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What is the cost/benefit explanation of “high efficiency” solar panels over standard efficiency panels?

At any given point, PV panels range from what’s standard at the time to what’s considered premium because of its performance characteristics. A few years ago, 250 watts per panel was considered standard and 280 watts commanded a premium. Currently 275 watts per panel is standard and 325 watts is premium. The outer frames of both panels are probably sized within an inch of each other, so the difference is in their efficiency, which is the term used to state the amount of output for a given physical area. In other words the premium high-efficiency panel produces more watts per square foot than the standard one.

When using standard panels would not allow you to achieve your electricity production goals because you are limited by your roof space or by shading rather than by your budget, high efficiency panels may be recommended.  The high performance design produces more electricity per square foot than standard.  These panels are appropriate for homeowners who are seeking a system that 1) can provide a greater percentage of household requirements from a small roof or 2) leaves room on a small roof for a future expansion of the system.

Let’s look at specific examples of two ways to provide 5,000 kWh annually from solar.

First, to generate 5,000 kilowatt hours of electricity per year from a system composed of standard 275 watt panels, you will need room for 14 panels. In the second example, you could produce approximately the same output using only 12 high efficiency 325 watt panels.

Assuming that they are both in full sun, the high efficiency panel will produce about 19 watts per square foot while the standard panel will produce about 15.5 watts per square foot.  In other words, the energy output of the high efficiency panel is 22% greater than that of the standard panel per square foot of roof area.

When you have the space, buying standard panels saves you money.  If you cannot meet your annual 5,000 kilowatt hour goal within the available roof area, you may want to consider high efficiency panels. You will pay a premium for them but you will buy less of them, along with less mounting hardware and labor (by two panels).

For purposes of illustration, let’s say that installing a system with 14 standard panels costs $10,000.  Installing a system with 12 high efficiency panels will cost about $1,700 more.

Both will provide you with about 5,000 kilowatt hours per year of electricity on average.

Remember, annual output varies slightly depending on the amount of sunshine from year to year. Sunny skies make more electricity than cloudy ones.



Category: Solar Basics

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