Newbie question

[samhal]

I guess maybe I don't understand things very well. I'm currently running 1200 watts of solar panels (series/parallel) for 24 volts into an older 'hybrid' controller/inverter (2.4K PWM EASUN, a chinese knockoff) hooked up to 6 x 100ah AGM batteries, again in series/parallel for 24 volts. The system is used for my powering my workshop.

The system works. However...

If I remove the line utility aspect, the system runs off batteries and uses solar only to charge the batteries. Once the batteries reaches a 'stable' charge for the task at hand, solar power tapers off unless needed to charge the batteries again. None of the solar seems to be used in actually powering the demand from the powertools...it's all about the batteries. Seems like a waste of solar energy to me!

Also, when selected, the battery bank every time drops immediately to 52% (even if all I have on are the shop light - about 200 watts).

Solar power maintains the battery bank around the 50-57% range, never more. When I activate the line utility mode the batteries jump back to 100%. I don't think I've ever hit beyond 600-ish watts of solar power even tho there's much more to be had. Why can't my solar panels take my batteries back to 100%?

So, is all this normal performance? I "think" I have things configured correctly, but who knows?

Thanks,
Sam

 

[Bobert]

How are your solar panels configured? What voltage do they output to your pwm controller. Pwm doesn’t work well unless you’re getting voltage in just the right range. What voltage are your batteries reaching with solar? What amperage is going into the pwm? Does the unit tell you how many amps are going into the batteries.

 

[samhal]

Bobert - thanks for the reply!!!

Yeah, I was wondering about the PWM aspect of things. I have 3 banks of 4 x 100 watt solar panels. Each bank consists of 4 panels, 2 each in series, and the bank itself in parallel. They to go an ECO Worthy combiner box. Ultimately I have three outputs from the combiner box to the inverter. 1200 watts, about 60+-ish in volts and less in amps. I think anyway.

My inverter maxes out at 80 volts/50 amps (like I said, it's old) , so I am trying to keep under that. I have designed this system under Will's design:
https://www.mobile-solarpower.com/all-in-one-122448v-packages.html
...sorta, kinda...

I am using WatchPower 1.16(?) to control everything.

To be honest I'm not sure about what amps reaches the inverter. I'll check...but since it's raining like crazy now, it may be a bit. But it should be at least 30 amps. Maybe...I think...possibly? But in any event, it should be more than enough to fully charge the batteries.

Thanks,
Sam

 

[Supervstech]

If you have the panels configured to output 60V, you are being limited by the pwm controller.

Either reconfigure the panels to output around 34V or better plan is get yourself a quality MPPT controller that can properly feed the pv energy.

 

[samhal]

?I kinda thought that upgrading to an MPPT might be the ultimate answer! I need to upgrade anyway, this thing is at least 6 years old.

Thanks all!

 

[MichaelK]

If you have the panels configured to output 60V, you are being limited by the pwm controller.

Either reconfigure the panels to output around 34V or better plan is get yourself a quality MPPT controller that can properly feed the pv energy.

I don't think that is the case. Go back to post #3, and you see this statement. "Each bank consists of 4 panels, 2 each in series, and the bank itself in parallel."
So, in fact, the voltage feeding into the battery bank is likely to be ~36V, so too high for a 24V system.

Samhal, you mention 60+volts. If you are seeing voltage that high, your panels are NOT 2 in series.

Samhal, can you controller be set for different charging voltages? What is it set at right now? I suspect that your charging voltage is not correct for your battery. What is the battery manufacturers recommendation?

Yes, you'll bet better performance out of an MPPT controller. Take a look at Epever's Tracer 4210AN. With an 85% fudgefactor, that 40A controller would be just maxing out at 40A around noon or so.

 

[samhal]

Thanks MichaelK!

Okay so I finally got some serious sunshine and can confirm my voltages from the solar banks runs about 37V...NOT the 60V I previously said. Dunno what I was thinking at the time. I blame the month of October.

Still, your previous post above stated even those voltages are too high...not sure how I can reduce it further. (Hints anyone?)

To recap my previous post: I would think 1200 watts of solar power would keep my batteries at 100%-ish with no real load on them...but not so.

As soon as I turn the inverter/controller to "solar only" the batteries immediately drop to ~52%, and continues to drop to around 49%, (even if all I'm running is about 200W of shop lights) until solar input begins to ramp up and starts charging!

AND, the controller/inverter hybred "solar only" option seems happy to maintain (and keep!) the batteries around 57%~60% (unless that's chinese for 100%). It's only when I turn on utility mode back on that it reports batteries back to 100%!

In my inexperienced mind, "solar" should be able to keep the batteries (with no real load) at 100% and run, let's say a table saw, with a dip in battery amperage during the saw's use...but with solar providing at least SOME of the power...but again, not so.

