cdherman
New Member
I am trying to get my head around an Hybrid/AIO system. Looking at the EG4 18k for instance, it uses up to 500v, but can handle up to 600v without damage. OK, seems straight forward enough. I will have a long run for the DC lines back to the AIO, so I want max voltage.
Then I look at panel spec sheets. These Canada solar 400w units have the following ratings: Wattage 400, VOC 36.8, ISC 13.85A
Canada Solar 400w
So the ignorant guy in me says I can take 500v / 36.8 = 13.58, round down to 13 panels and that string should be safe.
But someone, somewhere in my readings, notes that one must accommodate for "over production events" like light reflection off of snow or cold temps. I have tried PVWatts to get an idea if/when this could occur at the location where the panels will be, but to no avail.
Experience tells me that in the location the system is going, snow cover is seldom a problem, but can occur. This system would be oriented to the west, 270 deg. I would think that would also reduce events of "double insolation" but I could be wrong, thinking afternoon in January on a cold snow covered day as the sun is setting. But in that event, the panel orientation, while correct in terms of axis, would be VERY flat, like 30-40 tops (reference 90 as optimal for production), rendering the reflected light off the snow nearly parallel to the panels. The panels are going on a roof around 20 ft high, which further "flattens" the angle, if my aging brain is seeing my long lost trigonometry correctly....
Other variable I see mentioned that creates over production: Very cold temps. Now, these panels will be on western high plains. It does get very cold there, rarely a day with no clouds and it won't break 0F. Rare. But it happens. Polar vortex out of Canada and it gets darn cold. But happens again when the sun will be hitting the panels at really low angles.
In short, how does one arrive at an optimal string size to avoid over voltage situations, but also mindful that higher voltages allow better DC transmission with smaller (and cheaper) cables over a distance (150 ft)?
Then I look at panel spec sheets. These Canada solar 400w units have the following ratings: Wattage 400, VOC 36.8, ISC 13.85A
Canada Solar 400w
So the ignorant guy in me says I can take 500v / 36.8 = 13.58, round down to 13 panels and that string should be safe.
But someone, somewhere in my readings, notes that one must accommodate for "over production events" like light reflection off of snow or cold temps. I have tried PVWatts to get an idea if/when this could occur at the location where the panels will be, but to no avail.
Experience tells me that in the location the system is going, snow cover is seldom a problem, but can occur. This system would be oriented to the west, 270 deg. I would think that would also reduce events of "double insolation" but I could be wrong, thinking afternoon in January on a cold snow covered day as the sun is setting. But in that event, the panel orientation, while correct in terms of axis, would be VERY flat, like 30-40 tops (reference 90 as optimal for production), rendering the reflected light off the snow nearly parallel to the panels. The panels are going on a roof around 20 ft high, which further "flattens" the angle, if my aging brain is seeing my long lost trigonometry correctly....
Other variable I see mentioned that creates over production: Very cold temps. Now, these panels will be on western high plains. It does get very cold there, rarely a day with no clouds and it won't break 0F. Rare. But it happens. Polar vortex out of Canada and it gets darn cold. But happens again when the sun will be hitting the panels at really low angles.
In short, how does one arrive at an optimal string size to avoid over voltage situations, but also mindful that higher voltages allow better DC transmission with smaller (and cheaper) cables over a distance (150 ft)?