Advice appreciated on re-doing our home system with EG4 products

[OffGridBC]

My husband and I are fairly new to solar - we have had our system for about 18 months. We purchased everything through an off-grid company in Canada but have had consistent issues and in doing our own research realized the components they sold us don't work properly together. We have already purchased a replacement inverter and generator and have recently been told we need new controllers as well. We have lead acid batteries that we want to switch out with Lithium, so we’re basically redoing everything. I have been looking at EG4 products and would love advice on the best way to go so that we get a system that works well without having to continually buy more components. Thank you in advance for your feedback.

Solar Panels we have: 16 panels 450 watts each (7200 W total) - specs are attached. We are going to re-wire into two strings of 8 panels each.

Batteries: Looking to buy six 48v 100AH EG4-LifePower4 battery kit (30 kWh) - https://signaturesolar.com/eg4-life...enclosed-rack-with-door-wheels-busbar-covers/ OR six EG4 LL-S batteries

Current inverter: AIMS 12KW 120/240 split phase - https://www.aimscorp.net/product/12...split-phase-output-etl-listed-to-ul-1741-csa/


Options for the remaining components to purchase:

Option 1. Keep current inverter and get 2 EG4 charge controllers - https://signaturesolar.com/eg4-solar-charge-controller-mppt-500voc-100a-mppt100-48hv/ - each connected to a string of 8 panels

Option 2. Replace inverter and controllers with two EG4 6000XP Inverters (https://signaturesolar.com/eg4-6000xp-off-grid-inverter-split-phase/)

Options 3. Replace inverter and controllers with one EG4 12KPV inverter https://signaturesolar.com/eg4-12kp...in-one-hybrid-solar-inverter/?_hsmi=315974474


Questions that come to mind are:

1. Any feedback from others who have experience with EG4 products? I have seen some good and bad reviews regarding tech support.

2. Any significant difference between EG4-LifePower4 batteries vs EG4 LL-S batteries?

3. EG4 inverters/controllers say a combiner box is not required - is that true?

4. Option 1 would be the least cost and allow us to keep a newer inverter we have already paid for, but not sure how compatible EG4 products are with it or if better to get all same brand? Also, our current AIMS inverter idle consumption is 200 kWh which is a lot compared to EG4’s (50 kWh) and it doesn’t allow manual settings (you select type of battery and that’s it). Positives are they have good tech support and inverter seems to be working well.

5. We are in Canada and have to charge batteries with a generator almost daily in winter. We have a 14 KW generator. With option 1 the inverters max charge current is 125Amps (6000W). If we charge when the batteries get to about 20% then if my math is correct it would take 4 hrs to charge the batteries to full (24 kW / 6000 kWh charge = 4 hrs)? If we went with option 2 or 3 we can charge faster (8000kWh with EG4 12KPV or 2X Faster with two EG4 6000XP inverters - 12000kWh). That is appealing as it would save running the propane generator extra time.

6. I want to make sure the wiring we have buried in the ground will work with any of the above options as our system currently trips breakers. Our solar panels and backup generator are approx 75 to 100 feet from the house where the batteries and controllers/inverter are. The electrician used #6 wire from panels to controllers, and #4 wire to connect inverter to generator. If we put 8 panels in a string, according to the specs it will be 11.6 amps and 394.4 volts to each MPPT so I understand that should work with both the EG4 controllers or inverters, and should also be no problem with the 6 AWG wire - is that correct?

Also, I am not sure about the #4 wire connecting the inverter to generator. Is this equation correct? Generator sends 14KW to inverter (6000 Watts for battery charge and rest for domestic use) / 240 volts = 58.3 amps in which case #4 wire should be okay?

Then for wire from inverter to batteries: 6000 Watts / 48 volts = 125 amps. If upgrade inverter to two 6000 XP’s it would double to 250 amps? What wire size can handle that?

Currently when we start the generator manually it runs no problem and the inverter shuts it down when the batteries are charged, but when we set the generator to automatically come on when the batteries get low it will stay on for 10 to 20 minutes then quit, and keep starting and stopping, so we’re not sure if that’s an inverter issue, or #4 wire isn’t big enough to handle the amps (though seems implausible if it runs fine manually), or a loose connection with the auto start.


