I have a solar panel system installed at my house with three strings connected to a SunnyBoy SB7 inverter. Our home is two stories and is set at a 45-degree angle off cardinal directions, giving us both southeast and southwest roof options. Living in coastal California means we deal with morning clouds, making the southwest roofs more advantageous. Unfortunately, many of our southwest roofs are shaded due to trees, so most of our panels are on the southeast roofs. Recently, the HOA removed a large tree that was causing foundation issues for our neighbor, leaving an ideal section of southwest roof on the first story. However, during the morning, part of it gets shaded by the second story. If I were starting from scratch, I'd go for micro-inverters, which wouldn't let the shaded panel affect its neighbors. But since I'm looking to expand on the newly exposed southwest roof, my plan is to add these panels to the existing string with the second-story southwest panels. What I need is a simple device that can tell if a panel is in sunlight and disconnect it from the circuit if it's not. Does such a device exist and what is it called? Or is there a better approach to this situation? I'm under NEM2 with 22 panels currently and aiming to add 2 more without exceeding the 10% limit.
2 Answers
You might be overthinking this! The shading issue sounds like it’s only temporary, and it might not impact your system as much as you think. Those shaded panels will only be out for little stretches, so adding those panels could still work!
What you're really looking for are 'solar optimizers'. They maximize each panel's output individually and could be just what you need. However, I’m not sure if a standalone sunlight sensor exists. You might have to get a bit creative, or possibly consider micro-inverters if you’re building out your system more extensively.
Thanks for the tip about solar optimizers! I ended up researching that term, but it seems like information out there mostly discusses setups where all the panels already have optimizers. Can I use a panel with an optimizer and still connect it to my inverter along with panels that don’t have them?
But the shading can last longer than just a few moments! If one shaded panel brings down the whole string, that could become a significant problem, especially if you’re adding more panels.