The small type solar grid tie power inverter can obtain the solar energy from solar panel, and can tie to the grid through its output cable with no extra equipment. The installation is very convenient and reliable.
We call the system combining with small solar grid tie power inverter and solar panels as 'SGPV'. The system includes solar panels and small type grid tie power inverter. Solar panels can be mono silicon, polygon silicon, non-crystal film or any other material that can transform solar energy to electric energy. The power of grid tie inverter should be matched to the power of solar panels connected. So the power of SGPV is defined by its solar panels, it can be standardization according to the actual using.
The inverter can be connected to any outlet at home, when this line run by the conventional electric network. The small grid tie monitors the volume, frequency and phase of the home grid, then produce a pure sine wave that the frequency and phase are as same as the grid's, and the volume is a bit higher than the grid's, then according to the current controlled PWM, to control the output power to the grid. The small grid tie inverter just puts out power when the home grid is on.
When the sun shines, the PV panel will produces DC voltage, and the grid tie inverter will change the DC voltage to AC voltage and puts out power to the home grid. When the total power of electric apparatus that are using in the house is larger than the output power of the inverters, these power from the inverters will be consumed in the house, this will slow down the power meter, otherwise, the difference of the output power of the inverter between the total used power of the apparatus will go out from the house to the out grid, this will make the power meter backwards.

BACKGROUND:
Today's society, oil, coal and other fossil fuels become increasingly strained and eventually will be completely exhausted, so solar energy, wind energy and other renewable energy sources are inevitable directions in the future development of the energy field. So promoting large-scale solar photovoltaic power is an important way to solve the problem of the world's energy and environmental crisis.
PV power systems need a supporting body (installation place). One is using of open ground, such as desertification of semi-desert region, beach, farms to build large-scale PV power station. As same as traditional power plants, this kind power station need to construct long-distance transmission grid, the investment costs are high, and it will cause wear and tear during transmission.
The other is the promotion of photovoltaic building integration (BIPV). In this way, to build in the PV power system with all types of buildings of the cities, make full use of the building walls, windows, sunshade and other resources to expand the area of a solar energy generating electricity system.
"SOLAR ROOFS", it indicates to gather the solar energy from every home's roof. This initiates a new mode of clean renewable energy - "near production, local consumption". Both environmental protection and energy saving are realized, the land is conserved and the cost is reduced. It has now become a competition to encourage governments around the world to promote the new energy production methods.
How to tie the "million solar roofs" to the grid is a great obstacle, and it is a key to promote the "Solar Roofs". The SGPV is a powerful method to solve this obstacle.