So a question to the knowledgeable on these solar controllers. I understand the basic principles of them (retired elec eng) but I can't fathom out some of the logic.
I've just installed 2x150W solar panels atop the van, working in parallel. So in principle(excepting losses) I should be able to convert~ 300W into current into the back of my Clayton. The panels are rated as ~18v Vmax and 8.1A Imax.
I tested the setup initially with a very cheap, 20A Dokio PWM controller that came free with a portable solar panel. Current delivered to the PWM in this heat was a decent enough 13.4A, so 6.7A per panel. This was confirmed on the DC input that displayed on the Clayton, so this current level was hitting the battery.
So now I switch the panels over to the much more expensive 40A Renogy MPPT that I bought from a member of this forum. The current went down per panel to 5.72A (so 11.44A total) - almost a 2A difference. This was confirmed on the Clayton menu. Switched back to the PWM and it increased back to 13.4A immediately.
So the questions are:
1. why the difference? Does the Renogy MPPT need to "bed in" somehow?
2. If the panels are delivering 8A at 18v, should the solar controller be able to convert some of this power at 12v into a higher current output somehow (P=VI and all that)? Or will the current always be limited to ~ 8A per panel?
Cheers
Dave
I've just installed 2x150W solar panels atop the van, working in parallel. So in principle(excepting losses) I should be able to convert~ 300W into current into the back of my Clayton. The panels are rated as ~18v Vmax and 8.1A Imax.
I tested the setup initially with a very cheap, 20A Dokio PWM controller that came free with a portable solar panel. Current delivered to the PWM in this heat was a decent enough 13.4A, so 6.7A per panel. This was confirmed on the DC input that displayed on the Clayton, so this current level was hitting the battery.
So now I switch the panels over to the much more expensive 40A Renogy MPPT that I bought from a member of this forum. The current went down per panel to 5.72A (so 11.44A total) - almost a 2A difference. This was confirmed on the Clayton menu. Switched back to the PWM and it increased back to 13.4A immediately.
So the questions are:
1. why the difference? Does the Renogy MPPT need to "bed in" somehow?
2. If the panels are delivering 8A at 18v, should the solar controller be able to convert some of this power at 12v into a higher current output somehow (P=VI and all that)? Or will the current always be limited to ~ 8A per panel?
Cheers
Dave