I’m not sure I am thinking of all the angles and options so am open to any advice and suggestions. I know this is a lot of info but I want to make sure to get components that will work together well and last a while this time.

Thank you kindly

 

[EG4TechSolutionsTeam]

Option 2. Replace inverter and controllers with two EG4 6000XP Inverters (https://signaturesolar.com/eg4-6000xp-off-grid-inverter-split-phase/)

If you are looking to upgrade, we would recommend going with option 2. Having 2-6000XP will give you more power overall. The only thing about this would be that there are some features that the 12kpv has that the 6000XP doesn't have. For example, selling back to grid is only with 12kpv and 18kpv.

2. Any significant difference between EG4-LifePower4 batteries vs EG4 LL-S batteries?

The difference between Lifepower4 and the LL-S batteries is that the LL-S batteries have RSD (Rapid Shut Down), the BMS has more protocols available, and the DIP switches are 6 instead of 4 allowing up to 64 batteries to be connected together.

3. EG4 inverters/controllers say a combiner box is not required - is that true?

A combiner box would be recommended when combining 3 or more solar panel strings.

 

[HalfBaked]

I have been looking at EG4 products and would love advice on the best way to go so that we get a system that works well without having to continually buy more components.

I would look into brand reliability first.

 

[Brucey]

Keep the AIMS. If you are truly off grid then you won't be able to wait endless weeks or months for the Eg4/Signature Solar RMA process to replace a non functional AIO or charge controller.

 

[seneysolar]

Keep the Aims unit! That's a solid off grid LF inverter.

A chargeverter can speed up generator charging if thats all you want from 2 eg4 inverters.

Idle consumption of 2 - 6000xp inverters is significant too
Idle consumption post

 

[seneysolar]

My husband and I are fairly new to solar - we have had our system for about 18 months. We purchased everything through an off-grid company in Canada but have had consistent issues and in doing our own research realized the components they sold us don't work properly together. We have already purchased a replacement inverter and generator and have recently been told we need new controllers as well. We have lead acid batteries that we want to switch out with Lithium, so we’re basically redoing everything. I have been looking at EG4 products and would love advice on the best way to go so that we get a system that works well without having to continually buy more components. Thank you in advance for your feedback.

Solar Panels we have: 16 panels 450 watts each (7200 W total) - specs are attached. We are going to re-wire into two strings of 8 panels each.

Batteries: Looking to buy six 48v 100AH EG4-LifePower4 battery kit (30 kWh) - https://signaturesolar.com/eg4-life...enclosed-rack-with-door-wheels-busbar-covers/ OR six EG4 LL-S batteries

Current inverter: AIMS 12KW 120/240 split phase - https://www.aimscorp.net/product/12...split-phase-output-etl-listed-to-ul-1741-csa/


Options for the remaining components to purchase:

Option 1. Keep current inverter and get 2 EG4 charge controllers - https://signaturesolar.com/eg4-solar-charge-controller-mppt-500voc-100a-mppt100-48hv/ - each connected to a string of 8 panels

Option 2. Replace inverter and controllers with two EG4 6000XP Inverters (https://signaturesolar.com/eg4-6000xp-off-grid-inverter-split-phase/)

Options 3. Replace inverter and controllers with one EG4 12KPV inverter https://signaturesolar.com/eg4-12kp...in-one-hybrid-solar-inverter/?_hsmi=315974474


Questions that come to mind are:

1. Any feedback from others who have experience with EG4 products? I have seen some good and bad reviews regarding tech support.

2. Any significant difference between EG4-LifePower4 batteries vs EG4 LL-S batteries?

3. EG4 inverters/controllers say a combiner box is not required - is that true?

4. Option 1 would be the least cost and allow us to keep a newer inverter we have already paid for, but not sure how compatible EG4 products are with it or if better to get all same brand? Also, our current AIMS inverter idle consumption is 200 kWh which is a lot compared to EG4’s (50 kWh) and it doesn’t allow manual settings (you select type of battery and that’s it). Positives are they have good tech support and inverter seems to be working well.

