4 ms·

Ditch microinverters, get a large MPPT. Sure you spend more in cabling but microinverters are poorly-made and fail a LOT.

yjftsjthsd-h 2y ago
For those of us just tuning in, what is a MPPT? Doing a web search turns up https://en.wikipedia.org/wiki/Maximum_power_point_tracking https://en.wikipedia.org/wiki/Maximum_power_point_tracking but that's not a device like I'd assumed, it's... are you just saying to use something that can sink a lot of DC current straight from the panels? Or to just use a smaller number of bigger inverters?
- jaggederest 2y ago
  The one you link is the one he's talking about. They basically electronically optimize the panels to put out max power. It's a physical embodiment of the theoretical calculation. Instead of having a mini-inventer on each panel, you have one MPPT and inverter for ~20 panels in a string. This has cheaper costs but the downside that e.g. shading on one panel can cause the entire string to reduce output, depending on how your MPPT and panels are wired.
  - toomuchtodo 2y ago
    Indeed, this is why micro inverters are spec’d for residential rooftops, and MPPT for utility scale solar. Rarely is shading a concern with utility scale, where as it’s much more common in small scale installs. I've had great luck with Enphase IQ8 series micro inverters fwiw from a cost and reliability perspective on smaller scale systems.
    - jaggederest 2y ago
      They're still so expensive that it's hard to justify in my mind. I'd rather just install an extra string or two of cheap panels and eat the shading losses, since I have the space available
  - yjftsjthsd-h 2y ago
    Oh, this is the "string inverter" approach that came up in my search. I assumed it wasn't that because running in series seemed like it should result in less cabling [cost], not more. Is it less cabling but thicker to handle the current?
    - jaggederest 2y ago
      Yeah it's a straight DC high voltage (~150-500v) to the inverter, which means running two 10-gauge cables the entire length of the array. With mini-inverters you have ~6 inches of 10-gauge cable into a mini inverter and the rest of the connection is via standard 14gauge 3 strand romex or something.
      - yjftsjthsd-h 2y ago
        Thanks for explaining:)
        jaggederest 2y ago
        No worries at all, I just learned from youtube mostly, I think this guy has the best content https://www.youtube.com/@WillProwse https://www.youtube.com/@WillProwse

yjftsjthsd-h 2y ago

For those of us just tuning in, what is a MPPT? Doing a web search turns up https://en.wikipedia.org/wiki/Maximum_power_point_tracking https://en.wikipedia.org/wiki/Maximum_power_point_tracking but that's not a device like I'd assumed, it's... are you just saying to use something that can sink a lot of DC current straight from the panels? Or to just use a smaller number of bigger inverters?

jaggederest 2y ago
The one you link is the one he's talking about. They basically electronically optimize the panels to put out max power. It's a physical embodiment of the theoretical calculation. Instead of having a mini-inventer on each panel, you have one MPPT and inverter for ~20 panels in a string. This has cheaper costs but the downside that e.g. shading on one panel can cause the entire string to reduce output, depending on how your MPPT and panels are wired.
- toomuchtodo 2y ago
  Indeed, this is why micro inverters are spec’d for residential rooftops, and MPPT for utility scale solar. Rarely is shading a concern with utility scale, where as it’s much more common in small scale installs. I've had great luck with Enphase IQ8 series micro inverters fwiw from a cost and reliability perspective on smaller scale systems.
  - jaggederest 2y ago
    They're still so expensive that it's hard to justify in my mind. I'd rather just install an extra string or two of cheap panels and eat the shading losses, since I have the space available
- yjftsjthsd-h 2y ago
  Oh, this is the "string inverter" approach that came up in my search. I assumed it wasn't that because running in series seemed like it should result in less cabling [cost], not more. Is it less cabling but thicker to handle the current?
  - jaggederest 2y ago
    Yeah it's a straight DC high voltage (~150-500v) to the inverter, which means running two 10-gauge cables the entire length of the array. With mini-inverters you have ~6 inches of 10-gauge cable into a mini inverter and the rest of the connection is via standard 14gauge 3 strand romex or something.
    - yjftsjthsd-h 2y ago
      Thanks for explaining:)
      - jaggederest 2y ago
        No worries at all, I just learned from youtube mostly, I think this guy has the best content https://www.youtube.com/@WillProwse https://www.youtube.com/@WillProwse