How to convert an DC to AC signal more efficiently H-bridge?
If you synchronously rectify your "grid" by whatever means you will get a pulsating DC waveform .Mosfets will be fine for you to use here .This synchronous rectifier bridge runs at power frequencies not PWM frequencies.So there are basicly no switching losses here so with readily available low RDs mosfets the losses of this section can be well under 1% .Now your PWM could be a Buck convertor or buck boost or sepic or zeta or cuk .The key point here is that your losses will be much lower if you take the approach I mentioned.This approach is accepted and it is used by many solar manufacturers .You can now see that you can sleepwalk to 90% efficiency .If you trick up your buck with some switching loss reduction scheme and keep the PWM frequency sane you can crack 95% which is what people want.Because solar cells are not cheap it is worth it to squeeze the last drop of power out of them.