Mining with surplus solar power: when it beats the feed-in tariff
Mining with surplus solar power makes sense when the electricity would otherwise be exported to the grid at the feed-in price. A home miner today earns roughly 1.6–1.9 CZK per kilowatt-hour, while the buy-back price for exported power in 2026 usually ranges between 0.2 and 1 CZK/kWh excl. VAT. Mining cannot beat self-consumption, a battery or water heating, though – these save you the full price of grid electricity.
Summary
- The order in which to use surplus power: self-consumption → battery and water heating → mining → selling to the grid.
- Size the miner according to your typical midday surplus, not the peak output of your PV system.
- Machines with adjustable power draw are the best fit (Avalon Q 800–1,600 W, Avalon Mini 3 roughly 400–800 W).
- Mining on summer surpluses alone pays the machine off slowly. It makes sense year-round when the miner heats your home in winter.
Why surplus power is worth thinking about
Buy-back prices for power exported from home PV systems are low. For 2026, Pražská plynárenská, for example, pays a fixed 850 CZK/MWh to its own customers and 200 CZK/MWh to everyone else. Other suppliers offered around 900–1,000 CZK/MWh in 2025, often only if you also buy your electricity from them.
With spot-based buy-back the situation is even worse. At midday, when PV systems produce the most, the exchange price often drops to zero or below. And for new systems subsidised under the Nová zelená úsporám programme, exports have been capped at 50 % of installed capacity since February 2024 – so you are not even allowed to send part of your surplus to the grid.
What a kilowatt-hour of surplus earns: comparison
| Use of surplus | Value of 1 kWh | Note |
|---|---|---|
| Self-consumption at home | 4.5–6.5 CZK | saves buying from the grid, the best option |
| Battery, water heating, heat pump | almost the same | energy used later, with small losses |
| Mining – Avalon Mini 3 | 1.64 CZK | 37.5 TH/s × 0,84 Kč ÷ 19.2 kWh |
| Mining – Avalon Q | 1.88 CZK | 90 TH/s, 1,674 W |
| Mining – DG Home 1 (LTC + DOGE) | 1.73 CZK | 2.1 GH/s, 630 W |
| Fixed-price buy-back | 0.2–1 CZK | depending on supplier, excl. VAT |
| Spot-based buy-back at midday | often around 0 CZK | negative after the trader's fee |
Mining values apply at today's difficulty and exchange rate (as of 18 October 2026) and will change. On these figures, a kilowatt-hour is currently worth about twice as much in a miner as in a fixed-price buy-back.
How much surplus you really have
PV output varies greatly over the year. A 10 kWp home system with a 20 kWh battery produces 25–40 kWh a day in summer, but only 10–15 kWh in winter. After covering the household and charging the battery, there are typically a few to around ten kilowatt-hours left per day in summer, and almost nothing in winter.
In practice this means a miner running on surplus power will operate mainly from April to September, and only around midday. Before you buy a machine, check your inverter app to see how much energy you export to the grid and at what times.
How to size the miner
- Find your typical midday surplus on a sunny day – not the peak, but the output that lasts at least 3–4 hours.
- Choose a miner with a power draw below that figure. For a surplus of around 1 kW, an Avalon Mini 3 or DG Home 1 is suitable; for 1.5–2 kW, an Avalon Q.
- Make use of adjustable power. According to the manufacturer, the Avalon Q can be set between roughly 800 and 1,600 W; the Avalon Mini 3 has night and heating modes from about 400 W.
- Switch on according to surplus, not the clock. A smart plug, an inverter relay or home automation turns the miner on when exports exceed its power draw and off when they fall.
- Set a delay. A miner takes several minutes to start up. Switch it on only once the surplus has lasted at least 10 minutes, so it doesn't restart with every passing cloud.
Don't power the miner from the battery at night. A kilowatt-hour stored in the battery is worth 4.5–6.5 CZK to you, because in the evening it replaces buying from the grid – in a miner it would earn only a fraction of that.
Calculation: what a season on surplus power earns
Example: an Avalon Q runs at full power (1.67 kW) for an average of 6 hours a day on 180 days a year. It therefore uses about 1,800 kWh of surplus power.
| Option | Calculation | Per season |
|---|---|---|
| Mining | 1,800 kWh × 1.88 CZK | about 3,400 CZK |
| Buy-back at 850 CZK/MWh | 1,800 kWh × 0.85 CZK | about 1,530 CZK |
| Difference in favour of mining | 3,400 CZK − 1,530 CZK | about 1,870 CZK |
The figures apply at today's difficulty and exchange rate. Clearly, summer surpluses alone pay the machine off slowly. The payback period shortens considerably when the miner runs on grid power in winter as a heater – it then produces heat you would otherwise pay for with an electric heater. We show how to calculate this in the article Heating with an ASIC miner.
Practical tips from customer consultations
- Some customers place the miner in the utility room next to their PV batteries. In winter its heat keeps them at a comfortable temperature.
- A smart plug or a remotely controlled circuit breaker lets you switch the miner off as soon as the surplus ends and monitor it from your phone.
- A miner produces as much heat as the power it consumes. In summer, make sure the warm air can escape, otherwise it will overheat and throttle itself.
Which miners suit a PV system
Large ASIC miners drawing 3–5 kW are too power-hungry and too loud for home surpluses. For a typical home PV system, quiet machines under 2 kW with adjustable output make sense. You can find their current earnings and payback on the page miners for home mining. If you are also interested in running outside the surplus season, read our comparison Is home mining worth it in the Czech Republic.
What next
- Choose a machine to match your surplus: quiet miners for home mining with live earnings.
- Compare the efficiency of specific models in the ASIC miner profitability overview.
- Calculate your profit at your buy-back price and find out how a miner heats in winter: Mining with solar panels and heating with a miner.
Sources
Frequently asked questions
Can a miner run on solar panels alone, without the grid?
How large a PV system do I need for one miner?
Does frequent switching on and off harm the miner?
Is it worth buying a battery for mining at night?
Which miners are best for solar power?
This text was prepared with the help of AI. Facts, figures and procedures were checked by Yegor.
