Failure to Communicate

Meanwhile, it's back to figuring out why I'm 1) not seeing power being reported at the Tigo web site, and 2) not seeing any power at the inverter DC input.

Let's just make a long story less long.

December

We were never able to exactly identify the reason why the Tigo MMU/gateway was unable to communicate with the LMUs on each of the solar modules. I did discover that powering down the MMU would cause DC to appear at the inverter. This was somewhat of a surprise to me in that the individual LMUs moderate the voltage coming from the solar module to which it is attached and I had expected that failure to communicate would result in zero VDC. Tigo explained that the LMUs fall-back to just passing through the unmodified voltage in the case of a communication failure; makes perfect sense.

January

Once again I checked the continuity of the cable which runs between the MMU and the gateway. With Tigo's help I also checked the voltage inside the gateway and inspected the LEDs. Tigo sent out a new gateway. No change. Tigo sent out a new gateway cable. No change. Remember, this is all bleeding edge equipment so challenges like this were expected. In no way was I frustrated by these communication issues—the only anxiety I felt was that we could in fact get the Tigo Maximizers working.

February

So Tigo sent out replacements for everything: new MMU, new gateway, and 24 new LMUs!

I hate to keep you in suspense, but since this was still Winter and I despise working in sub-freezing weather I postponed getting back up on the roof until the daytime temperatures were going to be at least in the upper 40°F range.