Save 30 % on your heat pump with hourly spot pricing

This guide is for you if you already have a heat pump and an hourly spot contract — but suspect you're paying more than you have to. For us at Therilly, this is a favourite number: 30 % lower cost is absolutely achievable for many Swedish villas. But it requires several things to line up at once. Here we cover them.

What "30 %" means

The 30 % refers to the cost of heating the home, not the entire electricity bill. If the heat pump uses 18,000 kWh per year and costs you SEK 23,400 (avg. 130 öre/kWh), we're talking about dropping that to SEK 16,380. That's SEK 7,000 per year — more than a week's holiday for many households.

How much you actually save depends on four things:

1. How volatile spot prices are. Big swings between cheap and expensive hours = more to gain.
2. How thermally heavy your house is. Thick walls and underfloor heating = more to gain. Lightweight + radiators = less.
3. How well-insulated the house is. A well-insulated home can coast longer without losing comfort.
4. How smart the controller is. This is the biggest lever — and the only one you can change in an afternoon.

The four levers — one at a time

Lever 1: Pick a good electricity contract

It's not enough that the contract says "hourly spot". The details matter:

• Per-kWh markup. Tibber charges 0 öre but has a monthly fee. Others take 2–5 öre/kWh. On 18,000 kWh, 3 öre = SEK 540/year.
• Grid fee. Hidden demand charges exist at some operators (Ellevio, E.ON). Then it pays double to avoid peaks — you save on both spot price and demand charge.
• Correct price area. SE3 (southern central Sweden) has been historically more expensive than SE2. SE4 (Skåne) has the highest volatility, meaning the biggest savings potential with smart control.

Lever 2: Measure consumption in real time

Without real-time data the controller flies blind. We recommend one of:

• Tibber Pulse (if you have Tibber). Second-by-second, free.
• HomeWizard P1. Plugs into the HAN port, no electrician.
• Shelly EM or Pro 3EM. More flexible, but needs an electrician.

Real-time measurement lets the controller know "the pump is drawing 2.3 kW right now — if I pause now I save 2.3 kWh this hour." Without it, control becomes pure time-of-day scheduling.

Lever 3: Use the weather, not just the clock

SMHI updates forecasts every six hours. For a heat pump two things are critical:

• Upcoming low temperatures. Don't wait until it's −15 °C to start pre-heating. Start 12–18 hours earlier, while electricity is still relatively cheap.
• Solar gain. South-facing windows can deliver 1–3 kW for free on clear days. Then minimum pump operation midday is enough.

Lever 4: Have a thermal model of the house

This is the hard one. How long can your home pause without losing comfort? The answer depends on outdoor temperature, wind, insulation, and where the thermostat sits.

A modern AI handles this automatically. It observes your pump for a few days and builds a model. We've seen homes where the model finds the house can tolerate 4 hours of pausing at 0 °C outside but only 90 minutes at −10 °C. That kind of nuance makes an enormous difference.

Worked example: a family in Norrköping

• House size: 160 m², built 1985, insulation upgraded 2018
• Heat pump: Mitsubishi Ecodan, 11 kW
• Consumption: 17,500 kWh/year (pump + hot water)
• Contract: Tibber, price area SE3
• Average price 2024 incl. everything: 132 öre/kWh
• Annual cost without smart control: SEK 23,100

What smart control did in year one:

• Pre-heated overnight: −8 % annual cost
• Paused morning and evening peaks: −14 % annual cost
• Used sun and forecasts: −4 % annual cost
• Maintained comfort: unchanged, 20.5–22.0 °C indoors year-round

Total saving year 1: 26 %. Total saving after the model learnt the house (year 2): 31 %.

Common questions

Do I need to replace my heat pump? No. Smart control works with your existing pump in 95 % of cases.

What happens if the internet goes down? A serious controller has fail-safe — the pump returns to its built-in normal mode within minutes. You don't freeze.

Does the pump wear out more from starting and stopping? Good question. Modern AI avoids short compressor cycles — it optimises for energy and lifetime. Pauses happen at levels the pump already handles (e.g., gradually lowering the setpoint), not via hard shutdowns.

How quickly do I see the saving? Within the first week you see it in the app. The actual effect on the bill shows up after a full billing period (1 month).

What if I don't have hourly spot? Then smart control saves you nothing. Switch to hourly spot first — that saving alone is often larger than what smart control adds on top.

Quick check: will you get the 30 %?

You have the best conditions if:

• You have an hourly spot contract (preferably with low markup)
• You live in SE3 or SE4 (more volatility = more to save)
• Your house is at least moderately thermally heavy (stone, concrete, underfloor heating)
• You have a power meter (or are willing to add one)
• You have a heat pump built after 2010

If you tick all five, 25–35 % savings is realistic. Want to see exactly what your setup would deliver? Run the savings calculator.