Evacuated Tube Solar Hot Water System Project Guide

Buyers should not select an evacuated tube solar hot water system from tank volume and tube quantity alone. Instead, they should also evaluate the hot-water load, climate, water pressure, water chemistry, roof conditions, backup-heating strategy and local compliance requirements.

The CASSKY evacuated-tube solar water heater product page presents integrated, pressurized and indirect product configurations. This project guide covers the broader procurement decision. Therefore, it explains how an EPC, distributor or project buyer can assess technical fit, supporting evidence and delivery risk before preparing an RFQ.

CASSKY’s public product information provides preliminary configuration guidance. However, buyers must request the exact working pressure, tank material, insulation specification, collector performance, electrical configuration, certificate scope, warranty, MOQ and production schedule for the offered model.

What Buyers Need to Decide First

A suitable solar water-heating system must match both the building and the operating conditions. Consequently, the first review should answer six questions.

Decision question	Evidence required
Can the system meet the daily hot-water load?	Draw profile, inlet temperature, delivery temperature, climate data and modeled solar contribution
Does the hydraulic design match the building?	Supply pressure, static head, circulation arrangement, pipe layout and system pressure rating
Can the system tolerate the local climate?	Minimum temperature, freeze strategy, stagnation control, wind and snow conditions
Do the wetted materials suit the water?	Water analysis, tank material, heat-exchanger material and supplier limits
Does the offered model meet the project specification?	Model-specific drawings, test reports, certificates and market documents
Can the buyer receive and maintain the equipment?	Packing details, spare-tube plan, replacement parts, manuals and confirmed delivery schedule

If the project team cannot answer these questions, it should treat the quotation as preliminary.

Where Evacuated Tube Solar Hot Water Fits

Evacuated tubes reduce heat loss between the absorber and the surrounding air. As a result, they can remain useful when the ambient temperature falls below the required water temperature.

However, the evacuated tube forms only one part of the system. The tank, heat exchanger, pipework, controls, backup heater and installation conditions also determine project performance.

Suitable applications

An evacuated tube solar hot water system may suit:

Homes, villas and residential developments
Hotels, guesthouses and dormitories
Worker camps and staff accommodation
Sports facilities and changing rooms
Restaurants, kitchens and washing facilities
Hospitals and care facilities with suitable hygiene controls
Industrial water preheating within the declared temperature range
Decentralized buildings where shorter hot-water pipes reduce distribution losses

These applications usually offer regular hot-water demand. In addition, the solar system should replace a measurable amount of electricity, gas or another purchased fuel.

Applications that need additional engineering

Some projects require a pumped loop, external storage tank or hydraulic separation. For example, the following conditions usually need additional engineering:

Freezing winter temperatures
High mains-water pressure
Long distances between collectors and storage
Centralized hot-water production for several buildings
Hard, saline or chemically aggressive water
Highly seasonal or irregular demand
Low summer demand combined with high summer irradiation
Integration with boilers, heat pumps or building controls
Strict roof-loading, wind or service-access limits

In these cases, a complete system design matters more than the number of tubes.

Conditions that can make the product unsuitable

An integrated rooftop unit may not suit the project when:

The roof cannot support the full tank, water, frame and maintenance load.
The proposed tank cannot handle the building’s maximum water pressure.
The design connects a non-pressure tank directly to pressurized mains.
The process requires a temperature outside the manufacturer’s declared range.
The site lacks adequate solar access and has no acceptable backup source.
Nearby structures or vegetation regularly shade the collectors.
The water chemistry conflicts with the tank or heat-exchanger material.
The specification requires complete-system certification, but the supplier can only document the collector.

For example, a 200-litre non-pressure thermosiphon heater may suit a low-rise building with gravity delivery. However, it cannot replace a pressure-rated hotel system simply because both products have the same tank volume.

Comparing System Architectures

The correct architecture depends on pressure, climate, building layout and maintenance requirements.

