PWM MPPT Solar Water Heater Controller for PV Panels

Model: ACTii AC7391

EAN: 6931240073919 SKU: 739155867

• PWM controller for heating elements with MPPT (Maximum Power Point Tracking) algorithm for photovoltaic panels. The controller allows powering standard electric DHW boilers from solar panels.
• The controller is equipped with a temperature sensor, which allows stopping the boiler heating above a set temperature. It is possible to change the set temperature.
• The controller displays: Voltage (V), Power (W) supplied to the heater, Water temperature in the boiler.
• The controller can be switched on and off (plus and minus buttons).
• Flashing of the OUT LED signals that current is being supplied to the heater.
• Relay output indicating that heating has been interrupted. It can be used to connect external devices.
• The device is mounted on a TH35 DIN rail.
• The controller has thermal protection and active cooling depending on the temperature of the actuator and power.
• For safety reasons, the high-voltage part is galvanically isolated from the power supply.
• Two operating modes: Automatic mode, Mode with the ability to set activation voltage thresholds.
• Made in the EU, CE certified.

Description

PWM controller for heating elements with MPPT maximum power point tracking algorithm for photovoltaic panels.

The controller allows powering standard electric domestic hot water (DHW) boiler heating elements (operating on 230V or 110V AC) from solar PV panels.

A photovoltaic panel operates at maximum power only at optimal voltage. Connecting a heater directly to a photovoltaic panel causes excessive loading and, consequently, a voltage drop. At a reduced operating voltage, the panel produces even several times less electricity than at the optimal voltage. Using a charge controller eliminates this problem. Even on cloudy days, it will be possible to heat water in the boiler.

A buffer module containing capacitors, a choke, and diodes is included with the controller, which allows for higher efficiency (up to 30%) and reduction of interference caused by PWM regulation.

The controller is equipped with a temperature sensor, which allows for interrupting the boiler heating above the set temperature.

The device is equipped with an additional relay output (potential-free) allowing external devices to be notified that water heating has finished (set temperature reached) or that a device failure has occurred. This output allows connecting additional devices.

Specification

Parameters

Supply voltage: from 11V to 14.4V DC

Panel voltage: from 10V to 400V DC

PV panel current: up to 11A. The controller has a feature that allows safe operation with PV panels generating higher currents than 11A. If the PV panel generates higher current than 11A, the controller will supply a maximum of 11A to the heater. In practice, it is extremely rare for a PV panel that generates 13A of current under ideal conditions to exceed 11A (it requires ideal temperature, ideal sunlight, and a new PV panel).

Maximum heater power: 2kW

Maximum panel power: 2kW

Current drawn from the power supply without cooling: 0.08 A

Current drawn from the power supply with cooling: 0.23A

Temperature measurement accuracy 0.1°C

Operating modes

The controller has the option to change the mode to operate between minimum and maximum voltage.

Mode one:

It is fully automatic and starts working immediately after connection. When the input voltage exceeds the minimum voltage threshold (MINUS button), the controller starts sending current to the heater using the MPPT maximum power point tracking algorithm.

If the voltage drops below the minimum value, MPPT searching is interrupted and current to the heater stops flowing. Setting the minimum value allows for free water heating and simultaneous battery charging.

Mode two:

Option to set activation voltage thresholds (from which the PWM value begins to increase) and maximum voltage (from which the duty cycle is 100%), meaning all cell energy goes directly to the heater.

Additionally, using this method allows keeping the panels at the MPPT point (the maximum power point).

Additional information

Controller dimensions: 90x54x64mm

Buffer dimensions: 90x36x64mm

Temperature sensor cable length: approximately 100cm

What heater should I use, AC or DC, and what power?

Since the only parameter describing the heater is resistance, you can use an AC or DC heater.

The heater should be matched to the photovoltaic panels.

If your photovoltaic panels nominally provide 140V DC 7.14A 1000W, using a 140V DC heater with a power of 1000W will be most appropriate,

but you can also use a 230V AC or 110V AC heater. You only need to match the heater power to the PV panels. (We provide an online calculator to calculate the correct heater).

According to the above, (since the only heater parameter is its resistance, as well as current), it is possible to match a 230V heater for operation with PV panels of different voltage, using Ohm's law. 140V / 7.14A = 19.61 Ohm. Our heater must have 19.61 Ohm. For a 230V heater P=U*U/R. P=230*230/19.61=2697W. We can therefore use a 230V AC heater with a power of about 2700W for 140V 7.14A PV panels.

Other examples:

For 4x 400W PV panel with an operating voltage of 36V per PV panel, a standard 220V AC heater with a power from 3 to 3.5kW can be used

For 4x 450W PV panel with an operating voltage of 38V per PV panel, a standard 220V AC heater with a power from 3.8 to 4.5kW can be used

For 4x 500W PV panel with an operating voltage of 40V per PV panel, a standard 220V AC heater with a power from 3.5 to 4kW can be used

Heaters can have two independent coils. One coil can be used for heating water from PV panels and the other from the 230V grid.

To connect the controller to the heater, it is safer to use a heater with a single coil.

Set contents

Controller

Load buffer

Temperature sensor

Cable connectors (depending on the batch)

Packaging

Manual

Certificates and standards

CE, RoHS

Dimensions, Weight

Product dimensions: 90 x 54 x 64 mm (Depth x Width x Height)

Packaging dimensions: 100 x 120 x 60 mm (Depth x Width x Height)

Product weight: 330 g

Weight with packaging: 376 g

Zum Download

• User Manual
• CE Declaration
• SAFETY COMPLIANCE