How did your panels work out in the long run? I'm about to follow your steps on an ESL panel that's basically completely dead. This will be a massive life saver to bring it back to life. So you just sprayed the panels with the basic Simply Green spray cleaner first, then washed the simply green cleaner off the front and back of the panels with your regular shower head, then washed the panels front and back with distilled water? Did you put the distilled water in a spray bottle to spray it on the panels or just took a gallon jug of distilled water and slowly poured it on the panels? Sorry if these questions are stupid, lol I just really don't want to mess this up!
Is the kind of Simply Green you used?:
https://www.amazon.com/dp/B07S4D8QQ8/ref=twister_B0BWV3TZTT?_encoding=UTF8&th=1
I want to caution anyone doing a shower clean with detergent, that most liquid detergents contain conductive compounds (usually a sodium compound), and any residue left on the panel creates conduction paths that can drain charge off the diaphragm, or worse... a shorting path.
In fact, a popular and cheap conductive diaphragm-coating used by DIY ESL builders is a 50/50 mix of water & dish washing liquid applied with a cotton ball. I've used it myself and it works quite well (very high output) but it also attracts dust. These days I use Licron Crystal.
Just saying... use at your own risk, and if you do, rinse it off thoroughly!