Option 4: output square wave power instead of sinusoidal and hope you don’t destroy the downstream equipment.
In practice, isn’t most of that storage used as part of a boost converter to get a higher output voltage than you input? You either need to switch capacitors between series and parallel or feed a step-up transformer with low-voltage, high-current A/C, which ends up being enough copper wire to get heavy and expensive.
transforming to a higher or lower voltage can be done with small capacitors / inductors (just switch at higher frequency, for each doubling of frequency you can halve the capacitance and thus cost of capacitors / inductors)
but given a desired AC output wattage implies a specific output power, cycled at twice the line frequency, so with only 1 outlet you need to either throw away half the solar power energy, or have storage capacitors or inductors to store energy for the timescale of the line frequency (which is much much longer than the timescale for using capacitors or inductors for merely stepping up / down the voltage.
for example an ideal inverter drawing 10 kW DC and delivering 10 kW AC at 50Hz line frequency will by definition require an energy store of 10 kW / 2 50Hz = 100 J,
square waves would also work, but would still require 2 outlets, and would require the downstream equipment to tolerate it.
You’re assuming there’s a common ground between the two sides of the inverter. If it’s allowed to float, whichever terminal is supposed to be lower at the moment can be connected to the DC ground while the other is connected to the stepped-up voltage.
This is dual to using a full-wave bridge rectifier to get DC from AC, where a half-wave rectifier is simpler but needs energy storage to ride through the negative half of the cycle.
yes, now you display you understand what it would address (a good design that delivers clean sinusoidal wave forms for all combinations of output power -which sum to smaller than or equal to the total supported power, a square region of power combinations- would be non-trivial but is theoretically absolutely feasible without energy storage elements [other than small ones for stepping up or down, control etc])
it would be nice if a flexible (supporting all operating points in the power square) 1 DC-in 2 AC-out quadrature voltage storage-less inverter had an open-source design.
[One can not make a single outlet sinusoidal without equivalent storage capacitors / inductors, its simple mathematics, constant DC average power in - clean AC power out = power stored and released or simply wasted in sinusoidal oscillating fashion (regardless of implementation).
to avoid storing energy, while requiring clean sinusoidal output, 2 AC outlets is the lowest number of output outlets that admit an exact solution since the sum of 2 power sinusoids in counterphase result in a constant output power.]
the power operating point square is delimmited by 0 and 1/2 total power for each AC outlet.
In practice, isn’t most of that storage used as part of a boost converter to get a higher output voltage than you input? You either need to switch capacitors between series and parallel or feed a step-up transformer with low-voltage, high-current A/C, which ends up being enough copper wire to get heavy and expensive.