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Error Code - 1500 - Grid reconnection condition


Error No.ExplanationCorrective measures
1500The conditions for grid reconnection are not met after a grid error.• Check the Grid - line voltages and frequency must be within parameter ranges.

Grid voltage not within range of nominal: 

Often, multiple inverters will start, but the last one or two may not be able to connect and sometimes won't even give a fault code.

Check your inverter's production sticker to identify what the nominal voltage should be. Afterwards, you can now check the actual grid voltage by knocking on the display and navigating to the AC voltage. Typically, this should have a +/- 10% range, but often sites will customize this to be a tighter range. You can check your VCtlH and VCtlL limit parameters to understand how your inverter is set; refer to the user manual to understand how these are used.

Example image of an SMA production sticker which can be used to understand the nominal voltage

The inverter also has a 2% offset for operation versus start-up. This means that the inverter can use the entire +/-10% range when it is operating, but if it is stopped and you try to restart it, it will not start unless it is within +/-8%. This setting should not be changed in order to avoid nuisance trips. Contact Solar Support for more information.

If your grid voltage is either too high or too low, here are a couple ways that you can correct:

    1. Reactive Power. Try using reactive power from the operating inverters to correct the terminal voltage. This means that if the voltage is too low, have the inverter inject +kVArs to temporarily raise the terminal voltages; the opposite can be used if the voltage is too high.

    2. VCtlOp(Min/Max)Nom Parameter. This parameter controls the range that is required in order for the inverter to reconnect. If grid voltage is too low, you can temporarily change VCtlOpMinNom to a lower value that encompasses the current grid voltage, save, and restart the inverter. Once the inverter is in operation, remember to set ParaChangeEna to On and then change the parameter back to the previous setting. The inverter should remain in operation now.

    3. Transformer Tap Settings. If the voltage is consistently low or high, you can consider using your transformer tap settings to adjust the voltage back within range.

Grid, F5 Breaker Open, banana plug switches (Blade switches), or main AC breaker open:

Check the F5 Breaker. Also check the banana plugs. X55, X56, X57

Possible points which can cause the faultLocation of blade switchesSchematic reference


Voltage measurement cable fouled ferrule at X56:

It also looks like they have an L1 fuse blown in the transformer. or perhaps the VM to the board is misreading through the F5 or banana plugs. They should measure phase to phase grid voltages, I'm seeing 360Vac L2-L3, 201Vac L1-L3, and 209Vac L2-L1. It looks like the fuse cleared on 2/27 as dated by the inverter.

Screenshot of fuse clearing (still an active fault):

Data showing characteristics of a cleared fuseBad ferrule in voltage measurement connection at X56

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