Some advice from the programmer of the app:
"What OS are you running on your iPod? Please make sure you are running 3.1 or higher.
"Core Location" is the iPhone resource that determines your position using cell towers, WiFi or GPS. The iPod Touch has no cell tower or GPS location services, but it will try to find your location based on WiFi. This is not very reliable. The application should be detecting that it is running on the iPod Touch, disabling the core location capability. The position can be entered manually via the set-up page. So, I do not understand why you would be getting this error.
As a work around, If you exit the app and go to Settings > General you will see a "Location Services" switch. Turn this "OFF" and fire up Solar Analyser again. If asked "Do you would like to use/enable Location Services", select "NO" or "Cancel". you should then be able to manually enter your location in Set-up. if that does not do it, an update is coming very soon that will ensure this error is corrected for iPod touch users"