Hi Mark,
My prototype experimental solar sensor happens to also measure its own internal temperature, so I could write quite a lot, but I'll try to stay on-topic: Even in moderate UK sunshine its internal temperature rises by about 30 degrees C. It's basically a black "box" with a PV panel on most of its top face (used only to charge the battery, the sensor is a small BPW34). However, it heats up significantly more (in sunlight) than a white-boxed temerature-sender which I used for calibration. Therefore, a white box might be preferable; but black plastics are said to be more resistant to UV !
I was interested to discover that another "application" of PTFE is for light reflectors. Maybe that's for its high heat tolerance (e.g. from filiament lamps), but even a few mm thickness of the sheet that I tested will reflect much more light than it transmits. So perhaps a PTFE "wndow" will also help to keep the sensor/electronics cool?
But back to your question: It's well-known that the output power from all PV panels falls considerably when they heat up. But I believe this is almost entrely because the (maximum) output voltage falls; the current stays almost the same. That is one of the reasons why solar light sensors are designed to measure the (short-circuit) current from the sensor/panel.
So, in summary, I don't believe that you need to worry too much about errors due to overheating. But most electronic components "dislike" heat (above a moderate temperature), so it would be wise to keep the solar heating as low as practical. It is of course much less of an issue in the UK, compared with Australia (or even Portugal).
Cheers, Alan.
My prototype experimental solar sensor happens to also measure its own internal temperature, so I could write quite a lot, but I'll try to stay on-topic: Even in moderate UK sunshine its internal temperature rises by about 30 degrees C. It's basically a black "box" with a PV panel on most of its top face (used only to charge the battery, the sensor is a small BPW34). However, it heats up significantly more (in sunlight) than a white-boxed temerature-sender which I used for calibration. Therefore, a white box might be preferable; but black plastics are said to be more resistant to UV !
I was interested to discover that another "application" of PTFE is for light reflectors. Maybe that's for its high heat tolerance (e.g. from filiament lamps), but even a few mm thickness of the sheet that I tested will reflect much more light than it transmits. So perhaps a PTFE "wndow" will also help to keep the sensor/electronics cool?
But back to your question: It's well-known that the output power from all PV panels falls considerably when they heat up. But I believe this is almost entrely because the (maximum) output voltage falls; the current stays almost the same. That is one of the reasons why solar light sensors are designed to measure the (short-circuit) current from the sensor/panel.
So, in summary, I don't believe that you need to worry too much about errors due to overheating. But most electronic components "dislike" heat (above a moderate temperature), so it would be wise to keep the solar heating as low as practical. It is of course much less of an issue in the UK, compared with Australia (or even Portugal).
Cheers, Alan.