How do you define the Best Deal on solar modules?
Is it simply a matter of a big discount off the regular price? Or do you go one step further and do the quick calculation of $/Watt? Or, perhaps you are looking for the maximum power density in terms of Watts per square-meter in order to maximize the production of a limited amount of roof or ground space.
In this brief post, I will look at various ways you can determine what is the best value proposition for your solar array.

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Modern Outpost Solar Module Slate (Jan-2019)

The Best Deal : Low-Cost Leader

If you are looking for simply the best bang for your buck, you will want to calculate the solar module price tag in terms of $/Watt. This is very straightforward.
If you see a 300 Watt solar module on sale for $300, you will be paying $1 per Watt.
Run that division question for all the modules you are considering.
The module with the lowest number wins.

This is a simple means of comparing one module to another strictly in terms of the price per unit of power output. Of course, this leaves out other elements out of the equation, such as efficiency, quality, warranty, manufacturer reputation, aesthetics, manufacturing practices & ethics, etc. Check the solar scorecard for the companies that are doing it right!
After all, you might be able to find a 20-year-old 100W module at a garage sale for $30, which amounts to a smokin’ deal when compared to brand new equipment.

But, on your shortlist of modules, with all other factors being equal, the module with the lowest $/W number wins.

Here are our current leaders in this dimension…
Trina AllMax 300 : 300W, 60-Cell
Hanwha Q.Cells Q.Peak G4 : 305W, 60-Cell
REC Twin Peak 2S Bifacial : 330W, 72-Cell
Trina TallMax : 365W, 72-Cell

The Best Deal : Efficiency Leader

What we are talking about here is Watts per square-meter (W/m^3). This metric is used often, but not often calculated correctly. Let’s say you want to maximize the energy production for a restricted amount of space. So, you need the module with the largest power rating… correct?. Almost correct.
You have 2 tasks:
1. Choose the physical size that will create an array that will fill the space most completely, taking all necessary access setbacks into account. 36-cell, 60-cell or 72-cell modules
2. Choose the manufacturer & product model that provides the highest output for that given module size.

In the current solar PV module market space, the largest power ratings are on the spec sheets for the 72-cell modules. But, a quick bit of math, and you might find that just adding 2 more rows of cells to the module didn’t actually improve the efficiency calculation. It might simply multiply the same efficiency of the 60-cell module out to the larger frame size. What you need to do for accurate comparison between similar & dissimilar frame sizes is divide the power rating of the module by the area of the module (Length x Width). Don’t assume that all 72-cell modules are the same size. There are subtle differences, and sometimes a manufacturer will employ a unique module design, construction technique, or cell size, that makes simple comparisons more difficult.

Here are our current leaders in this dimension…
LG NeON 2 : 320W, 60-Cell : 195.12 W/m2
REC N-Peak : 330W, 60-Cell : 197.61 W/m2
Solaria PowerXT PowerXT-360R-PD : 360W, 60-Cell : 199.00 W/m2
Hanwha Q.Cells Q.Peak DUO L-G5.2 : 385W, 72-Cell : 193.08 W/m2
LG NeON 2 : 400W, 72-Cell : 193.00 W/m2
LG NeON 2 Bifacial : 390W*, 72-Cell : 206.99 W/m2

The Best Deal : Cost of Efficiency

This final calculation of value gives an indication of the cost you are paying for a solar module’s level of technology. In this comparison, we divide the cost of a solar module by its efficiency to arrive at a $/Eff number or cost per unit of efficiency (Eff being Watts/square-meter). The highest power module on the market might be charging you a premium for their product simply because it is the power leader. Is it worth it? How does it compare against a slightly lower-output module with a smaller footprint? This gives you a means of comparison.

Here are our current leaders in this dimension…
REC Twin Peak 2 : 60-Cell, 290W : $1.58
Trina AllMax 300 : 60-Cell,  300W : $1.28
Hanwha Q.Cells Q.Peak G4 : 60-Cell, 305W : $1.58
REC Twin Peak 2S Bifacial 330* : 72-Cell, 363W : $1.73
Trina TallMax 365 : 72-Cell, 365W : $1.57
Hanwha Q.Cells Q.Peak DUO L-G5.2 : 72-Cell, 385W : $1.79

Best Deal On Solar Modules : Last update: November 12, 2018
I will be updating this page regularly as solar technology progresses.
Please feel free to contact me with any questions regarding the information provided here.
Happy solar shopping!

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