Grundfos RSI Renewable Solar Inverter

The Grundfos Renewable Solar Inverter (RSI) is an off-grid solar inverter converting the DC power output from the solar panel to AC power supply for pump operation. RSI can be used in both new and existing systems as long as the motor specifications are compatible and the motor is suitable for use with a variable frequency drive. The Grundfos pump types for use in applications with RSI are CR, SP, NB, NK, MTR, CM and TP.

RSI is designed for continuous as well as intermittent operation. The system is suitable for various water supply systems, including irrigation, and can be used in existing systems with submersible pumps or dry-installed pumps — a very wide range of applications that leverage renewable energy sources with the ability to back up the system with grid or generator power.

The water production of an RSI system depends on the availability of solar power. The typical result is excess water production in the afternoon and insufficient water production in the morning and evening; a system equipped with a storage water tank enables a stable water supply throughout the day. In a combiner box, all cables from the solar panels can be connected into one set of power input cables before connecting them to RSI.

• Enclosure classes up to IP66 — IP66 units can be installed without a cabinet, outdoors, shaded from direct sunlight. IP54 units can be installed without a cabinet but not outdoors without additional protection against water and sun.
• Setup wizard with Grundfos product library — the motor library contains all related parameters, which reduces setup to a few clicks and a few minutes.
• Detachable operating panel — mounted with a magnet and a communication plug. The inverter operates without the panel on the last saved setup data.
• AC/DC compatibility — RSI can be connected to the grid or a generator as backup power during solar panel disruptions. It can also be connected to three-phase power in the workshop for off-site setup, for fast and simple on-site installation.
• Maximum power point tracking — built-in electronics with four MPPT algorithms continuously optimize the power output to the available solar irradiation and environmental conditions.
• Overvoltage and undervoltage, overload, overcurrent, overtemperature and no-load protection — the inverter disconnects the power connection to the motor and stays in fault mode with the error code displayed until reset.
• Dry-running and level switch inputs — connection to a dry-running switch and to a level switch in the storage tank.
• Operating history — historical operating data is stored and retrieved through the menu on the inverter.

Pump requirements for an RSI system. The rated frequency can be either 50 or 60 Hz. The pump must be able to operate with a voltage supply of 3 x 380-440 VAC or 3 x 208-220 VAC. As standard, Grundfos three-phase pumps can only be operated via an AC voltage supply, so the solar panels must not be connected directly to the pump but through an RSI.

An RSI system consists of a three-phase Grundfos motor, an RSI solar inverter and various protection accessories:

• Disconnect switch, DC — enables manual starting and stopping of the system. At least one DC disconnect switch is required for each set of solar panels connected in series to an RSI. 1000 VDC, 16 A. Product number 98341686.
• Surge protection, DC — at least one DC surge protection is required for the DC input of RSI; Grundfos also recommends one for each solar array connected. 1000 VDC, 40 kA. If the distance between the solar panel and the inverter is more than 32 ft, add extra surge protection closer to the solar panel. Product number 98341687.
• Combiner box (optional) — combines the output of multiple solar panel arrays for connection to RSI, instead of an array-to-array cable or exceeding the power range for the cable.
• Dry-running switch — recommended for submersible pump operation; prevents the pump operating in a dry well. For submersible pumps 98347579; for dry-installed pumps 97911215.
• Level switch (optional) — start / stop control on the water level in the tank. High water level: contact closed. Low water level: contact open. Product number 010748.
• Disconnect switch, AC (optional) — a standard disconnect switch between the RSI output and the motor.
• Sine-wave filter (optional) — protects the motor against overvoltage and increased operating temperature, and reduces motor acoustics.
• Solar panel — the number required depends on the water quantity and pressure required and the installation location.

High voltage range, 3 x 380-440 VAC

Low voltage range, 3 x 208-240 VAC

Type key. Example RSI 0100 3L 0003 4 X HMGR:

Operating panel. Display; scroll up / increase value; scroll down / decrease value; move cursor left and right; back (move backward in menu, exit edit mode, reset faults with a long press); OK (enter active level or item, confirm selection); home (change control place, access control page, change direction); OFF stop button; ON start button. Some parameters are hidden behind an advanced password given in the Grundfos instructions; changing them can influence the MPPT and may cause malfunction.

Grundfos GO Solar sizes an RSI system three ways — from a pump you already have, from the number of solar panels available, or from the application: head, flow, well depth, pumping distance and location — and pairs the RSI with the Grundfos three-phase AC pumps it can drive, with an estimate of the panels needed. It works offline, syncs with the Grundfos Product Center, and includes a water-demand calculator for homes, crops, livestock and community supply.