Solar Info Center

What Solar Info Center does

Solar-Info-Zentrum SIZ GmbH (SIZ) is a privately held German renewable energy systems integrator and installer headquartered in Neustadt an der Weinstraße, Rhineland-Palatinate. Founded in 1991 by Wolfgang Müller as an engineering office for solar technology and energy consulting, the company has since 2001 operated as a GmbH operating the distinctive Solarhaus showroom — a nearly spherical, energy-positive building that doubles as a live exhibition of working PV, heat pump, ventilation, and rainwater systems. SIZ serves residential and small commercial customers in the Pfalz region and beyond, with cross-border sales to the Netherlands and Italy through partner installers. Its core products include photovoltaic systems (with inverters from SMA, SolarEdge, TIGO, Fronius and storage from E3/DC, AlphaESS, neostore), the proprietary Steckdosenmodul plug-in solar module with VDE- and DGS-certified inverter, controlled residential ventilation with heat recovery (Pichler Ventech 150 and getAir decentralized units), heat pumps (IDM), solar thermal, infrared heating (Redwell), air conditioning, and rainwater harvesting systems.

The company's business model combines hardware resale, professional installation, and energy consulting services, distributed through three channels: a direct consultation-led showroom at the Solarhaus, an e-commerce shop with nationwide delivery across Germany, and a pan-European partner installer network. Pricing is fundamentally transaction-based (unit pricing per module, installation, or planning engagement), with end-customer prices listed gross of VAT under §12 Abs. 3 UStG for the shop and free shipping above €1,000. GTM is sales-led and consultation-heavy rather than digital-led, supplemented by an extensive content-marketing ecosystem (SIZ Mediathek, Expertenwissen portal, Instagram, Facebook, regional trade show participation at Baumesse and Maimarkt Mannheim). Customer segments split across homeowners seeking full PV+storage systems, new construction projects requiring multi-technology installation, renters served by the Steckdosenmodul, and partner installers and trade professionals who resell SIZ-sourced products. SIZ employs 26 staff across office and field operations as of 2026 and maintains a three-person Geschäftsleitung (Wolfgang Müller, Tobias Emmer, Daniel Roth) with no external institutional investment disclosed.

Name

Solar Info Center

Legal name

Solar-Info-Zentrum SIZ GmbH

Website

https://s-i-z.de

Company type

Private

Founded year

1991

Operating status

Operating

Headcount range

11–50 employees

Short description

Solar-Info-Zentrum SIZ GmbH is a German renewable energy systems integrator serving residential and small commercial customers in the Pfalz region and across Europe via partner installers, offering PV, the proprietary Steckdosenmodul plug-in solar module, heat pumps, ventilation, and energy consulting services.

Ownership category

akta.pro rank

Product category

Renewable Energy Systems

NAICS

Ventilation, Heating, Air-Conditioning, and Commercial Refrigeration Equipment Manufacturing (3334), Heating Equipment (except Warm Air Furnaces) Manufacturing (333414), Air-Conditioning and Warm Air Heating Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing (333415)

SIC

Air-Cond & Warm Air Heatg Equip & Comm & Indl Refrig Equip (3585), Heating Equipment, Except Electric & Warm Air Furnaces (3433), Heating Equip, Except Elec & Warm Air; & Plumbing Fixtures (3430)

akta.pro primary industry

Solar Plant Components Supply & Manufacturing (Modules, Cells, Wafers, Mirrors, Heliostats) (EUACAGAK)

akta.pro secondary industries

Solar Inverters, Power Optimizers & MLPE Manufacturing (EUAMAHAB), Solar EPC & Construction (Utility-Scale, Rooftop, Balance of System) (EUAMABAB), Solar Thermal & CSP Systems (Collectors, Receivers, Thermal Storage, CSP EPC) (EUAMABAL)

Keywords

• Solar PV systems
• Plug-in solar modules
• Heat pump installations
• Ventilation heat recovery
• Renewable energy consulting

Headquarters

HQ city

Neustadt An Der Weinstraße

HQ country

Germany

HQ region

Europe

Offices1 record

Markets served

GTM type

B2C

Offering type

Services

Cost components

Personnel, Operations, Supply Chain, Marketing or Sales, Infrastructure, Technology or R&D

Revenue model

1. Product Sales - Renewable Energy Equipment: Sale of PV modules, inverters, storage systems, heat pumps, ventilation units, infrared heaters, rainwater systems, and accessories. Products sourced from manufacturer partners and sold directly via shop and showroom.
2. Installation and Planning Services: Complete installation of PV systems, heat pumps, ventilation, and energy systems. Planning services including 3D planning and energy consulting for residential and commercial buildings.
3. E-commerce / Online Shop: Online shop selling solar components, mounting systems, and accessories with nationwide delivery. All prices listed as end prices with 0% VAT under §12 Abs. 3 UStG.

