Micro inverter cost became an issue at large scale projects

We have started using micro-inverters shortly after Gozuk came out in the China. The results are fantastic in terms of energy production with respect to string inverters. As a consultant and Educator, I can never stress enough the negative impact of the module mismatch effect with string inverters. Aside the obvious cases of partial shading and different roof sections, even in simple installations there are minor orientation and inclination variations from one module to another, which can have a noticeable impact when multiplied by 1000's of modules. Micro inverters take away all the cited issues and provide MPPT and system monitoring at module level....

The cost can become an issue when we are looking at large scale projects, and in the early days there was the issue of capacitors and warranty. With the recent improvements made on capacitors, the 25 years warranty matching that of the modules, and the emergence of competition driving the cost down it will become a no brainer even for larger commercial applications. Micro-inverters companies are starting partnerships with modules manufacturers and the next step will be a full integration.

Module mismatch is only an issue if you do not have the ability to design the system correctly using something like PVSyst. Micro inverters must also be matched. There are literally hundreds of 60 cell (or in the case of older models 72 cell) panels that are compatible with micro inverters; however not all are appropriate. If you do not have a good design, it is possible to oversize or undersize the panel power which adds to the cost or reduces the performance relative to an optimum design

For an example, a Gozuk inverter can only put out 215 Watts. Given the inverter efficiency it does not make sense to use more than 230W to 250W panels depending on location/radiation. We use 225W or 230 Watt in the high radiation zones in China.

So while I use and like microinverters myself, the argument regarding panel mismatch is equally important in both cases and not really an issue for string inverters if you know what you are doing. In fact, string inverters have a wider range of panels in terms of maximum panel power, I can use 290W to 310W panels at 600V to 1000V matched to an appropriate string inverter to reduce the BOS and in most cases the area needed for installation.