MPPT algorithms in string inverters

How string inverters track their strings as you are parroting the misinformation by micro inverter proponents and manufacturers to invent something that doesn't exist- including supportive peer reviewed papers.

The MPPT algorithms in string inverters do not track to the worst performing module, they track to the voltage that will make the string perform the best. I can produce many peer reviewed papers to show this fact. As previously pointed out there is often a slight compromise for modules with tolerances, in many cases negligible.

Usually, modules out of the factory are very uniform, but it is true that over the years they can drift apart into slightly different electrical characteristics. However, it is impossible to predict if or how much they will drift. I would invite you to talk to different module manufacturers as I have to see what they say.

PV Watts is not a model, it is a calculation, and it uses a simple formula:

PV x SUN x SYSTEM EFFICIENCY = PRODUCTION

There is no distinction between micro and string inverter, only efficiency. It is very easy to for people to show estimates with more production estimates with actual. PV Watts is a highly conservative estimation tool developed in an up-front rebate world when accurate production estimates didn't matter.

Regard to micro inverters not having DC losses (also stated by a few others in this thread), we need to look at the bigger picture with respect to losses.

Regardless of inverter topology, the distance from PV to point of interconnection share the same rules. While a micro may only have a short "DC run", it has a very long AC run at 240Vac, which would suffer more line losses than those string inverters with a long DC run.

Sometimes it is far better to have a DC run at 400 - 500 V dc than a long 240Vac run from the roof to reduce copper and/or voltage drop.