emonTx V3 in extreme temperature range

Hi I am interested in using this system to monitor and control a solar site.

The Utility power feed and the Inverter grid tie interconnection are in an outdoor Terminal Box
and from there the load feeds go underground to the house about 100 feet (33 meters) away.

I am in the North part of the U.S. and the temperatures in this Terminal Box will be in a range from a low of about -30C in the winter to a high of over 40C in the summer.

The CT’s and the emonTx V3 would also be in this Terminal Box --- any problems with this module operating over that temperature range ?

I also have a question, if when using the Raspberry Pi with the RFM12Pi wireless board if some of the GPIO pins
are also available to be set via a Python program to output control of relays.

I am doing something similar to this now at another site with an Onset wireless data logger and using a Raspberry Pi
and a Python program to control the GPIO output pins which switch a couple of small opto-isolated relays which in turn control a 30 amp 240 volt contactor for a water heater based on the data logger load and PV output data.

This system appears to have more data available and costs considerably less than the Onset system.

Thanks for any help you can give.


glyn.hudson's picture

Re: emonTx V3 in extreme temperature range

Hi Wallace, 


We have not tested the V3 in extreme conditions, however based on component datasheet and calculations it should be able to achieve the following :



sd solar's picture

Re: emonTx V3 in extreme temperature range

Hi gyln

Thanks for the info --- it does look like it should be able operate at those temps.

I reckon I will have to use a 433 MHz remote whip antenna mounted on the outside of the metal Terminal Box to get the signals out to the Raspberry Pi Base Station which will be located in the house over a 100 feet away.

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