A field, a well, and no grid connection within reach — the usual answer is a diesel generator: fuel deliveries, running hours to log, an engine to maintain, and a pump that stops the moment the tank runs dry or the generator needs service.
AT24 UB SolarSync is built to replace that entire setup with a photovoltaic array and, where useful, a grid or generator as backup rather than the primary source.
The main benefits are reduced energy costs, elimination of grid instability, improved environmental performance, and the ability to run pumping systems in remote areas with no centralized power supply at all.
Key specifications
| Parameter | Value |
|---|
| Power range | 0.75–500 kW |
| AC supply voltage | 380–480 V (-15%/+10%) |
| DC input voltage range | 300–800 V (minimum operating voltage 250 V) |
| Enclosure | IP20 VFD; typically supplied inside an IP54 outdoor system cabinet |
| MPPT efficiency | Up to 99.8%, with a Constant Voltage Tracking (CVT) fallback algorithm |
| Motor compatibility | Three-phase motors, or single-phase AC motors (with or without capacitor) |
| Control methods | Scalar V/f (5-point) · open-loop vector · closed-loop vector |
| Communication | RS-485 (Modbus RTU) + Wi-Fi via built-in web interface — both standard, plus optional modem for remote monitoring |
| Commissioning | Wi-Fi connection in ~10 seconds; guided wizard setup in under 5 minutes |
Table 1. AT24 UB SolarSync – key specifications.
Getting the most out of every panel
A solar panel's power output depends on both voltage and irradiance, and the voltage that produces maximum power shifts as sunlight changes through the day. A fixed operating point wastes a meaningful share of available energy. Maximum Power Point Tracking (MPPT) continuously finds that optimal voltage as conditions change, reaching up to 99.8% efficiency; a simpler Constant Voltage Tracking (CVT) algorithm is also available where fast, sharp changes in illumination call for a more stable, if less finely tuned, response.
Six ways to source power
Not every site is pure off-grid. Some have intermittent grid access; others want solar as the primary source with grid or generator strictly as backup.
AT24 UB SolarSync supports both extremes and everything between through six configurable power modes.
Six ways to source power
Not every site is pure off-grid. Some have intermittent grid access; others want solar as the primary source with grid or generator strictly as backup. AT24 UB SolarSync supports both extremes and everything between through six configurable power modes.
| Power mode | How it behaves |
|---|
| AC only | Runs entirely from AC power; PV panel algorithms are disabled. |
| PV only | Runs entirely from photovoltaic panels – no grid or generator connection. |
| Hybrid | Draws from the AC source and PV panels at the same time. |
| Hybrid with AC grid control | Automatically disables PV operation whenever AC grid power is detected (requires an external discrete AC grid sensor). |
| Sensorless AC/PV switching | Connects the AC grid when PV output is low, and disconnects it again after a set time, ramping performance down in a controlled way before switching. |
| Sensor AC/PV switching | Switches between sources based on an illuminance sensor and discrete AC grid signal (AC grid sensor optional). |
Table 2. AT24 UB SolarSync power-source modes.
Two behaviors specifically address what actually happens with solar input, rather than a clean, constant supply:
- Weak solar radiation detection prevents the frequent pump restarts that would otherwise happen during low-light morning and evening hours.
- Sudden power loss detection keeps the pump and drive from shutting down during brief, sudden shading — a cloud passing over the array, for instance.
On the connection side, DC-PV pre-charge solves a specific hazard: connecting photovoltaic panels to a VFD's DC terminals during the day, with no AC voltage present, can otherwise cause a serious current surge and risk equipment damage.
SolarSync's soft-charging algorithm brings the DC link up gradually instead (the contactor and charging resistor are external components).
Works with the motor you already have
Many solar pump installations — especially retrofits — use single-phase AC motors, which normally require a dedicated single-phase VFD.
AT24 UB SolarSync handles both: standard three-phase motors, and single-phase AC motors either with a built-in capacitor or without one, in which case the drive's third output phase supplies the auxiliary winding directly.
The motor type is set in configuration, not by ordering a different product.
Automation built for how solar pumps are actually used
SolarSync includes algorithms aimed at the most common solar-pumping pattern — filling a tank during daylight hours from a well or borehole:
- PID controller with sleep/wake, coordinated with power availability from the PV panels to hold system parameters precisely while minimizing energy use.
- Sensorless flow calculation provides an estimated real-time flow value for monitoring performance without an in-line flow meter.
- Automatic start on power-up, whether power arrives from the PV array or an AC supply.
- Time relay mode runs the pump on programmable intervals within a 24-hour period, independent of available sunlight.
What a complete system typically includes
In the field, the AT24 UB VFD (IP20) is normally supplied inside an IP54 outdoor cabinet built for solar pumping systems, along with the components needed for a safe, monitored installation:
- Control panel on the cabinet door
- Optional modem for remote monitoring
- Mains circuit breaker and contactor
- Discrete AC grid sensor
- Line/DC chokes
- EMC input filters
- DC circuit breaker or fuses
- DC-PV pre-charge unit
- DC surge protection
- Antireverse diodes
- Anti-condensation heating
- Braking components
Considering solar for your pumping system?
Considering solar for an irrigation or water-supply pump currently running on a generator?
Send us the pump power, well/borehole specs, and site location — we'll help size the panel array and confirm the payback versus your current fuel costs.
Request a sizing calculation and quote for AT24 UB SolarSync.
