Solar Intensity System Cut

[J1mbo]

Does there exist a device to provide a switch off signal to an ASHP based on solar intensity? Much like the sunshine sensor fitted to VWs Climatronic system.

[SteamyTea]

Could you not use a secondary thermostat that sits in a jamjar the sun?

Pretty easy to make a solar sensor with a photoresistor, a RPi and a capacitor.

 

[ProDave]

What exactly are you trying to achieve?

[jack]

41 minutes ago, J1mbo said:

Does there exist a device to provide a switch off signal to an ASHP based on solar intensity? Much like the sunshine sensor fitted to VWs Climatronic system.

 

Do you have PV? If so, then anything that can tell you how much the PV is generating could be the source of such a signal, which could be used in conjunction with your thermostats to block calls for heat.

 

If you don't have PV, I assume you're interested in solar gain, in which case I'd have thought letting the house do its thing based on temperature would be sufficient.

 

One thing to keep in mind is that ASHPs don't like short-cycling, so whatever you, ideally build in a minimum run time element.

[Bruno]

Are you happy with electronics? There are a few cheap projects with arduino which can help you.

Basically you need a solar cell and a resistor in series, than a way to measure the voltage drop across the resistor

https://create.arduino.cc/projecthub/jeffrey2/measuring-solar-radiation-with-arduino-f741ac

Or search "arduino solar intensity"

[J1mbo]

Thanks very much for the replies. So I was hoping there would be something off the shelf but equally I’m happy to make something.

 

@ProDave - I have a Vaillant system with room temp modulation as well as weather compensation. This means system can overshoot unnecessarily when it’s sunny, as it will continue to heat beyond the set point, backing off gradually. So I thought it might be possible to improve it by using the manual cut input to shut it down based on certain combination of sun intensity and inside temperature. And, well basically a little project too :-)

[ProDave]

2 minutes ago, J1mbo said:

Thanks very much for the replies. So I was hoping there would be something off the shelf but equally I’m happy to make something.

 

@ProDave - I have a Vaillant system with room temp modulation as well as weather compensation. This means system can overshoot unnecessarily when it’s sunny, as it will continue to heat beyond the set point, backing off gradually. So I thought it might be possible to improve it by using the manual cut input to shut it down based on certain combination of sun intensity and inside temperature. And, well basically a little project too ?

Turning off the room temp modulation function sounds like the best idea.

 

If I was going to add any automated solar control to my ASHP it would me more along the lines of trying to maximise the time it runs when the sun is out (to use solar PV generation) and shut it down when the sun goes behind a cloud.

[J1mbo]

I don’t have PV and cannot get it due to location. The room temp modulation makes the system more responsive as it turns up the flow when there is more deviation (and vice versa, leading I suppose to lower average flow temperatures).