Home »Blog» Frequently Asked Questions About Output Power Manager (EPM) Solutions
As an energy control device, Solis EPM accessory has extremely powerful functions. In addition to controlling the energy output of the photovoltaic system, it can also be used as a reactive power adjustment and power factor compensation device. During the installation process, we will hear some common questions, so in this episode of the Solis seminar, we have compiled the most common questions and answered them for you.
Q 1: What is the difference between the available EPM models? EPM1-5G, EPM3-5G, EPM3-5G-PLUS?
A: EPM1-5G: Applicable to 220V/230V single-phase systems, can be used across different inverter models, and can control up to 10 inverters.
EPM3-5G: Suitable for three-phase, three-wire system, 220VAC, 380/400VAC, 480VAC voltage, can be used for different inverter models, can control up to 10 inverters, suitable for three-phase Delta grid without neutrality.
EPM3-5G-PLUS: suitable for three-phase four-wire system, 220VAC, 380/400VAC voltage, can be used across inverter models, the maximum theoretical control inverter number is 80, does not support grid without neutral.
Q 2: Why is the power supply not controlled or controlled incorrectly?
Answer: This may be caused by the following reasons:
1. The number of inverters and system capacity settings do not reflect the actual situation. Follow the steps below to confirm and correct: – Advantage setting→Inverter Qty.set→Set INV NUM: (01-99) – Advantage setting→Set EPM regulator→Capacity setting→set capa: xxxx W
2. The primary current of the CT is less than the actual current of the grid connection point, causing damage to the CT. See below.
3. The secondary current of CT is not 5A. Solis 5G series EPM boxes require CT with a secondary current of 5A. If it is 200mA or 1A, inaccurate grid power detection may cause EPM problems.
4. The installation position of the CT relative to the EPM Box is incorrect. If installed on a load branch circuit, power control abnormalities may occur. See below.
Q 3: Why is the grid power displayed by the EPM different from the meter reading?
A: When this problem occurs, the following factors should be considered:
1. Check whether the CT current ratio setting of the EPM reflects the actual photovoltaic system specification advantage setting → set CT ratio → set parameters
2. Confirm whether the secondary current of CT is 5A
3. Use a clamp meter to measure the current on the CT and compare it with the current displayed by the EPM-Information to determine whether it is a CT failure or an EPM failure.
4. Check whether the grid voltage displayed by EPM-Information has an abnormal value
Question 4: What does the "CT Fail Safe" alarm mean?
A: This is usually caused by a connection failure between CT and EPM. The following measures can be taken to troubleshoot: CT fail-safe means that the EPM box detects that the CT is not connected. You should check the wiring between the CT and the EPM box or use the current value of each phase of EPM-Information to determine which CT caused the error message.
Note: When this fault occurs, all installed inverters will also display the "Failsafe" alarm message. If this message does not appear, it means that the "Fail Safe" option of the inverter is turned off.
Q 5: EPM box displays "RS485 Fail" or "RS485 AllFail" alarm
A: "RS485 Fail"-means there is a problem with the RS485 communication between the inverter and the EPM Box in the entire system. You should check the connection between each inverter and the RS485 bus.
Use a multimeter to measure the voltage between the A pin and B pin of each inverter's RS485 communication port. The reading should be about 1.6V during normal operation. If there is a large deviation from this, it means that the communication terminal of the inverter may be faulty. Also check whether the number of inverter settings on the EPM and the inverter's slave address settings are correct.
"RS485 ALLFail"-means RS485 communication failure between all inverters and EPM.
You should check the connection between RS485 bus and EPM by doing the following:
①Unplug the RS485 bus connector, use a multimeter to measure the voltage between the A pin and the B pin. Under normal circumstances, the reading should be about 1.6V. If there is a large deviation from this, the A pin and B pin of the RS485 terminal on the inverter side may be connected reversely.
② If there are intermittent "fail-safe" problems, it may be caused by on-site interference. If this is the case, it is recommended that you upgrade to a higher quality shielded RS485 cable.
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