The short and kind of misleading
answer is yes, capacitors can be and are used for handling startup surge on beefy motors.
However...
In most cases, people with the sort of loads you are talking about, will be running alternating current loads.
In this case, the limiting factor tends to be the inverter providing said AC, not the batteries or panels.
You need batteries that can handle the current thst the inverter demands, but batteries beefy
enough to run the intended load for even a modest amount of time are generally not the bottleneck.
And, you need enough
solar or other inputs to keep up with whatever amount of power you use. But, quadrupling your
solar panel count won't let the inverter handle a motor with even a slightly larger inrush current..
More panels would, in sunny times, help the *batteries*, if they are marginal for output current. Ie, if you have 100A coming in to a bank that can only output 100A, while this is going on you could output 200A. But, the output current shouldn't be the limiting factor for the battery bank, usually.
There are systems that run all DC loads, but this is much less common, especially when dealing with high wattage items like those listed.
There are also systems that go a step further and omit batteries, but these are much less common still for quite a number of reasons, including such inconveniences as 'nighttime' and 'cloudy days'.
As far as I can see, in all cases it is in theory possible to make it easier to start a load by adding (a) suitable capacitor/s. But, for the most common application involving an inverter, I would speculate that it is likely more practical to buy a more powerful inverter than a bunch of beefy capacitors..
