The incredible technological developments to have taken place in recent years and the simultaneous lowering of photovoltaic prices mean that solar trailers are no longer just an attractive future prospect, but a concrete reality within companies’ reach.
What is a solar trailer and what functions does it serve?
A solar trailer is nothing more than a conventional trailer equipped with a photovoltaic system capable of generating electricity.
Due to its eco-friendly nature, the solar trailer is an ideal choice for reducing carbon footprints and meeting increasingly stringent emissions targets even quicker.
Road freight transport offers ample possibilities for the integration of photovoltaics, due to mainly being done by means of diesel-powered trucks that offer large, unobstructed surfaces such as the roof or sides of the trailers. In such a context, solar panels have the potential to not only power auxiliary services, but also other important capabilities such as cooling systems or even the driving itself (1).
Particularly for trucks operating in cold chain logistics, the installation of solar panels on trailers can be an advantageous solution for powering the refrigeration system, offering greater autonomy and thus fuel savings and reduced emissions.
A solar trailer is not a bolt out of the blue, but an innovation that comes from studies and applications over time. Experiments in this regard, especially those involving TRUs (Transport Refrigeration Units), began more than 10 years ago, always with the aim of finding the most effective technologies to reduce fuel consumption and polluting emissions into the environment.
Why on refrigerated trailers?
Refrigerated trucks are one of the vehicle types that can benefit most from the installation of photovoltaics due not only to having high consumption levels in maintaining ideal conditions for cold storage, but also considerable space available for the solar system themselves.
The clean energy provided by photovoltaics can be used to power cooling units, thus lowering the operating expenses related to the consumption of diesel for cooling.
In addition to the economic aspect, there is also the environmental one – TRUs installed on trucks use an auxiliary engine (typically diesel) that in most cases came onto the market before 2019 and thus not in compliance with any European regulations on contaminants. EU Regulation no. 1628/2016 NRMM defining the emissions of Non-Road Mobile Machinery has been in force since January 2019, with refrigeration units currently in circulation in line with the Stage V requirements of the NRMM (2) legislation being in the clear minority. Reducing fuel consumption and thus the pollution of these units is of paramount importance. To this end, photovoltaics can make a great contribution, helping in the transition to less polluting solutions, since a non-compliant engine will face increasing restrictions in accessing low emission zones.
With this in mind, it is understandable how the study of photovoltaics applied to refrigerated trucks has far-reaching roots and has long aroused the interest of manufacturers and operators in the sector.
The first noteworthy studies on solar trailers applied to refrigerated transport date back to the early 2000s and refer to the pioneering installation of the Sainsbury’s supermarket chain on three of its trucks, the first of which went into operation as early as 1997 and – thanks to the photovoltaics – was able to eliminate the diesel engine used by the refrigeration unit. With the technology available at the time, both photovoltaics and batteries, the Return on Investment was calculated at 18 years.
These timescales are drastically reduced nowadays, thanks to technological developments that have considerably increased the capacity of panels to produce electricity and gradually reduced their costs.
So, why choose a solar trailer for refrigerated transport?
The answer is simple: convenience and sustainability.
Opting for a solar trailer means you can reduce the diesel consumption of the TRU by up to 85% in maintaining the trailer at temperatures of -18° C (3). This can translate into significant savings both in terms of money and emissions.
Solar energy thus reduces dependence on fossil fuel and consequently greenhouse gas emissions.
The German Fraunhofer Institute for Solar Energy Systems ISE (4), together with the logistics company DACHSER and the transport company Benzinger, carried out an experiment on six 40-ton refrigerated semi-trailers by equipping them with irradiance sensors and analyzing the data collected on standard routes within the US and Europe. On the basis of surveys carried out at the time, the Institute calculated that the electricity produced by solar panels on trailers could lead to savings of up to 1,900 liters of diesel per year per vehicle.
To fully understand the advantage of the solar trailer in refrigerated transport, one article may not be enough. This is why we have created an e-book dedicated to sustainable road transport.
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