Solar panels generate electricity without carbon dioxide emissions on the roofs of Heka buildings

Solar panels are part of the standard equipment of new Heka locations, but systems generating emission-free solar energy are also installed in older buildings.

Written by Petja Partanen Photos by Roope Permanto, Ville Tikkanen / Helen Oy

The colourful Heka buildings in Mellunkylä were equipped with roof-mounted solar panels in summer 2020. The new solar power system of the building at Virtarannankatu 3 generates electricity for the buildings’ lighting and ventilation systems whenever the sun is shining. The roof-mounted solar panels generate free and emission-free electricity, covering just over 17% of the buildings’ annual electricity consumption on average. 

Virtarannankatu is not the only location that utilises solar power. Over the course of the summer, the roofs of a total of five old Heka buildings were equipped with shiny new solar panels, provided by Helen Oy. 

- These are now appearing on the roofs of Heka buildings at a great pace, says Heka’s Property Director Vesa Jurmu

Hekan talojen kattoja ilmasta kuvattuna. Katoilla aurinkopaneelit.


Solar panels will continue to be added to the current buildings, at an annual rate of about five buildings. At Heka’s new construction sites, the panels are already a common sight. 

- Nowadays, solar panels are commissioned in most of our new construction sites. In the future, we will be outfitting practically all both new and renovated buildings with solar power systems, Jurmu says.  

According to Jurmu, solar electricity is a profitable investment for rental housing companies. The production of solar power can also be felt in the tenant’s wallet. The building’s maintenance costs will be paid through rents, which means that the savings brought by solar panels will also benefit the tenants. However, environmental values matter more than money. 

- Carbon neutrality is probably the main thing for many of our tenants regarding the solar panels on their roofs. They generate carbon dioxide-free electricity for our buildings, Jurmu states.  

Lähikuva Hekan talon katolle asennetusta aurinkopaneelista.


Heka’s solar power investments are boosted by the City of Helsinki’s ambitious climate objectives. The objective of the Carbon-Neutral Helsinki programme is to make the city carbon-neutral by 2035. In practice, this means that emissions need to be cut by 80% compared to the level of 1990. 

- The programme features many measures that help us cut down the energy consumption and climate emissions of Heka apartments, Jurmu says. 

Heka built its first solar electricity systems five years ago. These were also delivered by Helen Oy.  

- Only very few Finnish apartment buildings generate solar power. Heka has been a forerunner in its field in this matter. Investing in solar power is an important environmental action from Heka, which also benefit the residents, says Helen’s Sales Manager Timo Huolman.  

Hekan talojen kattoja ilmasta kuvattuna. Katoilla aurinkopaneelit.


Huolman says that a great deal has happened in the field over the past five years.  

- The panel prices have come down while their efficiency has improved. Today, they are an even better investment that pays for itself even faster than before, Huolman says. 

This can also be seen in the demand for these systems.  

- Sales of solar panels have doubled every year, Huolman states. 

Heka’s new solar power plants

The new solar power plants built on Heka buildings in summer 2020 were delivered by Helen Oy and installed by ProPower Oy. The solar power systems at Heka sites generate approximately 86,000 kWh of emission-free electricity a year, which equals the annual electricity consumption of about 35 two-room apartments.

Tilanhoitajankaari 20

  • The site was built in 2000.
  • Peak efficiency of the solar panels: 11.52 kW
  • Estimated annual production: 10,377 kWh
  • Solar power’s proportion of real estate’s annual electricity consumption: 14.4%

Sofianlehdonkatu 10

  • The site was built in 1988.
  • Peak efficiency of the solar panels: 21.76 kW
  • Estimated annual production: 16,325 kWh
  • Solar power’s proportion of real estate’s annual electricity consumption: 13.6%

Virtarannankatu 3

  • The buildings’ year of construction: 2017. 
  • Peak efficiency of the roof-mounted solar panels: 23.04 kW 
  • The estimated annual amount of electricity generated by the panels: 17,971 kWh. 
  • The panels at Virtarannankatu generate enough solar power to cover 17.4 % of the site’s annual real estate electricity consumption. 

Karstulantie 10

  • The site was built in 1961.
  • Peak efficiency of the solar panels: 16.64 kW
  • Estimated annual production: 14,185 kWh
  • Solar power’s proportion of real estate electricity’s annual consumption: 21.0%

Jakomäentie 4

  • The site was built in 2017.
  • Peak efficiency of the solar panels: 25.6 kW
  • Estimated annual production: 21,580 kWh
  • Solar power’s proportion of real estate’s annual electricity consumption: 5.3%