and if your system was installed just after covid lockdown then they are already about 6 years old. This would not be a problem if they were only lightly discharges, but if they were regularly discharged deeply then their capacity could already have reduced enough to become troublesome.

1 hour ago, Scorp007 said:

the 2 panels are connected in parallel but that makes the system not very efficient as you alerted to.

Thanks for the help. But should the panel be connected a different way to be more efficient then?

17 minutes ago, HennieL said:

Can you please elaborate on your roof size and layout

Sorry, not the best image, but a shot from Google earth.
I circled the 2 panels and North.

Problem is that this section of our roof gets the most sun during the day in summer as the rest of the roof is mostly in shade mornings and afternoon.

I did want to cut down every tree, but the bigger ones are neighbours trees mornings and afternoon, so that wouldn't happen.

We looked at every option, this was the best and most efficient.

3 hours ago, Deanos said:

Sorry, not the best image, but a shot from Google earth.
I circled the 2 panels and North.

Thanks, this helps us to understand your situation.

It's difficult to make out much detail on the photo, but it looks like the panels are on the eastern roof that is actually sloping down to the west, with an east facing roof to the left of the panels... Can you please confirm if this is the case?

Something else to check is the slope of the panels (degrees from vertical) - those panels appear to be quite flat (horisontal), and with the winter sun being much lower in the sky that would explain why your summer yield was OK but the winter yield is much less. Would it be possible to raise the angle of the panels? If you care to tell us where your house is located (town) we can easily calculate the optimum slope for summer, winter, or all-year yield for you.

3 hours ago, Deanos said:

looked at every option

Add two more panels on the eastern side of the smaller roofs, try vertical panels, drill holes in the trees and pour in diesel... Lots of options.

4 hours ago, Deanos said:

Thanks for the help. But should the panel be connected a different way to be more efficient then?

This issue cannot be resolved with a connection or a setting. It is a characteristic of the panel that is not optimal for the inverter's charger type.

Also, considering that the house is already facing around 20 degrees East, those panels are actually facing a bit towards South-East, further reducing the generation capacity. Would there be too many shadows if you fit them to the main roof facing North-East?

Unfortunately you've got a complex situation with possibly no easy solutions.