Location of the temperature sensor for the solar heater

[NomDePlume]

Hello,
On my solar heating system, the sensor that is used to evaluate the panel temperature (and circulate water through the panels or not) is very much influenced by the wind.

The Sensor is a usual 10K Thermistor Temperature Sensor, just attached on the side of the equipment area. Even on not so windy day, even though the sun is heating pretty good, the system sometimes turns off. Pool might be 83, but the sensor register 79, so turns off the valve.

The sensor is in an exposed area so not much shielding from the wind. The panel themselves are shielded from the wind but are way too far to attach the sensor to (the installer said that on long distance, there can be too much voltage variation to have accurate reading. (picture of the layout below).

I'm curious if anybody has/had similar issue and found a way around this. I think the solution is to increase the thermal mass of the sensor, which is basically a tiny black cylinder, by maybe hot gluing the sensor to a black piece of aluminium?

Thanks for any idea

 

[JohnT]

Wow, that is an unusual installation.

I think I'd try to duplicate the conditions at the panels for your sensor. Put a dummy sensor, like a piece of black pipe at the panels, and use a non-contact thermometer to measure the real sensor and the dummy. When you get similar readings under a variety of conditions, you should be set.

I bet the panels get more wind than you think though.

 

[NomDePlume]

Thanks JohnT, yes, this might not be a typical installation, we first thought of putting the panels right next to the pool. But once we realized what a rack of 500sqf of panels looks like, my wife thought of putting them in the back, builder cleared some space. We did some calculation of heat loss, and it was very minimal. Also it allowed us to orient the panel in the best direction for our location.

I didn't think of trying to match the 2 temperature (sensor/panels). I will certainly play with that. It is very surprising how much heat is collected on the panel even on a somewhat windy day as they are really shielded a lot by the bushes.

Thanks

 

[Isaac-1]

You could probably place the sensor at the panels without any real problem by upsizing the wire a couple of steps to minimize resistance drop, but that will probably be hard to do now as I suspect the pipes are already buried. I am guessing this is about 200 ft, simple 16 gauge low voltage landscaping wire would probably have worked fine.

Ike

p.s. I happen to have a spare temperature sensor here and it appears the stock wire is about 22 gauge, moving to 16 gauge would give you about 1/10th the voltage / resistance drop that you would get with 22 gauge (making some assumptions) for any given distance

 

[WardL]

This is an old thread and I was wondering how it worked out. It seems to me more wind should not change the temperature reading of a thermocouple. Wind chill is significant when you are using energy to stay warm. If it is 70 F out, it is still 70 F out with a breeze. It might feel like 65F, but it is really still 70F. I wonder if something else is going on. I too would like to mount my solar temperature sensor away from my solar panels. The Jandy solar temperature sensor says to not splice the connecting wire. I am pretty sure they say this because it will effect the reading of the sensor. Any other experience with a remote mount temperature sensor?