City of Lublin powers buses with solar cells from Midsummer

In a move to reduce energy consumption and make public transport ‘greener’, the Polish city of Lublin has installed flexible thin film solar cells from Midsummer on the roofs of its municipal buses. Midsummer is a leading supplier of production lines for cost effective manufacturing of flexible thin film CIGS solar cells.

The Municipal Transport Company (MPK) in Lublin has installed photovoltaic thin film CIGS solar panels on its buses’ roofs. The solar panels turn solar energy into electric energy and are used to load the buses’ batteries. This will decrease the buses’ alternators load, leading to lower fuel consumption and bringing both economic and ecological profits.

Potential savings are estimated at up to 8,000 zloty (1,900 euro) per bus per year. The system’s payback period is estimated at a mere two years, taking into consideration only the fuel consumption reduction and not the overall environmental benefits. After two years, the solar energy solution will create compound surpluses for MPK for the remainder of the panels’ life span that will outlast the lifetime of the bus

The Lublin solar bus project will initially run for two years, after which it will be evaluated. The first solar bus is already in operation.

The thin film solar cells have been manufactured by Midsummer, a leading Swedish supplier of equipment for cost effective manufacturing of CIGS thin film flexible solar cells, and installed on MPK’s fleet of Scania buses. The project is a cooperation between MPK and the Lublin University of Technology .

Ideal for vehicles and buildings

“As opposed to the more traditional silicon-based solar cells, thin film CIGS solar panels are flexible and light weight and therefore ideal to be mounted on moving vehicles – and also on many buildings, landfills etc,” said Sven Lindström, CEO, Midsummer. “If a city in north central Europe can install thin film solar panels on its public transport vehicles with energy cost efficiency and a short payback period, imagine the potential for larger cities in sunnier parts of the world for introducing solar energy to its vehicles and buildings.”

“We firmly believe that thin film CIGS solar cells are the solar cells of the future. They are increasingly efficient and have many advantages over traditional silicon-based solar cells. They are durable, can withstand vibrations, can be curved and bent, and can be manufactured cost-efficiently in small volumes.”

Midsummer’s “DUO” is a unique and compact CIGS turn-key system with a 5 MW annual production capacity. Midsummer’s CIGS cells looks like crystalline silicon solar cells, but are made on stainless steel substrates. This makes the cells suitable not only for regular solar panels, but also for flexible, light weight panels that can be used on membrane roofs, landfills or other structures where the traditional glass modules cannot be applied.

“The thin film panels on the buses in Lublin are characterized by flexibility and shock resistance,” said Professor Miroslaw Wendeker from the Faculty of Thermodynamics, Fluid Mechanics and Aerospace Propulsion at University of Technology in Lublin in an earlier interview with the Polish Press Agency. “These cells have better absorption feature than traditional silicon wafers. They can be configured at will and placed on any roof.”

MPK Lublin Ltd. is the biggest public transport carrier in Lublin with a fleet of 60 trolleybuses and 215 buses. Lublin is a city on eastern Poland with a population of approx. 350,000 inhabitants.

About Midsummer

Midsummer is a leading supplier of equipment for cost effective manufacturing of CIGS thin film flexible solar cells. Midsummer’s turnkey manufacturing lines have a small footprint, are perfectly scalable and allow for small-scale production of solar cells and modules.

Midsummer’s customers are thin film solar cell manufacturers all over the world. CIGS flexible solar modules are growing in popularity thanks to their low weight, flexibility and durability. Applications are e.g. floating modules, vehicles, landfills, portable power generation and membrane roofs on factories, offices and other structures that are not strong enough for traditional glass modules.

Founded in 2004 by people with a background from the optical disc manufacturing equipment and the photo mask industry, Midsummer has its head office in Stockholm, Sweden. Midsummer was the fastest growing greentech company in EMEA (Europe, Middle East and Africa) in 2007-2011 (according to Deloitte).

About CIGS thin film solar cells

CIGS stands for copper-indium-gallium-selenium, a metal alloy that converts the energy of light directly into electricity by the photovoltaic effect (PV). The CIGS absorber is deposited on a stainless steel substrate, along with electrodes on the front to collect current. The cells are then connected in series and covered by a protective layer of plastic to form a flexible solar module.

Since a stainless steel substrate is used, the modules can be made without glass. The CIGS solar modules are therefore much lighter, flexible and can be made frameless, to suit applications where traditional silicon solar cells cannot be used, e.g. on structures that are uneven, moving or weak.

CIGS solar cells are manufactured by sputtering the material onto 156×156 mm stainless steel substrates. The solar cells from Midsummer are free of cadmium, a toxic material usually used in CIGS and other thin film solar cells.

Flexible CIGS solar modules are gaining market share thanks to its high efficiency, low weight, flexibility and durability. There have been significant improvements in CIGS cell efficiency, with Midsummer achieving aperture area efficiency in excess of 15.8 per cent in an all-vacuum process.