The Cache is NOT located on the grounds of the solar station. There is a road that leads near the location of the Cache on the East side of Greenfield. Look carefully. It IS there. When you reach the Cache, look to the West; would be cool to bring binoculars if you are skittish about roaming the streets of Detroit; or after you sign the log and replace the Cache get back in your vehicle and work your way directly across Greenfield onto Capitol Street and get a closer view. I've never seen a solar development quite like it.
Important: This area: I-96/Greenfield is a very, very, very busy area. You will be safe no matter what time you go, but the development is best viewed in the wee hours of the morning when traffic is not so busy. Geocachers nervous about entering the City, no matter what time of day, should definitely go in the early hours so you can get a close-up of why I am bringing you here. Enjoy!