CONTENTS

MPS boost and buck mode description

Megarevo

·2025-03-19

Blog

As a hybrid inverter of PV + energy storage + diesel generation, in order to keep the PV power generation efficiency at the highest level, MPS needs to follow two configuration principles (boost mode and buck mode) when configuring.

Key Takeaways

When should I choose buck configuration mode?
When should I choose the boost configuration mode?
MPS Buck-Boost Mode Related FAQs

Buck Mode Configuration Rules

At the project application site, the working voltage of the photovoltaic module at extreme high temperature ＞ the maximum working voltage of the battery;

For example 1：Buck Mode

PV configuration table
Number of Solar Panel	57 pcs
Power Output of Each PV Panel	550 Wp
Actual Installed PV Capacity	31.35 kWp
Open Circuit Voltage-Voc(25°C)	37.5 V
Max. Power Voltage-V(Mpp)	31.2 V
Temp. Coefficient of P(MAX)	-0.34%/°C
Temp. Coefficient of Voc	-0.25%/°C
PV Panel Configuration	19S3P
Local Temp. Range	-15~40℃

Battery configuration table
Battery Type	LiFePO4
Number of Battery Packs	12
Voltage of Each Battery Pack	51.2V
Capacity of Each Battery Pack	102Ah
Battery Configuration	12S1P
Rated Voltage of Battery	307.2 V
Battery Voltage Range	268.8-350.4 V
Total Battery Capacity	62.6688 kWh

PV string open circuit voltage (under extreme low temperature conditions) = 37.5*19+(25°C-(-15°C))*37.5*0.25%=783.75V

783.75V (under extreme low temperature conditions) <1000V (maximum PV input voltage)

PV working voltage(Under extreme high temperature conditions)=522.26V

PV working voltage 522.26V (under extreme high temperature conditions)>350.4V (highest battery voltage)

conclusion: The configuration of this project meets the buck mode configuration principle of the integrated optical storage machine,Through the buck mode, the PV input voltage is reduced so that the PV voltage and the battery voltage are consistent at the DC side of the hybrid inverter.

Boost Mode Configuration Rules

At the project application site, the open circuit voltage of the photovoltaic module at the extreme low temperature is ≤ the minimum operating voltage of the battery;

For example 2：Boost Mode

PV configuration table
Number of Solar Panel	900 pcs
Power Output of Each PV Panel	550 Wp
Actual Installed PV Capacity	495 kWp
Open Circuit Voltage-Voc(25°C)	49.62 V
Max. Power Voltage-V(Mpp)	40.90 V
Temp. Coefficient of P(MAX)	-0.35%/°C
Temp. Coefficient of Voc	-0.28%/°C
PV Panel Configuration	12S75P
Local Temp. Range	5~50℃

Battery configuration table
Battery Type	LiFePO4
Number of Battery Packs	38
Voltage of Each Battery Pack	38.4V
Capacity of Each Battery Pack	240Ah
Battery Configuration	19S2P
Rated Voltage of Battery	729.6V
Battery Voltage Range	638.4-820.8 V
Total Battery Capacity	350.2 kWh

PV string open circuit voltage (under extreme low temperature conditions) = 49.62*12+(25°C-5°C)*49.62*0.28%=628.78V

PV working voltage 628.78V (under extreme low temperature conditions) <1000V (maximum photovoltaic input voltage),And PV working voltage 628.78V<638.4V (minimum battery working voltage)

conclusion: The configuration of this project meets the MPS boost mode configuration principle. The boost mode is used to increase the photovoltaic input voltage to the same level as the battery voltage, and the DC side of the hybrid inverter is converged.

MPS Buck-Boost Mode Related FAQs

Question 1: Does the buck-boost mode of MPS need to be determined before leaving the factory?

Yes, the buck-boost mode of MPS needs to be determined during the technical agreement stage. The wiring will be changed according to the buck-boost mode selection before leaving the factory. This buck-boost mode is determined by the hardware. (Although the buck-boost mode is determined at the factory, the buck-boost mode setting of the machine still needs to be set by the customer)

Question 2: What items does the purchaser need to provide for the calculation method of boost and buck?

PV module specifications, battery configuration such as voltage range, capacity, and project application location (confirm altitude and temperature)

Question 3: What happens if the buck-boost mode is not satisfied?

This affects the MPPT tracking efficiency, making it impossible for the photovoltaic system to work at the maximum power point, and even causing the photovoltaic system to be unable to charge the battery. The technical agreement review cannot be passed.

Question 4: When can we switch to adaptive boost and buck?

Currently the hardware supports it, but the software does not support it yet.

Question 5: Can different MPPT modules of the same MPS be connected to PV panels with different configurations?

The number of photovoltaic panels (or capacity) connected to different MPPT modules can be different, but the voltage must be consistent. If the customer chooses two types of photovoltaic panels, the two types of photovoltaic panels need to be connected to different MPPT modules and the parameters of the two should be as consistent as possible.