What better way to help reduce your carbon footprint than a gleaming row of solar panels on your roof?

With an increase in cheaper imports, particularly from China, making the transition more affordable for an increasing number of environmentally conscious consumers, what price do we pay in carbon for greater affordability?

In a paper presented at the 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC), researchers compared the lifecycle impact of manufacturing silicon photovoltaic (PV) solar panels in the United States (US) compared to that of China and then importing them for installation. The results show that the complete manufacturing of panels in the US decreased the solar panels lifecycles carbon footprint by 13%-22%.

Let’s explore why 

• Current commercially available PV panels, particularly silicon modules, are energy intensive to produce.
• Depending on the energy mix used in their manufacture, the impact on the environment and therefore the carbon footprint associated, differs.
• Furthermore, depending on the distances from place of manufacture to the location of installation, in this case from China to the US verses entirely manufactured and distributed within the US, the carbon footprint associated also differs considerably.

Which all makes sense, but what happens when they die?

The environmental impact of disposal at the end of a PV solar panels life is also important and all three components of energy usage (manufacture, transport and disposal) contribute to the energy payback time (EPBT), which is the time needed to compensate for the total cumulative energy demand (CED) of the products life cycle and therefore the products total carbon footprint.

To compare the lifecycle impact of manufacturing silicon photovoltaic (PV) solar panels researchers firstly investigated the environmental impact of installing PV panels within the US based on 3 differing production scenarios. 

1. PV panels that were 100% produced in China.
2. Modules that were assembled in US from Chinese produced PV cells.
3. PV panels that were 100% produced in the US.

They then calculated the ‘cradle to grave’ environmental impact and the energy payback time (EPBT) using 2 approaches to compare the actual life cycle assessment of US made solar panels with current databases. This included: 

1. Life cycle assessment method – utilising a standardised lifecycle inventory database (LCI) currently in use.
2. Life cycle inventory of modules – conducting laboratory experiments on two US manufactured modules.

What did they discover?

Well firstly, that the panels considered in this study are more energy efficient than those of 2007, which is the baseline for most lifecycle assessment studies for PV panels (Fig. 1).

Which is great news for consumers currently in the market for solar panels and proof that the technology is constantly improving.

Fig. 1. Average efficiency of new module over time compared with current Life Cycle Assessment studies assumption and panels considered in this work.

However, they also determined that even though the silicon modules manufactured in China had a lower carbon footprint than reported in previous studies, the assembly of Chinese manufactured cells in the US verses the importation of fully completed modules did not significantly reduce the footprint overall.

Complete manufacture and installation within the US did however, reduce monocrystalline (c-Si) and multi-crystalline silicon (mc-Si) PV panels footprints by 13% and 22% respectively. This was attributed to the differences in the energy mix used in manufacturing and decreased transportation during the panels life cycle.

The study also provided information to ensure current databases used to determine PV panels environmental impact remain valid, along with model based specifically on US manufacturing conditions.

But what does all this mean for you?

Well if you just want to save money on your energy bills, then nothing. Go ahead and source the solar panels that best suit your needs and budget.

But if your motivation behind a shiny new array of environmentally friendly solar panels on your roof is to decrease your carbon footprint and do your part to combat climate change, then perhaps consider buying locally manufactured multi-crystalline silicon (mc-Si) PV panels.

If everybody considered their carbon footprint when purchasing solar panels, imagine the accumulative effect of a further 22% reduction in carbon emissions would do to save the planet in the long-term?

But regardless of your motivation and ultimate decision, rest assured that installing solar panels will still be far more environmentally responsible than traditional electricity supplies, and you’ll still be doing your part to decrease emissions, your power bill and combat climate change. 

Want to know more? Check out the original article:

Collins, K., Powell, B., Anctil, A., 2015, Life cycle assessment of Silicon Solar Panel manufacturing in the United States, Photovoltaic Specialist Conference (PVSC), 2015 IEEE 42nd, New Orleans, LA,