Architecture	Conditions where it may fit	Main advantages	Important limitations
Direct thermosiphon, non-pressure	Warm climates, simple low-rise buildings and gravity-fed applications	Few moving parts; no solar-loop pump; compact package	Roof carries the tank; limited pressure capability; potable water may contact the tubes; scaling and freezing need review
Integrated heat-pipe pressurized	Villas and small commercial loads that require pressurized hot water	Potable water normally stays inside the tank; maintenance teams can replace individual tubes	Buyer must verify tank pressure, roof load, heat-pipe limits and backup-heater configuration
Integrated indirect-coil system	Pressurized supplies, cold climates or projects that require hydraulic separation	The coil can separate the potable circuit from another fluid circuit	Buyer must verify coil material, surface area, pressure drop and heat-transfer rate
Central pumped indirect system	Hotels, dormitories, multi-building projects and centralized plant rooms	External storage, controlled circulation and flexible backup integration	Requires more components, controls and commissioning work
Multiple decentralized units	Villas, cabins or separated accommodation blocks	Shorter distribution runs and possible phased installation	Creates more roof penetrations, tanks and maintenance points

CASSKY’s public product page lists preliminary market-reference configurations from 100 to 300 litres, 10 to 30 tubes and a common Ø58 × 1800 mm tube format. It also describes non-pressure, pressurized and indirect options.

Nevertheless, these ranges do not replace a model-specific datasheet. Buyers should confirm every quoted value before approving an order.

Conceptual Pumped Indirect System

evacuated-tube-solar-hot-water-system-diagram

Figure 1. Conceptual pumped indirect evacuated-tube solar hot water system. The solar heat-transfer fluid remains separate from potable water. Final collector area, tank volume, pressure ratings, safety devices and controls depend on the project.

In this arrangement, a pump circulates heat-transfer fluid through the collector and the lower tank coil. Meanwhile, potable water remains in a separate circuit.

A differential controller normally starts the pump when the collector temperature rises sufficiently above the tank temperature. Then, it stops the pump when the temperature difference becomes too small.

The solar loop also needs correctly sized expansion capacity, pressure relief, air management and filling points. Moreover, the designer must select these components for the loop volume, fluid type, design pressure and stagnation temperature.

The diagram shows a design concept. It does not represent the certified configuration or output of a specific CASSKY model.

Preliminary Product Configuration Boundaries

The following values summarize the preliminary information on the CASSKY product page. Therefore, buyers should use them only for initial screening.

Product item	Preliminary public range or option	Procurement requirement
Tank capacity	100, 150, 180, 200, 240, 250 or 300 litres	Supplier to confirm for the exact model
Tube quantity	10–30 tubes	Supplier to confirm
Common tube format	Ø58 × 1800 mm	Confirm dimensions, construction and replacement compatibility
Hydraulic configuration	Non-pressure, pressurized or indirect	Select according to building pressure and climate
Inner tank	SUS304 or market-specific option	Confirm grade, thickness, welding and water-quality limits
Outer casing	Stainless steel or coated steel	Confirm material and finish
Insulation	Approximately 50 mm PU as preliminary reference	Confirm thickness, density and declared heat loss
Frame	Galvanized or coated steel	Confirm material, coating and structural limits
Internal coil	Optional	Confirm material, area, pressure and pressure drop
Electric backup	Optional	Confirm voltage, rating, safety devices and certification
Controller and sensors	Optional	Confirm functions, sensor quantity and communications
Working pressure	Configuration-dependent	Do not apply one pressure rating to every configuration
OEM branding	Subject to order scope	Confirm MOQ, artwork, labels, packaging and charges

Project Selection Input Table

Before requesting final sizing, the buyer should provide the following information.

Input category	Information to provide	Why it matters
Project location	City, country and altitude	Determines climate and applicable requirements
Weather data	Irradiation, minimum and maximum temperature, wind and snow	Affects output, mounting, freezing and stagnation
Application	Rooms, beds, users, meals, shifts or process cycles	Establishes the source of hot-water demand
Daily demand	Litres per day at a stated temperature	Defines daily thermal energy
Draw profile	Hourly or 15-minute consumption where available	Determines storage and peak recovery
Cold-water temperature	Monthly or design inlet temperature	Directly affects heating energy
Delivery temperature	Normal setpoint and sanitation requirement	Affects collector output and backup demand
Water pressure	Minimum, normal and maximum pressure	Determines tank and heat-exchanger requirements
Water quality	Hardness, chlorides, pH and conductivity	Influences corrosion and scaling
Roof conditions	Area, slope, orientation, shading and structure	Determines installation feasibility
Plant room	Space, drainage, access and service clearance	Affects external equipment selection
Existing backup	Boiler, electric heater, heat pump or other source	Defines control and hydraulic integration
Electrical supply	Voltage, frequency, phase and available power	Supports pumps, controls and backup heaters
Destination market	Country, region and required program	Determines compliance documentation
Procurement plan	Quantity, delivery date and destination	Supports production and logistics planning
OEM scope	Brand, language, labels, cartons and manuals	Defines private-label requirements

If a value remains unavailable, label it “to be measured” or “supplier to confirm.” Likewise, identify assumed values as “for sensitivity analysis only.”

