To help keep your solar energy panels running efficiently, keep a record of your solar panels performance. On this record, note when the days are overcast and how much energy your panels produced. This will help you plan your energy consumption better. For example, if the forecast is cloudy, then you should wait to do household chores that use a lot of energy.
University of Maine Cooperative Extension discusses how to seal leaks in your home.
Larger solar panels are not necessarily a good option. The quality of each panel is affected by many factors, like wattage and warranty. Consider everything when making a hefty purchase like this.