Classic 150 w/6 panels and 99'F heat.. questions..

[epsgunner]

I have 6 panels..

145w
18 VMP
8.05 IMP
21.6 VOC
8.95 ISC

I used 15 feet of 10 AWG PV wire for testing.. to simulate my wire run..

The battery bank for testing was a 12v 100ah battery.. no frills.. and was at 12.4V when I 1st powered on the Classic.. I did not check the battery as I was just testing stuff.

The Classic 150 was set to 13.6 float & 14.4 absorb settings..

For a single panel in 99'F heat at 12pm (with the Classic 150 outside with it and reading 53'C on the internal temp with the fan running)


I got these numbers.. (granted it went up and down)..

16.2V in
13.0V out
5.7 A out
0074 watts



1) is there a reason I was only seeing 5.7 amps after MPPT conversion?? does the Classic taper down the PV input amps like a PWM controller as the battery get full??

at 10:25 am and 93'F I got numbers like this..

I got for 2 panels in series (aka 24v nominal with VOC showing at 37.7 on the 1st screen)

30.4V in
13.4V out
15.6A out
210 watts



at 99'F and 12 noon I got this for the same 2 panels in series (aka 24v)

27.8 V in
6.1 A in
13.3 V
13.1 A
37.6 VOC

which works to 174.23 watts or 87 watts per panel.. (and it did go upto 179 watts total in my video.. or 89.5 watts per panel)



I know the numbers change quickly with MPPT..

The concern is the 27.8V in and 30.4V in I saw on the input side as shown above..

2) If I were to run a 24v battery bank would using just 2 panels in series still be a safe bet??
(I am thinking yes as I would think the controller would not adjust the MPPT below the 28.8 Abosorb setting, but I don't know if your MPPT algorythym even looks at the controllers setting..)

3) Would that be a concern at all since the controller seems to switch pretty quick??

4) Did the HEAT on the Controller being 53'C inside cause the output to be lowered?? (thinking yes)..

Of course in real mounting the unit would be inside my cabin and not just under a lounge chair cooking in the grass..

For now I plan on running 2 panels in series * 3 in parallel and keep the 12v battery bank.. though the output based on what I saw would be 630 watts for 6 panels (210*3 parallel) vs. the 782 I got when I plugged the numbers into the Midnite String Calc before I bought it..

I was hoping for close to 60 amps out to the battery, but it seems like 39.3 Amps in 99'F heat.. and only 46.8 Amps in 93'F heat..

Again, unless with the controller being 53C HOT and NO LOAD that skewed the numbers.

I know in cooler temps the numbers will more than likely play out in my favor..

Suggestions, ideas, tips?? All ears..

[epsgunner]

Just an add on note.

The controller was in BULK for about 45 minutes and then Absorb for a little bit.. by 2:30pm I was in FLOAT..

I really didn't turn-on the unit for REAL running till 11:54am.. just before I got the 12pm (noon) readings as I wanted the hottest part of the day with sun overhead..

[epsgunner]

Anyone got suggestions or ideas..

[boB]

Looks like the input voltage being at 16 volts is lower than it should be.

53 degrees C inside will not make the Classic drop its output level.   I would try the
Legacy MPPT mode to see what it does.   53 C is cool for this unit.  Maybe around the 80 C range it might start to
bring the output power down, but you should see the message of "amp limit" and the bottom left MNGP LED
light up when that happens.

With a Voc of 37 volts, and if your array does not have any partial shading, the input voltage
should be running at around 28 to 30 volts.   SOLAR mode is not always the best mode
for 12V batteries, but we are working on the software to make it work better.

Try Legacy P&O to see if that helps.

The input voltage should be around 77% of open circuit voltage for sanity....  Usually, but only
if there is no shading.

What is the highest amps into the 12V battery you have seen so far  ?

boB

[epsgunner]

15.6 - 15.8..

I'd like to be at 17-18 amps..

6.1 in was getting 13.1 out

The panels are rated at 8.05 VMP.. and based on that 6-13 conversion I would think that would be do-able..

[boB]

15.6 - 15.8..

I'd like to be at 17-18 amps..

6.1 in was getting 13.1 out

The panels are rated at 8.05 VMP.. and based on that 6-13 conversion I would think that would be do-able..

If the Classic is consistently running the input voltage to 16 volts, then try Legacy MPPT mode and see if that helps you.

Imp is about the same at Vmp (~29V) as it is at 16V but the power is higher at ~29V input.

boB

[epsgunner]

Looks like the input voltage being at 16 volts is lower than it should be.

53 degrees C inside will not make the Classic drop its output level.   I would try the
Legacy MPPT mode to see what it does.   53 C is cool for this unit.  Maybe around the 80 C range it might start to
bring the output power down, but you should see the message of "amp limit" and the bottom left MNGP LED
light up when that happens.

With a Voc of 37 volts, and if your array does not have any partial shading, the input voltage
should be running at around 28 to 30 volts.   SOLAR mode is not always the best mode
for 12V batteries, but we are working on the software to make it work better.

Try Legacy P&O to see if that helps.

The input voltage should be around 77% of open circuit voltage for sanity....  Usually, but only
if there is no shading.

What is the highest amps into the 12V battery you have seen so far  ?

boB

I had seen 15.9 amps going in from the panels when they were setup in the 2 panels in a series test.. (aka 24v nominal).. and the voltage going in said 29-34 depending..

Like I had mentioned to HalfCrazy the VOC at standstill was showing like 5 volts.. even though NO panels were connected at all.. he said something like a bleed resistor was causing that and it was normal..

I must admit I did not adjust my voltages in the TWEEKS menu for the PV input  voltage..

Maybe that skewed my numbers DOWN..

[epsgunner]

I must admit I did not adjust my voltages in the TWEEKS menu for the PV input  voltage..

Maybe that skewed my numbers DOWN..

Does anyone know if NOT adjusting the tweeks menu to the correct voltage going into the controller (from the PV) could have messed up the MPPT in calculating the wrong numbers??

[Halfcrazy]

Should not have any bearing on it at all the tracking algorithm is really looking for the sweat spot the actual reading on the screen is a reference for you.

Ryan

[epsgunner]

I just got in my inverter tonight.. so now I can add a LOAD to the equation and see if I can MAX OUT my panel..

Keep you all posted..

[epsgunner]

Just a small update..

Since I last posted I did a single panel test.. got a high of 9.2 amps and 116w from a single panel with a small load (fan) running.. this was with Legacy PO (suggested by bOB) and 20% of PV selected vs. the default 10%..

This puts me more on track for the magic 18 amps to the battery from 2 panels in series (with MPPT kicking) or better I was looking for.  I now have 8 panels and 1160w so I should be alot higher anyway..

Cell pic from the day of recent testing..