Calculating the Daily Heating Load

The first calculation converts the hot-water volume into thermal energy:

Q = m × 4.186 × ΔT ÷ 3,600

Where:

Q represents thermal energy in kWh.
m represents water mass in kg.
4.186 represents the approximate specific heat capacity of water in kJ/kg·K.
ΔT represents the temperature rise in °C.

Illustrative load calculation

The following example supports sensitivity analysis. It does not describe a completed CASSKY project.

Assume a guesthouse uses 2,000 litres of hot water per day. The cold-water design temperature reaches 15°C, while the storage target reaches 55°C.

Q = 2,000 × 4.186 × (55 − 15) ÷ 3,600

Therefore:

Q = approximately 93.0 kWh per day

If the project initially targets a 60% solar contribution, the solar system would need to provide an average of:

93.0 × 60% = 55.8 kWh per day

Collector-area sensitivity

A buyer should not divide the load by peak irradiance to determine the final collector area. Instead, the project model should include collector coefficients, pipe losses, tank losses, shading, orientation, load timing and controls.

For early sensitivity analysis only:

Assumed useful daily solar delivery	Indicative area for 55.8 kWh/day
2.0 kWh/m²/day	27.9 m²
2.8 kWh/m²/day	19.9 m²
3.5 kWh/m²/day	15.9 m²

These assumed yields do not represent product ratings. Instead, they show how the result changes when usable solar delivery changes.

For initial weather analysis, the European Commission’s free PVGIS tool provides solar-radiation and temperature datasets. However, weather data alone cannot guarantee solar thermal yield.

How to Compare Collector Performance

A single efficiency percentage cannot describe collector performance across all conditions. In particular, output changes with irradiance and with the temperature difference between the collector and ambient air.

Collector reports commonly use a relationship such as:

η = η₀ − a₁(Tm − Ta)/G − a₂(Tm − Ta)²/G

Where:

η₀ represents the optical-efficiency term.
a₁ and a₂ represent heat-loss coefficients.
Tm represents mean collector-fluid temperature.
Ta represents ambient temperature.
G represents solar irradiance on the collector plane.

Therefore, buyers should compare products using the same reference area, test basis and operating conditions. They should not mix gross area, aperture area and absorber area.

Evidence to request

For each shortlisted collector, request:

Exact model designation
Overall dimensions and reference area
Tube quantity and dimensions
Optical and heat-loss coefficients
Incidence-angle modifier data where applicable
Test fluid and flow conditions
Pressure drop at the declared flow
Maximum operating pressure
Stagnation temperature or related test evidence
Permitted installation angle
Wind, snow and mounting limits
Freeze-protection requirements
Complete test-report identification

For example, a strong optical-efficiency term does not guarantee high output at a high operating temperature. Heat-loss coefficients also affect the result.

Storage and Backup Heating

The collector and storage tank must work as one system. Otherwise, an oversized collector may create frequent stagnation, while an oversized tank may remain at a low temperature and increase backup-energy use.

Storage values to distinguish

Buyers should separate:

Nominal tank volume
Usable hot-water volume
Dedicated solar-storage volume
Backup-heated volume
Heat-exchanger surface area
Maximum continuous draw rate
Peak short-duration draw rate
Declared standing loss

Furthermore, projects with concentrated morning or evening demand need hourly analysis. A daily-volume figure may hide a serious peak-capacity problem.

Backup control

A boiler, electric element or heat pump can supply backup energy. However, the control sequence should preserve useful storage capacity for solar input.

For example, a backup heater that warms the whole tank before sunrise may reduce solar utilization later in the day. Therefore, many projects separate the solar-storage zone from the backup-heated zone.

Freeze and Stagnation Protection

Climate protection must cover the complete installation. Vacuum insulation around the absorber does not protect every manifold, valve or exterior pipe.

Freeze protection options

Depending on the product and climate, the designer may consider:

A closed loop with an approved antifreeze fluid
Drainback operation
Controlled circulation where the climate and power supply permit it
Heat tracing for exposed pipework
Seasonal drainage
A product configuration designed for the local minimum temperature

However, the supplier must approve the chosen method. The project team must also check fluid life, concentration, pumping requirements and maintenance procedures.

