That's the ultimate question.
Going solar is an investment...it adds an additional expense to the cost of building your home. Solar is more expensive than a conventional home, but...
That investment pays off big time. In fact, it begins to pay off the moment the system is activated, using free fuel from the sun to heat and power your home.
Here are a few ways to justify the cost of solar:
Seriously, you cannot over-estimate the value of leaving your portion of the earth a better place than you found it.
On the financial side, let's talk numbers. Let's assume you are going to purchase a 2 kW PV system for your home. I have a 4.2 kW system - larger than most. My neighbors have just installed an 8 kW system because their home is heated in large part by electricity.
You've checked prices with local dealers and plan on paying approximately $18,000 for a 2 kW system installed. According to Solarbuzz.com, PV module prices are running $4.88/watt which means that the panels would cost just under $10,000. Add to that the ancillary equipment (mounting materials, wiring, inverter, etc.) and labor and you're in the $18-20k area. In Maine and many other states there are subsidies that will reimburse you for a portion of your costs - 30-50%! There are also federal tax credits available.
A 2 kW system will likely not power your full home unless you've done significant load reduction (gas/propane water heater, dryer and cooking stove) and have installed energy efficient appliances. But it's a significant reducton of your "carbon footprint" and there's nothing wrong with cutting your electric bill by 30-50%.
More ambitious systems can handle your annual electrical load. It's only a matter of how much you can afford to invest and how well you've eliminated unnecessary energy use. Your lifestyle need not be compromised - just made more efficient.