Pricing tiers

Go-to-market motion1 record

Distribution channels4 records

Marketing channels7 records

Core offering

Solar-Info-Zentrum SIZ GmbH designs, supplies, and installs photovoltaic systems, plug-in solar modules (Steckdosenmodul), heat pumps, ventilation with heat recovery, solar thermal, rainwater harvesting, infrared heating, and air conditioning for residential and small commercial customers. The company also provides professional energy consulting, 3D planning, and thermography services, anchored by an in-person Solarhaus showroom.

Product overview

Solar Info Center (SIZ) is a system provider of renewable energy and energy-saving technologies, operating as a single-source supplier for residential, commercial, and municipal customers in Germany. Its core product portfolio centers on photovoltaic (PV) systems — including PV arrays, mounting hardware, inverters (SMA, SolarEdge, TIGO), and battery storage (E3/DC, AlphaESS, GNB Sonnenschein, neostore Dynamic 3p) — alongside its proprietary Steckdosenmodul (plug-in/balcony solar module), a 300Wp system with built-in inverter for direct 230V socket connection. Complementary product lines include ventilation with heat recovery (Pichler Ventech 150, decentralized SmartFan/TOUCH systems achieving up to 95% heat recovery), heat pumps (IDM AERO ALM air-source, brine/water geothermal, and water/water systems), infrared heating panels (Redwell WE-LINE), air conditioning, solar thermal, rainwater harvesting, and an online shop offering mounting kits and accessories. Services encompass energy consulting, 3D building design, thermography inspections, and project coordination. All products are available for purchase and professional installation through SIZ's showroom (Solarhaus) in Neustadt an der Weinstraße.

Differentiator

Problem solved

Functional benefit

Brands

• Steckdosenmodul: A plug-in solar module system that can be easily mounted on balconies and connected to a 230V outlet for generating solar power for self-consumption.

Products and services

• Photovoltaikanlagen (PV systems) Grid-tied photovoltaic systems for residential and small commercial rooftops, supplied as a complete package with planning, installation, and grid-connection support for homeowners in the Pfalz region.
• Steckdosenmodul (Plug-In Solar Module) Proprietary plug-in solar module with VDE- and DGS-certified safety standard, allowing renters and homeowners to deploy solar power via a standard outlet without transformer lines or complex grid registration.
• Ventilation with heat recovery (Lüftungsanlagen mit Wärmerückgewinnung) Centralized residential ventilation systems with counterflow heat exchangers that recover thermal energy from exhaust air, reducing heating demand and improving indoor air quality.
• Decentralized ventilation (Dezentrale Lüftung) Room-by-room decentralized ventilation units with heat recovery, suitable for retrofitting in existing homes where centralized ducting is impractical.
• Heat pump (Wärmepumpe) Air-source and ground-source heat pumps for residential heating and domestic hot water, integrated with PV systems to maximize self-consumption.
• Air conditioning (Klimaanlage) Residential air conditioning systems for summer cooling, sold and installed alongside SIZ's heating and renewable energy product lines.
• Solar thermal (Solarthermie) Solar thermal systems for domestic hot water heating and heating support, designed to complement PV systems and reduce fossil fuel consumption.
• Rainwater harvesting (Regenwassernutzung) Rainwater harvesting and utilization systems for residential properties, reducing municipal water consumption for garden and household use.
• Infrared heating - Redwell WE-LINE (Infrarotheizung) Redwell WE-LINE infrared heating panels for residential and commercial heating, offered as a complementary heating technology alongside heat pumps and solar thermal.
• Energy consulting and 3D planning (Energieberatung & Planung) Standalone energy consulting service including on-site assessment, 3D planning visualization for solar and heating installations, and thermography diagnostics for building envelope analysis.

Quantifiable outcome

• Up to 95% heat recovery efficiency in ventilation systems, saving up to 40% on heating costs
• +4 more outcomes

Named customers8 records

Segments4 records

Ideal customer profiles3 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Integration5 records

Feature4 records

Partnerships

15 partnerships are on record, tiered core, secondary and minor.

