Thin film solar panels: Do they make sense for residential?

thin film solar panels graphic

In a world where new solar panels and breakthroughs in solar technology are emerging almost every month, homeowners have a lot of panel options to choose from in 2017. Among the many innovations in the panel manufacturing space, none may be more appealing and visually exciting than thin film (TF) solar panels. In this article we’ll dig into what makes thin film stand out from standard silicon photovoltaic (PV) panels and offer some insight on when thin film solar is an ideal option for homeowners and the residential market.

What is a thin film solar panel?

Thin film solar panels are made with solar cells that have light absorbing layers about 350 times smaller than that of a standard silicon panel. Because of their narrow design and the efficient semi-conductor built into their cells, thin film solar cells are the lightest PV cell you can find while still maintaining strong durability.

Thin film solar panels are typically made with one of the following four technologies:

    • Cadmium Telluride (CdTe) – The most widely used TF technology, CdTe holds roughly 50% of the market share for thin film solar panels. CdTe contains significant amounts of Cadmium – an element with relative toxicity – so this is a factor of consideration. First Solar is the top innovator and seller in this space.
    • Amorphous Silicon (a-Si) – The second most popular TF option after CdTe, a-Si is the most similar technology to that of a standard silicon wafer panel. a-Si is a much better option than its counterparts (CdTe, CIGS) in terms of toxicity and durability, but it is less efficient and is typically used for small load requirements like consumer electronics. The quest for scale is always a hindrance for a-Si.
    • Copper Indium Gallium Selenide (CIGS) – Laboratory CIGS cells have reached efficiency highs of 22.3%. However, these performance metrics are not yet possible at scale. The primary manufacturer of CIGS cells was Solyndra (which went bankrupt in 2011). Today, the leader is Solar Frontier.
  • Gallium Arsenide (GaAs) – A very expensive technology, GaAs holds a world record 28.8% efficiency for all single-junction solar cells. GaAs is primarily used on spacecrafts and is meant for versatile, mass-scale installments of PV energy in unusual environments.





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Thin film solar panels vs. monocrystalline and polycrystalline PV

When comparing thin film panels to the standard solar panels more commonly used in the residential market, there are a few factors that clearly distinguish one from another: carbon offset, efficiency, roof space and installation cost.

In terms of carbon offset, TF solar panels will have a major edge over traditional panels. The silicon required for standard panels is much more significant than TF panels, which means that the emissions required to create a TF cell and panel are much lower than mono or polycrystalline panels. However, this “environmental benefit” of thin film solar cells may be cancelled out by the fact that TF often contains moderate amounts of Cadmium – a known carcinogen. If this is a major concern for you, CIGS TF panels will be a better bet as they are manufactured with practically no cadmium. Another potential solution for this is to seek out a community solar installation with CdTe technology in order to ensure the panel plant is not in direct proximity to your house or yard.

Efficiency has been the ultimate deciding factor that has prevented TF panels from gaining a foothold in the residential PV market. Whereas today’s standard silicon PV panels will have somewhere in the range of 15-16% efficiency, thin film panels will likely hold a median closer to 11-13%, which can significantly impact your system’s physical size and electricity output. However, tests of TF panels in 2016 demonstrated upwards of 25% efficiency, and it is expected that the efficiency lag of TF will be remedied in years to come.

Because of the aforementioned underwhelming efficiency averages, TF installations will be impacted by how much roof space you have for your system. A standard panel installation can significantly cut your electricity bills even if you have limited roof space, but TF needs to be installed on larger roofs to accommodate the increased amount of space necessary for the system.

Finally, installation cost will differ significantly between TF and typical PV because thin film panels are very easy to install and require much less labor. As long as you are working with a company that provides a mounting solution for thin film, reduced labor costs are a hard selling point for a TF installation over standard PV panels.

What are the main thin film solar panel manufacturers?

These are the leading manufacturers of thin film PV:

    • First Solar – The top thin film manufacturer, First Solar dominates the CdTe technology space. To date, First Solar has only served the commercial market, offering low cost installations at the mass scale for businesses, institutions and solar power plants. Holding the world record for CdTe cell efficiency at 18.7%, this manufacturing behemoth is also offers an impressive 25 year warranty. First Solar TF is also known for its gorgeous aesthetic designs such as their frameless, glass on glass model that boasts increased panel output due to its hyper reflective glass coating.
    • SoloPower – The San Jose solar firm is known for versatility and ultra-lightweight design, making it an ideal candidate for building-integrated photovoltaics (where the panel is integrated into a building’s envelope, often along vertical surfaces). SoloPower is one of the world leaders in CIGS manufacturing.
    • Sharp – Sharp Solar is a global leader in thin film, having been in business for over 50 years, and is the top manufacturer of a-Si technology. The Japanese firm is known for being one of the first innovators in solar cell development and has been contributing to research and development for cell and module efficiency improvements of PV technology since 1959.
  • Solar Frontier – The world’s top manufacturer for CIGS thin film, Solar Frontier also hails from Japan. This manufacturing giant is partially responsible for the strong forecasted growth for CIGS PV installations worldwide. Solar Frontier’s world record conversion efficiency for TF (22.3%), achieved in 2015, has certainly boosted outlooks. If TF continues to scale in the commercial sector and penetrate the residential market, CIGS will be the technology that can achieve it. Sharp Solar has stated that they have the capability to produce a 30% efficiency CIGS cell – a feat that would revolutionize the concept of thin film solar.

What do thin film solar panels cost and when do they make the most sense?

Ultimately, thin film solar panels have seen the majority of their use to date in commercial- and utility-scale installations like solar panel farms, solar for corporations, and solar for schools and universities. The “economies of scale” concept is hard at work with TF panel technology because the lightweight, versatile panels are easy to install. Thus, the larger the system being installed, the more cost effective it becomes as reduced installation costs offset the panel output losses due to lower efficiencies.

That being said, there is still an opportunity for TF in the residential sector: larger houses with adequate roof space can benefit from an economies-of-scale installation as well as the aesthetic benefits of the frameless and glass-on-glass TF models that are commonly offered by the leading manufacturers. If aesthetic design is a strong priority for your PV installation, thin film may end up being the most cost-effective way to get the look you want. As market efficiencies of these panels continue to increase in 2017 (as expected) TF could make a strong entry into the residential market. Only time will tell.

Regardless of your preference for thin film or silicon wafer panels, it’s important to get some figures regarding the estimated cost of your installation, long term electric bill savings and payback period. Our Solar Calculator offers personalized instant estimates based on your roof and local offers in your area and can offer insight on the costs and benefits of going solar. If you are ready to begin comparing bids from vetted installers in your area, check out the EnergySage Solar Marketplace and specify your panel technology and model preferences in your dashboard.





Don



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