| Name | Modified | Size | Downloads / Week |
|---|---|---|---|
| Parent folder | |||
| README.txt | 2011-09-03 | 2.3 kB | |
| PVSim.pdf | 2011-09-03 | 137.4 kB | |
| PVSimGraphs.pdf | 2011-09-03 | 33.0 kB | |
| Shade.ods | 2011-09-03 | 195.6 kB | |
| Totals: 4 Items | 368.3 kB | 1 | |
Attention: If you find this spread sheet too hard to use or modify, try asking questions. Better help or some documentation could be easily generated if it was of value. As it is effective elec eng its never going to be user friendly, the 3 graph pdf is user friendly. ============================================================= It is expected that if anyone uses this spreadsheet they need no help and just want to leverage something produced earlier. The only other value of this is the PDF file showing the results of shading on specific examples. Those specific examples show The relationship between IV curves, which are actually easy to guess the shape of and power vs V curves. The larger effect shade has on pairs of strings due to the MPPs reduce ability to move. The Jagginess of such a system that derives from the MPP being very close to the Isc of the shaded panel. Which thus has implications for MPPT stability. ========== The Shade.ods spread sheet computes a variety of topologies with one panel shaded. It does this uses a reasonably accurate piecewise cubic interpolation algorithm, with the cubic patches constrained at both ends to ensure linearity. The gradient near the MPP is defined to produce the MPP. The Isc Voc Vmpp and Impp values are taken from a Conergy P190M spec sheet. It was partly chosen as Isc exceeds Impp by an amount that creates a stable numerical solution. A fairly rough approximation of the bypass diode is also encoded into the IV curve. A shaded IV curve is computed by simply subtracting a constant amount of current from the full sun curve. This produces plausible looking results and matches at least one more sophisticated exponential based models found on the internet. Errors is this should only produce accuracy errors in location and height of MaxPP and depth MinPP. Those IV curves are combined using Kirchoffs laws to compute an IV curve for the entire systems. The following topologies are analysed 2 Full sun panels in series with 1 50% shade. 2 Full sun panels in series with 1 70% shade. 2 Full sun panels in series with 1 70% shade. In parallel with 1x3 Full sun panels 2 Full sun panels in series with 1 70% shade. In parallel with 2x3 Full sun panels Many of those parameters can easily be tweaked in the spreadsheet to answer other questions.