Stagnation and summer overproduction

Stagnation can occur when solar energy remains available but the building stops using hot water. Schools, dormitories and seasonal hotels provide common examples.

Therefore, the project may need:

Correct collector-to-storage sizing
A heat-rejection strategy
Drainback operation
Vacation control
Approved collector-isolation procedures
High-temperature-compatible fluid and insulation
A documented shutdown plan

Simply covering part of the collector array does not provide a general engineering solution. Instead, the manufacturer should approve any covering method.

Water Quality and Hygiene

Water chemistry affects tanks, heat exchangers, valves and maintenance intervals. Therefore, buyers should provide an actual water analysis rather than rely on a general description such as “municipal water.”

Water data to provide

The analysis should include:

Total hardness
Chloride concentration
pH
Conductivity
Sulphates or other locally relevant constituents
Existing filtration or treatment
Planned inspection and descaling procedure

Stainless-steel grade names alone do not prove water compatibility. For example, chloride concentration, temperature, fabrication quality and cleaning chemicals can all influence corrosion risk.

Hygiene and outlet temperature

Hot-water projects also need a hygiene strategy. The World Health Organization’s Legionellosis guidance identifies temperature management, maintenance and reduced stagnation as important controls.

Nevertheless, the project must follow local regulations and its water-safety plan. In addition, the designer should address scalding risk.

A thermostatic mixing valve can reduce distribution temperature where appropriate. However, the engineer must confirm its capacity, location, fail-safe behavior and maintenance access.

Testing, Certification and Compliance

Buyers should distinguish laboratory testing from certification, market compliance, factory quality control and project acceptance. Each category answers a different question.

Evidence category	What it establishes	What it does not establish
Collector laboratory test	Thermal coefficients and applicable durability, reliability or safety results	Complete-system certification or annual project yield
Factory-made system test	Performance of a defined system configuration	Performance of a materially different collector, tank or controller
Product certification	Third-party conformity for the listed models and rules	Compliance of unlisted variants or the installed project
Market documentation	Conformity with stated destination-market requirements	Solar yield or installation quality
Factory quality control	Consistency of materials, assembly and inspection	Field performance after shipping and installation
Project commissioning	Flow, controls, temperatures, alarms and functional operation	Long-term annual output without continued monitoring

ISO 9806 collector testing

ISO 9806:2025 specifies test methods for the durability, reliability, safety and thermal performance of fluid-heating solar collectors.

Therefore, an applicable report can support collector comparison. However, the report must cover the exact product.

ISO 9806 addresses collector-level testing. Moreover, its scope excludes arrangements where integral storage prevents separate collector-performance measurement. Consequently, an ISO 9806 report does not automatically establish complete-system performance.

ISO 9459 system performance

The ISO 9459 series covers solar domestic water-heating systems through different procedures:

ISO 9459-1 covers an indoor rating procedure within its stated scope.
ISO 9459-2 addresses outdoor performance characterization and annual-performance prediction for solar-only systems.
ISO 9459-5 covers whole-system testing combined with computer simulation within its specified conditions.

Therefore, the buyer should identify the exact part, test configuration and operating conditions. A reference to “ISO 9459” without a part number provides insufficient evidence.

Solar Keymark

The Solar Keymark scheme rules distinguish collector products, factory-made systems and custom-built systems.

Consequently, buyers should check whether the certificate covers only the collector or the complete factory-made system. They should also compare the certificate model, collector variant, tank, controller and certificate holder with the quotation.

ICC-SRCC

For North American projects, ICC-SRCC separates collector and system programs. According to the ICC-SRCC program explanation, OG-100 applies to collectors, while OG-300 addresses complete solar water-heating systems.

Therefore, buyers should check the exact model in the ICC-SRCC certified product directories. An OG-100 collector listing alone does not create an OG-300 system listing.

Electrical backup components

An electric backup heater requires a separate electrical-safety review. IEC 60335-2-21:2022 covers particular safety requirements for electric storage water heaters within its stated limits.

In addition, the project must confirm national adoption, voltage, wiring, earthing, residual-current protection and ingress protection.

Model-specific documents to request

Request the following files for the offered configuration:

Model-specific datasheet
General arrangement drawing
Hydraulic connection drawing
Collector test report or report summary
Certificate number and scope where required
Pressure and leakage test procedure
Tank material declaration
Insulation specification
Controller and electrical schematic
Installation and operation manual
Packing specification
Quality inspection plan
Spare-parts list
Warranty terms and exclusions

CASSKY does not publish every model-specific document on the product page. Therefore, buyers should request the applicable files during the inquiry.

