Hi,
Another feature of the PV/Forward Silicon Diode voltage issue is that the ~600 mV has a negative temperature coefficient of ~2 mV/degree C. That's why all Panels lose about 0.3% of their output voltage/power for each degree C rise in temperature.
No, the "surprising" answer is that most PV systems must "shut down" if a power cut occurs. It's primarily a "safety" requirement to prevent any locally generated power being sent out to the "National Grid" where people may be attempting to repair the cables! I don't know how or if the MicroInverters can handle this situation, but our "Hybrid" (combined PV and Battery) Inverter does have a separate "Un-Interruptable" output facility up to 3 kW (for one 13A socket). Sadly, our installer didn't even offer to connect this up as an option, which I probably would have accepted, if the price had been reasonable. However, it is only primarily intended to run a PC or Router, etc., it's not going to keep the Lights on, or the Pump and Gas valve running in a typical Central Heating system.
Incidentally, we did have a (very rare) power cut recently and not only did the PV system "stop", but because the Router and all the communications also failed, the (one hour) event is still almost "invisible" on our data logs.
Perhaps it's also worth mentioning that there are separate "ac" and "dc" parts of the system. The PV panels themselves generate dc (typically 200 - 350 volts) and so does an (optional) battery (typically 48 volts) whilst the (National) "Grid" is ac. ALL other ac power, e.g. from the Inverter(s), must be perfectly synchronised to the 50 Hz Grid, or there will be a very big bang.
Thus a fundamental difference between MicroInverters and Optimisers (or basic PV panels) is that the "downlead" from the roof will carry ac instead of dc. I guess that optimisers are far cheaper than MicroInverters since they only need to handle ~50v dc compared with ~230v ac (rms, so ~700v peak-peak). Similarly, I believe that some battery packs interface with ac rather than dc.
Even relatively small batteries can be a large added cost to the installation, so it's worth considering their benefits. At best, the most you will be paid for any energy you "Export" (via the "Smart Export Guarantee") will be about 25% of what you have to pay to buy the same energy, and a recent quote I got from BG was nearer 5%. Thus it makes sense to store energy to use overnight (or alternatively charge the battery from lower cost overnight energy after "dull" days). Also, in winter, early morning, late evening or "overcast" weather, etc., the PV system may be only "ticking over" at perhaps 0.2 - 1 kW, so the battery can handle any "surge" load such as boiling a kettle (3kW), Microwave Oven, etc., without needing to pull in any expensive power from the Grid. Sadly, there's nothing that a battery can do about the considerable over-generation in summer (e.g. the last 10 days) and severe under-generation through most of the winter, in UK.
Cheers, Alan.