Submitted by alexandra.naumanen on Mon, 09/25/2017 - 08:30

The environmental aspects of solar energy were of interest to the decision-makers of Helsinki at the beginning of the millennium. This interest was one of the driving forces for Naps to install the first building integrated photovoltaic system to an apartment building Salvia in the Eko-Viikki area in 2002. The system is still a modern and energy-efficient solution today.

At the beginning of the millennium, solar modules for summer cottages had been built already for a couple of decades, but larger, grid connected integrated solar power systems were still very rare. The Salvia apartment building guarding the entrance to the Eko-Viikki district in Helsinki got solar modules integrated to the balcony facade 15 years ago, as the first building in Finland.

Helsinki decision makers wanted ecological living  

The city of Helsinki designed a new district for Viikki fields and ecology was one of the key starting points. Each building permit required some ecological features, so some of the houses received solar heat and Salvia a photovoltaic system. "My Nordic partners asked me to join within the framework of the PV-Nord project to get EU funding for solar systems. My company, Solpros, controlled back then the Finnish PV-Nord projects and we had just built a 16.5 kW photovoltaic system together with Naps Solar to NCC's headquarters at Mannerheimintie ", explains Professor Peter Lund of Aalto University's Technical Physics.

"It was all new to integrate solar modules into the balcony railings in Finland at that time. But as the rooftop solar would have been too complex solution in this house, Naps and the architect came up with an idea to utilize the railings. Helsingin Energia (present Helen) was also involved in the project and built an advanced measurement system for the house. We even tested net measuring”, recalls Lund.

Naps Solar glass panel, Salvia

Energy and aesthetics

Salvia's solar modules were made with glass-glass technology, where solar cells are between two glasses. There is a few millimetres gap between the cells, so the light can partially pass the glass. At the same time, the blue cell prevents direct vision to the balcony. The Salvia modules used a vibrant dark blue polycrystalline silicon cell, giving their own stylish impression to the appearance of the property.

"Naps was the leading builder of building integrated photovoltaic systems (BIPV) throughout the Europe. They were already able to make fully customized modules and systems, could implemented innovative cabling solutions and were a highly capable partner", sums up Lund.

The system resist time well

Integrated photovoltaic systems and glass-glass modules similar to Salvia’s are still being made, albeit more cost-effective and even further tailored. Salvia’s modules were placed facing both south and west, thus being able to produce energy long into the night. According to Lund, the project went according to plan and the day-to-day production profile of the system is still very modern.

The Salvia apartment building company has kept accurate records of the system output at monthly level. Terho Lintula, Chairman of the Board of the Salvia housing company, has lived in Salvia almost from the beginning. "The photovoltaic system has according to my calculations saved the company about a thousand euros a year in electricity costs”, Lintula says.

Power electronics has developed rapidly

"A total of 170 modules were installed in Salvia's photovoltaic system, tailor-made for this purpose, with a total power of 24 kilowatts", says Jyrki Leppänen, Marketing Director at ABB, who previously worked at Naps and was responsible for the Salvia project.

"The technical implementation contained many details. The inverters at that time were very undeveloped and small, so we needed as many as 12 inverters in the system, while today it would be built with only one or two inverters."

According to Leppänen, after 15 years of use, the inverters are approaching the end of their life cycle. While renewing them, the whole system will be checked, all module connections tested and inverters modernized for at least the next 15 years.

The system has a sunny future

Salvia's photovoltaic system was a valuable investment at that time, and would hardly have been implemented without the city's incentive and EU support. The price level of solar modules 15 years ago was something totally different compared to today. But the typical lifetime of the modules was - and still is - 25 to 35 years, so the modules of Salvia are now only halfway through their technical lifetime. The inverters will typically be renewed midway through the lifetime of the total system. Thereafter, the system and the apartment building have the next 15 years of sunny future ahead.

Text and Photos: Jouko Lampila

Naps Solar System at Salvia Viikki, Helsinki (2002)