Product Overview & Area of Application
The Nexol NEX R2 is a PV heating rod retrofit kit for suitable hot water and drinking water storage tanks with two free threaded sockets. The system uses the direct current from connected photovoltaic modules directly for electric hot water preparation. An additional inverter is not required for PV heating operation.
The NEX R2 is particularly suitable for larger hot water storage tanks and for systems where rapid hot water availability is to be combined with the most comprehensive possible use of the available photovoltaic power.
Two-zone heating for targeted tank loading
The system operates with two electrically insulated heating elements. The upper heating element preferentially heats the upper tank area so that usable hot water is available more quickly. The available PV power can then be used to further heat the lower tank area.
Thanks to this two-zone control, the tank is not exclusively heated evenly from below. Instead, the NEX R2 first prioritizes the upper zone relevant for hot water draw-off and then uses additional solar energy for further tank loading.
Energy Controller with integrated MPP tracking
The Nexol Energy Controller handles the control, temperature monitoring, and power distribution between the two heating elements. Operation is via a 2.8-inch color touch display.
The integrated MPP tracking adapts the power consumption to the currently available power of the connected photovoltaic modules. The maximum usable PV power is 1.5 kW. For a suitable system design, an installed PV power of approx. 2.5 kW is recommended.
The photovoltaic modules are connected via MC4 connectors. The permissible PV input range includes a minimum rated voltage of 100 V, a maximum open-circuit voltage of 300 V, and a maximum short-circuit current of 15 A.
Optional backup heating via the power grid
When photovoltaic power is low or unavailable, hot water preparation can optionally be supported by electric grid backup heating. The grid connection operates at 230 V with a power of 1.5 kW.
The grid backup heating can be used or deactivated depending on the system configuration and the selected settings. For the grid connection, a fuse rating of 10 to 16 A is required.
For retrofitting suitable hot water storage tanks
For installation, two suitable threaded openings with 1 1/2 inch threads each are required. The insertion depth of the heating elements is 350 mm. In addition, the required installation space inside the tank must be taken into account.
The two heating elements have an unheated area of 100 mm. The housing of the heating elements is designed with IP65 protection rating. The Energy Controller has IP21 protection rating and is intended for installation in a dry indoor area.
Technical Data
| Energy Controller |
| Display | 2.8-inch color touchscreen |
| Ambient temperature range | 5 to 40 °C |
| Permissible humidity | 10 to 95 %, non-condensing |
| Permissible degree of pollution | 1 |
| Protection class | IP21 |
| Weight | 2.4 kg |
| Dimensions | 339 × 177 × 104 mm |
| Heating elements |
| Number of heating elements | 2 |
| Maximum heating output | 1.5 kW |
| Screw-in depth | 350 mm |
| Protection class | IP65 |
| Screw-in thread | 1 1/2 inch |
| Unheated area | 100 mm |
| Maximum tightening torque | 60 Nm for brass thread |
| Wrench size | 60 mm |
| Maximum operating pressure | 1 MPa / 10 bar |
| Dimensions per heating element | 89 × 89 × 500 mm |
| Electrical insulation | Yes |
| Photovoltaic specifications |
| Recommended installed PV output | 2.5 kW |
| Maximum usable PV output | 1.5 kW |
| Minimum PV rated voltage | 100 V DC |
| Maximum PV open-circuit voltage | 300 V DC |
| Maximum PV short-circuit current | 15 A |
| PV connections | MC4 |
| MPP tracking | Integrated |
| Optional mains connection |
| Output | 1.5 kW |
| Input voltage | 230 V AC |
| Input frequency | 50 to 60 Hz |
| Required fuse protection | 10 to 16 A |
Installation instructions
The two heating elements must be screwed horizontally into the designated tank sockets. During operation, the heated areas of the elements must be completely surrounded by water.
Before installation, check the existing connection threads, the available installation space, the tank geometry, and the position of existing immersion sleeves or heat exchangers. The heating elements must not touch the tank wall or any other components.
The maximum tightening torque of 60 Nm must not be exceeded for a brass thread. A wrench size of 60 mm is required for installation.
Electrical installation
The Energy Controller may only be operated within the specified ambient conditions. Installation must be carried out in a dry and adequately ventilated indoor area.
Work on the photovoltaic DC circuit, the optional 230 V mains connection, and the protective conductor may only be carried out by appropriately qualified specialist personnel. The maximum PV open-circuit voltage of 300 V and the maximum PV short-circuit current of 15 A must not be exceeded.
Scope of delivery
- Nexol Energy Controller
- Two electrically insulated screw-in heating elements
- Connection cables for the system components
