Denns

Zero complaints my side. Hitting almost 2 years with mine with zero issues.

Very nice! My saving this year will be 36000 rand. Will be paying off my system next year in June. A bit over 2 years payback.

Not a bad idea at all!

His batteries are in parallel already. If he runs the comms from one inverter to the batteries I just don’t know if it will cause issues having another inverter connected to the same bank without comms. If he removes the comms between inverter and batter and lets both not have communications to the battery bank that definitely works. If he wants to keep comms. Then yeah, split the battery bank in 2

I disagree on the second point. I have used 2 devices (MPPT and inverter) to simultaneously charge the same bank for a time now. The only way you will overcharge is if your charging current is set higher than what the batteries can handle. set both so that the sum of both don’t exceed the max charging current of the entire bank. No competition will occur. You can have a 100 charge controllers on a bank and as long as the current total is within the battery spec it is perfectly fine.

Yes but he is not paralleling the inverters. The only thing they will share is the battery bank.

Maybe some of the forum members can explain if you can do comms with 2 inverters to the same battery bank. I am unsure as haven’t done that myself. And yes, your second inverter would also charge the batteries. They will charge together. Can only one inverter have comms and charge the batteries and the other not have comms and do the same? I don’t know. Can you run both with comms to the battery. Also don’t know. Can you charge the battery bank with both inverters in voltage mode? Yes definitely that will work.

He hopefully should have done that already even with current setup.

I assume you are using busbars for the positive and negative? It will be as simple as connecting the other inverter to those busbars and ensuring both have the same charge voltages set. do you have comms to the batteries by any chance or are you just running in voltage mode?

Your batteries can handle having 2 inverters on them without issues. So the most budget friendly thing I see you can do is just hook up a second 24V inverter. There are 4kW inverters for under 4k available and same MPPT ratings as yours. so just split the DB and have each inverter supply certain breakers there. You have 11 panels in total also so you can have you 8 on 1 and out the other 3 on the other (just check the minimum voltage required for the MPPT for the second inverter in case 3 panels aren’t enough to turn it on but I think you should be good otherwise just split them half and half on each inverter, just add the 6 on new inverter) You could put the 4kW to supply just the kitchen. Then the whole house will be on solar.

If money is something to strongly consider then the cheapest is to just get a second 24V. Split the DB. they both share the same battery bank. A 4kW 24V is under 4000 rand. Then you will have about 7.5kW of AC capacity. What specs are the batteries btw? The C rating for discharge in particular

Not worth it in my opinion. You can’t parallel them per se. But you can supply different circuits in the house with 2 inverters without them being in parallel. Can you not convert your battery bank to 48V? Then you just buy a larger inverter? otherwise you can do what I did.

The 4000W solar power rating is not really important. I have seen my inverter pull 4000W and no more. The extra 550W on it it’s there for extra generation during cloudy days that’s all. His would do the same, just pull up to a max of 4kW when he installs the 8 panels on it. Even if he had 6000W on his 4000W MPPt it would be fine.

Lol, we have similar setups. I have a 3.6kW 24V with 7 panels, a GeyserTech controller with 4 panels for the geyser, also gas stove. I also have 10x100ah 12V batteries connected in 5S2P to make 24V. I literally went off-grid with just that and had my kitchen on that 3.6 lol. Self-installed, also like you. I have since added a 5kW/5kWh inverter I got off builders for cheap to supply the kitchen, which allows my 3.6 to coast now and more freedom to run kitchen appliances, whereas I used to only run 1 appliance at a time in the kitchen to avoid overloading it. The only thing you need to look at really is your voltage. You have a 500 VOC limit. So the number of panels is dictated by that. Not the wattage limit of your MPPT. I am running 4500W on my 4000W limit on the inverter, but am well below the voltage limit on it. Has been like that for 1.5 years now. The remaining 3 panels you can put on an MPPT, or, since MPPTs are pretty pricey, just get another inverter on a deal if you don't want to spend too much and hook it up to the 3 remaining panels. Then you can boost your AC output and supply the kitchen with solar power also. I have 1 extra panel, which is connected to a Victron MPPT, since I couldn't add any more to the 3.6kW. My 5kW has no panels on it and is charged off my 3.6, but that's on the cards in the next 3 years. Will boost my array to some 13kWp when I do add to that inverter, as I still have the whole house roof to add panels on, as they are all currently on top of the 3 garages.

