How to install 2 instances of Kerbal Space Program from Steam, on one computer

You can do this with Action Groups.

This youtube tutorial provides a good example of how to do exactly what you want:

In short, once you have the solar panels added to your ship:

1. Click on the "Action Groups" icon at the top of the screen. It's the blue button that looks like two gears.

2. Select "Custom1" or whichever number you would like the action to bind to.

3. Click on the solar panels you would like to extend/retract when the key is pressed.

4. Then select "Toggle Panels" (or "Extend Panels"/"Retract Panels", if you only want this action to work in one direction.)

Now when your ship is launched, you can use whichever number key you bound this action group to to toggle your solar panels.

I know this is an old post but it IS possible to "undo" a quickload because I've done it before more than once with 0.20 and 0.22.

The key is to react as soon as you realize what you've done. In Windows, just hit Alt-Ctrl-Del and bring up the task manager, select ksp.exe from the processes tab and click on "End Task", this will kill the game. Restart the game and load your mission, then you will be at the point where your game last autosaved, before you did the quickload.

This works only if you do it quick enough, because a short time after the quickload mistake, the game WILL autosave again which will overwrite the persistent file, but it doesn't do it right away, and a quickload does NOT overwrite the persistent save file.

Again, I have done this more than once because I've made the same mistake, and I can tell you that it works.