Greetings from Tug Hill NY

[nycamper62]

Hey, I am into practical & conservative off grid solar system maintenance & use. Looking forward to learning & sharing advice on solar before I expand & improve my system at camp. It's my peace of mind there. I started out over a decade ago with a few small hf kits, was an active member of an old diy solar form back then. My system today is about a half kw, with a 30amp pwm controller feeding a 4x 6v 12v lead acid bank in series/parallel. This keeps my rv/camper ventilated, including the composting toilet. Lights, entertainment (am/fm/cd/usb/bt deck) and a laptop primarily used as a dvd player. Also use a 1000w pure sine on occasion to charge my tools, and back up for the fridge.
In summary:
3x 100watt polycrystalline
1x 145watt polycrystalline
1x 60watt polycrystalline
9x 45watt amorphous
pr30/30 (steca knock off)
4x 6v gc2's (15's still going)

Purchased my 1st polycrystalline back when monocrystalline panels were still - more coin $. And when the whole 1$ a watt thing was just an nice thought. Before anyone sneezes at the amorphous panels let me say they afforded a learning curve, they trickle charged in overcast & they still work. But they are aging and I'd like to phase them out. Plus repurpose the 60.
There is a few things to consider before I expand & go to mppt with about 1kw in mind. There's the aging battery bank. Should I include the remaining panels, which means a second controller, more wiring, buss bars, etc. And of course a new chainsaw blade to help open up the canopy.
Happy camping.

 

[houseofancients]

Welcome !

 

[MisterSandals]

My system today is about a half kw, with a 30amp pwm controller feeding a 4x 6v 12v lead acid bank in series/parallel.

3x 100watt polycrystalline
1x 145watt polycrystalline
1x 60watt polycrystalline
9x 45watt amorphous

I am VERY curious how you have these connected to a 30A PWM controller at 24V.

 

[Supervstech]

I am VERY curious how you have these connected to a 30A PWM controller at 24V.

I mean... they gotta be in parallel...

I am VERY curious how you have these connected to a 30A PWM controller at 24V.

And they gotta be 24V panels...
Very sketchy numbers though...
About 8 amps lost in translation if panels ever produced full output...

 

[nycamper62]

In parallel, 12v panels.
Not visible but panels are wired into a combiner box into copper buss bars, then wired through conduit into the rv/camper.

 

[MisterSandals]

In parallel, 12v panels.

How many volts are your "12V panels"?
How many amps do you figure you have adding the amperage (Isc to Imp) of all panels? 35 to 40A?

 

[Supervstech]

In parallel, 12v panels.
Not visible but panels are wired into a combiner box into copper buss bars, then wired through conduit into the rv/camper.

Wait...
12V panels all in parallel connected to a 24v bank?
How does the system charge?
Boost converter?

 

[nycamper62]

To answer that accurately, I will recheck the panels info next weekend and post.

 

[nycamper62]

Wait...
12V panels all in parallel connected to a 24v bank?
How does the system charge?
Boost converter?

It is a 12v bank. Perhaps I made a typo or there was a misunderstanding.
The bank is 4 6volt golf cart batteries in series / parallel.

 

[MisterSandals]

Before anyone sneezes at the amorphous panels let me say they afforded a learning curve, they trickle charged in overcast & they still work.

I'm not dissing them at all!

I am thinking that with your 30A PWM controller, if you switched to an MPPT SCC, you can probably arrange your panels into a higher voltage array to charge better under low light conditions (early morning, late afternoon, overcast days).
Heck, i'd consider keeping the PWM for any panels that don't mix and match an MPPT should you upgrade. It would also provide some redundancy.

Maybe your hodge lodge of panels can be kept in service. I'd definitely get an MPPT SCC though (the heart and brains of every solar system).

 

[Supervstech]

I'm not missing them at all!

I am thinking that with your 30A PWM controller, if you switched to an MPPT SCC, you can probably arrange your panels into a higher voltage array to charge better under low light conditions (early morning, late afternoon, overcast days).
Heck, i'd consider keeping the PWM for any panels that don't mix and match an MPPT should you upgrade. It would also provide some redundancy.

Maybe your hodge lodge of panels can be kept in service. I'd definitely get an MPPT SCC though (the heart and brains of every solar system).

Yeah, I'd pull the 9 panels into series on a 60A mppt, leave the rest on the pwm, and probably gain a lot of usefulness of the system.

 

[nycamper62]

How many volts are your "12V panels"?
How many amps do you figure you have adding the amperage (Isc to Imp) of all panels? 35 to 40A?

The two rich solar 100w panels are now in series to the combiner box.



The dmsolar 145w

The cynery 100w

These two are in parallel to the combiner box. Then the box feeds a 25foot run to the controller inside the camper.

Edit: the dmsolar & cynergy panels are the oldest but in good shape. As camp is in a woods setting I thought of putting them in series as well to help with shading. But I am not sure of the loss and they are not equal wattage.

 

[nycamper62]

By the way over this last weekend I brought a digital tv & antenna up to camp to test what if any channels I could get. Turns out with the right antenna placement about a dozen channels come in. Including the one that broadcasts the super bowl.?
With the inverter just powering a small tv, the booster, phone, some led lights & a small crock pot I discovered my first attention to expansion needs to be the battery bank. Went from 12.8 to about 12.2 in less than an hour.

 

[MisterSandals]

The two rich solar 100w panels are now in series to the combiner box.

37V 5.4A

The dmsolar 145w

18V 8A

The cynery 100w

18V 11.2A

Combining these in parallel clips all strings to 18V
18V x (5.4 + 8 +11.2) = 442W (out of 545W of panels)

 

[nycamper62]

18V 11.2A

Combining these in parallel clips all strings to 18V
18V x (5.4 + 8 +11.2) = 442W (out of 545W of panels)

I'm not following how you got that math on the cynergy panel.

 

[MisterSandals]

I'm not following how you got that math on the cynergy panel.

The cynery 100w

These two are in parallel

The pic shows 17.99Vmp and 5.57Imp

Connecting in parallel sums the amps: 5.6A Imp x 2 = 11.2A
I rounded the 17.99V up to 18V

 

[nycamper62]

The pic shows 17.99Vmp and 5.57Imp

Connecting in parallel sums the amps: 5.6A Imp x 2 = 11.2A
I rounded the 17.99V up to 18V

Ahh ok, the two rich 100w panels are in series, the cynergy is not.

 

[MisterSandals]

Ahh ok, the two rich 100w panels are in series, the cynergy is not.

This seemed rather odd. What was your thinking on this?

Ideally, each string going to the combiner box should have as equal voltage as possible because all strings connected in parallel by the combiner box will clip the voltage of all strings to the lowest strings' voltage. Thats lost watts, never to be recovered.

 

[nycamper62]

This seemed rather odd. What was your thinking on this?

Ideally, each string going to the combiner box should have as equal voltage as possible because all strings connected in parallel by the combiner box will clip the voltage of all strings to the lowest strings' voltage. Thats lost watts, never to be recovered.

Well, placing two 100w panels in series seemed like a way to deal with some shading issues from trees depending on the time of day. Then I thought of placing the other two in series as well but they are different specs. Now I'm wondering if I should put them all back to parallel.
Before I expand and go with matching panels I'm working with what I bought 10 years ago plus the two new rich 100w set.

 

[MisterSandals]

Well, placing two 100w panels in series seemed like a way to deal with some shading issues from trees depending on the time of day.

Series panels both get significantly affected by shade on either panel. Parallel limits shading affects only the shaded ones.