5. We are in Canada and have to charge batteries with a generator almost daily in winter. We have a 14 KW generator. With option 1 the inverters max charge current is 125Amps (6000W). If we charge when the batteries get to about 20% then if my math is correct it would take 4 hrs to charge the batteries to full (24 kW / 6000 kWh charge = 4 hrs)? If we went with option 2 or 3 we can charge faster (8000kWh with EG4 12KPV or 2X Faster with two EG4 6000XP inverters - 12000kWh). That is appealing as it would save running the propane generator extra time.

6. I want to make sure the wiring we have buried in the ground will work with any of the above options as our system currently trips breakers. Our solar panels and backup generator are approx 75 to 100 feet from the house where the batteries and controllers/inverter are. The electrician used #6 wire from panels to controllers, and #4 wire to connect inverter to generator. If we put 8 panels in a string, according to the specs it will be 11.6 amps and 394.4 volts to each MPPT so I understand that should work with both the EG4 controllers or inverters, and should also be no problem with the 6 AWG wire - is that correct?

Also, I am not sure about the #4 wire connecting the inverter to generator. Is this equation correct? Generator sends 14KW to inverter (6000 Watts for battery charge and rest for domestic use) / 240 volts = 58.3 amps in which case #4 wire should be okay?

Then for wire from inverter to batteries: 6000 Watts / 48 volts = 125 amps. If upgrade inverter to two 6000 XP’s it would double to 250 amps? What wire size can handle that?

Currently when we start the generator manually it runs no problem and the inverter shuts it down when the batteries are charged, but when we set the generator to automatically come on when the batteries get low it will stay on for 10 to 20 minutes then quit, and keep starting and stopping, so we’re not sure if that’s an inverter issue, or #4 wire isn’t big enough to handle the amps (though seems implausible if it runs fine manually), or a loose connection with the auto start.


I’m not sure I am thinking of all the angles and options so am open to any advice and suggestions. I know this is a lot of info but I want to make sure to get components that will work together well and last a while this time.

Thank you kindly

What charge controller do you currently have?

 

[OffGridBC]

Wow thank you all for your replies - much appreciated.

Keep the AIMS. If you are truly off grid then you won't be able to wait endless weeks or months for the Eg4/Signature Solar RMA process to replace a non functional AIO or charge controller.

We are fully off-grid and also have a home business so definitely don't want to be waiting for power if a component goes offline. I'm glad to hear from multiple people that AIMS is a good product. It has worked well for us so far and tech support has been great.

What charge controller do you currently have?

We have two AIMS 100 amp controllers (8 panels going into each). A few months ago I posted a thread about an issue with the breakers tripping in our combiner box between the panels and controllers. The AIMS controllers have a max PV voltage of 150 Vdc. Our panels are rated at 49.3 Voc/V. If we put 3 in a string we're right at the max voltage without allowing extra for cold (we can get to -30 C in winter) so we currently have our 16 panels wired in strings of 2 then parallel in two separate groups of 8 panels total (2s4p). So the amps are high and surge beyond the panels specs in certain situations (when it rains on the panels then gets sunny, or fluctuates between sun & cloud) which is likely why breakers are tripping. AIMS said rewiring to 3s3p into each controller should be okay but that worries me with the voltage so close to the controller max. They also said the breakers tripping could be because we have the breakers in a single combiner box - suggested to have a separate combiner for each set of 8 panels. In the other thread it was recommended to get higher voltage charge controllers and rewire array to 8 panels in a string into each controller, OR 8s2p with one controller, as it would likely be cheaper and easier than getting new combiners/breakers. So that's why I was looking at the EG4 controllers which would also eliminate the combiner box. I would appreciate any feedback on a recommended solution / configuration / controller?

Keep the Aims unit! That's a solid off grid LF inverter.

A chargeverter can speed up generator charging if thats all you want from 2 eg4 inverters.

Idle consumption of 2 - 6000xp inverters is significant too
Idle consumption post

Good to know! I have not heard of a chargeverter. I googled it and see the EG4 chargeverter. Our current inverter max charge is 6000W. The EG4 chargeverter says 5120W output. So that's less, unless I am misunderstanding how it works. Our backup generator is 14KW so if there is a way to use more watts from the generator to charge the batteries faster that would be of interest (but not a necessity).

Thanks again!