AND as I stated earlier, when solar gets the batteries back up to about 57-60% charge, the inverter/controller scales the solar input to almost nothing.

*** So, my observations are that if I take the system off "utility line mode", the batteries run everything. Period. End of story - no more discussion. Solar is only there to charge the batteries and nothing else. Yes? No?

If yes, what do I have to do to make use of the 1200 watts of solar power (even if the batteries are at 100%) instead of just seeing all that beatiful sunshine wasted on nothing?!

Also, I've gone thru the invereter/controller settings ad-nauseum following Will Prowse's guidlines in one of his articles.

So maybe I simply need a good education on how all this is REALLY suppose to work and not how I think it should!

Rant over.
Sam

 

[MichaelK]

Okay so I finally got some serious sunshine and can confirm my voltages from the solar banks runs about 37V...NOT the 60V I previously said. Dunno what I was thinking at the time. I blame the month of October.

Still, your previous post above stated even those voltages are too high...not sure how I can reduce it further. (Hints anyone?)

What I said previously about the voltage being too high might be incorrect for your PWM controller. With a PWM controller, it should allow the batteries to drag the panel voltage down to what the battery wants to charge at, maybe 25-29V. How are you reading 37V? Is it from the disconnected +/- leads of a panel, at the controller terminals, or the battery terminals? I'd expect the Voc to be 37V at the panel leads, but drop to maybe 27-28V at the battery terminals?

As soon as I turn the inverter/controller to "solar only" the batteries immediately drop to ~52%, and continues to drop to around 49%, (even if all I'm running is about 200W of shop lights) until solar input begins to ramp up and starts charging!

AND, the controller/inverter hybred "solar only" option seems happy to maintain (and keep!) the batteries around 57%~60% (unless that's chinese for 100%). It's only when I turn on utility mode back on that it reports batteries back to 100%!

What brand of batteries are these? Did the manufacturer state what their charging parameters are? This sounds to me that the charging parameters are not set correctly for your batteries. Have you gone into the Eason's settings to see that the charging voltages are?

In my inexperienced mind, "solar" should be able to keep the batteries (with no real load) at 100% and run, let's say a table saw, with a dip in battery amperage during the saw's use...but with solar providing at least SOME of the power...but again, not so.

Amperage does not dip under load, the voltage does. The best way to determine if your panel output is good is to place a large resistive load, such as a toaster oven on the system around noon. You should see full output of your panels under these conditions.

AND, the controller/inverter hybrid "solar only" option seems happy to maintain (and keep!) the batteries around 57%~60% (unless that's chinese for 100%). It's only when I turn on utility mode back on that it reports batteries back to 100%!

In my inexperienced mind, "solar" should be able to keep the batteries (with no real load) at 100% and run, let's say a table saw, with a dip in battery amperage during the saw's use...but with solar providing at least SOME of the power...but again, not so.

How are you actually determining that the batteries are at 60% charge? What is giving you that number? Voltage is only a rough guide to what the state of charge is, and that's after the battery has rested for a while, and is not under load.

 

[samhal]

What I said previously about the voltage being too high might be incorrect for your PWM controller. With a PWM controller, it should allow the batteries to drag the panel voltage down to what the battery wants to charge at, maybe 25-29V. How are you reading 37V? Is it from the disconnected +/- leads of a panel, at the controller terminals, or the battery terminals? I'd expect the Voc to be 37V at the panel leads, but drop to maybe 27-28V at the battery terminals?


What brand of batteries are these? Did the manufacturer state what their charging parameters are? This sounds to me that the charging parameters are not set correctly for your batteries. Have you gone into the Eason's settings to see that the charging voltages are?

Amperage does not dip under load, the voltage does. The best way to determine if your panel output is good is to place a large resistive load, such as a toaster oven on the system around noon. You should see full output of your panels under these conditions.

How are you actually determining that the batteries are at 60% charge? What is giving you that number? Voltage is only a rough guide to what the state of charge is, and that's after the battery has rested for a while, and is not under load.

Pictures probably tell the best story...
It's 6:30 pm here now so not much help from the sun, but here's some pictures of my setup Outside, I have 2 sets of 4 panels on the shops roof, and a set of 4 on a Eco-Worthy tracker. 1200 watts.

The box in the top right corner uses shunts to get my readings...the top is solar and the bottom two are showing Input and Output from the batteries. In full sunshine I can get well over 35 volts. All my solar panels are tied into a combiner box (outside and not seen) and the shunts display the output from it, then the connection continues on to the inverter. The inverter is also a source for readings. But to be honest, I'm mainly using the WatchPower program for my readings...voltages and percentages.

I'm using 6 of these batteries:


The Easun Inverter I'm using has long been discountinued and it's hard to find info on it...including a manual since mine got lost a long time ago. I bought the thing on Amazon back in August 2019. Yep, old.