Resol
- Company typePrivate
- Founded1977
- HeadquartersDublin, Ireland
- Headcount51–100
- GTM typeB2B
- OfferingHardware or Manufacturing
What Resol does
RESOL GmbH (legal name: RESOL – Elektronische Regelungen GmbH) is a German manufacturer of electronic controllers, sensors, and accessories for solar thermal, heating, fresh water, and energy management systems, founded in 1977 and headquartered in Hattingen, Germany. The company is privately held and controlled by the Pfeil family, with Isabel Pfeil, Marcel Pfeil, and Rudolf Pfeil serving as Managing Directors. RESOL operates a single-site model with high manufacturing depth — hardware and software development, production, laboratory and test-field operations, documentation, and distribution are all conducted under one roof at Hattingen.
The product architecture centers on the proprietary VBus communication protocol, which connects RESOL controllers (DeltaSol solar, DeltaTherm heating, DeltaTherm PV/PHM Power-to-Heat, DeltaTherm FK biomass, DeltaSol Fresh fresh water, and DeltaTherm HIU heat-interface units) to a broad accessory ecosystem including the KM2 communication module, DL2 Plus datalogger, VBus-Repeater, USB and CANopen interface adapters, alarm modules, displays, heat meters, and Grundfos Direct Sensors. Software and digital products include the VBus.net cloud visualization portal (Basic and PRO), VBusTouch mobile applications for iOS and Android, the ROSA online system selector, and the RPT parameterization tool. Integration with BACnet/Modbus building automation is supported via the DL2 Plus datalogger.
RESOL generates revenue across three streams: hardware sales (controllers, solar stations, sensors, valves, accessories), software and services (VBus.net visualization subscriptions, parameterization tools, training, repairs, programming), and OEM professional services for custom product development including bespoke housing design. The go-to-market is sales-led, combining direct B2B sales via the website (inquiry-only pricing across price groups A/B/C), OEM partnerships with dedicated product managers, and a regional network of professional installers and system integrators. Primary customer segments are solar thermal installers/system integrators and heating-system manufacturers/OEMs, with residential building owners as a downstream user segment. Recent geographic certification activity covers Germany as the primary market, with new certifications obtained for Canada, the United States, and Australia in 2025.
Resol firmographics
Firmographics- Name
- Resol
- Legal name
- RESOL – Elektronische Regelungen GmbH
- Website
- https://resol.de
- Company type
- Private
- Founded year
- 1977
- Operating status
- Operating
- Headcount range
- 51–100 employees
- Ownership category
- akta.pro rank
Resol industry classification
Industry- Product category
- Solar and Heating Control Systems
- NAICS
- Automatic Environmental Control Manufacturing for Residential, Commercial, and Appliance Use (334512), Relay and Industrial Control Manufacturing (335314), Ventilation, Heating, Air-Conditioning, and Commercial Refrigeration Equipment Manufacturing (3334)
- SIC
- Industrial Instruments For Measurement, Display, And Control (3823)
- akta.pro primary industry
- Customer Grid-Edge Enablement Services (HEMS/DR Device Integration, VPP Enablement) (EUAEANAL)
- akta.pro secondary industry
- Volt/VAR Optimization (VVO), CVR & Voltage Management with DER (EUADALAH)
Keywords
Where Resol is headquartered
LocationHeadquarters
- HQ city
- Dublin
- HQ country
- Ireland
- HQ region
- Europe
Offices1 record
Markets served
Resol business model
Business model- GTM type
- B2B
- Offering type
- Hardware or Manufacturing
- Cost components
- Personnel, Operations, Technology or R&D, Supply Chain, Marketing or Sales, Infrastructure
Revenue model
- Hardware Products: Sale of controllers (solar, multifunction, heating, biomass), compact solutions, solar stations, sensors, valves, and accessories for heating and energy systems.
- Software & Services: VBus.net visualization portal (Basic and PRO versions), parametrization tools, service software, programming services, repairs, and training.