• E3/DCcoreStrategic or Co-development Partner · 1 January 2024Certified Premium Partner of E3/DC since 2024. E3/DC provides home power station and energy storage systems. SIZ integrates E3/DC products into residential PV installations and actively refers E3/DC electricity contracts. Multiple joint installations completed for E3/DC's network of customers.
• SMAcoreTechnology or IntegrationMarket leader for PV inverters in Germany (>50% market share). SMA provides string inverters that convert battery DC current to 230V AC. SMA invented and commercialized the string inverter. SIZ installs SMA inverters across its PV system portfolio.
• Heckert SolarcoreTechnology or IntegrationFamily-run company founded in 2001 in Chemnitz, Germany, producing high-quality crystalline PV modules with 170 MW annual production capacity. SIZ sells Heckert Solar modules as part of its product range.
• SolarEdgesecondaryTechnology or IntegrationTechnology leader in module-level power electronics. SolarEdge devices increase PV system efficiency, enable monitoring, and provide safety shutdown functions. SIZ offers SolarEdge optimization as an add-on for installations with shading or complex roof layouts.
• Pichler (Ventech)coreTechnology or IntegrationAustrian manufacturer of innovative ventilation systems. SIZ installs Pichler's Passivhaus-certified Ventech 150 ventilation units with heat recovery, ranging from 100 to 6000 m³ capacity.
• getAirsecondaryTechnology or IntegrationGerman manufacturer of decentralized ventilation systems with heat recovery based in Mönchengladbach. SIZ offers getAir products for residential decentralized ventilation solutions.
• IDM (Energiefamilie)coreTechnology or IntegrationAustrian manufacturer of efficient, cost-saving heat pumps. IDM has been integrating smart control via smartphone and smart grid for years. SIZ offers IDM's AERO ALM 6-15 modulating air-source heat pump as part of its heating solutions.
• redwell ManufaktursecondaryTechnology or IntegrationAustrian manufacturer specializing in high-quality infrared heating systems with distinctive design, functionality, and individual planning. SIZ offers redwell's WE-LINE infrared heating panels (250-1600W) as part of its heating product line.
• TIGOsecondaryTechnology or IntegrationPV power optimizers that enable module-level optimization for installations with shading, different roof orientations, or diverse obstruction types. SIZ offers TIGO optimizers as add-on for challenging PV installations.
• AlphaESSsecondaryTechnology or IntegrationEnergy storage system provider. SIZ offers AlphaESS storage systems as part of its battery storage product portfolio for residential PV installations.
• FroniussecondaryTechnology or IntegrationInverter manufacturer. SIZ offers Fronius inverters as part of its PV system product range.
• AxitecsecondaryTechnology or IntegrationSolar module manufacturer. SIZ offers Axitec solar modules as part of its PV product range.
• Willkomm NeustadtminorGTM or Marketing PartnerRegional business networking initiative in Neustadt an der Weinstraße. SIZ participated in a networking event hosted at its premises with Willkomm and other regional businesses in October 2025.
• EWS SchönausecondaryStrategic or Co-development PartnerPioneer green energy provider since the historic buyback of the electricity grid 30 years ago. SIZ is a long-standing partner firm of EWS, has completed multiple PV installations for EWS, and actively refers E3/DC/green electricity contracts. SIZ participated in EWS trade fair events.
• Zero Emission Product e.V.coreStrategic or Co-development PartnerNon-profit association that certifies products and services as 100% CO2-free. SIZ received the Zero-CO2 2015 certification (ZEP Register No. H-3-2015) from this association, validating that SIZ produces more renewable energy than consumed in manufacturing at its Neustadt location.

Scale indicators8 records

Recent moves9 records

Expansion highlights5 records

Broad incumbents

• Enpal: Germany's largest residential PV leasing company, also offering heat pumps and battery storage. Competes with SIZ's direct-sale model via a subscription/leasing alternative for the same customer profile.
• Zolar: Digital-first German PV installer with standardized online quoting and partner installer network. Comparable to SIZ in serving homeowners but uses a marketplace model rather than showroom-based sales.
• DZ-4: German residential PV installer with proprietary monitoring platform and standardized installation processes. Competes with SIZ for German homeowners seeking integrated PV + storage solutions.
• Heckert Solar: Family-run German PV module manufacturer with 170 MW annual capacity based in Chemnitz. SIZ is a channel partner for Heckert modules; comparable as a German crystalline PV module specialist with complementary system offerings.
• Solarwatt: Established German PV manufacturer and system provider offering glass-glass modules, battery storage (MyReserve), and full system installation. Comparable as a premium 'Made in Germany' residential renewable energy one-stop-shop.
• 1Komma5°: Well-funded German residential PV, heat pump, and EV charging installer (heartbeat climate product). Competes with SIZ for end customers but operates at vastly larger scale and capital intensity.

Direct peers

• GreenAkku: German online retailer specializing in small PV systems, solar batteries, and plug-in solar modules. Competes directly with SIZ's e-commerce shop and Steckdosenmodul offering for DIY and renter customers.
• priwatt: German D2C brand focused on balcony power plants and plug-in solar modules with integrated inverters. Direct competitor in the Steckdosenmodul category, leveraging digital sales rather than showroom-based selling.
• Yuma Energy: Berlin-based Balkonkraftwerk specialist selling plug-in solar modules with integrated inverters. Closest direct competitor to SIZ's Steckdosenmodul product line in the German plug-in solar category.

Emerging players

• Pichler Lüftung: Austrian manufacturer of Passivhaus-certified ventilation systems with heat recovery (Ventech 150). SIZ is a partner installer; comparable as a residential ventilation specialist whose products SIZ integrates into whole-home energy packages.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights6 records

Customer concentration

• Facebookfacebook.com/solarinfozentrum
• Instagraminstagram.com/solarinfozentrum

Compliance12 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles5 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Solar Info Center