I am sitting here at the annual Solar power conference in Denver, CO learning the basics of photovoltaics (PV) and how to design and build a system that can offset some portion of utility power.
For some, especially in undeveloped parts of the world, the issue is how do we create a stand-alone system to power our homes or villages "off-grid" or independent of any power utility. For others (myself included) the goal would be to augment utility power through PV or other renewable source (what is known as a grid-tied system).
Mostly, I was here to learn. However, something about all this is very wild-west-ish and had the kind of intoxicating feel of the web 1.0 world a decade ago. It is exciting to think about both the "powering a village" parts of all this and also the less romantic bits about saving money on the electric bill.
1. Efficiency First. Before you do ANYTHING with PV or any other renewable energy source, make the time and financial investment in reducing your power consumption. There is a commonly referenced ratio of 3:1--i.e., the ratio of savings you can achieve from energy efficiency over the amount you will spend for the same energy delta with the installation of a PV system. A $10K investment in insulation, different light bulbs, and a more energy efficient fridge, will do as much as a $30K investment in PV.
2. PV alone is not the answer. For example, using the sun to generate electricity via PV, and then send that into the house to power a water heater, which then provides hot water to your shower, is a terribly inefficient way to solve the problem. Instead, a solar thermal system in your attic (essentially a plumbing solution) to heat water directly from the sun, and then pump that water through your house is a very efficient way to solve the same problem.
3. Long-term ROI. The equipment for all this is getting better and better, but there are still sun-to-electricity conversion issues that make this a long-term ROI in most parts of the country. For example, to generate 10kW of power, you will need to invest about $100k in PV and the related gear (inverters, charge controllers, other electrical work). This 10kW of power will most likely not power even half of my family's power needs (replace "needs" with "current wasteful usage patterns").
One of the main things I took away from all this, is that regardless of how expensive per kWh Solar is, it is still a constant and perpetual energy source in a world of rising fossil fuel costs--and one that has no carbon liability. In high rebate states, it is an attractive prospect. In lower ones, it is a known quantity in a world of volitle energy.
There are tons of opportunities here--I will try to distill some of mine when I am on the plane flying home.