Energy firms have slashed the amount they are “paying” solar panel owners to feed their surplus electricity back into the grid, according to research by comparison website energievergelijk.nl.

Website researchers studied 51 energy contracts and found the credit has dropped from more than 20 cents per kWh at the beginning of the year to an average of just eight. Over two million households in the Netherlands currently have solar panels.

Vattenfall is top of the list of good payers, crediting customers with a variable energy contract of 16.8 cents per kWh. However, the Swedish state-owned company is bottom of the list with a credit of just 4.5 cents for customers with a three year fixed agreement.

Energy expert Koen Kuijper said the low payments are linked to the drop in electricity prices and the increase in the number of solar panels.

“On sunny days there is a surplus of electricity and that has led to falling or even negative prices,” Kuipers said. “This means that energy companies are actually paying for the electricity they are being delivered even though there is a surplus.”

The government plans to change the rules on feeding electricity back into the grid, because the current system is costing the treasury more than €400 million in lost energy taxes.

The government argues that by reducing the amount of energy solar panel owners can offset against their own usage, they can be encouraged to use more of their own power and invest in a domestic battery storage system.

In addition, households will be paid a ‘reasonable’ amount for the energy they do supply to the grid, climate minister Rob Jetten said.

Both the Dutch consumer and markets authority ACM and the consumer association Consumentenbond have said they do not object to the government’s plans, as long as consumers are paid properly for the electricity they generate.

The Consumentenbond also wants guarantees that households can earn back their investment in seven years.