With over a dozen solar manufacturers worldwide, creating hundreds of panel options annually and 16 central inverter companies creating 320 or more model options annually, how do you know you’re getting the best for your solar project? And what about the micro inverter, racking and monitoring choices that need consideration as well?
The easy answer is to choose the best efficiency panel you can afford and then rely on your vendor to handle the rest. But the easy answer is often not the right answer. The right answer is based on your unique set of factors; your energy usage patterns, your utility and state’s solar policies, your finances, your roof condition and your house site’s solar exposure. It’s a lot to figure out.
There are three types of solar module technologies, polycrystalline, monocrystalline and thin film. They have different application scenarios, efficiencies and cost. All have a unique substrate sandwiched between a backing material and tempered glass and then encased in weather tight aluminum framing. All solar modules create direct current electricity of various power levels depending on their design and the strength and duration of the sun shining on them. Here are the differences.
• Polycrystalline has a single layer of multiple silicon crystals jumbled together which makes them easier to manufacture and cheaper than mono. Poly performs a little better in high heat conditions but hasn’t reached the conversion efficiency ratings that mono have. Poly averages around 12% efficiency.
• Monocrystalline has individual silicon wafers arranged in rows and columns to fill the module space. They are the go to choice for most residential projects due to their higher conversion efficiency. Though the average is 16-18%, some are as high as 21% and maintain 85-90% of their power output at 20 years. Some studies indicate they now do as well as poly in high heat.
• Thin film is the technology you find in solar calculators, toys, etc. It’s a specially coated material that also converts light into direct current electricity. This substrate is glued directly to a metal roof in its flexible form or made into a rigid solar module for ground mounted and sloped roof applications. A thin film solar project requires 20% or more space than poly or mono to produce the same amount of power. Thin film solar modules are the least expensive module to purchase but must be weighed against how much more roof space, attaching equipment and labor costs accompany that choice.
Knowing what options are right for you before getting vendor bids is the optimal position you can be in. In a future blog, I will talk about central vs. micro inverters, another important choice you’ll need to make.