I'm confused in my design, any help please

I'm new to solar and working on my first system. A few months ago I went on a buying spree because of all the Covid stuff and I was worried I wouldn't be able to get what I wanted. I did as much reading as I could and then I ordered my major components without really understanding what I was doing, lol. Now I have all my major components, I just need to connect it all together. This will be an off grid, backup/ emergency system for my home. I have 14x 250 watt solar panels (picture of specs is attached), 2x 48v/ 3000w inverters, and 2x 10kwh 48v powerwalls. The solar panels will be set up approximately 120-150 feet away from my batteries and inverters. My plan is to connect the solar panels in a 7s2p system, the 2 10kwh powerwalls in series, and the 2 48v/ 3000w inverters in series. The panels already have MC4 connectors so linking them should be easy. I will be connecting a fuse between the panels and inverter for safety. I was told that I should go with 10gauge wiring for my panel to inverter connection and 4 gauge for my inverter to battery connection. However, from what I have read with some of the calculators and some of the posts here I need a bigger wire for my panel to inverter connection, maybe 8gauge is better? Anyone that can offer advice on this would be GREATLY appreciated. I want to order my wiring this week and hook everything up over the holiday. Please point out any problems I have in my general plan as well, I don't want to burn the house down.

What's clear is that you really need to RTFMs and ask questions about things you don't understand.

This is a DIY forum, not a HSEDIFY (have somebody else do it for you) forum.

To the above point, the idea that you can put your panels in 7S2P configuration is ludicrous. The charge controllers clearly state a 145V PV limit.

7 * 37.6 = 263.2V - say goodbye to your Growatt. The most you can go series is 3, but you have an even number of panels not divisible by 3, so you're limited to 2S7P. Having them only 2S over 150' is going to demand heavy gauge wire or multiple conductors. Your sketch is unconventional to the point that it's confusing as to your intention.

You don't put inverters in series. You put them in parallel operation mode, so they can synchronize - read the manual about this.

You don't put two 48V batteries in series unless you're trying to make a 96V battery. You put them in parallel if you want two 48V batteries to make a bigger 48V battery. You at least use the correct label on your sketch.

I suggest you read your manuals and brush up on the basics. Look at the various blueprints on Will's site and develop your own diagram with suitable labels including fuses, breakers, wire gauge, etc. Then, ask for feedback.

This probably comes across as harsh. Harsh isn't the intent. Blunt and direct is the intent. Happy to help when you've done a little more leg work of your own.

dawgleader1 said:

I'm new to solar and working on my first system. A few months ago I went on a buying spree because of all the Covid stuff and I was worried I wouldn't be able to get what I wanted. I did as much reading as I could and then I ordered my major components without really understanding what I was doing, lol. Now I have all my major components, I just need to connect it all together. This will be an off grid, backup/ emergency system for my home. I have 14x 250 watt solar panels (picture of specs is attached), 2x 48v/ 3000w inverters, and 2x 10kwh 48v powerwalls. The solar panels will be set up approximately 120-150 feet away from my batteries and inverters. My plan is to connect the solar panels in a 7s2p system, the 2 10kwh powerwalls in series, and the 2 48v/ 3000w inverters in series. The panels already have MC4 connectors so linking them should be easy. I will be connecting a fuse between the panels and inverter for safety. I was told that I should go with 10gauge wiring for my panel to inverter connection and 4 gauge for my inverter to battery connection. However, from what I have read with some of the calculators and some of the posts here I need a bigger wire for my panel to inverter connection, maybe 8gauge is better? Anyone that can offer advice on this would be GREATLY appreciated. I want to order my wiring this week and hook everything up over the holiday. Please point out any problems I have in my general plan as well, I don't want to burn the house down.

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Hey, I'm also really new to this and these guys really do a great job of giving advise. I would suggest that you click on "DIY Solar Blueprints" at top of page. It's a great place to start. You want to be careful-how items are configured, size of wires/fuses/breakers can protect your equipment and yourself. Check out some of the plans, diagram, etc. on this forum and try to figure out why they did what they did

Here's another vote for "do more reading". There is a FAQ for the forums. It's as good a place to start as any other I can think of..

Im a noob to solar myself, but i see 2 of everything, wouldn't it make more sense to therefore keep everything separate to create redundancy? One string to one growatt to one battery kind of scenario?

dawgleader1 said:

... However, from what I have read with some of the calculators and some of the posts here I need a bigger wire for my panel ...

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A lot of calculators are voltage drop only and don't consider ampacity. Try this calculator and the NEC ampacity table.

Hi everyone, thanks for chiming in. I am good at may things but this engineering and especially electrical stuff makes me confused and makes my head hurt. I have been doing research for awhile and I have gotten many different opinions so that's why I came here to verify and see if what I'm planning makes sense.

Snoobler: Harsh? maybe, direct? definitely, appreciated? GREATLY and thank you. My original plan was to go 2s7p as my drawing shows, however, when I was talking with one of the companies I was considering ordering some of my components from I had them look over my plan and they said "Each inverter may have 2 MPP trackers, please reconfirm with inverter supplier. That's the same meaning each inverter allows 2 parallel connections max. So we suggest 7S2P instead of your 2S7P or you may consider as our engineer offered as below with 2 inverters." And they also offered the picture below as another option with the inverters separated as Ryang suggests. While I absolutely like the idea of redundancy, splitting into 2 separate systems seems to weaken my total solar output capabilities but I'll look into this a little more. The engineer suggesting the 7s2p kind of confused me but I figured an engineer at a solar company should know better than me so I changed my plans accordingly. As I mentioned I get confused with this stuff and you're obviously correct with the parallel connections on the inverters and batteries vs the incorrect series I typed in my original post, I understand that both the batteries and inverters need to be parallel connections, my post was a brain fart. In actually I do have 15 panels, I bought a total of 16 to have 2 extras as back up in case I lose one to damage or something. So I will look into your idea of 3s5p, which if I can do that would actually be better since it will give me another 250 watts of panel. I definitely want to have the best, safest solar set up as possible so I do want the correct plan and I want to incorporate the right gauge wiring and fuses.

As suggested by everyone who posted, I will do some more research and review, as I understand this a little more I'll come up with a new plan. Once I think I have something more clear I will post back here to try to get some feedback. Thanks very much.

Hey snoobler,

I took your advice and have been doing quite a bit of research and reading. I completely understand your pointing out that I sounded way off base and ignorant in this posting. I've opened up a new thread with updated information and plans. If you have time, I would appreciate you looking over the new stuff and seeing if it makes more sense. It's titled

help please- off grid system review​

Anything you can provide would be appreciated. Thanks.