question

You may not have enough voltage from that panel to start the controller. Check the manual, Vbat + ? Often it needs to be 5 volts more than the battery. The 17 volts you mention may be cutting it too close. (or you reversed your panels polarity.)

-Bill

Thanks for the pointers Bill. I will be testing for everything plus reverse polarity as suggested now that I am back from the trip we went on through Zambia and Malawi just after the installation of the mppt - which was a last minute recommendation of a 4x4 workshop when doing final preps. I have only previously used pwms. Had no time to personally test it and trusted it would work. The problems were picked up on the trip when needing solar which resulted in us having to move on early from places without 220v mains and drive around a bit more to ensure substantial fridge stock remained cold/frozen, which was a bit frustrating. Seems like there is actually a bit more to mppt technology when it comes to proper installation, wiring and panel pairing etc. Previous experience with pwms was good. Simple and straight forward and reliable in my personal case. Must say this experience is making me nervous. Cant afford such problems in eg central kalahari in Botswana where you have to be totally self sufficient.