When it comes to choosing solar panels for your do-it-yourself projects, one question many have is does solar cell efficiency matter? Answering that is actually quite simple.
The answer is yes, solar cell efficiency does matter. The important thing to note here is that it may not be for the same reasons you would think. It isn’t choosing the most efficient cells that matters the most, it’s balancing cost versus efficiency that will make all of the difference to the final price of your residential solar energy system.
Without getting into the different grades of solar cells, or talking about how you can save money by choosing grade B cells, let’s discuss how to correctly balance these two aspects of building a solar panel (or a number of them).
Solar Cell Efficiency in a Nutshell.
When it comes to choosing the right solar cells, it's recommended to stick with your standard polycrystalline cell. These types of cells are readily available on the do-it-yourself markets, and as far as efficiency is concerned most are rated at 16% – 20% efficiency. To translate that into a number that is more usable. A single 3″ x 6″ (80 mm by 150 mm) will produce 1.6 Watts to 2.0 Watts of power.
These are the best cells to use when building solar panels for one simple reason – cost. Your standard polycrystalline cell can be found for as little as $1.50 each (even less if you choose grade B cells) and they usually average around $1.80 on sites like eBay. Using this type of cell you can build a complete 100 Watt panel with about $85 worth of cells.
Where some confusion is beginning to appear is with the availability of 30% to 35% efficient solar cells. Although these aren’t yet as common on the do-it-yourself markets, they are becoming available and some people are looking to increase the efficiency of their residential solar power system using these cells.
The problem isn’t that high-efficiency monocrystalline, or thin-film, cells don’t work. You can just as easily build a solar panel using this technology as you could with the older standard cells. The problem is the cost. With the new 30% efficient cells costing as much as five times more than a standard cell, they simply aren’t worth it. You pay five times more for only a 10% gain in power production.
If you had determined that you needed 10, 100Watt, solar panels to run your home, with the standard cells you could feasibly expect to build your panels with about $850 worth of cells. To build the same system in the with high-efficiency cells you’d still need 9 panels, and the cost of the cells would suddenly increase to about $3825.
So to answer our original question, yes solar cell efficiency matters. but not for the reason you probably thought; it’s balancing cost versus efficiency that will really make the difference when you convert your home to solar energy.