10
Fig 2
.
I-V Curves
Fig 3. Temperature Dependence of Isc, Voc, Pmax
The I-V Curves shown in the Fig. 2 is a solar panel’s I-V curves that the power is 230W.
You can get the information from this I-V curves that different irradiance under sunshine
will get different power from same solar panel, and also different power will be converted
under same irradiance but the output of DC voltage is different, the solar panel just can get
maximum power at one point under a certain irradiance, this point is called maximum
power point(MPP). The MPP also is sensitive with temperature of surroundings.
The temperature dependence of Isc, Voc, Pmax shown in the Fig. 3. You can see that the
Pmax and Voc have negative temperature character, Vmp also has same character.
Choosing solar panels
The most important specifications when selecting solar panels are Pmax,Voc, Vmp and
Isc.
1, The total Pmax of solar panels should be equal to or less than the Rated Power(Peak)
of the inverter that you will connect.
2, The total Voc of solar panels should be less than the maximum point of the DC input
range of the inverter, it is according to the connecting method, if you connect solar panels
in parallel, all panels must have same Voc, the Pmax of each panel can be different or
same, so the total Voc is as same as one Voc, but if you connect solar panels in serial, the
Isc of each solar panel must be same, the Pmax of each panel can be different or same,
so the total Voc is the summation of all solar panels connected in serial. Connecting solar
panels with same specifications in a single system is the best choice.
3, The total Vmp of solar panels should above the minimum point of the DC input range of
the inverter. The connecting method principle is as same as item 2 above.
Step3.
Selecting Accessory for Grid Tie Power System installation.
The accessory for grid tie power system including:
1, DC cables will be connected with solar panels and inverters.
2, Connectors.
3, AC cables.
4, Power meter(Optional).
5, Bracket for solar panels installation(not included in this user manual).
