OK I read through the Solar 101 PDF - great work Jim and a bunch of other threads (here and elsewhere). As I am sending my slightly undersized MPPT controller back (100/20 model) due to exceeding the recommended PV wattage. I was double checking that the 100/30 is what I need for the series connection. Then I saw a post or two or three (elsewhere) on shading issues if in series (70% loss in output or more ??).
A lot of the places we try to pick camp sites that has shade (SWMBO wants shade) That shade moves across the trailer, or whatever makes it through the trees. I know panel output will suffer but would Parallel suffer less?. We would be staying in these spots for several days to a week, so solar output becomes important. (I do have 2000i Honda generators (2) if things get critical) However what I am trying to figure out is as I only have 2 panels is do I series or parallel for my situation. I am seriously considering going back to parallel and dealing with up sizing the 10 awg PV wiring from the junction box to the controller (going to 8 awg for about 15' distance). My plan is 4-6V Deka DC45 255AH (20hr) battery bank. I cant get the Trojan T145's here unless I about double my budget for shipping. Please don't beat me up too bad on this. So charging voltage of 20.4V should work with the Victron MPPT 100/30 unit B+5v to start?. In parallel my panels will be close to 20 amp if I do the math correctly so the 100/30 should still work.
So I need expert input as to the true effects of shading. I'm not sure I understood the diagrams in the solar 101 presentation as to the amount of loss.
BTW - I know there is 8 AWG PV wire, but are there MC4 connectors sized for it? The ones I have are very very tight on the 10 awg PV wire
Reference material
I have 2-190Watt Go Power Panels 380 watts total.
In series Max panel output (used open circuit numbers) is 48.18v @ 9.98 amps. Max power numbers are 40.8v @ 9.45 amps .
In parallel Max panel output voltage 24.09.v @ 19.96 amps. Max power numbers are 20.4 V @ 18.9 amps
Is my math correct?
Solar cell type Mono-crystalline ( Information taken from the back of solar panel ) Does not match what Go Power has on their web page. Numbers are higher.
Output power 190 W
Max Power current 9.45A
Short Circuit current 9.98A
Max Power voltage 20.4V
Open-circuit voltage 24.09 V
Thanks for any help folks
Keith
A lot of the places we try to pick camp sites that has shade (SWMBO wants shade) That shade moves across the trailer, or whatever makes it through the trees. I know panel output will suffer but would Parallel suffer less?. We would be staying in these spots for several days to a week, so solar output becomes important. (I do have 2000i Honda generators (2) if things get critical) However what I am trying to figure out is as I only have 2 panels is do I series or parallel for my situation. I am seriously considering going back to parallel and dealing with up sizing the 10 awg PV wiring from the junction box to the controller (going to 8 awg for about 15' distance). My plan is 4-6V Deka DC45 255AH (20hr) battery bank. I cant get the Trojan T145's here unless I about double my budget for shipping. Please don't beat me up too bad on this. So charging voltage of 20.4V should work with the Victron MPPT 100/30 unit B+5v to start?. In parallel my panels will be close to 20 amp if I do the math correctly so the 100/30 should still work.
So I need expert input as to the true effects of shading. I'm not sure I understood the diagrams in the solar 101 presentation as to the amount of loss.
BTW - I know there is 8 AWG PV wire, but are there MC4 connectors sized for it? The ones I have are very very tight on the 10 awg PV wire
Reference material
I have 2-190Watt Go Power Panels 380 watts total.
In series Max panel output (used open circuit numbers) is 48.18v @ 9.98 amps. Max power numbers are 40.8v @ 9.45 amps .
In parallel Max panel output voltage 24.09.v @ 19.96 amps. Max power numbers are 20.4 V @ 18.9 amps
Is my math correct?
Solar cell type Mono-crystalline ( Information taken from the back of solar panel ) Does not match what Go Power has on their web page. Numbers are higher.
Output power 190 W
Max Power current 9.45A
Short Circuit current 9.98A
Max Power voltage 20.4V
Open-circuit voltage 24.09 V
Thanks for any help folks
Keith
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