The National Renewable Energy Lab's Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors can help you determine the average, minimum, and maximum amount of solar energy available at your location, by month or for the entire year. Combined with the efficiency of your system, this can tell you how much energy your PV system will produce. Note that a typical PV system is considered a flat-plate collector, which is mounted at a fixed tilt, and it could be mounted horizontally (0°), vertically (90°), at an angle equal to your latitude, or at angles less than or greater than your latitude.

If you have a savvy enough browser, you can also use NREL's United States Solar Atlas. NASA provides more detailed numbers on anticipated solar energy for your latitude and longitude at their Surface Meteorology and Solar Energy website. You'll need to first create an account.

The University of Oregon provides more generalized Solar Resource Maps for Washington, Oregon, Idaho and western Montana, as well as a Sun Chart Program.

If you're thinking of using some of your solar energy for AC equipment, the Northwest Solar Center has a Load Calculator to help you determine the proper size for your inverter.

Sandia National Labs provides an excellent discussion and examples of different pumping technologies, and worksheets to help you design your own.

Once you have a better idea of your solar resource and various design considerations, talk with your statewide groups and government contacts about financial assistance, the experience of other landowners in the area, and their thoughts on various vendors and consultants. If your local utility is a member of the Northwest Solar Center or a similar collaborative effort, financial and technical assistance may be readily available.