I’m working on a project for automated cleaning of solar panels, and I’m looking for a reliable sensor to detect dirt (dust, sand, etc.) directly on the panel surface.
I’ve looked into sensors like the GP2Y1010AU0F and DSM501A, but these are designed for detecting airborne particles.
What I need is a way to detect dust accumulation on the panel itself, not in the air.
Do you have any recommendations for:
A sensor suitable for surface dirt detection?
Or an alternative technical approach to determine if a panel is dirty?
Knowing nothing about the material properties of solar panels, so just a wild guess, but maybe you could test how reflective the surface is - maybe by measuring the amount IR is reflected back using a IR Tx/Rx pair.
Or maybe just clean the panels regularly regardless.
Just as @markd833 I find it difficult to think of any sensors for this, and would recommend regular cleaning. But there might be one way of knowing actually, a reference PV panel that is cleaned every day, week or so often deemed necessary.
It also occurred to me that - given the lack of information from the OP - that the surface of the panel may need to be scanned rather than just a simple point check. That would involve 2 axis mechanical stuff, motors, electrics etc per panel. Would all that extra equipment take more power from the solar panels and kinda defeat the purpose.
I've no off-grid knowledge - other than watching too many episodes of Homestead Rescue - but others here may have first hand experience of this sort of thing.
Or maybe you are wanting to carry out laboratory testing and then the scenario is completely different.....
It wouldn't be difficult to make a "sensor" with a visible light source combined with light sensor measuring light through a flat transparent "reference" glass or measuring scattering on the same side of that glass. It would give you good estimate how dirty that reference glass is.
The problem is that also rain, fog, condensed humidity and frost changes the glass transparency, not just dust.
@arieloss
You might think about having your reference LDR arranged so that you could protect it from contamination and just uncover it when you wanted to make a measurement. That plus an LDR that was positioned to get the same contamination as the panel would make for a pretty reliable system.
Solar production forecasts are available. Google a bit - you might be able to find one that's reliable enough over several days to tell you that your panels need a clean.
Can't be a new problem either - what have other folks done?
I was thinking that you could compare the forecast production with actuals (by talking to the MPPT or whatever controllers), keep records about how the two compare and when the actuals consistently lag the forecast, call for a clean.
I understand your point, but forecast doesn't count clouds, (mis)orientation of panels, shadows from trees etc.
Those not counted variables have more effect than dust.
Ok, orientation of panels and fixed shadows could be calculated to match the forecast. But local weather with clouds would be more difficult.
With very clever algorithm it would be possible though I expect.