Earlier this summer, my wife said it was time: Rip off the roof and put on a new one.

Simple right?

Hardly. I'm still not done.

But it got me thinking: With a fresh, new 30-year composition shingles, what would it cost to put a solar system on the roof? Hmmm... So I called Julie at Solar City. I told her some of the details of my house -- that it's 1,278 square feet, that my kWh consumption according to my PG&E bill never exceeded 900 per month and that I was only looking to pick her brain for information.

Not a great way to get information, but at least I was straightforward. Julie told me a number of things I missed but did say I'd be spending between $20,000 and $25,000 for a system and that I could get a 30 percent tax incentive. One thing I would have that she said was important: a new roof.

Or at least I will have a new roof. Some day. Anybody ever watch an asphalt shingle melt in your hands? Not a pleasant experience. That means, when it's hot, don't roof.

That's -- mostly -- another story.

Solar panels affix to a roof with a series of hardware. Bolt them in, caulk up the mounts and you're off. The panels instantly convert the sun's rays into direct current, which is fed into an inverter, converted into alternating current and distributed throughout the house. At their peak, the panels can produce enough power to send excess back to the utility.

There are multiple styles and companies. You've got to choose your system, financing and installer. Or you can do it yourself. But there's a lot to know. Size matters. Do you want 18 75-watt panels or fewer 150-watt panels? Does your roof offer enough south-facing surface or will you need to convert north-facing area with complex hardware?

Solarexpert.com does a good job of explaining the types of solar panels:

• Single crystal modules are the most efficient (10% to 17%) and the most expensive. The technology has been around longer than any other and has demonstrated long-term, 30-year stability and can produce power in everything from deep space, hot desert and marine environments. They are usually recognizable as the modules with polka dots or octagons.
• Poly or multicrystalline units are less expensive but demonstrate lower efficiencies (9% to 14%). Polycrystalline modules are pure blue and its size is about the same as its more efficient polka-dotted single-cell cousin.
• Amorphous or thin film cells are manufactured by vaporizing and depositing silicon on either glass, ceramic or steel. The process to manufacture this module is simple and cheap, but efficiency (5% to 7%) is so low that a very large area is required to produce the same kind of power made by the single or polycrystalline modules. This technology is most often seen in toys and calculators as well as in building integrated photovoltaic (BIPV), where the solar module is actually built into the roof or structure.

In the San Joaquin Valley, there are many companies offering the service. In addition to Solar City, the list includes REC Solar Inc., Unlimited Energy, Lifestyle Solar, Nova West Solar, Real Goods Solar, SolarWorld, ACRO Energy Technologies, SunPower Corp., Suntech Solar Inc., Arise Solar, Green Energy Consulting and a number of others.

Here's an hour-long video I found interesting in which a Google research scientist talks about his efforts to install solar with others in the industry. One speaker talks about doing it himself.

As for my own roof, I'm on the fence. I just got AC after four years of a swamp cooler, and keeping the house 78 degrees cost me $250 in July, about half that for June. Hard to make solar pencil.