Fothermo System
Fothermo System AG is a German hardware company that designs and sells photovoltaic DC water heaters — solar heating rods, hybrid boilers, off-grid boilers, and storage tanks — direct to European residential households and installers via its own e-commerce and B2B partner portals.
- Company typePrivate
- Founded2020
- HeadquartersStuttgart, Germany
- Headcount11–50
- GTM typeB2C
- OfferingHardware or Manufacturing
What Fothermo System does
Fothermo System AG is a German hardware company headquartered in Neu-Ulm that develops and sells photovoltaic DC water-heating products. Its core technology converts solar electricity directly into hot water through patented MPP (Maximum Power Point) trackers with 99% efficiency, operating below 50V SELV so that no inverter and no certified electrician are required and the systems qualify as "island" installations that bypass grid registration and feed-in bureaucracy.
The product portfolio spans 550W and 1,000W solar heating rods, hybrid boilers with automatic 230V grid reheating, off-grid boilers in 10/30/80L sizes, and 200L/300L solar standing storage tanks, complemented by accessories such as PV extension cables, MC4 parallel connectors, anode replacements, and TSUN TSOL-M800 micro-inverters. The company also offers a proprietary "Umschaltgerät" switching device with a maintained whitelist of approved micro-PV inverters for routing excess solar power to the household grid.
Fothermo operates a direct-to-consumer e-commerce model through fothermo.com and a separate B2B partner portal at b2b-fothermo.com for installers and dealers, with a localised storefront in six European languages. Hardware is sold on a one-time unit-pricing basis (€269–€1,816) with free shipping on flagship SKUs and a 45-day free-return policy. The company self-reports over 10,000 installed systems and over 460,000 products sold across Europe, supported by content marketing, SEO, YouTube tutorials, and interactive savings calculators; no external funding rounds or investor ownership have been disclosed.
Fothermo System firmographics
Firmographics- Name
- Fothermo System
- Legal name
- fothermo System AG
- Website
- https://fothermo.com
- Company type
- Private
- Founded year
- 2020
- Operating status
- Operating
- Headcount range
- 11–50 employees
- Short description
- Fothermo System AG is a German hardware company that designs and sells photovoltaic DC water heaters — solar heating rods, hybrid boilers, off-grid boilers, and storage tanks — direct to European residential households and installers via its own e-commerce and B2B partner portals.
- Ownership category
- akta.pro rank
Fothermo System industry classification
Industry- Product category
- Solar Water Heating Systems
- NAICS
- Heating Equipment (except Warm Air Furnaces) Manufacturing (333414), Power Boiler and Heat Exchanger Manufacturing (33241)
- SIC
- Heating Equipment, Except Electric & Warm Air Furnaces (3433)
- akta.pro primary industry
- Heat Exchangers, Coils & Hydronic HVAC Components (IMADANAF)
- akta.pro secondary industries
- Solar Inverters, Power Electronics & MLPE (String/Central Inverters, Optimizers, Microinverters) (EUAMABAE), Solar Balance-of-System Components (Cables, Combiner Boxes, Switchgear, Transformers) (EUAMABAG)
Keywords
Where Fothermo System is headquartered
LocationHeadquarters
- HQ city
- Stuttgart
- HQ country
- Germany
- HQ region
- Europe
Offices1 record
Markets served
Fothermo System business model
Business model- GTM type
- B2C
- Offering type
- Hardware or Manufacturing
- Cost components
- Supply Chain, Operations, Technology or R&D, Personnel, Marketing or Sales
Revenue model
- Hardware Sales - Solar Heating Products: Fothermo generates revenue through the sale of physical solar water heating products including heating rods, hybrid boilers, standing storage tanks, and off-grid boilers. Revenue is one-time per product with no recurring subscription component.
- Accessories and Components: Sale of complementary products including PV extension cables, parallel connectors, battery cables, anode replacements, and micro-inverters.
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Unit Pricing | Pay-as-you-go | 1.000 W Solar-Heizstab |
| Unit Pricing | Pay-as-you-go | 550 W Solar-Heizstab |
| Unit Pricing | Pay-as-you-go | 80 Liter Solar-Hybridboiler |
| Unit Pricing | Pay-as-you-go | 30 Liter Solar-Hybridboiler |
| Unit Pricing | Pay-as-you-go | 200 Liter Solar-Standspeicher |
| Unit Pricing | Pay-as-you-go | 300 Liter Solar-Standspeicher |
| Unit Pricing | Pay-as-you-go | 80 Liter Solar-Offgridboiler |
| Unit Pricing | Pay-as-you-go | 30 Liter Solar-Offgridboiler |
| Unit Pricing | Pay-as-you-go | 10 Liter Solar-Offgridboiler |
| Unit Pricing | Pay-as-you-go | Mikro-Wechselrichter TSOL-M800 mit WIFI |
| Unit Pricing | Pay-as-you-go | Zubehör: PV Verlängerungskabel 10m |
| Unit Pricing | Pay-as-you-go | Zubehör: PV Verlängerungskabel 5m |
| Unit Pricing | Pay-as-you-go | Zubehör: PV Verlängerungskabel 20m |
| Unit Pricing | Pay-as-you-go | Zubehör: Parallelstecker - 4 Module |
| Unit Pricing | Pay-as-you-go | Zubehör: Parallelstecker - 2 Module |
| Unit Pricing | Pay-as-you-go | Zubehör: Parallelstecker - 3 Module |
| Unit Pricing | Pay-as-you-go | Zubehör: Batteriekabel für Offgridboiler |
Go-to-market motion1 record
Distribution channels2 records
Marketing channels6 records
Fothermo System product offering
Product offeringCore offering
Fothermo System develops and produces photovoltaic water heating products that convert solar DC electricity directly into hot water without inverters or grid feed-in. The portfolio includes solar heating rods (550W and 1,000W), solar hybrid boilers with automatic grid reheating, solar off-grid boilers (10/30/80L) for locations without grid access, and solar standing storage tanks (200L/300L) integrated with existing heating systems.