Factory and Pre-Shipment Checks

The purchase specification should define the inspection plan before production starts. Otherwise, the buyer and supplier may apply different acceptance criteria.

Product checks

The inspection plan may cover:

Bill-of-material comparison with the approved configuration
Tube quantity, dimensions and visible condition
Tank material and thickness
Tank pressure or leakage test
Coil pressure or leakage test where applicable
Controller and sensor functions
Electric-heater rating and electrical checks
Frame material, coating and fasteners
Labels, serial numbers and carton marks
Manuals, fittings and accessories
Spare-tube and replacement-part quantities

Packing and loading checks

The buyer may also request:

Packing-material confirmation
Carton and pallet dimensions
Stacking limits
Loading photographs
Container packing list
Accessory count
Spare-tube identification
Damage-reporting procedure

However, sample inspection does not replace routine factory quality control. Therefore, the purchase order should also define the response to nonconforming goods.

Delivery and Installation Risks

Evacuated glass tubes require careful packing and site handling. Nevertheless, tube breakage risk does not automatically make the technology unsuitable.

Transport questions

The buyer should confirm:

Whether the factory ships tubes separately or inside the unit
How the packaging protects each tube
Whether the factory uses pallets or crates
How many cartons the factory can stack
How the factory loads the container
How many spare tubes the order includes
Who handles transit-damage claims
Whether replacement tubes will remain compatible
How the buyer should store tubes before installation

Site questions

Before delivery, the project team should also check:

Lifting access
Roof loading
Wind anchorage
Roof waterproofing
Pipe support
Drainage
Maintenance clearance
Safe access for tube replacement

Furthermore, maintenance teams should be able to replace a tube without dismantling unrelated roof equipment.

Illustrative Project Case

The following scenario demonstrates the decision process. It does not represent a completed CASSKY project.

Project assumptions

Application: 20-room guesthouse
Daily hot-water demand: 2,000 litres
Cold-water design temperature: 15°C
Storage target: 55°C
Daily heating load: approximately 93.0 kWh
Existing backup: boiler
Water supply: pressurized
Climate: occasional freezing
Plant room: available at ground level
Roof: adequate unshaded area, subject to structural approval

Architecture decision

A non-pressure thermosiphon system conflicts with the pressurized building supply. Moreover, several full rooftop tanks would increase roof loading and complicate boiler integration.

Individual pressurized rooftop units could serve separate rooms. However, that approach would create multiple tanks, valves and maintenance points.

Therefore, a centralized pumped indirect system provides the stronger concept for further evaluation. It offers external storage, a separated freeze-protected loop and controlled boiler backup.

Nevertheless, the final decision still depends on roof structure, water chemistry, hydraulic distance, collector coefficients and lifecycle cost.

Next engineering step

At a 60% solar contribution, the conceptual solar target reaches approximately 55.8 kWh per day. However, the sensitivity calculation produces an indicative collector range from 15.9 to 27.9 m².

That range remains too wide for procurement. Therefore, the EPC should complete a project simulation using:

Hourly or monthly weather data
Exact collector coefficients
Roof orientation and inclination
Pipe lengths and insulation
Storage configuration
Hot-water draw profile
Boiler control sequence
Freeze-protection fluid
Stagnation strategy

Afterward, the EPC can finalize the collector quantity, storage capacity and backup power.

Commissioning and Acceptance

The commissioning plan should use measurable conditions. A visual check that the pump runs does not prove correct system operation.

Mechanical acceptance

Confirm that:

Collectors match the approved orientation and inclination.
Frames and anchors match the structural design.
Pipe materials and insulation match the submittal.
Valves, drains and vents remain accessible.
The solar and potable circuits remain separate.
Expansion vessels have the correct pre-charge.
Relief devices discharge to a safe location.
Tanks, coils and pipes show no leakage.

Hydraulic acceptance

Next, confirm that:

Circuit pressure remains within the approved range.
The commissioning record states the antifreeze concentration.
The installer has filled and purged the loop correctly.
Measured pump flow matches the design requirement.
Check valves allow the correct flow direction.
Pressure drop does not cause unstable pump operation.

Control acceptance

Then, verify that:

Sensors occupy the approved positions.
Displayed temperatures agree with reference measurements.
Pump start and stop differentials match the approved settings.
Freeze and high-temperature functions operate correctly.
Backup controls follow the intended priority.
Alarms and remote signals work where specified.

