Renogy Solar Panels

14.4 is a pretty good charge. I have no idea how your controller is programmed but it may be going into absorb. This happens when the batteries reach the absorb voltage which is often 14.4 v. Your controller is simply trying to not overcharge your batteries. If it regulates down to 2.5 amps try turning on a bunch of lights and see it it goes back up. It should.

sounds normal to me
what is the battery state of charge ?
near full batteries don't need much
and
panels reduce output as they heat up

moved from Technology corner

They were very close to full charge...I don't recall the voltage but remember thinking they're almost done. I'll try putting a larger load on them. I had tried but was focused on the Load screen and not the Battery screen on my controller. The Load screen wasn't showing a load and I had turned ON all of my LED lights in the camper. I'll try things like my furnace/blower, DVD player, etc.

Does 17 vdc on the PV sound right? I thought that was a bit high. First solar system so I'm not sure of what's normal yet.

Thanks for the replies!

MrWizard wrote:
sounds normal to me
what is the battery state of charge ?
near full batteries don't need much
and
panels reduce output as they heat up

Very interesting observation...! I was wondering about that. I noticed that the panel temps had increased from 70 degrees F to around 82 degrees F. I don't know if that's a big temp increase because temps here in Idaho during the summer can easily get in the 90s.

I also noted in my manual that you can configure the controller to change it's algorithm to be more efficient as the panel temps go up. I'm a noobie so I haven't figured that out yet.

14.4V is normal when battery is "near" full. This type of controller cuts the excess voltage off, while passing all the amps through. PV amps drop because battery is near full and can't accept more current.

Controller should not measure panel temps. It measures temps at the sensor, and the sensor is either remote on wire, or inside the controller. If sensor is close to the panel, it will screw your setpoints up. Setpoints, i.e. Bulk 14.4V and Float 13.6V, should be changed when battery temps change, hence the correct placement of sensor would be on the battery or very close to it - not on the panel.

I also noted in my manual that you can configure the controller to change it's algorithm to be more efficient as the panel temps go up.

Content of Renogy kits varies, God knows what controller you've got and whether the manual is the right one, but this phrase sounds like part Chinglish and part marketing hype. You don't change algorithm when temps change. But you should change setpoints then. If controller has temp compensation feature and it works, it will change setpoints automatically. It will lower or raise the setpoints when temps are getting higher or lower, respectively.

The Load screen wasn't showing a load and I had turned ON all of my LED lights in the camper.

If you don't use the Load terminals, it will not show any load. Normally, people don't use those.

jstaffon

the 17v PV voltage is due to PWM, the controller it turning on and off (very fast) to limit power to the battery since it is @ 14.4. The panels are making more power than is needed and the controller is limiting panel output.

The on voltage is 14.4v and the off voltage is ~21v and the display shows the average. As the off time increases the display should show even higher voltage (PV) as current tapers lower.

After the set absorption time, the controller goes into float, a lower set voltage, the controller continues PWM to limit power to the battery to maintain the float setting.

Temp compensation is based on the controller's temp unless you have the temp probe that allows the probe to be at the battery. Not much temp comp @ 82F, in hot temps the 14.4v is lowered and in cold it is increased. 3 milivolt/degree C/cell

It's too bad that 100 W is not really enough to do much.
Good start.

jstaffon wrote:

I also noted in my manual that you can configure the controller to change it's algorithm to be more efficient as the panel temps go up. I'm a noobie so I haven't figured that out yet.

Temp compensation default setting is adequate.

Hot batteries do not need as much voltage, cold ones need more. That is what the temp comp does, yes, the amount is programmable to match a particular battery maker specs but programing is not necessary, the default is fine and automatic.

gatorcq wrote:
It's too bad that 100 W is not really enough to do much.
Good start.

I've been on the fence whether to install a permanent solution on top of my camper with much more capacity. Right now my goal is to keep the batteries topped off while dry camping to minimize the time I need to run my generator. The 100 W Renogy solution wasn't very expensive so I thought I'd play around with solar before I jump in with both feet. We also park our 5th wheel under trees while camping...the portable solution should work well in those situations. Once I play around with this system more, I may decide I want to invest in an inverter and get a bigger system. I'm excited! Thanks!