 

[LydMekk]

Easy. Buy and use 2 x Chargeverters in parallel. I do this but from the grid as a source and not a genny but it is the same use case.
Running 2 can max pull around 10000w/5k per. so still under your gennys max of 14k.
You set up each of the Chargeverters to your max wanted amps per box. I am running mine with 80% per CV. I like to keep them below rated max ^^.
Have had mine running for a year - works perfectly. Now in summer I have enough PV though so they are turned off in the summer months but gets used again in the fall and all winter.

 

[OffGridBC]

Easy. Buy and use 2 x Chargeverters in parallel. I do this but from the grid as a source and not a genny but it is the same use case.
Running 2 can max pull around 10000w/5k per. so still under your gennys max of 14k.
You set up each of the Chargeverters to your max wanted amps per box. I am running mine with 80% per CV. I like to keep them below rated max ^^.
Have had mine running for a year - works perfectly. Now in summer I have enough PV though so they are turned off in the summer months but gets used again in the fall and all winter.

Very interesting. So much I don't know about off grid. I will look into how to set them up in parallel. If I understand correctly, they are hooked up directly from generator to batteries, not through the inverter? If so, does the inverter still provide power for household use from the batteries while they are charging with the chargeverters? Can they be set to auto start/stop the generator when the batteries are low/re-charged or is it done manually? I watched a video about the EG4 chargeverter - the guy said he uses a small genny (3000W) and it still charges the full 5000W through the chargeverter? I had a 7KW portable genny but that only left 1000W max for domestic operations when charging the batteries through the inverter so we got the 14KW Kohler. It's definitely a high quality reliable generator, but does that mean instead of getting the bigger genny we could have done the 2X chargeverters and gotten more power out of the previous generator?

 

[LydMekk]

Yes, parallel so the inverter will pull from the batteries and run your house and the Chargeverters will charge the batteries at the same time.
Several people in here does this without issues using Chargeverters.

 

[seneysolar]

You can use just 1 chargeverter parallel with the inverter charger. It will supplement the Aims charger when generator runs. Keeping the Aims unit wired like you have it now for its built-in charger.

For the AGS issue, the Magnum stand alone AGS is great. Its very simple installation and it just works. Worth a look. The built in AGS in the Aims inverters are lacking.

Id look at going 4S2P with your panels and use 2 Midnite Classic 250 charge controllers. Regardless the breaker size remains the same for each single string. That problem may persist until you upsize 5A

 

[OffGridBC]

You can use just 1 chargeverter parallel with the inverter charger. It will supplement the Aims charger when generator runs. Keeping the Aims unit wired like you have it now for its built-in charger.

For the AGS issue, the Magnum stand alone AGS is great. Its very simple installation and it just works. Worth a look. The built in AGS in the Aims inverters are lacking.

Id look at going 4S2P with your panels and use 2 Midnite Classic 250 charge controllers. Regardless the breaker size remains the same for each single string. That problem may persist until you upsize 5A

Thank you for suggestions, much appreciated. I looked at the chargeverter and Magnum AGS - both look like great options. Re charging batteries through an inverter vs chargeverter - I saw a couple YouTube videos that said it is it better to charge with the chargeverter because inverters can crash due to charging with generators because it's not a clean energy? I think the backup Kohler generators are a lot better that way vs portable generators but I thought I would ask anyway (if better to parallel 2 chargeverters direct from generator or use one paralleled with the Aims inverter as you suggest).

Sorry, not sure what you mean by "that problem may persist until you upsize 5A"

With the Midnite charge controllers, they should work with the AIMS inverter? It looks like I still need the combiner box with those. Any thoughts on comparison to the EG4 controller? Less cost is appealing to me with having already bought charge controllers that are basically new but need replacing. But I do want to get something that works well and will last a while, and internet monitoring is a plus.

 

[OffGridBC]

Any feedback on EG4 batteries or if there are other suggested lithium batteries to look at? Also EG4-LifePower4 vs EG4 LL-S?

 

[seneysolar]

Thank you for suggestions, much appreciated. I looked at the chargeverter and Magnum AGS - both look like great options. Re charging batteries through an inverter vs chargeverter - I saw a couple YouTube videos that said it is it better to charge with the chargeverter because inverters can crash due to charging with generators because it's not a clean energy?

