Troubleshooting Item: No Heat

No Heat Generated Diagnosis

Systematic approach to diagnosing a SunHopper^®-D system that is powered but not heating water.

Introduction

When the SunHopper^®-D unit is active, showing no fault codes, but water is not heating, the issue is typically linked to external control interlocks or incorrect physical component matching.

The unit relies on a physical call for heat (thermostat contact closure) and a minimum voltage solar PV before initiating energy transfer to the immersion heating element.

Note when using the SunHopper® algorithm, the unit will follow a schedule based upon weather and usage conditions. There may be times where the sun is bright but the system uses AC grid if there was excessive cloudiness earlier in the day.

Troubleshooting Steps

Control & Heater Checks

1 Verify that the mechanical thermostat contact is closed.

2 Check thermostat wiring connections for loose terminals.

3 Verify that the tank temperature has not already reached its setpoint.

4 Check for active vacation mode or timers restricting operation.

PV Solar Input Verification

1 Measure open-circuit DC voltage (Voc) at the PV input. It must be above 75V DC.

2 Check for partial shading on the PV panels.

3 Ensure PV polarities (+ and -) are correct.

4 Verify correct element power rating has been programmed into the unit.

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