/// <summary>
/// Digraph of bypass diodes for calculation.
/// </summary>
/*private class BypassNode {
public int minCell, maxCell;
public List<BypassNode> childs = new List<BypassNode>();
}
private static BypassNode GetRoot(ArraySpec.CellString cellStr) {
BypassNode root = new BypassNode();
root.minCell = 0;
root.maxCell = cellStr.Cells.Count;
foreach (ArraySpec.BypassDiode diode in cellStr.BypassDiodes) {
BypassNode node = root;
while(true){
bool found = false;
foreach (BypassNode child in node.childs) {
if (diode.CellIxs.First >= node.minCell &&
diode.CellIxs.Second <= node.maxCell) {
node = child;
found = true;
break;
}
}
if (!found) break;
}
BypassNode newNode = new BypassNode();
newNode.minCell = diode.CellIxs.First;
newNode.maxCell = diode.CellIxs.Second;
node.childs.Add(newNode);
}
return root;
}*/
public static IVTrace CalcStringIV(ArraySpec.CellString cellStr, IVTrace[] cellTraces, DiodeSpec bypassSpec)
{
Debug.Assert(cellTraces.Length != 0);
Debug.Assert(cellTraces.Length == cellStr.Cells.Count);
int ncells = cellTraces.Length;
double strIsc = cellTraces[0].Isc;
for (int i = 0; i < cellTraces.Length; i++) {
strIsc = Math.Max(strIsc, cellTraces[i].Isc);
}
// which nodes connect to which others via bypass diode?
// there's one node between each cell (subtotal ncells-1),
// plus one at each end of the string, total ncells+1
List<int>[] links = new List<int>[ncells+1];
for(int i = 0; i <= ncells; i++){
links[i] = new List<int>();
}
foreach (ArraySpec.BypassDiode diode in cellStr.BypassDiodes) {
links[diode.CellIxs.Second + 1].Add(diode.CellIxs.First);
}
// sweep current this time, compute voltage
int nsamples = 200;
int ngoodsamples = nsamples;
double[] veci = new double[nsamples];
double[] vecv = new double[nsamples];
for (int i = 0; i < nsamples; i++) {
double current = i * strIsc / (nsamples-1);
// what cells are in bypass?
double[] nodevs = new double[ncells+1];
nodevs[0] = 0; // string starts at ground, zero volts
for (int j = 1; j <= ncells; j++) {
// first, voltage assuming no bypass
double nodev = nodevs[j - 1];
if (current < cellTraces[j - 1].Isc) {
nodev += cellTraces[j - 1].InterpV(current);
} else {
nodev = Double.NegativeInfinity;
}
// then, can we do better with bypass?
foreach (int linkIx in links[j]) {
nodev = Math.Max(nodev, nodevs[linkIx] - bypassSpec.VoltageDrop);
}
nodevs[j] = nodev;
}
veci[i] = current;
vecv[i] = Math.Max(nodevs[ncells], 0);
// cut off the part of the trace that's invalid (unachievable current)
if (nodevs[ncells] >= 0) {
Debug.Assert(ngoodsamples == nsamples); // should not "bounce"
} else if(ngoodsamples == nsamples){
ngoodsamples = i;
}
}
// calculate summary info such as mppt power
double vmp = 0, imp = 0;
for (int i = 0; i < nsamples; i++) {
if (veci[i] * vecv[i] > vmp * imp) {
vmp = vecv[i];
imp = veci[i];
}
}
// return a trace. supports lin interp, etc
IVTrace trace = new IVTrace();
ngoodsamples = Math.Min(ngoodsamples + 1, nsamples);
Debug.Assert(ngoodsamples > 0);
trace.I = new double[ngoodsamples];
trace.V = new double[ngoodsamples];
Array.Copy(veci, trace.I, ngoodsamples);
Array.Copy(vecv, trace.V, ngoodsamples);
trace.Isc = veci[ngoodsamples - 1];
trace.Voc = vecv[0];
trace.Imp = imp;
trace.Vmp = vmp;
return trace;
}
public static IVTrace CalcSweep(CellSpec cell, double insolationW, double tempC)
{
double voc = cell.CalcVoc(insolationW, tempC);
double isc = cell.CalcIsc(insolationW, tempC);
int n = 100;
double[] vecv = new double[n + 1];
for (int i = 0; i <= n; i++) {
vecv[i] = voc * (double)i / n;
}
double[] veci = CalcIV(cell, vecv, insolationW, tempC);
//Debug.Assert(Math.Abs(veci[0] - isc) < 0.001);
//Debug.Assert(Math.Abs(veci[n]) < 0.001);
double pmp = 0.0;
double imp = 0.0, vmp = 0.0;
for (int i = 0; i < n; i++) {
double p = veci[i] * vecv[i];
if (p > pmp) {
pmp = p;
vmp = vecv[i];
imp = veci[i];
}
}
IVTrace trace = new IVTrace();
trace.I = veci;
trace.V = vecv;
trace.Isc = isc;
trace.Voc = voc;
trace.Imp = imp;
trace.Vmp = vmp;
return trace;
}
/// <summary>
/// Reads the compute textures from OpenGL.
/// This gives insolation for each cell.
///
/// Uses this to calculate IV curves, etc, and ultimately array power.
