Renogy dcc30s less output than pwm with same panel

[Gompka]

I have upgraded from a 30amp pwm wander to a dcc30s. It is charging a renogy 100ah lithium battery using a 75w solar panel. The panel was putting out 4amps with the pwm, but if i switch over to the dcc30s it barely puts out 2amps. It is averaging about 1.5 amps or less of output, 30w or less according the the dcc30s. The panel is working correctly and checking it with a multimeter shows that it is in spec. Renogy is doing a bad job helping me trouble shoot because the solar panel isn't one of theirs, which is a crock of bs, but that aside. Could it be possible the pwm was working better than the mppt because the solar panel voltage is too low? I do plan on upgrading to another 100w renogy panel, the 75w is a portable one I pull out, but I don't want to buy more stuff until I get this figured out. I have another 80w poly sharp panel I can play with, but I believe the specs are similar to the shell I currently have. I realize the mppt works by turning excess voltage into current, but can it actually work worse than a pwm when battery/panel voltage are close to one another?

 

[timselectric]

Yes, if the panel voltage is fairly close to the battery charging voltage. This is where the PWM shines. MPPT's shine, when they have a higher voltage to work with.

 

[Gompka]

Yes, if the panel voltage is fairly close to the battery charging voltage. This is where the PWM shines. MPPT's shine, when they have a higher voltage to work with.

The shine part I understand, but will the mppt kill 1/2 of my solar output when the panel voltage is low? I have an adjustable bench power supply 30v 10a coming from amazon to test this theory.

* especially considering the fact that the renogy dcc30s only accepts 25v maximum on the solar input. So I can't even run panels in series.

 

[timselectric]

The shine part I understand, but will the mppt kill 1/2 of my solar output when the panel voltage is low? I have an adjustable bench power supply 30v 10a coming from amazon to test this theory.

* especially considering the fact that the renogy dcc30s only accepts 25v maximum on the solar input. So I can't even run panels in series.

MPPT's are not very effective without a wide voltage difference to work with. I'm not familiar with the renogy dcc30s. So, I can't say much about them.

 

[Whinny]

Does the battery need charging? What is it's state of charge or voltage? The charge parameters may be different between the 2 controllers. When testing you should have a load applied that is a little greater than your expected charging capability.

 

[Bobert]

If you still have the pwm scc compare the 2 to make sure it’s not another factor.

 

[camelCase]

How did you measure the charging current? Did you use a multimeter or DC clamp meter or were you just going by the charge controllers' displays? Trust but verify.

 

[12VoltInstalls]

Panel amps at a higher voltage… I’m curious if the amps are a panel output number. What are the SCC to battery amps? That is the critical figure.

Plus battery state of charge could be higher - and the mppt settings could be suboptimal; and an A/B in-the-moment switch from one to the other would give an accurate assessment.

 

[iwasforcedtopickausername]

I think that PWMs can be more efficient in some cases, but that difference is surprising.

Is your battery 12V? What panel voltages are you seeing?

 

[Gompka]

I fixed this issue, it was the panel. Even though the panel shows the correct numbers with a multimeter, once its under load it was doing something whacky. New renogy 100w panel and the dcc30s is pumping out 5.5-6amps!

 

[iwasforcedtopickausername]

I fixed this issue, it was the panel. Even though the panel shows the correct numbers with a multimeter, once its under load it was doing something whacky. New renogy 100w panel and the dcc30s is pumping out 5.5-6amps!

Wow, weird! Nice find.

Can you test the new panel with the PWN controller? Curious what you get with it.

 

[Gompka]

Wow, weird! Nice find.

Can you test the new panel with the PWN controller? Curious what you get with it.

I'll try to do it over the weekend.