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Norwegian family generates more energy than they need with solar and heat pump

by Minenergi - 8 September 2023

Back in 2021, Christoffer Karlsen and his family moved into their very own "plus house”. What happened out of his interest in technology turned out to be a very smart decision.

Christoffer not only saved, but also earned a lot of money in his warm “plus house” in Norway.

Right before the energy price crisis started, the Karlsen family had 52 solar panels installed on their sustainable home. The large solar PV installation is complemented by a geothermal heat pump. After nearly 2 years (716 days) of using the installation, Christoffer provided an update on his situation.

A “plus house” is defined as a house that produces more energy than it consumes over its entire lifetime, including construction and demolition. The house of the Karlsen family does exactly that. Over the 700+ day lifetime of the house, it has produced 30,800 kWh of electricity, with the family’s power demand being 18,630 kWh over that same period. This means, the house was ‘solar positive’ by 57%. Annually, this equates to roughly 15,700 kWh of electricity produced, of which around 2,700 kWh is consumed directly. The remaining >80% of the electricity is exported. So far, the solar electricity production is estimated to have earned the family around to €2,000 (latest data: NOK 20,000 after past winter).

Around 85% of the Karlsen family’s electricity demand is linked to their geothermal heat pump. The heat pump covers all their heating needs while a fan convector makes sure the heat is quickly spread across the house. Additionally, the same installation cools down the house efficiently in the summer. Although the house is detached, its energy efficiency is remarkable.

The house is well insulated, has a smart energy management system, and faces south. Thanks to the floor heating system, the Karlsen family can walk barefooted through their house while requiring less than 10,000 kWh per year. The developer of this project was Flaget. Project leader Torger Terum estimates the additional cost of a “plus house” to be between €20,000 and €25,000 (250,000 NOK). To cover cost of construction, a “green home loan” was used at a favourable interest rate from Sparebanken Øst.

Read more about this family and others, in our new paper Solar Powers Heat and EVs: Case Studies.