How Solar Modules or Panel Systems Work
Solar modules or panel are made up individual solar cells. The cells contain two layers: one positively charged layer and a negatively charged layer. When light shines on the cells, electrons bounce back and forth between the layers, creating voltage. Each cell generates approximately 0.5 volts DC. These cells are wired in series to create a nominal voltage: typically 12 or 24 volts DC.
Solar modules are typically mounted to a rack on the roof or on the ground at an angle. The most effective angle in our climate is 35 degrees. The most effective azimuth or direction is South.
Because solar modules create DC electricity and houses and businesses typically consume AC electricity, the power must be converted to AC using an inverter. These inverters can be battery-based or battery-less, which is most common with grid tie systems. The inverter converts the power to AC and the power is fed into the electrical service panel. From there, it is consumed by the local loads or fed back to the grid if not being used.
This arrangement with BC Hydro is called Net Metering. This program allows customers to produce a portion of their power onsite. BC Hydro monitors the inflows and outflows from the meter and creates “credits” for excess energy sent back to the grid. This works especially well in our climate where we receive an abundance of sunlight and long days during the summer and shoulder months but we receive very little sun in the winter months. In the summer, a customer can build up credits during the long, sunny days and use those credits during the winter when energy consumption is greater.
Solar systems have very long lifespans - typically 35 years or more. Based on historical weather data, the production from a solar system can be estimated quite accurately. If the capital cost of a system is amortized over a conservative lifespan of 30 years, a unit cost per kilowatt-hour can be calculated. As this unit cost is a fixed cost, comparing it to the current and projected utility rates will give the system owner a sense of cost savings over the system’s lifespan.
The current estimated cost of using a solar PV system over a 30-year period is $0.121 kWh. The current price of BC hydro electricity is $0.09 kWh, but is expected steadily rise over the next 30 years.