reconsidering recomendataions on solar
so after 1 year using my solar my outcome is a little less than expected.
I have 2 100W panels mounted on front slope of roof, and 1 additional panel mounded flat on roof behind the DS panel that is on sloped part of roof.
When I park, I do my best to face south so I get full exposure during the complete day.
Typical summer day goes like this.
Wake up and Bogart meter shows I have 70% of my 180 AH (27 series AGM's) left.
The morning sky the sun is low(er) on horizon, so cells are producing maybe total 12A, but its enough to bring the charge up into the mid 80% by 10 am when sun is getting higher in the sky. Since the charge % is going up, the current required to "finish" the batteries is lower so the solar current shown in Bogart shows even less Amp output power. by 12:00-1:00 I see 95% charge, by afternoon its finished off at 100% (and for those that know bogart, I have my charge finish set on #4 which is harder to reach "full charge".)
Now I make the same trip in October.
sun is much lower in sky all day.
again, morning shows around 70% charged. as morning progresses I am seeing 7-8 amps, mid day I am seeing in the 12a range or so, but without running generator I will not see 100% charged by end of day.
This is all caused by sun being lower in the sky, less output from cells.
now in theory, at 100% efficiency, my three 100w panels should be able to produce 25A @ 12 V. But I never see this because when I need max charge (morning) sun angle is not perfect, and when sun angle is perfect I am already into finish charge period. and nothing is 100% efficient.
Now my thoughts.
Since I am PWM controller I am wired in parallel.
(No need to bring up other charger, If I did it again, I would still buy a Bogart Engineering system with charge controller).
Now all the "work sheets" that talk about 3% wire loss show my input cable should be good for "near" 30A. (actual run from roof is 3' 12G wire, than 3' of 10G wire)
But these "wire loss" charges are for FULL SUN and FULL outputs, which I never see because my charge requirements go down ad sun comes up (as well as low sun angles in spring/fall.
Using this line of thought, I am thinking of adding one more 100W panel onto roof.
sure if I ever saw 100% efficiency charge in middle of day It may cause a little more then 3% voltage drop through wire loss, but the other 99.999% of the time I will be less than 3% voltage loss through wire.
Sound like a good idea? that 4th panel will give me more charge at lower solar angles, when I need it most.
I have 2 100W panels mounted on front slope of roof, and 1 additional panel mounded flat on roof behind the DS panel that is on sloped part of roof.
When I park, I do my best to face south so I get full exposure during the complete day.
Typical summer day goes like this.
Wake up and Bogart meter shows I have 70% of my 180 AH (27 series AGM's) left.
The morning sky the sun is low(er) on horizon, so cells are producing maybe total 12A, but its enough to bring the charge up into the mid 80% by 10 am when sun is getting higher in the sky. Since the charge % is going up, the current required to "finish" the batteries is lower so the solar current shown in Bogart shows even less Amp output power. by 12:00-1:00 I see 95% charge, by afternoon its finished off at 100% (and for those that know bogart, I have my charge finish set on #4 which is harder to reach "full charge".)
Now I make the same trip in October.
sun is much lower in sky all day.
again, morning shows around 70% charged. as morning progresses I am seeing 7-8 amps, mid day I am seeing in the 12a range or so, but without running generator I will not see 100% charged by end of day.
This is all caused by sun being lower in the sky, less output from cells.
now in theory, at 100% efficiency, my three 100w panels should be able to produce 25A @ 12 V. But I never see this because when I need max charge (morning) sun angle is not perfect, and when sun angle is perfect I am already into finish charge period. and nothing is 100% efficient.
Now my thoughts.
Since I am PWM controller I am wired in parallel.
(No need to bring up other charger, If I did it again, I would still buy a Bogart Engineering system with charge controller).
Now all the "work sheets" that talk about 3% wire loss show my input cable should be good for "near" 30A. (actual run from roof is 3' 12G wire, than 3' of 10G wire)
But these "wire loss" charges are for FULL SUN and FULL outputs, which I never see because my charge requirements go down ad sun comes up (as well as low sun angles in spring/fall.
Using this line of thought, I am thinking of adding one more 100W panel onto roof.
sure if I ever saw 100% efficiency charge in middle of day It may cause a little more then 3% voltage drop through wire loss, but the other 99.999% of the time I will be less than 3% voltage loss through wire.
Sound like a good idea? that 4th panel will give me more charge at lower solar angles, when I need it most.
