Tinkering on a DIY Solar Generator/ Questions if I'm on the right track for power expectations.

[CrossPike77]

Hi All.
I've been tinkering on an off grid system for a barn workshop since 2020 lock down. Harbor Freight 25W kits strung together expanded to more robust components a yr later. Been trying to get to the point of just having lights on (and maybe a few small power tools for short bursts) on the solar, has become a new interest in having a diy solar generator for power down options. I will layout what I have done and my concerns with if I have done correct and what may need correction (willing and wanting to learn if I have done incorrect).
I have 4 100W Renogy Panels on all coming in with adapters and cable into a new 40Amp Mppt BougeRV charge controller. From there, I have a 2000W AC inverter. Connected to 4 batteries, 1 is a 100AH Gel Weize, and the other 3 are 75 AH Deep Cycle Marine batteries. One 12V 40Amp breaker on the solar in before controller. Breaker/Fuse from controller to bus bar. 1 - 200AMP fuse on the battery in to bus bar and 1 on the out to inverter. Shut off on battery bank main in before fuse.

I have done some small testing, I had a heat gun running for a couple minutes, a Harbor Freight router table for a few minutes. Both seemed to use some battery power and to 75%, and then it bounces right back to the 90's after turn off.

I tried plugging in my shop light array this morning ( there are around 10 LED shop lights at 42W each). The battery power started going down fast into the 50% range within a minute or so and after disconnecting, came right back into the 90's again moments later.

My question mainly is, Should I be expecting such a drastic drop in battery power? I feel the panels should be providing some power as I'm trying to draw for this usage. I feel like if I try to test out the LED lights for too many minutes, they won't stay on for long at the rate I witnessed. I plan to start with one light at a time until I see a drastic drop and know that's my threshold.

Is my bottleneck having two different types of batteries and I will see better results with multiple Weize gel instead? Currently they are daisy chained to each other, I have seen multiple batteries run to a common bus bar then out to distribution bus bar (Am I better of with this config?)

I'd like to try and run my fridge or deep freezer (saw a guy on youtube with similar specs run a chest freezer for 6 days, but his drop didn't seem so drastic on draw) if power goes down.

Any help or insight on my questions is greatly appreciated.

 

[jpimlott]

Oh this reminds me of how i started. Same kit from harbor freight (a designer drug).
I then went on to add some 100 watt panels and an eperver charge contoller.
I now have 4 growatt all in one hybrid off grid inverters doing the whole house (AC and dryer).

Batteries are tricky on the percent state of charge and voltage.
You need an amp meter that will record to know much is used.

You are not seeing a 40 % drop in charge like that in a few minutes then a charge right back.
The voltage drops quickly because of the load and surface charge is gone.

After a bit it will reflect true stat of charge with no load or charge on it.

I was disappointed on the lead acid charge and discharge.
I built some lipo4 batteries from cells and a BMS and now an active ballancer.

to quote a movie "welcome to party"

 

[Rednecktek]

I have 4 100W Renogy Panels on all coming in with adapters and cable into a new 40Amp Mppt BougeRV charge controller.

4s? 2s2p? 4p?

From there, I have a 2000W AC inverter.

That is a HUGE inverter for a system that small.

Connected to 4 batteries, 1 is a 100AH Gel Weize, and the other 3 are 75 AH Deep Cycle Marine batteries.

Are those connected to bus bars or just to each other? Picture or diagram would be helpful. If you have them connected to each other rather than a central point you can't discharge the batteries very evenly as wherever the wires are will do the most work and the ones farther away will provide less.

I have done some small testing, I had a heat gun running for a couple minutes, a Harbor Freight router table for a few minutes. Both seemed to use some battery power and to 75%, and then it bounces right back to the 90's after turn off.

That's normal. Those small batteries can only put out so much and the harder they work the lower the voltage goes. What you're seeing is that voltage drop. An amp meter or shunt is the only way to be accurate.

I tried plugging in my shop light array this morning ( there are around 10 LED shop lights at 42W each). The battery power started going down fast into the 50% range within a minute or so and after disconnecting, came right back into the 90's again moments later.

So you're saying YOU are the STC testing lab?

That's 420w or 42 amps of draw. Those poor little 75a batteries are giving it all she's got. Again though, that's normal.

I feel the panels should be providing some power as I'm trying to draw for this usage. I feel like if I try to test out the LED lights for too many minutes, they won't stay on for long at the rate I witnessed.

There's a time delay between the time a load is applied and the time the MPPT controller figures out all its math and starts pumping amps into the system. What you should see is the MPPT ramp up after a couple minutes and start putting out amps. It'll still be a net loss but it'll help raise the voltage of the batteries as they're sharing the load with a 5th source.

Is my bottleneck having two different types of batteries and I will see better results with multiple Weize gel instead? Currently they are daisy chained to each other, I have seen multiple batteries run to a common bus bar then out to distribution bus bar (Am I better of with this config?)

Yes, or you can spend the same money and get a LFP battery that will be able to use 100% of its capacity rather than the 50% you're limited to by lead acid flavors. Taking everything to a common point will help with charging and discharging more evenly and spreading the amperage draw evenly across all the supply points.

As for connecting up to bus bars, you'll hear about equal length wires. Most people miss that ALL the wires don't have to be equal. If you need a 3ft wire from the positive of the furthest wire, then you need 3ft wires on ALL the positives. If you need a 8ft wire from the furthest Negative, then ALL the negatives need to be 8ft. However, only each end has to be the same length, so you don't need ALL 8ft wires.

Harbor Freight 25W kits strung together expanded to more robust components a yr later.

I've bought 4 of those over my life, and now I work at HF. I need to call my therapist...