Your utility company does total power grid monitoring for the entire area. As you're now generating some of your own power, it falls on you to do that monitoring for your solar power system. We covered basic monitoring gear in the "What You Need To Buy" section earlier; there are lot of choices, but the most basic meters you need are a voltage meter (which tells you how much power you've got stored in the batteries) and an amp/hour meter (preferably with an instantaneous read function), which shows how much current is coming in and how much is being pulled by your utilities.
When setting up your meters, it's important that you have them where you can see them without going out of your way; some meters can be network accessible, so you can check them on your computer screen, others are straight analog. If you don't have a meter that can be checked remotely, we recommend putting the meter near your kitchen. Your kitchen has the single largest electrical load in your home, and this makes it a place to get decent performance metrics under different usage patterns.