Here's a fun question: would smoke from a wood stove chimney passing over solar panels be dense enough to cast a significant shadow on the panels, thus cutting off power?

I was planning on roof-mounting my PV panels for my off-grid house, but I understand that this opens me up to many roof leaks. (I have a steel roof, and I'm looking at 22 200-Watt panels.) An alternative is a pole-mount behind the house -- the back/north yard is earth-bermed, so 10' from the house the ground is 2' below the roof eave and thus 9' below the 7'-high roof ridge. So I was considering a pole mount high enough to cast no roof or chimney shadow on the panels at winter solstice, but then I said, wait, would the chimney smoke itself be an issue?

The roof is 46' deep (N-S), so a mounting 10' north of the house would be 46/2 + 10 = 33' away from the smoke. Would the smoke cast enough of a shadow to affect the PV system?

Thanks, ...Paranoid Terry in eastern Ontario

Cutting off power, unlikely, but reducing peak power is likely.

By how much depends a lot on the volume & contents of the wood exhaust. (Sooty emissions will block more light than condensing water vapor, etc.) But when conditions are such that you can see the shadow of the smoke, of COURSE it will cut into PV output, at least by SOME. It's unlikely to amount to cut the average output by more than a few percent, but I suppose it could be well into double-digits for optimally worst-case conditions (smoky startup on the woodstove, etc.)

In the overall scheme of things prevailing wind, the outdoor temps vs. dew point of the exhaust, etc will all be factors to consider. Putting the PV array further away from the chimney is beneficial only if it's not directly downwind of the chimney most of the time. I'd worry more about keeping sooty deposits from forming on the PV panel surface than the temporary issues about smoke casting a shadow. In eastern Ontario you'll probably suffer a far greater loss of performance from winter snow/ice cover or springtime tree-pollen deposition than from smoke-shadow. Cleaning the front surface of the PV panels at least quarterly to clear dirt, pollen, soot, etc. isn't a bad idea. Ground mounting rather than pole or roof mount makes this task a lot easier, if there's a spot where it will be shadow-free.

Good points, Dana. Fortunately the panels would be north of the roof/chimney and we have a wind from the west, so soot isn't likely to be an issue. But quarterly cleaning is a great tip.
Thanks,
...Terry

Solar PV module installation, “handling and installation” safety are aspects that are of prime importance. These guide lines are meant to safe guard your property and loved ones from possible injury and damage. Follow them and you will avoid a lot of head aches.
Installation safety

* Always wear protective head gear, padded leather gloves and rubber soled safety boots.
* Due to potential electrical hazard do not work on the modules if the terminals are wet.
* Stop working on the modules if the weather is wet, snowy or windy.
* Insert well and true all inter connecting connectors. Double check connections for trueness.
* Secure cables to module frame, installations supports, raceway or structures to avoid movement and make them sag.
* Avoid direct sunlight falling on the connectors.
* Do not touch interconnecting cable ends, or terminal box with bare hands under sun light or during installation, whether or not the modules are connected to each other or the system.
* Do not disconnect a connector while the system is in operation with a working load.
* Do not damage the back cover during installation as this too is an important component of the module.
* Take extra precaution when replacing a module from an array so as to not damage other modules or the supporting structures.
* Keep in mind the PV modules are always installed out doors. Any components used in installing should withstand rigors of nature. Use UV resistant cable ties, corrosion resistant material, sealants and components etc for electrical interconnections.
* Avoid physical injury by taking appropriate safety precautions suitable for working at heights. Always avoid body grounding through un-insulated tools etc.
* Keep away children and pets during installation.
* Last but not least, ensure your work to reliable and approved professional such as Kinggroup.ie Keep in mind, there is a warranty applicable on your PV Modules, Grants are available and that taking insurance cover is a good practice. All these will require a professional installation