Your panels VOC is a bit too high. I have 650W panels and each has a VOC of 45V and Vmp of 42 so I could overspec my inverter quite a bit. 9 with your panels would be around 470VOC but with 10% leeway you overshoot the 500Vdc limit. So 8 would be the safest. If you had similar panels to me you could have done 10 panels very easily and hit about 6500W. Not the 4480W you will potentially hit now. Not bad though as you are still over-paneling your inverter decently well.

9 8 to be absolutely safe

To be honest, panel ageing shouldn't be a concern in 20 years of service. There are many utility-scale PV farms from the 90s, over 3 decades old, still outputting over 80% of their initial rating. And one look at most datasheets would show that they are rated to have at least 80% of their output after 25 years. So in a 20 year span, one should not be considering replacing panels unles damaged from some weather incident, etc. And batteries also, after 10 years, one would still have some 80% of the capacity on the cells. So if one is able to get the BMS replaced, you should also theoretically get 15 or 20 years? Maybe I am being optimistic on the batteries but I don't see why not as they are rated for 6000 cycles and will still retain 80% of their capacity after that 6000. Factoring temps etc. One should still see 3000/4000 cycles which is 10 years basically and it would be up to them to replace the battery or not but no real reason you cant continue using the battery after that.

Adding the fixed charge section for when off grid dropped my payback quite a bit. That 1485 rand in fixed charges with Citi power was the reason I got disconnected. And your calculator reinforced it, especially with the long-term money back in my pocket. Being Off-grid was one of the best financial decisions I made in the last year. Only spent about 20k on my battery bank for the 17kWh I have so unless prices more than double in the next couple of years your 43k calculation should be good. Maybe add in for those that are off-grid their monthly fuel expenses etc if they have a generator. I don't use a generator so your calculator is perfect for someone like me.

Its time to cover the lawn with ground mounted solar panels🤣

I assume you mean series? I am curious, so the element is in only 1 geyser and that one feeds another which doesnt have a supply? And you have hot water as long as there was enough generation to heat the first geyser that feeds the second one?

I get 0V. I have no panels connected to it as it is charged off my other inverter and runs its own circuits at night. 30V is a bit odd.

My Omnivolt 5kW/5kWh all in one inverter is set to charge at 0.1C. But I do discharge very rarely a bit over 0.5C from it depending on loads. It is a 1C battery.

Any reason you need to charge quicker? 50A on 2 batteries will already get them full in 4 hours assuming 5kWh each. You dont have the array to charge any higher really unless you dont run any load during the day. Your array will max out at peak generation at 100A into the batteries with ZERO load. Only the grid will get you anywhere near the 100A limit of the inverter. More current means more heat, you inverter will work a little harder, your fans also, and your batteries work a little harder also even though its mostly safe for most LFP to be charged at 0.5C which is about 50A per battery. My only concern going higher is that you have 2 batteries, lets say each is rated for 0.5C max charging. If one gets full before the other and you set the inverter to charge at 75A for example then when one battery gets full, its own BMS will kill the charge to it, the remaining charge will go to the remaining battery and you will charge it higher than its spec. But a quick check shows your batteries can do 100A charging. So you can set it to whatever you want. I would leave it at 50A personally.

Oh you are 3 phase? That changes the ball game lol. Yeah, that will work fine also. But I think you got the idea for the kind of options that will suit your application. This would be far better than what I suggested as mine is geared for single phase. Yours is also cheaper per unit, considering you get 16. I would go for that.

Yeah its worth it also. I have 2, one that takes 2 CTs and another that takes 1 CT. I just left the one that takes 2 CTs connected permanently to keep a record of my consumption of the essential and non-essential after I was done with my tests. I use it for some of my home automation scenarios, also using Tuya. It will looklike below when you have it open on the app. Can name them whatever you want. You can see today my consumption is pretty low as noone is home. Just the pool that ran for 2 hours (winter so not running it long).