What type of solar panel should I install?

With the boom in solar power, there is some confusion about what particular technologies and materials are the best choice. It turns out that’s far from a simple matter, but a team of researchers at MIT and elsewhere has developed  a way to ascertain the best option for a given location and type of installation. The important question is whether for household-scale rooftop systems in relatively dry locations, the more efficient but more costly panels would be better. But for grid-scale installations or for those in wetter climates, the established, less efficient but cheaper panels are often a better option.

Solar costs continue to fall

The costs of solar cells continue to drop, while the costs of installation and the associated equipment remain mostly constant. So, figuring out the trade offs in planning a new installation has gotten more complicated. But the new study provides a clear way to estimate the best technology for a given project, the authors say. The findings are reported today in the journal Nature Energy, in a paper by MIT graduate student Sarah Sofia, associate professor of mechanical engineering Tonio Buonassisi, research scientist I. Marius Peters, and three others at MIT and at First Solar and Siva Power, solar companies in California. The study compared two basic types of solar cells: standard designs that use a single type of photovoltaic material, and advanced designs that combine two different types (called tandem cells) in order to absorb more of the energy in sunlight. For the tandem cells, the researchers also compared different types: those in which each of the two cells are connected together in series, called two-junction tandem cells, and those in which each cell is separately wired, called four-junction tandem cells.

Instead of just looking at the amount of power each kind can deliver, the team analyzed all the associated installation and operational costs over time, to produce a measurement called the levelized cost of electricity (LCOE), a measure that incorporates all the costs and revenues over the lifetime of the system.

“Standard single-junction cells have a maximum efficiency limit of about 30 percent,” Sofia explains, whereas “tandem cells, using two materials, can have much higher efficiency, above 40 percent.” But while higher efficiency is obviously an advantage in principle, “when you make a tandem, you basically have two solar cells instead of one, so it’s more expensive to manufacture. So, we wanted to see if it’s worth it,” she says.

For their analysis, the team looked at three types of environment — arid (Arizona), temperate (South Dakota), and humid (Florida) — because the amount of water vapor in the air affects how much sunlight reaches the solar cell. In each of these locations, they compared the standard two kinds of single-junction solar cells (cadmium telluride, or CdTe, and copper-indium-gallium-selenide, or CIGS) with two different types of tandem cells, two-junction or four-junction. Thus, a total of four different technologies were studied in each situation. Moreover, they studied how the overall LCOE of the installations would be affected depending on whether overall electricity prices remain constant or decline over time, as many experts expect.

To learn more about Solar Power Pros and Cons read this blog.

The results were somewhat surprising. “For residential systems, we showed that the four-terminal tandem system [the most efficient solar cell available] was the best option, regardless of location,” Sofia says. But for utility-scale installations, the cell with the lowest production costs is the best deal, the researchers found.

In summation, it is wise to research the various kinds of solar technology available since innovations and new incentives are possible at any time.

Make sure to check out other pages on our website, look at the links below and see how you can learn more about solar.

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