Our journey to the zero Euro electricity bill - a status update

At Robinsun, our mission is to decarbonise residential energy and make households save on their power bills as much as possible, ideally to zero Euros. Today we want to review where we stand on that mission.

Plug & play solar kits lower bills by up to 50%

When we launched Robinsun, selling plug & play solar kits, we saw that our solar kits alone could save customers up to 50% of their bills. In Southern Europe, solar kits produce up to 60% more than in Germany, where they are extremely popular, while kits cost the same. For smaller households, we found that a smaller kit of just one panel, like our Robinsun Performance 400, would usually make most sense.

Battery systems increase use of surplus and lower bills further

The question we had was “what can we do about the other 50%”? And how can we help bigger households that have higher consumption levels, where our kits can reduce the bill by less than 50%? We found a battery system from Zendure among the many that we screened and tested, that was reliable and affordable. What we liked particularly about this system was its modularity. Customers could start small, test the effect, and if it worked for them buy additional batteries as needed, up to a maximum of 4 kWh. This gives households also a sense of autonomy and independence from the grid.

Feed-in compensation can get you close to the “zero Euro bill”

Looking at the market for rooftop installations, we saw that surplus energy is an important factor in the equation. Batteries are a solution to store that surplus, but also one that costs money. Looking at the regulations in different European countries, we saw that in Spain there is a possibility to get compensated easily for surplus power fed into the grid, by certifying the kit. With an installation certificate, you notify your power company, which then enables bidirectional metering digitally, and accounts for kWh consumed and fed back into the grid. On your bill these two get balanced out, further lowering the amount of kWh you end up paying.

This allows households with lower consumption levels to install two-panel kits, like our Robinsun Performance 800, to produce much more than they consume during the day, feed this surplus into the grid and with this eliminate the need to pay for these kWh when you consume them at night. This enables customers to save a lot more than 50% on their electricity bill.

In our first test installations we verified this assumption. The graph above shows a full month’s consumption of a two person household that initially dropped their €80/month bills to €38/month with a one-panel kit. After certifying, they installed a second panel, whose production is solely meant to be fed into the grid, for compensation of the power consumed at night. The result is a total consumption of 85 kWh with a surplug fed into the grid of 72 kWh in April 2024. They expect to have more surplus electricity than consumption over the coming months, as days get longer in summer. The result is a €22 electricity bill, or -73% on the original average! Of these €22, about ¼ is VAT, taxes and meter rent that cannot be offset with the surplus.

As an additional benefit, the family has also been able to reduce the contract power of the household for a second time, since peak consumption levels have dropped consistently over the past 12-18 months. Since this is a fixed cost on the bill, it will further impact the reduction during the coming months.

Conclusions

While we would love to see that “zero Euro bill” there will always be taxes, installed power capacity, meter rental and other items on the bill that a household will have to pay for. Also, the peace of mind to be able to consume extra when you need it is worth a lot. But knowing that with a simple plug & play solar kit of two panels and a certificate that allows for feed-in compensation you can not only drive down your bills by much more than just 50% and live off self-produced, fully renewable energy is just amazing!