Holy mark up! thats just a $30 morning star controller with weird prefab clips on it for over twice the price.
Thats a great charger and i used it for years before upgrading my solar system. I just use a clean volt meter. when volts are up I can see its working.
I have it where I can easily see it by just walking by and looking through the window.
The watt meter is a great product from what ive heard but it need to be inline with the charger and batt and most likely be in a hard to see place.