I have just finished writing an article about one of my iOS apps that is not available on the AppStore. Its name: AuroraViewer and only works on iPad with iOS 5.x and higher.
Its purpose is to view data from inverters connected to solar panels that are installed at my parents’ house. In its current version, the app can only be used by my parents as it requires a JAVA program installed on a server to be able to retrieve the data from the inverters and store it into a MySQL database. Then, an API on the server that allows the iPad app to fetch the data.
There is also a PHP daemon on the server that looks for alarms and send them to the iPad via the APNS (Apple Push Notification Service) so my parents are automatically alerted when there is something wrong with their inverters (e.g. grid fails, read timeout, low power, etc.).
In the future, I may write another version that would allow anyone to use it with their own installation. This version would be available on the AppStore.
To see more about this app, please go to this link.