Partial Shading Losses
PV panels are connected in parallel, in case of shading of certain PV panels the V/I curve changes, Micro-Inverter’s MPPT algorithm tracks MPP for that panel, the total power available will still be the sum of the peak power available from all the panels. In this solution one shaded panel cannot make any appreciable difference in the total power harvested. Since there is no concept of strings this problem of shading does not have any cascading effect. This approach therefore saves 5% to 25% of the power lost in the conventional system.
MPP Efficiency Losses
The MPPT uses incremental conductance with proprietary algorithm to ensure that the MPPT does not get locked into the local Maxima & in case of dynamic changes in the atmospheric conditions the MPPT algorithm tracks the MPP in fraction of second. This approach of MPPT per module improves energy extraction from 1% to 10%.
System Design and Roof Utilization
This approach eliminates any problem like maintaining the optimum voltage for the inverter. The problem is non-existent as this architecture uses Micro-Inverter in the PV panel, that provides AC voltages for the grid connectivity directly. This approach uses the roof area efficiently as there are no constraints on the string length & shading.
System Feedback and Troubleshooting
As explained earlier because of series & parallel combination in the conventional approach fault diagnosis becomes difficult and there is no information available for the energy audit from the individual panels. The only information available is the power provided to the grid & loss of power from faulty panels goes unnoticed for days.
RealEnergy approach to this problem is to deploy RealEnergy Communicator which keeps pinging individual Micro-Inverters using PLC (Power Line Communications) tied to each PV panel. Micro-Inverter provides data of power extracted from the PV panel & provide information of the power loaded onto the Grid. This data locates faulty PV panel real time & maintenance becomes easy.
Retrofit and Long Term Fault Tolerance
In RealEnergy approach of using PV panels in parallel with embedded Micro-Inverters there is flexibility of matching the panels. Panel with different peak powers may be installed together.
Human Safety
In RealEnergy approach, the voltage levels are dropped to AC mains voltage instead of DC 600V normally required by the string inverters to operate. In case of Fire Hazard, as soon as the grid voltage is disconnected, the Micro-Inverters stop producing any voltage making safe for the Fireman to enter building or touch panels.
Installation
Micro-Inverter architecture enables simpler wiring that translates into lower installation costs. By making consumer’s solar power systems more efficient, the time taken for the system to “pay back” on the initial investment for the technology shortens.
There are many clients in demand of very big solar inverter for their big solar systems. Many of the big power supply module parallel capacity is acknowledged as one power transformation technology is one of the important direction. Several power supply models in parallel can share the load power, and then the main switch device of current will be reduced much, and improving the reliability and cost. At the same time, each module power capacity to reduce power density increased significantly. In addition, several modules in parallel, flexible and various power capacity, with a series of modular replace, so as to shorten the development, the production cycle and reduce the cost, improve the standardization level of all kinds of switch power supply, maintainability and interchangeability, etc.
What's the idea of Wuhan Wellsee New Energy Industry Co., Ltd ?
Conventional Series & Parallel Connected PV Panels
In RealEnergy solution the PV panels are connected in parallel & each Micro-Inverter embedded in the PV Panel provides MPPT for the maximum power harvesting. This approach provides us the sum of Peak powers of all the panels instead of average peak power point of the string or array. Thus, we save 5% of power which was lost in the series conventional approach.
