HOW TO DESIGN OFF-GRID PV ENERGY STORAGE SYSTEM COMBINED WITH GENERATOR
In some remote areas and islands, because there is no stable grid power or no power brings great inconvenience to people’s life, the diesel generators are often used to provide power.
In recent years, as the price declines of photovoltaic power generation equipment such as modules, batteries and inverters, the cost of PV system decreases year by year, off-grid PV energy storage system has also started to enter people’s life.
The existing diesel generator set and PV system are formed into a power generation system with PV as the main source and diesel generator as the auxiliary support, which guarantees the power supply for end-users and the whole system with better economic and environmental value.
How to design the whole system between off-grid storage system and diesel generator according to the actual customer needs?
Growatt off-grid inverter SPF 5000ES already integrates the ftjnction of compatible with generator input, also with Growatt ARK series modular lithium battery to offer the whole energy storage system. Through reasonable design and setting, the off-grid storage system and generator can complement each other to provide stable and reliable power for users. It would help customers to enjoy the green and comfortable life anytime and anywhere.
As the fllowing, we will introduce the details of how to design the whole system of of-gid energy storage system combined with generator:
1.Basic Considerations Of System Design
1.1Load condition: maximum power during peak load period
1.2Battery backup time and backup load power rating
13 Generator power selection: the output power of generator must be higher than the maximum load powei; if the generator is considered to charge the battery the power should be increased more, generator with remote dry contact switch for start/stop ■function (only diesel generator available).
1.4 A/erage sunshine duration.
2.1 Customer Needs: The actual daily load consumption is 20kWh for the house, the peak load power is around 4kW, the average daily sunshine duration is 4 hours, the backup power request is 3kW with backup time of 3 hours.
2.2 System Configuration:
2.2.1 PV Inverter: SPF 5000ES, 5kW AC output, 6kW PV panel input
2.2.2 Battery capacity: Back-up power X Back-up time + Eficiency + Battery
DOD = 3kW X 3hours + 90% efficiency + 80% DOD = 12.5kWh Based on the calculation,
we propose the 12.8kWh ARK series Lithium battery, configure 5 pcs battery modules (2.56kWh/module).
2.2.3 Generator: 5kW diesel generator, could support dry contact startup.
2.3 Inverter Configuration:
2.3.1 AC input type should be setting to”Generator’ ‘from program 003
2.3.2 Lithium battery settings: inverter program 05 Battery type needs to be set to U type,and the corresponding communication protocol should match the inverter protocol (CAN communication protocol L51, RS 485 communication protocol L01) from program 036.
2.3.3 Battery discharge DOD Sttings: Battery low voltage protection point SoC set to 20% from program021
2.3.4 Solar panel configuration (330W): 9PCS solar panels for one series, two series paralle total 18PCS with 5940W.
2.4 The connection between inverter and generator
2.4.1 Dry contact output port of the inverter as below
Note: Generator remote start/stop function wire should connect to NO and C port System connection diagram as below