Can I get some help finding an inverter

[lectric74]

Helping my in-laws with an off grid system. Currently have 3600 watts of solar, just waiting on the 2/0 cable, with 20 12 v 100 AH batteries, that will be wired in series for 24 volts and 1000AH. The issue I have is that the Magnum Power MagnaSine inverter that he wanted to get is backordered, looking like late next month but that's been updated from late this month. This means I need to find something else that will meet the needs he has.

Specs are 24 VDC input, 240 VAC split phase output at 4-5 KW, must be true sine, and needs a 120/240 VAC battery charger built in so that nothing needs to be done in the rare event they need their generator due to low batteries. Basically if they start the generator it should either be hybrid to supply additional AC power, or straight charging the batteries. As my in-laws are up there in age, the goal is to make it as easy to use as possible. They've run a generator for over 30 years, finally have the money for a decent solar power system that will meet/exceed their needs. The cabin is currently set up with 240 from the generator to a breaker box, then the legs are split to provide power to washer/dryer, internet, TV, and other small devices, so we don't want to have to rewire the whole thing. Since I don't have a background, I'm looking for recommendations for a good inverter that will meet the needs.

He has tried non-true sine inverters and they will not run his on-demand hot water heater's electronics. I think the new gas dryer they have also has issues with electronics if they aren't true sine.

 

[Darren67-72]

Check with growatt or generty solar or watts24. These are decent inverter distributors.
Growatt is a big company if you like that, Signature Solar has them, or did. I'm not sure of current stock. Generty Solar has 6k inverters that meet your needs, I think.

 

[K8MEJ]

Check out Sol-Ark inverters. You can message me privately if you would like to discuss. These are very simple to install for a DIYer with some electrical knowledge.

 

[MichaelK]

I could suggest the 24V inverter I'm using, the Schneider Conext 4024, which is split-phase, 4000W continous, and has a built in generator charging circuit.

I have to say though that there appears to be a bit of system imbalance here? 1000Ah is a VERY large battery for 24V. What's the battery chemistry? 1000Ah is usually 48V territory? Let's say it's lead-acid, which charges at an optimal 1/8th of C, which would be 125A. You'll be hard-pressed to find a single charge controller that can handle that many amps. More likely, you'd need two in parallel, each handling 60+amps.

Alternatively, can these batteries be wired for 48V instead. 500Ah at 48V is very managable with one charge controller, and 4 gauge wire. Take a look at the 48V of the Conext, the 4048, or the bigger 6848 XWPro. (mine also).

I think having a battery bank with 10 individual strings is a serious mistake. For my own 48V system, I have 580Ah as one single string.

 

[lectric74]

Thank you everyone for the recommendations, I ended up going with a GroWatt 6k with dual built in charge controllers. Part of the confusion with the charger was I was only talking about a 120/240 VAC charger from the generator to charge the batteries should they get low, I already had 2 Victron charge controllers that were going to handle the solar charge side of the installation. These controllers have been returned in favor of the all in one unit here.

MichaelK: Lead acid yes, 20 12V DC batteries wired in pairs. The inverter I went with (and the original plan) has 2 charge controllers to handle the 3600 watts of solar we have installed, and help keep the load a bit balanced. I had no hand in the design of this system, I just purchased what my father-in-law wanted, but realistically what they have should be more than enough. My in-laws have lived very low consumption (oil lamps and wood burning stoves, propane for cooking, DC lighting) for over 30 years, in that time they had 3 smaller cells feeding to 10 12 v lead acid batteries in the basement. That system is apparently staying online, the new stuff is replacing their oversized generator and the batteries are way more than I would have done, but he's hopeful they will ensure they don't use the generator much at all.

 

[MichaelK]

MichaelK: Lead acid yes, 20 12V DC batteries wired in pairs. The inverter I went with (and the original plan) has 2 charge controllers to handle the 3600 watts of solar we have installed, and help keep the load a bit balanced. I had no hand in the design of this system, I just purchased what my father-in-law wanted, but realistically what they have should be more than enough.

That is not really how it works. Doesn't matter how many charge controllers you have if all the batteries are wired in parallel. It will be very hard for a battery with 5 parallel strings to be charged and discharged evenly. I feel that 5 strings is a hallmark of poor design. In any case, an even number of controllers can't evenly charge an odd number of strings. They might though handle the amps.

What is the maximal amperage that your new Growatt can handle? It's not 80A is it? A bank of that size would want to be at 125A for best charging. 3600W of solar is likely to meet that, but will the controller section?

 

[rhino]

Also be sure the Growatt is installed somewhere where noise is not an issue. It is also good you did not find a Magnum to buy. It is "backordered" because it sounds like they went out of business. See https://diysolarforum.com/threads/i-fear-magnum-is-done.44947/

 

[12VoltInstalls]

My only thought on this is the batteries confuse me. UNLESS you are using 100Ah walmartha batteries for convenience of accessibility of replacement (and even that is dubious), golf cart or other purpose-designed heavy 6V or 12V lead acid batteries are probably a better choice economically due to longevity- if you maintain them.
If it’s not too late I’d explore that.

 

[MichaelK]

golf cart or other purpose-designed heavy 6V or 12V lead acid batteries are probably a better choice economically due to longevity- if you maintain them.
If it’s not too late I’d explore that.

Second that. Bigger batteries and if it's possible, trade the 24V version of the inverter for a 48V version. Two parallel 48V strings of golf-cart batteries will equal what you are attempting in terms of capacity, and will result in a far more manageable system.

 

[lectric74]

Sorry I've been absent, some personal issues have tied me up.

So, I'll do my best to answer why things are what they are:

Batteries, my in-laws neighbor has a deal on cheap lead acid batteries. I do agree that the number is way off the scale, and I broke them into 2 groups of 5 pairs. Each group connects to one of the GroWatt inverters. I had zero say in the design, except the final wiring which split them into 2 groups. My preference would have been a 48 volt system from panels though storage and I would have used LiFePo batteries for longer life expectancy.

Peak charge amps is 10.86 per panel, so max is 108.6 amps, the inverter controllers are rated for 60 amps each. I should point out that the panels are 410' from the charge controllers, so there is going to be some loss coming down the hill, even using the 2/0 aluminum cable, so I'm not overly concerned about the charge controllers not handling what's coming down.

While 48 volts would have been great, I had no say and batteries were bought before he even gave the go ahead to order the inverter/chargers. I discussed at that time that 48 volts would be better but he was against it. Panels were based on the frame he built on top of the hill. At the end of the day, this system isn't mine, isn't what I would do, and has far more storage than would ever be needed by them. Honestly, with an actual power audit I think they could have used about half the batteries, and panels, and still had more than enough for what they use. That's not an exaggeration either, they have lived on 2 KW generator for several years before upgrading to a 5 KW unit.

Someone mentioned having the inverters in an area to avoid the noise, they are mounted in a shed outside the house where the generator runs so that isn't a big concern, although I have seen that they can be noisy at times.