BobDylanSolar
New Member
I have some future shading concerns from tree growth. Inverter is Tesla 7.6kW with 4 MPPT which are rated to 60V minimum input voltage per string. Panels are REC Pure Alpha Pure R 420W with nominal voltage of 50V.
What is the minimum number of panels per MPPT? Is 2 enough? What I don't understand is if the panels are partially shaded or low sun angle will they still produce some volts but fail to meet the 60V threshold? Meaning 3 or 4 panels might be better.
More generally, I have 2 7' sapplings planted 15 feet west of the house. My roof is 16' tall at the west edge and 21' at the center spine. I could put panels on the east roof, but with time of use AND net metering in Colorado, the afternoon sun is much more valuable (12c before noon, 18c from 12-3, and 28c from 3-6pm). I figure the panels will receive no shade for the first 5-7 years. After 5-7 years, the lower 3 panels may receive shade after 6 or 7pm. In 10 years, there would be shade after 4pm on the lower panels and 5pm on the upper panels. Even when the trees are mature (20+ years from now), I don't think the upper panels will receive shade until 3pm or so. That's based on the Maple growing to 45' which is 25' above the upper panels which are 25' away from the tree, which is a 45 degree. The sun altitute is 45 degrees at 4:15pm here in June and July. And 3:15pm in March and September.
By that point I will have gotten a ton of valuable afternoon sun out of them. Am I making the right decision?
What is the minimum number of panels per MPPT? Is 2 enough? What I don't understand is if the panels are partially shaded or low sun angle will they still produce some volts but fail to meet the 60V threshold? Meaning 3 or 4 panels might be better.
More generally, I have 2 7' sapplings planted 15 feet west of the house. My roof is 16' tall at the west edge and 21' at the center spine. I could put panels on the east roof, but with time of use AND net metering in Colorado, the afternoon sun is much more valuable (12c before noon, 18c from 12-3, and 28c from 3-6pm). I figure the panels will receive no shade for the first 5-7 years. After 5-7 years, the lower 3 panels may receive shade after 6 or 7pm. In 10 years, there would be shade after 4pm on the lower panels and 5pm on the upper panels. Even when the trees are mature (20+ years from now), I don't think the upper panels will receive shade until 3pm or so. That's based on the Maple growing to 45' which is 25' above the upper panels which are 25' away from the tree, which is a 45 degree. The sun altitute is 45 degrees at 4:15pm here in June and July. And 3:15pm in March and September.
By that point I will have gotten a ton of valuable afternoon sun out of them. Am I making the right decision?
