C_fSombra {solaR}R Documentation

Shadows on PV systems

Description

Compute the shadows factor for two-axis and horizontal N-S axis trackers and fixed surfaces.

Usage

fSombra(angGen, distances, struct, modeTrk = 'fixed',prom = TRUE)

fSombra6(angGen,distances,struct,prom = TRUE)

fSombra2X(angGen,distances,struct)

fSombraHoriz(angGen, distances,struct)

fSombraEst(angGen, distances,struct)

Arguments

angGen

A zoo object, including at least variables named Beta, Alfa, AzS, AlS and cosTheta.

distances

data.frame, with a component named Lew, being the distance (meters) between horizontal NS and two-axis trackers along the East-West direction, a component named Lns for two-axis trackers or a component named D for static surfaces. An additional component named H can be included with the relative height (meters) between surfaces. When modeTrk = 'two' (or when fSombra6 is used) this data.frame may have five rows. Each of these rows defines the distances of a tracker in a set of six ones.

struct

list. When modeTrk = 'fixed' or modeTrk = 'horiz' only a component named L, which is the height (meters) of the tracker, is needed. For two-axis trackers (modeTrk = 'two'), an additional component named W, the width of the tracker, is required. Moreover, two components named Nrow and Ncol are included under this list. These components define, respectively, the number of rows and columns of the whole set of trackers in the PV plant.

modeTrk

character, to be chosen from 'fixed', 'two' or 'horiz'. When modeTrk = 'fixed' the surface is fixed (inclination and azimuth angles are constant). The performance of a two-axis tracker is calculated with modeTrk = 'two', and modeTrk = 'horiz' is the option for an horizontal N-S tracker. Its default value is modeTrk = 'fixed'

prom

logical, only needed for two-axis tracker mode. If TRUE the shadows are averaged between the set of trackers defined by struct$Nrow and struct$Ncol

Details

fSombra is only a wrapper for fSombra6 (two-axis trackers), fSombraEst (fixed systems) and fSombraHoriz (horizontal N-S axis trackers). Depending on the value of modeTrk the corresponding function is selected. fSombra6 calculates the shadows factor in a set of six two-axis trackers. If distances has only one row, this function constructs a symmetric grid around a tracker located at (0,0,0). These five trackers are located at (-Lew, Lns, H), (0, Lns, H), (Lew, Lns, H), (-Lew, 0, H) and (Lns, 0, H). It is possible to define a irregular grid around (0,0,0) including five rows in distances. When prom = TRUE the shadows factor for each of the six trackers is calculated. Then, according to the distribution of trackers in the plant defined by struct$Nrow and struct$Ncol, a weighted average of the shadows factors is the result. It is important to note that the distances are defined between axis for trackers and between similar points of the structure for fixed surfaces.

Value

data.frame including angGen and a variable named FS, which is the shadows factor. This factor is the ratio between the area of the generator affected by shadows and the total area. Therefore its value is 1 when the PV generator is completely shadowed.

Author(s)

Oscar Perpiñán Lamigueiro.

References

See Also

calcShd, optimShd, fTheta, calcSol

Examples

lat = 37.2;
sol <- calcSol(lat, fBTd(mode = 'prom'), sample = '10 min', keep.night = FALSE)
angGen <- fTheta(sol, beta = 35);
Angles = CBIND(as.zooI(sol), angGen)

###Two-axis tracker
#Symmetric grid
distances = data.frame(Lew = 40,Lns = 30,H = 0)
struct = list(W = 23.11, L = 9.8, Nrow = 2, Ncol = 8)

ShdFactor <- fSombra6(Angles, distances, struct, prom = FALSE)

Angles$FS = ShdFactor
xyplot(FS ~ w, groups = month, data = Angles,
    type = 'l',
    auto.key = list(space = 'right',
                    lines = TRUE,
                    points = FALSE))

#Symmetric grid defined with a five rows data.frame
distances = data.frame(Lew = c(-40,0,40,-40,40),
                       Lns = c(30,30,30,0,0),
                       H = 0)
ShdFactor2 <- fSombra6(Angles, distances, struct,prom = FALSE)

#of course, with the same result
identical(coredata(ShdFactor), coredata(ShdFactor2))
[Package solaR version 0.46 Index]