I think that Solar Probe was an idea first proposed back in the 1950s, although it could have been 1964. It took a long time for a bunch of things to happen to make it possible. That included technology development, but also time for enough people to declare that it was important to do.
The concepts have evolved a lot. Back around 2006 or so the concept for Solar Probe involved several RTGs (nuclear batteries) because they did not know how to use solar panels that close to the sun. There was some technology development that enabled them to come up with high temperature systems so they could do the mission with solar.
If you want to see some clever design, look into the design for the solar panels on SP+. The panels actually retract as they get close to the sun, but they have small tips that still stick out a little bit to provide some power.