Differentiator
Problem solved
Functional benefit
Products and services
- 1,000 W Solar Heating Rod (Solar-Heizstab)
Quantifiable outcome
- Up to 75% reduction in hot water energy costs for 2-person households
- +4 more outcomes
Companies that use Fothermo System
Customer profileSegments5 records
Ideal customer profiles3 records
Fothermo System technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
Integration3 records
Feature5 records
Fothermo System partnerships and signals
Strategic signalScale indicators6 records
Recent moves6 records
Expansion highlights5 records
Fothermo System competitors and assessment
Company assessmentDirect peers
- my-PV: Austrian manufacturer of solar-electric heating products (AC ELWA, AC ELWA-E) that convert PV electricity directly into heat and hot water. Most directly comparable peer to Fothermo: same core concept of using PV power for heat, overlapping residential customer base in DACH, and similar DC-direct product architecture.
- SolarBayer: German solar thermal systems manufacturer focused on residential collectors and storage. Overlaps with Fothermo in the solar-supported hot water and heating support use cases, primarily via installer channels.
Emerging players
- RESOL: German manufacturer of solar thermal controllers and system electronics. Comparable as an adjacent supplier into the solar hot water value chain, with overlapping installer and customer base in DACH.
- GreenAkku: German online retailer and integrator of off-grid solar, balcony solar, and solar heating products. Comparable via the off-grid/tiny house and Balkonkraftwerk channels that Fothermo targets, and a potential distribution partner.
Broad incumbents
- Viessmann: Major German heating systems manufacturer offering solar thermal, heat pump, and condensing boiler solutions. Competes indirectly via conventional solar thermal water heating and the broader residential hot water market that Fothermo targets.
- Stiebel Eltron: German manufacturer of hot water storage, heat pumps, and electric heating. Directly competes in the residential hot water market and is a natural incumbent competitor for Fothermo's replacement-electric-boiler use case.
- Bosch Thermotechnology: Bosch's heating and hot water division offers solar thermal and heat pump water heating in Europe. Comparable to Fothermo via the residential hot water and solar-supported heating segments, with significantly broader portfolio and distribution.
- Vaillant: Established German heating brand with solar thermal and heat pump water heating product lines. Targets the same residential hot water retrofit and new-build customer segments as Fothermo, with a much larger installer channel.
Others
- TSUN: Manufacturer of micro-inverters (including the TSOL-M800 referenced by Fothermo) for balcony solar and small PV systems. Comparable as an enabling ecosystem partner; Fothermo actively sells TSUN micro-inverters as compatible accessories.
- Reflex Winkelmann: European manufacturer of hot water storage tanks and heating system components. Comparable as an adjacent supplier into the residential hot water market and a potential bundling partner for Fothermo's storage-based products.
Market position
Strengths5 records
Weaknesses5 records
Competitive moat4 records
Key risks6 records
Key highlights7 records
Customer concentration
Fothermo System social profiles
Digital presenceFothermo System financial estimates
Financial estimateRevenue estimate
Valuation estimate
Fothermo System leadership team
Management profileNumber of profiles
Fothermo System funding detail
Funding detailFunding overview
Funding rounds
Investors
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
Fothermo System 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 Fothermo System
What does Fothermo System do?
Fothermo System develops and produces photovoltaic water heating products that convert solar DC electricity directly into hot water without inverters or grid feed-in. The portfolio includes solar heating rods (550W and 1,000W), solar hybrid boilers with automatic grid reheating, solar off-grid boilers (10/30/80L) for locations without grid access, and solar standing storage tanks (200L/300L) integrated with existing heating systems.
Is Fothermo System a public or private company?
Fothermo System is a private company. It is classified as unknown and is currently operating.
When was Fothermo System founded?
Fothermo System was founded in 2020. It employs 11 to 50 people.
Where is Fothermo System based?
Fothermo System is headquartered in Stuttgart, Germany, in the Europe region.
How does Fothermo System make money?
Two revenue lines are on record. Hardware Sales - Solar Heating Products are the primary driver. The others are accessories and Components.
Who are Fothermo System's main competitors?
Direct peers on record are my-PV and SolarBayer. Emerging players are RESOL and GreenAkku. Broad incumbents are Viessmann, Stiebel Eltron, Bosch Thermotechnology and Vaillant. Others are TSUN and Reflex Winkelmann.
Does Fothermo System have an API?
No public API is recorded for Fothermo System.
What industry is Fothermo System in?
Fothermo System's product category is Solar Water Heating Systems. Its primary akta.pro industry code is IMADANAF, Heat Exchangers, Coils & Hydronic HVAC Components, with a secondary code of EUAMABAE, Solar Inverters, Power Electronics & MLPE (String/Central Inverters, Optimizers, Microinverters). Its NAICS code is 333414 and its SIC code is 3433.