PHOTOTHERMAL ENERGY

What is Photothermal Energy? It involves heating water with photovoltaic panels, using a FOT-T regulator connected to a conventional electric water heater or an inertia accumulator or a heat pump, with a conventional electric resistance, operating with direct voltage from the PV panel (Vcc) to the water heater without a battery or inverter.

WHAT IS PHOTOTHERMAL ENERGY?

Photothermal Energy involves heating water using conventional photovoltaic panels, with an MPPT FOT-T regulator connected to a conventional electric water heater, using a conventional electric resistance (230V), and operating with direct voltage from the PV panel (Vcc) to the water heater, without a battery or inverter.

WHAT IS NEEDED?

a) Photovoltaic panels (410-550W), in a separate off-grid line with a maximum power of 1800-2800W (depending on the FOT-T regulator used) and a line voltage of Vmp 170-230Vdc.

b) The FOT-T regulator 2000 or 3000. The regulator adjusts the power value of the PV panels, operating in PWM-MPPT mode, and acts as a thermostat.

c) A water accumulator or electric water heater or inertia accumulator with an electric resistance. It is important that the accumulator has a connector for the temperature sensor. The resistance can be any model or brand, and it must be 230Vac or three-phase 230/400Vac (3 phases of 230V).

WHAT SAVINGS DOES IT PRODUCE?

For Domestic Hot Water (DHW): With a 200-300L accumulator at 80ºC, suitable for 3-5 people, conventional energy savings are 95-100%.
For heating (as heating support): Using radiators or underfloor heating, savings can range from 35-85% of conventional energy not used.
For large hot water consumers (e.g., hotels, public pools): Gas expenses can be reduced significantly, from €523/day to €38/day (real case).

HOW IS PHOTOTHERMAL ENERGY INSTALLED?

a) Install a photovoltaic panel array on the roof, terrace, or ground.
b) DC protection panel (includes DC fuses/circuit breaker + DC transient overvoltage protectors).
c) FOT-T regulator.
d) Hot water accumulator or electric water heater.
e) Electric resistance for water heating: Any model or brand, as long as it is rated for 230Vac nominal voltage.

NOTE: It is essential to perform calculations to correctly select the power of the resistance based on the available photovoltaic panels or vice versa.

PHOTO THERMAL REGULATORS FOT-T 3000

Panel power up to 2900 W.

Nominal current up to 13.5 A

Built-in thermostat. Allows temperature adjustment of 10-99ºC

Temperature sensor with 2 m cable.

Relay output (potential free), which is activated when the set temperature is reached.

WORK OPTIMUM:

• 4 PV panels (465-550W) any brand. Q: 1860-2200Wp. U: 159-166Vdc. And: 12.9-13.5A
• 1 Resistance 230V-4000W (or 2000W+2000W connected in parallel)

The FOT-T 3000 regulator needs a minimum of 150V (4 PV panels) and accepts up to 350V (about 8 PV panels). The input current Ioc cannot exceed 13.75A. With voltage 150-250V you can use conventional resistance of 230Vac. With voltage >250-350V it is necessary to use three-phase resistors 400Vac

Transistors with high headroom (provide long, trouble-free operation)

Huge heatsink for passive cooling, eliminating the need for a fan.

Built-in load buffer

Built-in power supply, which works from panels, not from the mains.

Two screens: one shows the current temperature of the thermos, the other shows the current default power or the voltage of the panels and the maximum power. 

RS485 communication to read operating parameters from a computer.

Built-in acoustic alarm Temperature control of the heat sink and inside the casing.

Dimensions 140x120x125mm

FOT-T 3000 Instruction Manual

Download technical sheet

REGULATION CTE DB HE4

The FOT-T regulator complies perfectly with the CTE Basic Document HE4 regulations section 3 and 4:

3 Quantification of the demand

3.1 Minimum renewable contribution for ACS and/or pool air conditioning

1 The minimum contribution of energy from renewable sources will cover at least 70% of the annual energy demand for DHW and for pool air conditioning, obtained from the monthly values, and including thermal losses for distribution, accumulation and recirculation This minimum contribution can be reduced to 60% when the DHW demand is less than 5000 l/d. Only the renewable contribution of energy originating on site or in the vicinity of the building will be considered.

In addition, from Hidric ús we can offer the Justification, as described in the Base Document HE4-Annex F:

4 Justification of the demand

To justify that a building meets the requirements of this DB, the project documents shall include the following information about the building or part of the building evaluated:

a) the monthly demand for domestic hot water (DHW) and pool air conditioning, including thermal losses due to distribution, accumulation and recirculation.

b) the renewable contribution made to meet the energy needs for DHW and pool air conditioning.

c) the contribution of the residual energy provided, if applicable, for the ACS;

d) verification that the renewable contribution for ACS needs used covers the mandatory contribution.