Some inverters won't accept generator input if the voltage or frequency is out of spec. Aims inverter chargers are some of the most tolerant I've seen and obviously its currently working for you.
On the other hand EG4 inverters are very picky, so much that EG4 developed the chargeverter to operate with generators.

I think the backup Kohler generators are a lot better that way vs portable generators but I thought I would ask anyway (if better to parallel 2 chargeverters direct from generator or use one paralleled with the Aims inverter as you suggest).

I would just supplement with one.

Sorry, not sure what you mean by "that problem may persist until you upsize 5A"

If the string is 2 panels or 8 panels the string breaker is the same size. Your panel should spec a max breaker size per series string. Perhaps 20A?

With the Midnite charge controllers, they should work with the AIMS inverter?

Yes, any charge controller will work, the inverter has no say.

It looks like I still need the combiner box with those.

Don't you already have a combiner box? How are you currently combining strings? Id recommend Midnite for those while using their PV breakers, good quality.

Any thoughts on comparison to the EG4 controller? Less cost is appealing to me with having already bought charge controllers that are basically new but need replacing.

Yes the panel choice for the charge controller was not well planned. When buying panels, I look for VOC to be around 40V instead of 50V, this way I can do stings of 3 safely vs. 2 as you found out.

I haven't used the EG4 charge controllers, the price is certainly attractive.

Midnite, Victron and Morningstar are the go-to charge controllers for higher voltage inputs. They have been around for years with proven reliability.

But I do want to get something that works well and will last a while, and internet monitoring is a plus.

I can't comment on internet monitoring, not my forte.

 

[seneysolar]

Any feedback on EG4 batteries or if there are other suggested lithium batteries to look at? Also EG4-LifePower4 vs EG4 LL-S?

What are your current batteries? Just curious.

Will your new LFP batteries be kept warm? (above freezing)

 

[Brucey]

Any feedback on EG4 batteries or if there are other suggested lithium batteries to look at? Also EG4-LifePower4 vs EG4 LL-S?

The eg4 rack mounts tend to have problems with cell balancing. Not sure if that applies to their wall mounts. Midnite are apparently going to be releasing both a 5 kWh rack mount and a 16kwh wall mount in August so if you can wait till then that would prob be a good way to go. Other affoptions are SOK and Ruixi

 

[OffGridBC]

The eg4 rack mounts tend to have problems with cell balancing. Not sure if that applies to their wall mounts. Midnite are apparently going to be releasing both a 5 kWh rack mount and a 16kwh wall mount in August so if you can wait till then that would prob be a good way to go. Other affoptions are SOK and Ruixi

Okay great, thank you!

 

[OffGridBC]

What are your current batteries? Just curious.

Will your new LFP batteries be kept warm? (above freezing)

Currently lead acid. I think they have consistently been undercharged no matter with us adjusting the settings - they have been going down fairly quick. Want to get lithium. All equipment is kept warm, indoors.

 

[Hedges]

EG4 has PowerPro batteries, which are based on 280 Ah so 14kWh each. Might be better than larger number of 100 Ah 5kWh batteries.

Midnight will have batteries of both sizes, I think.

Communications with battery can allow for better cell balancing (slow down charge to let BMS do its work). If sticking with your existing inverter, that may not have communications. See if you can get charge controller and battery that play together.

Exactly what batteries do you have at the moment? Some lead-acid can be very long life (forklift, Rolls Surette). Some can be low maintenance (AGM.)
They don't charge as fast as lithium, and consume some amount of power. But maybe what you've got now will serve your needs if charged properly and not over-discharged.

You have 7200W (STC) of PV now. What does an insolation calculator say they should produce?
What is your consumption?
You may need more PV, or energy conservation.

 

[dougbert]

what one can do with chargeverters

(I have 2 myself that I can use on GRID or on generator - with 50 amp inlet)

and if you really need charging this video shows a large application

and just an hour old from EG4 a nice information tutorial and background info

 

[OffGridBC]

Some inverters won't accept generator input if the voltage or frequency is out of spec. Aims inverter chargers are some of the most tolerant I've seen and obviously its currently working for you.
On the other hand EG4 inverters are very picky, so much that EG4 developed the chargeverter to operate with generators.

I would just supplement with one.

Great!

If the string is 2 panels or 8 panels the string breaker is the same size. Your panel should spec a max breaker size per series string. Perhaps 20A?