- OEM Product Development: Custom product development and design services for OEM customers including custom housing design and full development support.
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Other | Multi-year contract | B2B pricing through inquiry only |
Go-to-market motion1 record
Distribution channels3 records
Marketing channels7 records
Resol product offering
Product offeringCore offering
RESOL GmbH develops, manufactures, and sells electronic controllers and accessories for solar thermal, heating, fresh water, and energy management systems, centered on its proprietary VBus communication protocol. The portfolio spans solar controllers (DeltaSol series), multifunction controllers (DeltaSol MX/BX Plus), heating controllers (DeltaTherm HC), power-to-heat solutions (DeltaTherm PV/PV MAX/PHM), biomass controllers (DeltaTherm FK), pre-assembled solar stations (FlowSol), and a cloud visualization platform (VBus.net) with companion mobile apps. RESOL also provides OEM custom development, repairs, and training services, with all R&D and production performed in-house at Hattingen, Germany.
Product overview
RESOL GmbH is a German manufacturer offering a comprehensive portfolio of controllers, compact solutions, and accessories for solar thermal, heating, energy management, and visualization applications. The product ecosystem centers on the proprietary VBus® communication protocol, which connects controllers to a wide range of accessories including sensors, displays, data loggers, and communication modules. The core product lines include: DeltaSol® solar controllers (A/AX, AL E HE, CS/CS Plus, SLL, SL, BX, SLT) for differential temperature control in solar thermal systems; DeltaSol® BX Plus and MX/MX Plus multifunction controllers for complex installations; DeltaTherm® HC heating controllers (HC mini, HC MAX, HC Plus) for weather-compensated heating circuits; DeltaTherm® PV/PV MAX/PHM Power-to-Heat solutions for utilizing excess PV power; DeltaTherm® FK biomass controller; DeltaSol Fresh® fresh water controllers with self-learning algorithms; FlowSol® solar stations (S HE, B HE, XL) as pre-assembled hydraulic units; and comprehensive visualization/remote access tools including VBus.net cloud portal, VBus®Touch mobile apps, KM2 communication module, DL2 Plus datalogger, and ServiceCenter software. Supporting accessories include sensors (temperature, flow, humidity, radon), valves (thermostatic mixing, switching, motorized ball valves), pump signal converters (PSW series), measurement devices (heat meters, flow meters), and service tools (HE-Check, LIN-Check, SBS 2000 filling station). The modular architecture allows systems from small residential installations to large commercial complexes with multiple heat sources and heating circuits.
Differentiator
Problem solved
Functional benefit
Brands
- VBus.net: Visualization portal for monitoring RESOL controller data, offering Basic and PRO versions with live data and personalized filter settings.
- VBusTouch
- VBusTouch HC
- VBusTouch Trainer
- VBusTouch FK
- ROSA
- DeltaSol
- DeltaTherm
- FlowSol
Products and services
- DeltaSol Solar Controllers
- DeltaSol MX/MX Plus Multifunction Controllers
- DeltaTherm HC Heating Controllers
- DeltaTherm PV MAX Power-to-Heat Controller
- DeltaTherm PV and PHM Power-to-Heat Controllers
- DeltaTherm FK Biomass Controller
Quantifiable outcome
- Optimal utilization of PV surplus through intelligent power-to-heat conversion
- +1 more outcomes
Companies that use Resol
Customer profileSegments3 records
Ideal customer profiles3 records
Resol technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
Integration7 records
AI capability5 records
Feature5 records
Resol partnerships and signals
Strategic signalScale indicators2 records
Recent moves6 records
Expansion highlights6 records
Resol competitors and assessment
Company assessmentDirect peers
- Caleffi: Italian manufacturer of components and electronic controls for HVAC, solar thermal, and hydronic systems; directly comparable product mix in solar thermal controller and accessories for installers.
- Danfoss: Danish manufacturer of heating and HVAC controls, including district heating and electronic climate controls; comparable in heating-controller portfolio and OEM system integrator customer base across Europe.
