Partial Shade and Disconnecting your Solar Panels at Night

[wtwnnil]

Is it harmful to leave a solar panel connected while under partial shade, and to leave it connected during the night?

This is potentially a very basic question. I've got a Canadian Solar 445W bifacial panel (CS3W-445MB-AG, see: https://solarshop.baywa-re.ca/site/assets/Product Specs/CAN-3713_DS.pdf). I've read that continual exposure to partial shade can damage the solar panels by forcing their bypass diodes to compensate and work extra hard. Is this a prevalent issue, and/or was this more of an issue with earlier models of solar panels?

As such, I'm wondering if I should disconnect my solar panels when I'm parked under dappled shade, and during the night? (I have a dual-pole breaker installed so it'd be easy to disconnect the solar panel).

 

[wattmatters]

Dappled light/shade and low or no no light conditions (e.g. cloudy or nighttime) are not a threat to your solar PV. No need to disconnect them. The current will be low or zero.

What does stress PV panels is partial hard shading, like a chimney casting a hard shadow across a portion of the panel on a sunny day. The diodes will help protect the panel, and they are designed to manage that situation - but only up to a point. If a panel is constantly subjected to such conditions over many years then there is a fair chance it will fail eventually (and the fix is not to place them there in the first place or to remove the object casting shade). But if it's a temporary situation then no big deal, they are designed to cope with that.

As for switching PV disconnects on/off, if you do need to do it, it's best done under low/no light conditions when there is little to no current flowing. It avoids any chance of DC arcing in the breaker.

 

[wtwnnil]

Thanks, wattmatters. That makes perfect sense! I appreciate you sharing your time ?