Yep panel specs say 20A fuse.

Don't you already have a combiner box? How are you currently combining strings? Id recommend Midnite for those while using their PV breakers, good quality.

Yes the panel choice for the charge controller was not well planned. When buying panels, I look for VOC to be around 40V instead of 50V, this way I can do stings of 3 safely vs. 2 as you found out.

Yes unfortunate choice for controllers. At the time we were starting to build a new house and didn't know anything about off-grid solar so we gave all our usage/house info to an off-grid company and trusted what they put together. Turned out to be a disaster and had to re-buy most components because the specs weren't meant to work together and they wouldn't return our original purchases. So I have been doing a lot of research to learn the math myself and try to figure out how to get stuff working together properly.

We have a combiner box. Because the controllers can't handle more than 2 panels/string we currently have it set up 2s4p going into each controller (16 panels total - 2 sets of 8). The panel ratings are 11.6 Isc/A and 49.3 VOC. So if my math is correct it's 46.4 amps and 98.6 volts from each 2s4p PV set to each controller. I saw in another post someone said the Isc amps should be multiplied by 1.5 to allow for surges and such. So 11.60 x 1.5 = 17.4 amps x 4 = 69.6 amps. I have been watching specs on our controllers and a few times this spring I saw the amps showing around 69A and wattage higher than our panel specs state so it definitely surges. In the combiner box it's currently set up with each set of 8 panels going into a breaker (so just 2 breakers in the box). Originally that's how we were told to set it up but recently AIMS said to have a separate combiner box inbetween each set of panels/controllers. I also read somewhere that when you combine 3 or more strings, each string must have its own fuse or circuit breaker and then the combined output will also need a larger circuit breaker. Since we have 4 strings in each set of 8 panels, there would be 2 sets of 4 fuses or breakers, with each set then combined into one large breaker. Our combiner box isn't large enough for that, so I was originally looking at getting new combiner boxes and fuses/breakers but then someone suggested getting new controllers and re-wiring the panels might be less costly. So I have been looking at different options. The other consideration is that the electrician used a #6 wire from the panels to controllers. It goes about 75 to 100 feet in the ground so we don't want to have to dig it up. He said it's big enough for the amps but he was looking at the 46.4 amp rating and not adding 50% for surges, so I'm not sure the wire is big enough for the current amps, so it's another potential reason to re-wire the panels to get the amps down but would need higher voltage controllers. Ugh.

I haven't used the EG4 charge controllers, the price is certainly attractive.

Midnite, Victron and Morningstar are the go-to charge controllers for higher voltage inputs. They have been around for years with proven reliability.

I can't comment on internet monitoring, not my forte.

Great thank you. I will look into all those.

 

[OffGridBC]

what one can do with chargeverters (I have 2 myself that I can use on GRID or on generator - with 50 amp inlet)

and just an hour old

Great, thank you. Will check those out.

 

[OffGridBC]

EG4 has PowerPro batteries, which are based on 280 Ah so 14kWh each. Might be better than larger number of 100 Ah 5kWh batteries.

Midnight will have batteries of both sizes, I think.

Communications with battery can allow for better cell balancing (slow down charge to let BMS do its work). If sticking with your existing inverter, that may not have communications. See if you can get charge controller and battery that play together.

Exactly what batteries do you have at the moment? Some lead-acid can be very long life (forklift, Rolls Surette). Some can be low maintenance (AGM.)
They don't charge as fast as lithium, and consume some amount of power. But maybe what you've got now will serve your needs if charged properly and not over-discharged.

You have 7200W (STC) of PV now. What does an insolation calculator say they should produce?
What is your consumption?
You may need more PV, or energy conservation.

Okay thanks will look into the EG4 PowerPro and Midnight.

