Wire a solar pump inverter in a safe, checkable order: isolate everything first, earth the drive, fit the DC disconnect, connect the pump cable, then connect the PV string to the MPPT input — and only close the DC disconnect after polarity, string voltage, earthing and motor settings have all been checked. This order matters because a PV array can be live in daylight even when the pump is stopped, so no step should rely on “the system is off” without a disconnect and a measurement to prove it. Wiring and commissioning must be completed by qualified electrical personnel, following the model manual and local electrical rules.
Before you connect anything
Start from three documents, not from the cable drum: the pump nameplate (rated power, voltage, phase and full-load current), the PV module data (open-circuit voltage, maximum-power voltage, power and the planned series/parallel layout) and the inverter manual for the exact branch you bought. Confirm single-phase or three-phase output, cable length and whether water-level sensors or an AC backup arrangement are fitted. For outdoor mounting, shade, clearance, gland direction and flood level, follow the IP65 Solar Pump Inverter: Outdoor Installation Without a Control Cabinet guide; for coastal or dusty sites, the protection routine also differs, as explained in Coastal Salt Fog vs Dusty Inland: How Does Outdoor Protection Differ?
Verified voltage windows: QB100-PV
The table below uses only the verified figures on the QB100-PV Solar Pump Inverter White Plastic Shell 0.4–37kW product page. MPPT efficiency is rated up to 99% on that page. Do not copy these windows to another family: the IDEEI IP65 Solar Pumping VFD 0.4–37kW product page lists different recommended ranges — DC 200–400V for its 220V branches (maximum 440V) and DC 300–750V for its 380V branch (maximum 900V) — so always check the exact model page and manual before you build a string.
| QB100-PV branch | Output | PV input class on the product page |
|---|---|---|
| S2 | 3-phase 220V | DC 180–450V |
| SS2 | Single-phase 220V | DC 180–450V |
| 4 | 3-phase 380–400V | DC 250–900V |
How to wire a solar pump inverter, step by step
- Isolate first. Keep the DC disconnect or breaker OFF and any AC supply OFF. Treat PV conductors as live in daylight until you have isolated them and verified the state at the terminals.
- Mount and earth before power conductors. Fix the drive on a solid, upright support with the manual clearances and shade, then connect the protective earth to the drive earth terminal. Earth continuity is a safety check, not a finishing touch.
- Fit DC isolation between array and drive. Install a DC disconnect or breaker in the PV line, rated for the array voltage and current in the manual, in an accessible position. This is the switch you will use to make the system safe again.
- Connect the pump cable. Match the cable to the pump nameplate voltage and phase, terminate it at the drive output, and earth the pump as the manual requires. Connect the pump before you apply PV power.
- Connect level and sensor inputs only if fitted. Where high/low water-level terminals are provided, wire them as the manual shows. Never bypass dry-run protection to force a start.
- Build the string and check polarity off-line. Choose the series count so the string open-circuit voltage stays inside the model window, including cold, bright conditions when voltage is highest. Measure the string voltage, label positive and negative, and check polarity twice.
- Connect the PV string to the MPPT input. With the DC disconnect still OFF, connect positive to positive and negative to negative, tighten terminals to the manual specification, and seal every unused cable entry with a proper blanking plug.
- Keep AC backup separate unless the configuration allows it. Do not connect AC and DC sources simultaneously on a standard PV pumping branch: the QB100-PV page states that simultaneous AC/DC access requires customisation. If backup is needed, use only a model and wiring configuration approved for it.
- Run the pre-power checklist. Recheck polarity, string voltage against the model window, terminal tightness, cable glands, earth connections and heatsink clearance, and confirm the drive motor parameters still match the pump nameplate (rated current and voltage).
- Energise in order and watch the first run. Close the DC disconnect, observe the display and MPPT behaviour, then start the pump and check rotation, flow and current. If a three-phase pump runs backwards, isolate power first and swap two motor phases only as the manual allows — never swap PV polarity to fix rotation.
Common wiring mistakes and what they cause
| Mistake | Typical symptom | Correct action |
|---|---|---|
| Reversed PV polarity | No start, fault, or possible damage | Isolate, recheck labels and meter readings, and correct before energising |
| String voltage above the model maximum | Overvoltage trip, especially on cold mornings | Reduce panels per string and recheck against the maximum, not just the typical voltage |
| Three-phase pump rotation reversed | Pump runs but delivers little or no water | Isolate, then swap two motor phases as the manual allows |
| Missing or loose earth | Shock risk and unreliable protection | Stop, isolate, and have a qualified electrician re-terminate the earth |
| AC and DC tied together on a non-hybrid branch | Unsafe operation and possible damage | Remove the link and use only an approved backup configuration |
If the drive will not start after wiring, do not keep resetting it. Use the step-by-step flow in How Do I Troubleshoot a Solar Pump Inverter That Won’t Start? and record the exact display, time of day and conditions before you change anything. Send the pump nameplate, PV module data, string layout and cable length with any inquiry so the model and string can be confirmed against the product page.
Frequently asked questions
Should I connect the panels or the pump first?
This is the trap: “first” means first to receive power, not first to touch. Connect the pump cable while everything is isolated, connect the PV string with the DC disconnect OFF, and only then close the disconnect. Never energise the PV array with the pump cable still disconnected and the drive left to run unloaded.
What happens if PV polarity is reversed?
The drive may refuse to start, show a fault, or be damaged, depending on the model. Isolate the array, verify polarity with a meter rather than by cable colour alone, and correct it before closing the DC disconnect.
How do I know my string voltage is correct?
Compare the measured string open-circuit voltage with the exact model window in the table above — for QB100-PV, DC 180–450V on 220V branches and DC 250–900V on the 400V branch — and allow for the highest voltage on a cold, bright morning. A string that is correct at noon can still exceed the maximum at dawn in cold weather.
Can I connect grid or generator backup at the same time as solar?
Not on a standard PV pumping branch. The QB100-PV page states that simultaneous AC/DC access requires customisation, and the IP65 product page likewise says supported AC backup arrangements depend on the selected model and wiring. Confirm the approved configuration before you wire any backup source.
Do I still need a DC breaker if the array is small?
Yes. A DC disconnect or breaker between the PV array and the drive is part of the protection set in the IP65 installation guide, regardless of array size. It is also what makes future maintenance safe.
The pump runs but delivers little or no water. Is the wiring wrong?
It can be: reversed three-phase rotation, a dry well, a blocked intake or a parameter that does not match the nameplate all produce a similar result. Isolate power, check rotation and water level first, then follow the troubleshooting flow linked above instead of raising drive limits.