Even in Seattle WA, there is plenty of sunlight to power solar cells to generate electricity. Below is a summary of my experience with installing solar panels on our house. A version of this is available as a two-page pdf file here.
Why Did We Install Solar Panels?
We had ‘Itek’ solar panels (8 kWh max output) installed on our NE Seattle home the first week of July 2014 by A&R Solar (http://www.a-rsolar.com). Since installation, the panels have generated over 3.5 MWh of power and put 1.7 MWh of power back on the grid. As of mid-October, our energy generation was net positive with no electricity charges and in fact, we have a $95 credit with Seattle City Light.
The 30 solar panels are located at roof locations favorable for maximal capture of solar energy. The solar panels are grouped and wired in series, which means that the lowest producing panel in a series dictates the amount of power generated by that group. This is important if there is shading from chimneys or trees. Panels generate Direct Current (DC) electricity, which is sent to inverters at ground level that convert the DC to AC power. Inverter data can be tapped to provide information about power generation. It is possible to install a micro inverter on each panel so that AC is generated separately for each panel. For more information on how solar works and system components see at A&R Solar: http://www.a-rsolar.com/how-does-solar-power-work
Electric power use and generation can be monitored in real time using the eGauge system (see http://www.egauge.net/). This system is not part of the standard installation, but is highly recommended to monitor system functioning, plus it is fun and informative. Below is an example of a partly sunny, 24-hour period (October 15-16, 2014). The red shading is power usage from the grid, green shading is power sent back to the grid, and white shading indicates power generated and used. The variability of the green shading indicates periodical cloud cover. The two spikes in the green shaded area indicate power used (and generated by the solar panels) to run the dishwasher. The display bar on the right illustrates real time power use and generation. The sensitivity of the display can be adjusted down to 10-minute increments so the influence of turning on and off room lights can be observed. The eGauage system is an added cost but worth the investment for system tracking, feedback, and education.