- JUMO: German manufacturer of measurement and control instrumentation for industrial, HVAC, and heating applications; comparable German Mittelstand profile serving similar installers and OEM customers with sensor-controller combinations.
- Belimo: Swiss manufacturer of HVAC actuator and control devices (damper actuators, control valves, sensors); closest direct peer in control hardware for HVAC systems, addressing installers and OEMs in the same building-services channel.
- Eberle Controls (a Schneider Electric brand): German-based thermostat and heating controller manufacturer (now part of Schneider Electric); highly comparable as a German Mittelstand controls specialist selling into installer/OEM channels for residential and commercial heating.
Others
- Wilo: German pump manufacturer whose PARA high-efficiency pumps are bundled into RESOL's PSW Premium Set for solar stations; ecosystem partner/adapter-supplier relationship rather than head-to-head competition.
- Grundfos: Danish pump manufacturer whose Direct Sensors and high-efficiency pumps are integrated with RESOL controllers via the VBus protocol; an enabling supplier and ecosystem partner rather than direct competitor.
Broad incumbents
- Siemens Smart Infrastructure: Siemens division covering building automation, HVAC controls, and energy management; competes indirectly as a portfolio provider of climate-control controllers where RESOL focuses on solar and residential heating.
- Honeywell Building Technologies: Large incumbent division offering building automation and HVAC controls; overlaps with RESOL's controllers but operates at much greater scale across full BMS stacks rather than specialist solar/heating niches.
- Viessmann: German heating-systems manufacturer (heat pumps, biomass, solar thermal) serving installers with full heating solutions; an OEM customer class for RESOL controllers while also competing at the higher system level.
Market position
Strengths5 records
Weaknesses5 records
Competitive moat4 records
Key risks6 records
Key highlights7 records
Customer concentration
Resol social profiles
Digital presenceResol compliance and trust
Trust signalCompliance2 records
Resol financial estimates
Financial estimateRevenue estimate
Valuation estimate
Resol leadership team
Management profileNumber of profiles
Profiles3 records
Resol funding detail
Funding detailFunding overview
Funding rounds
Investors
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
Resol M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about Resol
What does Resol do?
RESOL GmbH develops, manufactures, and sells electronic controllers and accessories for solar thermal, heating, fresh water, and energy management systems, centered on its proprietary VBus communication protocol. The portfolio spans solar controllers (DeltaSol series), multifunction controllers (DeltaSol MX/BX Plus), heating controllers (DeltaTherm HC), power-to-heat solutions (DeltaTherm PV/PV MAX/PHM), biomass controllers (DeltaTherm FK), pre-assembled solar stations (FlowSol), and a cloud visualization platform (VBus.net) with companion mobile apps. RESOL also provides OEM custom development, repairs, and training services, with all R&D and production performed in-house at Hattingen, Germany.
Is Resol a public or private company?
Resol is a private company. It is classified as family owned and is currently operating.
When was Resol founded?
Resol was founded in 1977. It employs 51 to 100 people.
Where is Resol based?
Resol is headquartered in Dublin, Ireland, in the Europe region.
How does Resol make money?
Three revenue lines are on record. Hardware Products are the primary driver. The others are software & Services and OEM Product Development.
Who are Resol's main competitors?
Direct peers on record are Caleffi, Danfoss, JUMO, Belimo and Eberle Controls (a Schneider Electric brand). Others are Wilo and Grundfos. Broad incumbents are Siemens Smart Infrastructure, Honeywell Building Technologies and Viessmann.
Does Resol have an API?
No public API is recorded for Resol.
What industry is Resol in?
Resol's product category is Solar and Heating Control Systems. Its primary akta.pro industry code is EUAEANAL, Customer Grid-Edge Enablement Services (HEMS/DR Device Integration, VPP Enablement), with a secondary code of EUADALAH, Volt/VAR Optimization (VVO), CVR & Voltage Management with DER. Its NAICS code is 334512 and its SIC code is 3823.