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[dgmcfadden]

I have a little off grid system. 3 - 100 watt panels tied together in parallel. (All positives are connected to a distribution block and all negatives to another). Each block is connected to 4 gauge that goes to the controller. Each positive from the panels leading to the box has a fuse. When I unplug two panels, I measure the current off the + 4AWG and get five amps. I measure the + on the hot panel and get 5amps. (Perfect) So here is what confuses me.... when I insert a fuse for the second panel the current from the first decrease by almost half. When I check the current at the 4AWG around 5amps (I would expect 10). When I put the fuse in for the third panel and test the +4AWG about 5 or 6amps. If I test any panel individually i get about 5amps. When I test the voltage at the blocks 15 volts, add a panel 17 volts and the third 19 volts. Does this make sense?

[sensij]

What is the state of charge of the battery? If it is close to full, the charge controller could br operating in a constant voltage mode, which means current would be limited no matter how much is potentially available. What charge controller are you using? Have you tried running some loads with all three panels to see if it makes a difference?

[dgmcfadden]

Renogy Wanderer. When I saw the voltage at the distribution blocks I jumped down and checked the controller. At the controller with all three panels on I was getting 19 volts (panel side) and 14.8 volts battery side. Battery was not full and in bulk charge mode (maybe). Not sure how to running a load to check them? I appreciate your input.

[sensij]

Renogy Wanderer. When I saw the voltage at the distribution blocks I jumped down and checked the controller. At the controller with all three panels on I was getting 19 volts (panel side) and 14.8 volts battery side. Battery was not full and in bulk charge mode (maybe). Not sure how to running a load to check them? I appreciate your input.

14.8 V sounds like absorb, so yes, the battery may not have been accepting more current at that voltage. Your observation of higher voltage on the input side with increasing panels could be result of lower PWM duty cycle to maintain the 5 A the battery was accepting, which is healthy.

If you want to do the test again, try adding some load (turn on some lights? What are you powering with his system?) that can consume the additional current.

[NEOH]

I have a little off grid system. 3 - 100 watt panels tied together in parallel. (All positives are connected to a distribution block and all negatives to another). Each block is connected to 4 gauge that goes to the controller. Each positive from the panels leading to the box has a fuse. When I unplug two panels, I measure the current off the + 4AWG and get five amps. I measure the + on the hot panel and get 5amps. (Perfect) So here is what confuses me.... when I insert a fuse for the second panel the current from the first decrease by almost half. When I check the current at the 4AWG around 5amps (I would expect 10). When I put the fuse in for the third panel and test the +4AWG about 5 or 6amps. If I test any panel individually i get about 5amps. When I test the voltage at the blocks 15 volts, add a panel 17 volts and the third 19 volts. Does this make sense?

Yes, this makes sense.
The PV panels are "sharing" the load of charging the battery, which is now minimal.
This is exactly what is supposed to happen when the Battery is almost full and you have little or no load.
With no load, the amps will decrease as the battery voltage rises.
As you add more PV Panels in parallel, each one supplies a portion of the needed amps and therefore the PV Voltage input to the Charge Controller rises.

Connect a 300 Watt Load to the Battery Bank.
That would be 23 amps into the DC-to-AC Inverter.
With the sun shining, now measure the amps flowing from each PV Panel (+) wire !!!

Always, shut-off all loads from the battery before connecting or disconnecting PV Panels.