PV grid-connected power system includes PV modules , grid-connected inverter, meter and power switchboard. The PV modules convert the solar energy to the DC power Then the grid-connected inverter convert the DC power to the sine wave AC power which has the same frequency and phase with the grid voltage. The AC power feed-in the grid partly and the other power supply the local loads.

Main Characteristics:

* Using 32bit DSP from TI company as the controller ;

* Using the fifth generation IPM from Mitsubishi company as the power components.

* PPT (Maximum Power Point Tracking) technology.

* Max Efficiency 95%.

* Zero power concept at night.

* Perfect protect functions include anti-islanding.

* Multi selection: Low frequency transformer isolation type, transformer less type , wide DC input range type.

* Self consumption at night 0W

* Utility monitoring in accordance with UL 1741,IEEE929-2000

* EMC: EN50081,part1 EN50082,part1

* Grid interference: EN6 1000-3-2

* Grid monitoring : DIN VDE 126

System Composing Schemes

Scheme 1	Scheme 2

A. Single grid-connected mode (Scheme 1)
The most suitable for use in that way in villa or family, power at 1kw to 5kw or so, combining can pass the communication of RS485 connects with the personal computer.
B. Multi strings and multi inverters mode (Scheme 2)
 

This way suits to apply to tilt to one side in the different PV array, or have the sub PV array of various model numbers, different DC bus voltage.
C. DC bus paralleling and multi inverters mode (Scheme 3)
This operation mode is suited to apply in big power PV system, request PV array is installed in same inclination, and request the each array have the same power to merge with the module string of the DC voltage. In these parallel system , there is a central control unit. In the morning with the sunlight becoming from weak to strong, the control unit random select one inverter to run. When the output of the first inverter is near the nominal power of this inverter, the control unit starts second inverter and controls the grid-connected current of the two inverter to be same. This controlling process is going on with the sunlight becoming strong. At sunset, the control unit will stop the inverters in the same way. There are many advantages in this system composing scheme and operation mode. First of them is the customer can use the solar energy of morning and dusk mostly. The second is the "sit the Chuang by turn" operation mode can prolonged the inverters life greatly.
a. When the some set in inside in network SG grid- connected inverter appears the breakdown, a redundancy for controlling machine making its with handing over direct current mother line breaking opening, realizing whole system circulates. From but increase the movement dependable of the system consumedly.
b.An all movements for controlling machine can passing total line in CAN obtaining each inverter changing machine parameter, break down the appearance with generate electricity the parameter, pass the RS232 gross the on- line passing control the PC;
c.The control PC can pass a cluster of SG inverters that control the machine to change to network according to the demand the machine proceeding or stop to set up the etc. operation with the parameter.
 

System Composing Schemes

Scheme 3	cluster

Cluster

The cluster control the machine to provide the friendly man-machine interface at the same time.The customer can pass directly the LCD of LCD holds to realizes with the key the movement parameter inspect, generates electricity the deal searches, break down the search, parameter set up to wait the function