DESCRIPTION FOR TECHNICAL SPECIFICATIONS

If you have to write a project or technical prescriptions that include Photothermia and you want to use our FOT-T 3000 system in Vcc system you can use the following description:

Photothermal regulator type FOT-T 3000 working with Vcc voltage in PWM – MPPT mode. PV panel maximum power of 2800-3000W, working voltage 150-250Vdc (max 350Vdc), working current 9-13A, (max 13.5A), capable of providing power to a conventional electric resistance of 1500-4000W of voltage nominal 230Vac. It incorporates a temperature probe with a standard 2m cable. On-screen display of the vessel temperature (accumulator), and plate power. Allows you to adjust the setpoint temperature in values ​​of 1ºC between 10-99ºC. Relay output 8 without potential) which is activated when the set temperature is reached.  Box with passive cooling (external finned resistance). 100% US design and manufacture. CE certificate.

FAQS

* What is Photothermal for DHW production?

Heat water using photovoltaic panels (not to be confused with thermal solar panels), using a FOT-T regulator, an ACS hot water accumulator or electric thermo, associated with an electrical resistance of nominal voltage 230Vac

* Can a conventional electrical resistance be used?

Yes This is the great simplicity of the FOT-T regulator. You can use a 230Vac nominal voltage resistor or a 400Vac three-phase resistor. Each regulator will be associated with a 230Vac phase

*What power and resistance voltage must the electric heater or thermos have using the FOT-T 2000 or 3000 regulator?

The resistance of the electric heater does not need to match the power of the photovoltaic panels. You can use any resistance. But before buying it you need to do calculations to determine the power. Consult us to ensure. The power of the photovoltaic field is limited by the input power of the regulator (1900-2900W depending on the regulator). We recommend that the voltage of the photovoltaic field does not exceed the nominal voltage of the resistor (230V).

*What conventional electricity or gas (natural) energy savings can I get?

If you have mains electricity to heat water (electric heater). The average monthly consumption with a resistance of 2000W (8333W/month), is These values ​​you will stop paying with photothermia.

If you have a mixed boiler (DHW + heating) and it is used for DHW 1.5h/day, with an average consumption of 0.19m3/h of gas, €24.73/month is spent.

This would be the amount you will stop paying the gas supplier, stopping importing 11.4m3 of gas per month (136.8m3 per year).

*If there is not enough insolation (rainy, cloudy days, etc.), does photothermia work?

The electrical resistance works from the first rays of the sun, but indeed the voltage will be low on cloudy days. You can use accumulators with two independent resistors. One controlled by photovoltaics (photothermal) and a second with conventional network support, and adjusted by means of a thermostat to a low temperature, but sufficient for comfort (for example at 23ºC).

On an annual scale (energy needed to heat the DHW for a year), Photothermia will produce much more than the minimum required by the CTE standard, although on a specific day it may need support from another energy source.

Our advice is that when buying the accumulator think with a sufficient reserve (2 or 3 days without sun). More hot water reserve, greater non-photovoltaic (or support) energy savings.

*What is the disadvantage of heating water directly with photovoltaic panels?

The solar panel works at maximum power only at optimum voltage. Connecting the thermocouple resistor directly to the PV panel causes too high a load and as a result a voltage drop. At reduced operating voltage, the panel produces even several times less current than at optimal voltage. Nothing happens to the panel, but it involves more work time.

To solve this fact, the FOT-T regulator incorporates the PWM-MPPT option into its work algorithm. It therefore allows at the time of start-up to activate the PWM operating mode and from there it searches for the point of maximum efficiency (MPPT mode). In this way, both in one case and in the other, an optimum of energy transferred from the plate to the resistor is guaranteed.

*Once the water is heated, can I use the excess energy?

Yes. The FOT-T regulators have a relay output (no potential), which is activated once the internal thermostat has reached the set temperature.

* Can Photothermia be used for vertically constructed buildings/apartments?

Yes. Complies creditably with CTE DB HE4 regulations. It can perfectly replace solar thermal panels. PV panels are placed on the roof and the wiring (Vcc) is lowered to each apartment. The FOT-T 3000 regulator is placed next to the electric heater. The electric heater will have a double resistance (2 230V resistances).

* Can Photothermia replace a heat pump?

The objective of Photothermia is to heat water with a conventional resistance, located inside a conventional accumulator. It can help the heat pump or a heating system to reduce energy expenditure. It can also help reduce energy expenditure when heating water for DHW or for heating or for industrial processes or heating swimming pools. What is certain is that photothermia with the FOT-T regulator and a suitable resistance, the heat pump or the conventional heating system will stop consuming a lot of external energy.

AGRICULTURAL – INDUSTRIAL PHOTOTHERMY – WATER DISINFECTION BY TEMPERATURE

-We can also offer solutions for industry and the agricultural sector.

Having hot water, depending on which processes it is essential (dry cleaners, public swimming pools, food industry, etc.).

Photothermia can also be used to disinfect water using temperature, in processes where you don’t want to apply chemicals or UV lights.

Ask for more information on how our products can help you reduce your carbon footprint.