Homeowner Professional

Here you will find the most common questions related to natural slate and our selection of products.

Frequently asked questions

1. General

What does thermal solar energy consists of?

The thermal solar panels use solar radiation to produce energy which can be used to produce hot water, control swimming pool temperatures or central heating.

  • Thermal solar energy uses space more efficiently than photovoltaic energy.
  • The panels are smaller and have an average efficiency of over 70% compared to the 10-25% produced with photovoltaic.
  • It can generate hot water, control swimming pool temperature or central heating. It does not generate electricity.
  • It is not subject to special taxes.
Can THS be installed on an existing roof?

Yes, by replacing part of the previously installed slate with THERMOSLATE panels. For aesthetic reasons, it is necessary for the slate format of the roof to match the slate used in THERMOSLATE. This means that the slate is of the same format and quarry, and is installed with the same overlap.

Are the panels made to measure or do they have standard dimensions?
They have standard sizes:
  1. THS 3222.S07 (hook) 2458x645x37 mm Spainths 3233 gancho 750x177 uk
  2. THS 3222.S10 (hook) 2458x605x37 mm France ths 3233 gancho fr 750x174 uk
  3. THS 5025.S10 (nail) 2267x743x37 mm Great Britainths 5025 s10 750x201 uk
  4. THS 4022.S11 (hook) 2458x745x37 mm Belgiumths 4022 s11 750x177 uk
  5. THS 4020.P (flat) 1200x800x35 mm

    thermoslate flat

Does THERMOSLATE produce electricity?

No, it doesn’t. THERMOSLATE is a thermal solar panel not photovoltaic. It generates energy to produce hot water, control swimming pool temperature or central heating.

Where can THERMOSLATE be installed? What does the integration consist of?

 THERMOSLATE panels can be installed on sloping or flat roofs as well as façades. The panels are always hidden and perfectly integrated with the natural slate. 

Who is in charge of installing it?

THERMOSLATE panels should be installed by the slate roofer in charge of the project and a plumber will need to carry out a water tightness test to ensure the installation is working properly.

When was the first THERMOSLATE installation done?

The first THERMOSLATE installation was in 2008.

Is THERMOSLATE a recyclable material?

Yes, the majority of the panel is composed of: (1) slate, (2) aluminum and (3) XPS. All three of these materials can be recycled.

2. Compatibilities

Can it be done with a material other than slate?

No, because these panels work by taking advantage of the natural characteristics of slate (its color and thickness) which transmit the captured heat to the absorber.

Can it be installed with slate other than that supplied by CUPA PIZARRAS?

No, it has to be CUPA PIZARRAS slate, as this has been tested and certified.

Can THERMOSLATE be produced in any format?

No, THERMOSLATE is only produced in a rectangular format. The following formations do not allow a complete integration or water tightness; Pico Pala, Redonda, Rombo, Granel, Media Luna and Shuppen.

Is it compatible with any heating system? What about radiant heating? Is it for any type of radiator?

It is compatible with radiant flooring systems or low-temperature convectors (radiators of 45-60°C).

Is it compatible with any brand and model of battery?

Yes, in principle there should be no problem. This answer should be confirmed by the battery manufacturer.

Can the solar panels overheat? Do THERMOSLATE systems need to be combined with drain-back?

The solar panels will not overheat due to the intrinsic properties of the slate which dissipate the heat. No action is needed thereon.

Drain-back systems are used exclusively with solar collectors that, due to their design features, are capable of producing gas in the primary circuit due to overheating. It is feasible for it to be installed with any type of collector, however, due to its design features, Thermoslate does not reach dangerous temperatures that make the use of drain-back necessary.

3. Profitability And Performance

How much does it cost?

Our THERMOSLATE rates include both the collector and the rest of the components necessary for installation, including fixing and integration accessories, as well as waterproofing.

When will I amortize the system?

It depends on the geographical location of the residence, the orientation and slope of the roof, as well as on energy needs.

To get an idea of how many panels a building needs and their amortization period, we calculate the installation requirements for each project using the T-SOL calculation program.

For example, in our general product catalog we showcase a residence in the French Pyrenees. With a useful life of 25 years, it is estimated that the owners of this house will amortize their investment in thermal panels in just 10 years.

What performance and advantages does it have compared to other conventional thermal panels?

The main advantages of THERMOSLATE are its aesthetics (complete integration into the roof), its durability (slate) and its need for zero maintenance. THERMOSLATE has a similar investment-to-energy production ratio to other standard collectors on the market. In other words, with a similar investment, similar annual energy yields are obtained.

