There are several technologies available, however, a 100 Watt photovoltaic panel is a 100 Watt panel no matter what the technology. Your decisions are usually cost sensitive. Efficiency is essentially a matter of square inches to watts produced, a 5% difference is solar panel size doesn't matter to most installations. However, cost does matter! We help you find the most cost effective solution for your budgets and plans. For this reason we do not list "packages", but design your system with without specific items and specific manufacturers in mind. When it comes time to finalize and cost the system out, we shop the manufacturers and distributors to find out what's most cost effective today.
Colour matters in Canada. Photovoltaic panels with white separating borders are great in the south where heat dissipation is important because photovoltaic panels lose some efficiency with heat. However experience has proven that light coloured patches on the panels will accumulate and not melt or slide off snow. Of course this does not matter if you only need your solar panel to create electricity in the summer.
Photo-voltaic panels are manufactured with differing materials. Some are more dense (Polycrystalline) requiring smaller panel area for the same power output . An older and less dense technology is Monocrystalline; the panels are just a bit larger. Both technologies carry warranties of 25 years or more. BOTH TECHNOLOGIES produce their rated watts. The only difference is the relative size of the panels.
New technologies such as Thin Film Silicon (TFS) and Copper Indium Gallium Diselenide (CGIS or CIS) are also available. Thin film materials are less efficient and generally cost less. Remember again, a 100W panel is a 100W panel! Only area size required for the same output will be different. Less efficient only means you need a larger surface area to achieve the same amount of power.
Making Photovoltaic panels more efficient (smaller) is the focus of considerable effort. The two primary methods used to concentrate light on photo voltaic systems are achieved by use of mirrors and lens.
Sharp Corporation recently displayed its new system. A Fresnel lens was used to focus more sunlight onto super efficient solar cells. The more expensive multi junction semiconductors used were about twice as efficient as conventional silicon cells.
Efforts for more efficient panel substrate continuously feeds the news media. U.S. Department of Energy (DOE) Assistant Secretary for Energy Efficiency and Renewable Energy Alexander Karsner recently (Dec. 06) announced that with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance.
What Output can you really expect ?
Time of year (angle of sun and number of sunlight hours), haze, clouds, rain and snow, and of course location, all affect the performance of your photovoltaic array. Performance logs taken over a period of years from a location a number of miles from you may not apply exactly to your location, however, they will be a good indication of what you can expect.
The following measurement is based on how many Watts are actually produced, not the number of sunlight hours in a day.
Based on logs developed over the past three years in our area in Ontario at a Latitude of about 450 North we get an annual average of almost 3 3/4 hours of sunlight per day, taking into account all of the points listed in the previous paragraph. To get to the point quickly, expect about ONE kilowatt hour of power per year from per Watt photovoltaic panel. (1 watt * 3.75 hr/day * 365 days [less total system losses and inefficiencies of 20%]) (1*3.75*365*.8= 1095 Watt hour ). If your usage is only in summer you can expect about 5 usable hours of sunlight daily in our area. Latitude has less to do with available light than environmental conditions. South of us humidity haze and smog reduce productive hours to just over 3 1/2. To the north of us in the Sudbury area they average just under a four hour annual average.
PV cells operate at a relatively stable voltage, while the direct current (Amps) produced varies with light intensity.
Summarizing Factors affecting PV performance
Temperature: Photovoltaic cell efficiency improves producing higher currents in cold temperatures. Voltage improves by 0.3 - 0.5% for every degree Celsius below 25° C.
Seasonality: (hours of light per day) The near north of Ontario receives about 3.7 hours of sunlight per day. Winter average in our area is about 2 hours per day with the summer peaking during the longest days with an average of more than six hours per day.
Weather: Even an hazy day will affect performance adversely. On an overcast day the solar module may generate as little as one tenth of its rated power.
System Voltage: PV cells operate at a relatively stable voltage while the direct current (amps) they produce varies with light intensity. The current and power output of photovoltaic modules is approximately proportional to sunlight intensity. At a given intensity, a module’s output current and operating voltage are determined by the characteristics of the load. If the load is a battery, the battery’s internal resistance will dictate the module’s operating voltage. A module with a rating of 17 volts will put out less than its rated power when used in a battery system. This is because the working voltage will be between 12 and 15 volts. As POWER (Watts) is a result of VOLTS times AMPS, the module output will be reduced. For example a Shell 80 Watt SP 80 module (rated 4.76 Amps at 16.9 Volts ) module working at 13.0 volts will produce 61.88 Watts.
What will it really cost?
All in, expect the "system" to cost between $6 and $10 per watt. If your objective is produce sufficient power to sell it back to your energy supplier who sells electricity to you for a current average of $0.12 per kilowatt (taking into account all of the other charges on your electric billing), you can expect a 30 to 50 year payback (using an average household example). Currently the hydroelectric supply companies will only pay $0.05 per kilowatt for energy sold to them.)
Still with us? You may have other reasons for producing electrical power through photovoltaic electrical generation. They may include a conscience towards our environment, cost of bringing in electrical power or fuel costs, or "minimum" billings for power when you're not at the cottage or... Whatever your motivation, your decision to proceed should NOT based on overblown promises and understated costs.
Photovoltaic Power Generation Makes Sense
If you use power frugally and produce just enough for your needs, Photovoltaic generated power:
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