Wrong!
Here's a spec sheet for some random solar panels. I chose it because it has the right specs on it.
http://decolineinc.com/wp-content/uploads/2013/04/Solar-panel-specs-21.jpg
The top panel is rated for 120 to 140 watts. The
efficiency is 13.7 to 16.6%. Output is therefore 16.44 to 23.24 watts. That is how solar panels are rated. I've only been doing this shit professionally for like 40+ years in one capacity or another. I know how to read the spec sheets. The best solar panels on the market like the LG ones have an efficiency of about 20 to 22% for residential installations.
Under "perfect" conditions, the sun is aligned exactly 90 degrees to the panel, a rarity unless you have 2 axis solar tracking, which NO residential array uses. Therefore, the efficiency of residential panels is even lower than the full capacity of the panel because it is either never, or next to never aligned perfectly with the sun.
You obviously have never run a large generator or operated on a grid. I have. Most non-commercial solar arrays are not monitored. Many residential ones shutdown automatically as a protection feature if the array is producing differential power from portions of it, like if a shadow from a cloud or tree covers part of the array. It takes much more than a "simple switch" to control such an array. Voltage sensing is necessary as it power sensing for each group of panels. On a typical residential array, 4 to 8 panels in series make up a group depending on the voltage desired, and those are then grouped in parallel for the entire array.
As for large generators, you can change the excitation of the armature to vary the power output. They are monitored and much easier to operate and control than a mass of solar panels any day of the week.