Currently, however, it's a necessity if you want to be completely independent. One way around the problem is to connect your house to the utility grid, buying power from the utility when you need it, and selling to them when you produce more than you need. This way, the utility acts as a practically infinite storage system. The utility has to agree, of course, and in most cases will buy power from you at a much lower price than their own selling price. You will also need special equipment to make sure that the power you sell to your utility is synchronous with theirs, in other words that it shares the same sinusoidal waveform and frequency.
Safety is an issue as well.
The utility has to make sure if there's a power outage in your neighbourhood, that your PV system won't try to feed electricity into lines that a lineman may think is dead. This is called islanding. If you decide to use batteries, keep in mind that they will have to be maintained, and replaced after a certain number of years. The PV modules should last 20 years or more, but batteries just don't have that kind of useful life. Most large inverters will also allow you to automatically control how your system works.