/// </summary>
private ArraySimulationStepOutput AnalyzeComputeTex(ArraySpec array, double wPerM2Insolation, double wPerM2Iindirect, double encapLoss, double cTemp)
{
Color[] texColors = ReadColorTexture(FramebufferAttachment.ColorAttachment0);
float[] texWattsIn = ReadFloatTexture(FramebufferAttachment.ColorAttachment1, 0.0001);
double arrayDimM = ComputeArrayMaxDimension(array);
double m2PerPixel = arrayDimM * arrayDimM / COMPUTE_TEX_SIZE / COMPUTE_TEX_SIZE;
float[] texArea = ReadFloatTexture(FramebufferAttachment.ColorAttachment2, m2PerPixel / 4);
double dbgmin = texArea[0], dbgmax = texArea[0], dbgavg = 0;
for (int i = 0; i < texArea.Length; i++)
{
dbgmin = Math.Min(dbgmin, texArea[i]);
dbgmax = Math.Max(dbgmax, texArea[i]);
dbgavg += texArea[i];
}
dbgavg /= texArea.Length;
// find the cell at each fragment...
int ncells = 0;
var cells = new List<ArraySpec.Cell>();
var colorToId = new Dictionary<Color, int>();
foreach (ArraySpec.CellString cellStr in array.Strings) {
foreach (ArraySpec.Cell cell in cellStr.Cells) {
cells.Add(cell);
colorToId.Add(cell.Color, ncells);
ncells++;
}
}
// finally, find the area and insolation for each cell
double[] wattsIn = new double[ncells];
double[] areas = new double[ncells];
double wattsInUnlinked = 0, areaUnlinked = 0;
for (int i = 0; i < computeWidth * computeHeight; i++) {
Color color = texColors[i];
if (ColorUtils.IsGrayscale(color)) continue;
if (colorToId.ContainsKey(color)) {
int id = colorToId[color];
wattsIn[id] += texWattsIn[i];
areas[id] += texArea[i];
} else {
wattsInUnlinked += texWattsIn[i];
areaUnlinked += texArea[i];
}
}
if (areaUnlinked > 0 || wattsInUnlinked > 0) {
Logger.warn("Found texels that are not grayscale, " +
"but also doesn't correspond to any cell. Have you finished your layout?" +
"\n\tTotal of {0}m^2 cell area not in any string, with {1}W insolation.",
areaUnlinked,wattsInUnlinked);
}
// add indirect insolation, encapsulation loss
for (int i = 0; i < ncells; i++) {
wattsIn[i] += array.CellSpec.Area * wPerM2Iindirect;
wattsIn[i] *= (1.0 - encapLoss);
}
// find totals
double totalArea = 0, totalWattsIn = 0;
for (int i = 0; i < ncells; i++) {
totalWattsIn += wattsIn[i];
totalArea += areas[i];
Debug.WriteLine("cell {0}: {1}W, {2}m^2", i, wattsIn[i], areas[i]);
}
Debug.WriteLine("total: {0}W, {1}m^2", totalWattsIn, totalArea);
// MPPT sweeps, for each cell and each string.
// Inputs:
CellSpec cellSpec = array.CellSpec;
int nstrings = array.Strings.Count;
// Outputs:
double totalWattsOutByCell = 0;
double totalWattsOutByString = 0;
var strings = new ArraySimStringOutput[nstrings];
int cellIx = 0;
for(int i = 0; i < nstrings; i++){
var cellStr = array.Strings[i];
double stringWattsIn = 0, stringWattsOutByCell = 0, stringLitArea = 0;
// per-cell sweeps
var cellSweeps = new IVTrace[cellStr.Cells.Count];
for(int j = 0; j < cellStr.Cells.Count; j++){
double cellWattsIn = wattsIn[cellIx++];
double cellInsolation = cellWattsIn / cellSpec.Area;
IVTrace cellSweep = CellSimulator.CalcSweep(cellSpec, cellInsolation, cTemp);
cellSweeps[j] = cellSweep;
stringWattsIn += cellWattsIn;
stringWattsOutByCell += cellSweep.Pmp;
totalWattsOutByCell += cellSweep.Pmp;
// shading stats
stringLitArea += areas[i];
}
// string sweep
strings[i] = new ArraySimStringOutput();
strings[i].WattsIn = stringWattsIn;
strings[i].WattsOutputByCell = stringWattsOutByCell;
IVTrace stringSweep = StringSimulator.CalcStringIV(cellStr, cellSweeps, array.BypassDiodeSpec);
strings[i].WattsOutput = stringSweep.Pmp;
strings[i].IVTrace = stringSweep;
// higher-level string info
strings[i].String = cellStr;
strings[i].Area = cellStr.Cells.Count*cellSpec.Area;
strings[i].AreaShaded = strings[i].Area - stringLitArea;
IVTrace cellSweepIdeal = CellSimulator.CalcSweep(cellSpec,wPerM2Insolation,cTemp);
strings[i].WattsOutputIdeal = cellSweepIdeal.Pmp * cellStr.Cells.Count;
// total array power
totalWattsOutByString += stringSweep.Pmp;
}
ArraySimulationStepOutput output = new ArraySimulationStepOutput();
output.ArrayArea = ncells * cellSpec.Area;
output.ArrayLitArea = totalArea;
output.WattsInsolation = totalWattsIn;
output.WattsOutputByCell = totalWattsOutByCell;
output.WattsOutput = totalWattsOutByString;
output.Strings = strings;
return output;
}