What performance and advantages does it have compared to other conventional thermal photovoltaic panels?

THERMOSLATE is not a photovoltaic panel.

What is the percentage of hot water and heating generated with THERMOSLATE?

The THERMOSLATE output is dependent on the geographical location of the building and characteristics in that area as well as the roof pitch. On average, the panels usually cover between 30-70% of the annual requirements.

Will shadows on the building affect the performance of THERMOSLATE?

Our engineers will assess the building taking into consideration any trees or objects blocking sunlight from the thermal solar panels. Any objects in the way will reduce the solar radiation and THERMOSLATE performance.

Can rain or snow affect the performance of THERMOSLATE?

The system requires direct solar radiation therefore, if weather conditions limit this then the full efficiency won’t be reached.

4. Technical Questions

How thick is the collector slate?

3.5-3.75 mm

How thick is the slate on the rest of the roof?

It has to be the same in order for the collector to be integrated into the roof. Cupa 10 selection R10 Excellence.

What degree of incline should the roof have?

Installation below 22º is not recommended. This is to guarantee that the roof is sufficiently watertight.

Is raised flooring for flat roofs or terraces watertight?

No, it is a type of raised floor that is installed on watertight flat roofs.

Can the raised floor be walked on? What is the maximum weight it can bear?

Yes, it can be walked on. The maximum weight is 300 kg/m².

Can a sensor be placed inside the panel to monitor the temperature?

Yes. The installation is monitored by fitting a sensor in the lateral connection line between the insulator and the absorber of the highest collector in the array. Effective contact with the absorber must be ensured for it to function correctly.

sonda thermoslate

What difference in temperature between the THERMOSLATE panel and the tank usually causes the pump to turn on/off?

The temperature difference is 3ºC.

The 4-7 Kit shows a “Female Blind Terminal”. Is it designed for a temperature sensor to be inserted?

No, the sensor is placed between the insulator and the absorber of the highest panel of the array.

Does T-SOL software output include kWh “losses” from media transport (pump electricity use)?

Yes.  T-SOL software takes into account all existing thermal losses in each section and component of the solar installation.

What is the collector’s loss coefficient in W/m2/K?
  • THS.3222.S07 collector = 11.53 W/m²K
  • THS.3222.S10 and THS.4022.S11 collectors = 13.55 W/m²K
What is the optical performance factor of the THERMOSLATE collector?
  • TH3222.S07 collector = 0.82
  • TH3222.S10 and THS.4022.S11 collectors = 0.86
Is it necessary to insulate the connector pipe we supply?

This is not necessary, because it has the same temperature as the collector. There is a maximum of 90ºC, and no possible losses. Meanwhile, the other pipes (hot and cold water pipes) and the collector inlets and outlets must be insulated. Armaflex is an insulation brand we recommend.

How many liters is a THERMOSLATE panel capable of producing?

50 liters of DHW per day in conditions of average exposure and solar radiation, and with a 45º slope. A project-specific solar study needs to be conducted in order to find out the exact answer.

What material is used to make the thermal adhesive under the slates?

Thermally conductive resin.

Is it advisable to install an expansion vessel to protect the tank to which the THERMOSLATE is connected?

It is always advisable to install a small expansion vessel to protect the tank. In Spain, it is compulsory according to RITE installation regulations. However, the expansion vessel depends on the tank and not on the THERMOSLATE collection system.

What is the flow rate necessary for the panels?

The recommended design flow rate for the THERMOSLATE collector is between 42-84 (l/h m²).

The software we work with (T-SOL) uses a calculation flow rate of 60 (l/h) m2 per collector surface. To find the total flow rate for all panels, simply multiply this flow rate by the number of panels.

What would be the diameter of the pipes, both for series and parallel connection of the collectors?

This depends on the design flow rate of the installation:

Flow rate of 30 l/h m² for connection of collector batteries connected in series:

Collectors number Pipe diameter (mm)

Flow rate of 60 l/h (m²) for connection of collector batteries connected in parallel:

Collectors number Pipe diameter (mm)
When should the panels be connected in series, and when should they be connected in parallel? What do we advise?

THERMOSLATE can be connected in series or in parallel, forming arrays. The number of collectors connected will depend on the conditions and location of installation.

connection series parellel

The collector surface area can be multiplied by connecting collector batteries in parallel. This type of connection increases the system’s final output. Where feasible, Cupa Pizarras recommends the parallel installation of arrays of 4 or 6 modules.