Current batteries are Rolls open lead acid (890 ah). I should have clarified - when I said they are going down quick I meant the battery life. When they get a full charge on a fully sunny day, when the PV stops generating for the day the batteries are only about 70% charged. And with lead acid we're only supposed to use to 50% so it's a small window. The capacity has been going down consistently. I think they are sulfated. I have been in lots of communication with the battery manufacturer and controller/inverter manufacturer. It could be a combo of things - we originally ordered the system when we started building the house but things got delayed so batteries sat longer than expected, then got the system set up in middle of winter and got no sun for months so we charged a lot with a generator and the generator we were originally sold with the solar package was undercharging the batteries. Battery manufacturer gave us recommendations to change settings on the controllers/inverter to try to get the battery capacity back up but it didn't work. They say the AIMS equipment consistently undercharges but AIMS warned changing the settings from their default could affect the batteries worse which it seems to have done. So we're chalking it up to a learning experience and switching to lithium.

Summer energy consumption is between 10 to 15 KW per day. We have a 12KW inverter and it generally shows using 3-4% unless something like the well pump or microwave comes on which uses a lot for a short period. In winter we use more - between 15-20kWh.

 

[seneysolar]

Great!

Yep panel specs say 20A fuse.

Per string.
You currently have 4 strings per mppt correct? So you have 4- 20A breakers?

Yes unfortunate choice for controllers. At the time we were starting to build a new house and didn't know anything about off-grid solar so we gave all our usage/house info to an off-grid company and trusted what they put together. Turned out to be a disaster and had to re-buy most components because the specs weren't meant to work together and they wouldn't return our original purchases. So I have been doing a lot of research to learn the math myself and try to figure out how to get stuff working together properly.

We have a combiner box. Because the controllers can't handle more than 2 panels/string we currently have it set up 2s4p going into each controller (16 panels total - 2 sets of 8). The panel ratings are 11.6 Isc/A and 49.3 VOC. So if my math is correct it's 46.4 amps and 98.6 volts from each 2s4p PV set to each controller. I saw in another post someone said the Isc amps should be multiplied by 1.5 to allow for surges and such.

Thats why the 20A breaker per string.

I have been watching specs on our controllers and a few times this spring I saw the amps showing around 69A

Input or output of the controller?

and wattage higher than our panel specs state so it definitely surges. In the combiner box it's currently set up with each set of 8 panels going into a breaker (so just 2 breakers in the box). Originally that's how we were told to set it up but recently AIMS said to have a separate combiner box inbetween each set of panels/controllers.

Yes

I also read somewhere that when you combine 3 or more strings, each string must have its own fuse or circuit breaker

Yes

and then the combined output will also need a larger circuit breaker.

I would

Since we have 4 strings in each set of 8 panels, there would be 2 sets of 4 fuses or breakers, with each set then combined into one large breaker.

The larger breaker can be near the controller. The combiner should be at the array.

Our combiner box isn't large enough for that, so I was originally looking at getting new combiner boxes and fuses/breakers but then someone suggested getting new controllers and re-wiring the panels might be less costly. So I have been looking at different options.

2 of the Midnite MNPV6 would be what you want if buying new. Post a pic of your current combiner box.

The other consideration is that the electrician used a #6 wire from the panels to controllers. It goes about 75 to 100 feet in the ground so we don't want to have to dig it up. He said it's big enough for the amps but he was looking at the 46.4 amp rating and not adding 50% for surges, so I'm not sure the wire is big enough for the current amps, so it's another potential reason to re-wire the panels to get the amps down but would need higher voltage controllers. Ugh.

Should be useable, 6awg UF wire for example is rated for 55a continuous. Any surge over will be short lived.

 

[Hedges]

7kW (STC) of PV in summer ought to supply at least the ~ 21kW of PV needed to cover 15kW consumption and 70% round-trip efficiency. Charging takes hours of bulk at 0.12C and a couple hours absorption. If not fully charged, maybe voltage (or current) settings not correct. Or power harvesting way below the expected 5kW +/- from those panels.

Possibly cells need equalization. What voltage per cell (or per 6V or whatever is accessible to measure)?
What specific gravity per cell?

Winter you might get only 2 hours effective sun, depending on exposure and angle. I'd think panels sloped to maximize winter is what's needed.

(at least some) Rolls batteries are super-premium quality and expensive, could give 20 years service.
Try to fully charge, as a pack or as individual batteries, test specific gravity, equalize as required.

You're from the frozen north. Lead acid works there, so long as not left discharged to freeze. Lithium works (except in extreme cold) but has to be above freezing. Near freezing charge rate can be 0.05C to 0.15C, comfortable temperature can be 0.5C maybe higher.