Handover acceptance

Finally, record:

Outlet temperature
Mixing-valve setting
Controller settings
Fluid type and concentration
Pump flow
System pressure
Equipment serial numbers
Operator training
Maintenance schedule
Approved drawings and manuals

OEM and Distributor Support

The CASSKY product page describes configurable components and private-label options. In addition, the CASSKY support page provides channels for technical files and OEM discussions.

Depending on the project and order scope, buyers may request:

Private-label branding
Market-specific rating labels
Carton artwork
Manual translation
Tank, casing or frame options
Controller and sensor options
Electric-backup configurations
Installation accessories
Spare tubes and components
Model-specific technical files
Packing and loading information
Pre-shipment inspection arrangements

However, buyers should not assume MOQ, tooling charges, lead time, certificate availability, spare-parts commitments or response times. Instead, they should record these terms in the quotation and purchase agreement.

Public Technical Resources

Buyers can access the following public materials:

The CASSKY catalog provides a public download. In contrast, buyers need to request exact model datasheets, drawings, test reports, certificates, inspection records and OEM files.

RFQ Checklist

A complete RFQ should include the following information.

Project conditions

Project name, city and country
Building or process type
Number of users, rooms or process cycles
Daily hot-water volume
Hourly draw profile where available
Cold-water temperature
Required storage and delivery temperatures
Minimum and maximum ambient temperatures
Solar-resource data
Wind, snow and altitude
Water-pressure range
Water analysis

System requirements

Preferred architecture
Required solar contribution
Available roof area
Roof orientation and shading
Structural restrictions
Plant-room space
Existing backup-heating source
Electrical supply
Monitoring or BMS requirements
Freeze-protection requirement
Stagnation strategy
Potable-water and hygiene requirements

Product evidence

Exact collector and tank model
Collector quantity and reference area
Solar and backup storage volumes
Tank and coil materials
Pressure ratings
Thermal-performance coefficients
Applicable test reports
Required certificates
Connection drawings
Controller functions
Installation manual
Spare-parts schedule
Inspection plan

Commercial requirements

Order quantity
OEM branding
Packaging requirements
Delivery destination
Target delivery date
Incoterm
Spare-tube quantity
Third-party inspection
Warranty terms
After-sales requirements
Document submission schedule

When information remains unknown, use “to be measured,” “for sensitivity analysis only” or “supplier to confirm.” Consequently, preliminary assumptions will not become hidden contractual requirements.

Frequently Asked Questions

Are more evacuated tubes always better?

No. Tube quantity must match tube dimensions, collector area, climate, storage and hot-water demand. Moreover, excessive collector area can increase stagnation risk.

Can a non-pressure heater connect directly to pressurized mains?

No, unless the manufacturer specifically designs and approves that arrangement. Instead, use a configuration with a suitable pressure rating or hydraulic separation.

Does ISO 9806 certify the complete system?

No. ISO 9806 addresses solar collectors within its scope. Therefore, the buyer needs separate evidence for complete-system performance or certification.

Does a vacuum tube prevent freezing?

No. The vacuum reduces absorber heat loss. However, water inside manifolds, valves and pipes can still freeze.

Can the buyer size the tank from occupant numbers?

Occupancy provides a starting point. Nevertheless, the buyer should also determine daily volume, delivery temperature and peak draw profile.

Does laboratory output guarantee project yield?

No. Laboratory data supports engineering calculations. In contrast, actual yield also depends on weather, orientation, shading, storage, controls, pipe losses, consumption and maintenance.

What should an OEM buyer verify?

The buyer should verify the exact model, bill of materials, pressure rating, electrical configuration, test scope, certificates, artwork, packing, inspection criteria, spares, lead time and warranty. Finally, the buyer should place every agreed requirement in the quotation or contract.

Request a Preliminary CASSKY Selection

For an initial evacuated tube solar hot water review, submit:

Project country and city
Daily hot-water volume
Hourly draw schedule where available
Cold-water and delivery temperatures
Water pressure
Water-analysis results
Minimum winter temperature
Roof dimensions and orientation
Roof photographs
Existing backup-heating source
Required certification
Quantity and OEM scope
Delivery destination

CASSKY can then review the possible system architecture and identify the technical files that apply to the proposed configuration. After that, the buyer can request model-specific drawings, test information and a commercial quotation.

Final selection should rely on the confirmed product configuration, project conditions and approved technical submittal—not on a generic tube quantity or tank-volume claim.