How is the hydraulic balance of THERMOSLATE panel arrays achieved?

The hydraulic balance of the complete system can be achieved in two ways:

  • Balancing valves.
  • Connecting arrays with the same number of collectors and using the inverted return pipe design.
What are the wind and snow load limits on the THERMOSLATE collector?

The collector allows maximum positive wind and snow loads equivalent to 0.3 MPa.

The maximum negative wind load allowed by the collector is 3.6 KPa.

How do I calculate how much space should be left between arrays connected in parallel?

The necessary space is calculated according to the width of the slate pieces and the thickness of the hook used. Below is a simple rule to correctly define the separation space:

  • For panels 3222.S07 and THS.3522.S10, it is calculated using the formula: D = 223 x N / D ≥ 670 mm
  • For panels 3222.S10 and THS.4022.S11, it is calculated using the formula:

D = 225 x N / D ≥ 675 mm

  • For the panel 5025.S11, it is calculated using the formula: D = 250 x N / D ≥ 750 mm

N = Number of slates

CUPA PIZARRAS does not recommend defining a minimum separation between arrays in parallel of less than the distance required for the installation of 3 pieces of slate. Using a smaller distance between the arrays may cause difficulties during installation, and could compromise the strength of the slate in the integration zone.

Are shut-off valves necessary in the THERMOSLATE installation? Where are they placed?

Yes, they are necessary. They are placed at the inlet and outlet of each panel array to isolate the array from the rest of the installation in case of breakdown or maintenance.

Is a deaerator necessary in the THERMOSLATE installation? Where is it placed?

Yes, it is necessary for air extraction. It is placed at each outlet of a THERMOSLATE panel array.

In addition to the shut-off valves and deaerator, what other elements should be installed in a THERMOSLATE panel array?

The recommendation is to install an extendable anti-vibration hose at the inlet and outlet of each array to absorb any possible thermal expansion.

What recommendations need to be taken into account when laying out the THERMOSLATE solar thermal installation on the roof prior to starting construction?

The entry point of the primary circuit pipes to the area under the roof must be taken into account, so that there is no interference with the installed collectors from this point.

If it is a new build, the location of the drainpipes should be considered during the design phase in order to prevent problems during construction. The passage to the area under the roof must be completely sealed after installation is completed.

Are there temperature limits for the operation of the system?

The system works properly at temperatures below 0°C. A mixture of water and glycol should be used inside the panel for this purpose. In our case, we market a heat transfer fluid (THS.ANTIFROGEN SOL) which allows the panels to operate at temperatures from -23°C to +200 °C. 

On a sunny day, the system will operate at 40-45ºC above ambient temperature on average.

Do we have to plan for any plumbing to circulate the glycol?

The glycol circulation system through the solar collectors is forced, meaning there is a pump which is regulated by a control unit, and starts or stops depending on the difference between the temperature of the collectors and the temperature of the tank. There are compact pumping units on the market that include all the necessary elements.

5. Warranty period

Does THERMOSLATE have a warranty? What does it cover?

CUPA PIZARRAS provides a TSV6.X warranty. Terms and conditions;

  • Production defects which appear in the first 5 years after the original purchase of the product.
  • Permeability and integration of the system on the roof; in the first 10 years after the original purchase of the product.
  • Internal corrosion of the absorbers; in the first 5 years after the original purchase of the product.
What maintenance is needed?

THERMOSLATE does not require any maintenance. However, we advise customers to have an annual inspection to ensure no breakages and if necessary, cleaning of the roof.

5. Regulation

Does THERMOSLATE comply with current regulations established in the RITE (Regulations on Thermal Installations in Buildings), the IDAE Technical Specifications for Solar Thermal Installations (2009 version) as well as the recognized RITE document “ASIT (Association of Solar Thermal Installations) Guide to Solar Thermal Energy”, prepared by ASIT and available on the website of the Ministry of Energy, Tourism and Digital Agenda?

Yes. We belong to ASIT (Association of Solar Thermal Installations).

Are THERMOSLATE solar panels certified by the Spanish Ministry of Industry, Trade and Tourism?

Yes, they are certified.

What certificates does THERMOSLATE have?

Thermoslate has the European Solar Keymark certificate and the French Avis Technique certificate.

What is the Solar Keymark Certificate?

This certificate is issued by ICIM, an Italian public body, which is authorized to issue certificates (AENOR type). This institution issues the Solar Keymark certificate on the basis of tests carried out by the Giordano Institute, in accordance with European standards EN 12975-1 and EN 12975-2.

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