Solar panels and ASIC mining: turn surplus electricity into a controllable load and useful heat

A solar installation does not produce the same amount every hour, and exported energy does not always receive the same price. The useful comparison is therefore not mining revenue against a headline retail tariff. It is the expected net value of exporting a specific kilowatt-hour versus consuming it on site, after network charges, taxes, contract terms and any curtailment rules are included. Day-ahead prices can be very low or negative during oversupplied hours, but a single cheap day is not a permanent tariff.

Build the baseline from metered data whenever possible: at least several months of 15- or 60-minute PV production, building demand and export. PVGIS can provide a location-specific production profile when an operating history is unavailable. This reveals the actual surplus window and the seasonal gap between a bright summer roof and a Baltic or Nordic winter. Only that surplus profile should be offered to the mining model.

• Record PV output, self-consumption and export by interval
• Use the site's real export contract, not a national average
• Separate summer surplus from winter grid consumption
• Test low, base and high market scenarios

A current-generation air-cooled ASIC is commonly a multi-kilowatt load. BITMAIN, for example, specifies 3,500 W at the wall for the 200 TH/s S21 under stated conditions. That makes one unit large enough to matter to a small commercial roof, and a group of units can absorb a meaningful industrial surplus. It also means the connection, cable, breaker, phase balance, ventilation and operating temperature must be engineered before hardware arrives.

The control strategy matters as much as the miner. A simple installation may enable units in stages when export exceeds a threshold. A more advanced controller can read the inverter or site meter, limit total demand, reduce frequency where supported and shut down during expensive hours or grid events. Mining hardware is not infinitely responsive, and repeated thermal cycling affects operations, so the plan needs minimum run times, restart logic and a safe fallback state.

• Size from available kW and interval data
• Reserve capacity for the building's essential loads
• Define start, stop and restart rules
• Model network difficulty, pool fees and downtime separately

Almost all electricity consumed by computing equipment ultimately appears as heat at the site. In practical planning, a 3.5 kW miner is therefore roughly a 3.5 kW heat source before distribution losses. That is useful thermal output, but it is not the same as a heat pump: electric resistance-type conversion has a coefficient of performance near one, while a heat pump can move more heat than the electricity it consumes. The mining case adds a revenue stream, yet that revenue is volatile and must not be treated as guaranteed heating credit.

A house size or floor area alone cannot determine how many miners are needed. Design heat loss, outdoor temperature, supply-water temperature, domestic hot-water profile, buffer capacity, acoustics and summer heat rejection all matter. In winter, captured heat may offset another source. In summer, the same heat can become a disposal cost unless it serves hot water, a pool or a process. The correct design keeps the existing boiler or heat pump available as backup and never makes occupant comfort depend on a coin price.

• Calculate the building's design heat loss
• Map useful heat demand by month and temperature level
• Keep an independent backup heating source
• Provide a summer heat-rejection route

Immersion cooling places compatible mining hardware in dielectric fluid. Heat moves through the fluid circuit to a plate heat exchanger, then into a separated building-water loop or buffer tank. The approach can remove high-speed miner fans, reduce airborne dust and make a larger share of the thermal output easier to collect. It can also support compact technical-room or container layouts where air cooling and ductwork would be awkward.

It is an engineering system, not a box to fill with oil. Fluid compatibility, pumps, filters, seals, expansion volume, electrical isolation, leak containment, sensors, fire and building rules, maintenance access and an emergency heat dump all need review. Hydraulic separation protects the building loop, while controls must prevent overheating if the circulation pump, external radiator or heat consumer stops. An air-cooled solution can be simpler for one or two machines when noise and heat routing are manageable.

• Choose fluid and wetted materials as one compatible system
• Separate the miner loop from building water with a heat exchanger
• Design alarms, shutdowns and secondary containment
• Compare immersion capital cost with a well-ducted air system

The original idea is strongest when direct solar surplus is used first. Adding a battery can extend operating hours, but storage losses, usable capacity, cycle life and the alternative value of backup power must be priced explicitly. It is rarely sound to assume that every stored kilowatt-hour should be sent to mining. The battery may be more valuable for peak shaving, resilience or selling energy in another period.

Model cash flow by interval and month, not with one annual electricity price. Include hardware, electrical works, cooling or immersion equipment, monitoring, pool fees, service, downtime, network difficulty and a residual value assumption. Add heat benefit only for the hours when heat replaces a real paid source. A payback range can then be shown under documented assumptions; a fixed claim such as three or five years cannot be responsibly guaranteed.

• Compare export, direct use and battery use for the same kWh
• Stress-test coin price and network difficulty
• Value heat only when it is actually useful
• Keep taxes, permits and grid conditions site-specific

ForMiners can turn the concept into a site-specific scope: review the PV and export data, size a controllable ASIC load, compare air, immersion and hydro options, plan electrical distribution and heat interfaces, and model operating scenarios. For commercial roofs and energy sites, we can also develop a technical-room or container concept, monitoring logic and a commissioning plan together with the client's electrician and heating engineer.

We also supply suitable mining equipment on request from current availability and project requirements. Selection is based on algorithm, wall power, efficiency, voltage, cooling method, acoustic limits and the intended control strategy—not on a single revenue screenshot. Share the inverter data, connection limit, tariff, location and heat demand through the contact form. We will return with the missing measurements, a shortlist and a practical next step.

• Solar-surplus and electrical-load audit
• ASIC sourcing and compatibility review
• Air, immersion or hydronic heat-reuse concept
• Controls, installation support and commissioning