Use your excess solar for heating, not export
Solar panels often produce more than your home uses at midday. Here are the four things you can do with that surplus, and when storing it as heat makes sense.
Why so much solar goes to the grid
Solar output peaks around midday. Home heating demand peaks in the morning and evening, and it is highest in the colder months.
When panels produce more than the home uses, the surplus is exported. Export payments are usually below the price you pay to buy electricity back.
In the Netherlands, net metering (salderingsregeling) ends on 1 January 2027. From then until 2030, suppliers must pay at least 50% of the bare supply tariff for exported electricity.
Four ways to use surplus solar
Each option suits a different home. Many homes combine two.
Export it
No extra equipment. You are paid for each kWh you send to the grid, at your supplier's export rate.
- Nothing to install
- Usually earns less than electricity costs to buy
Solar diverter
Sends surplus to the immersion heater in your existing hot-water cylinder.
- Low cost
- Hot water only, limited by cylinder size
Home battery
Stores electricity for use in the evening.
- Powers anything in the home
- Higher cost per kWh stored
Store it as heat
A thermal battery like Batbubble turns surplus into heat for heating and hot water.
- Covers your biggest energy need
- Needs water-based heating and floor space
When storing surplus as heat makes sense
- You have solar panels and export a large share of what they produce.
- You heat with a heat pump or electricity, through radiators or underfloor heating.
- You have room for a 1,000 L or 2,000 L tank in a utility room, garage or basement.
- You are on, or considering, a tariff where electricity prices change through the day.
How much surplus a tank can absorb depends on its size and temperature range. Check it with the storage calculator, then see how Batbubble works.
Sources: Rijksoverheid – Salderingsregeling.
Questions about excess solar
Can I use excess solar for heating?
Yes, if the heat can be stored until the evening. Heating water in a large, insulated tank is one of the simplest ways to do it.
Is a solar diverter enough?
A diverter sends surplus to the immersion heater in an existing hot-water cylinder. It is low-cost, but it can only heat as much water as the cylinder holds, and only for hot water.
Is a battery or heat storage better for surplus solar?
It depends on what you use most. A battery covers any evening electricity use. Heat storage covers heating and hot water. Compare them.
What about winter, when there is little solar?
In winter, Batbubble is designed to charge from the heat pump and from cheaper grid hours instead. Dynamic-price charging is a planned capability.
Be among the first to get Batbubble.
Batbubble is in development. Join the waiting list for development and availability updates. It is not a purchase or reservation.