# fSolD: Daily apparent movement of the Sun from the Earth In solaR: Radiation and Photovoltaic Systems

## Description

Compute the daily apparent movement of the Sun from the Earth. This movement is mainly described (for the simulation of photovoltaic systems) by the declination angle, the sunrise angle and the daily extra-atmospheric irradiation.

## Usage

 `1` ```fSolD(lat, BTd, method = 'michalsky') ```

## Arguments

 `lat` Latitude (degrees) of the point of the Earth where calculations are needed. It is positive for locations above the Equator. `BTd` Daily temporal base, a `POSIXct` object which may be the result of `fBTd`. `method` `character`, method for the sun geometry calculations to be chosen from 'cooper', 'spencer', 'michalsky' and 'strous'. See references for details.

## Value

A `zoo` object with these components:

 `decl` Declination angle (radians) for each day of year in `dn` or `BTd` `eo` Factor of correction due the eccentricity of orbit of the Earth around the Sun. `ws` Sunrise angle (in radians) for each day of year. Due to the convention which considers that the solar hour angle is negative before midday, this angle is negative. `Bo0d` Extra-atmospheric daily irradiation (watt-hour per squared meter) incident on a horizontal surface `EoT` Equation of Time.

## Note

The latitude is stored as the attribute `lat` of the result, and thus it is accessible with `attr(object, 'lat')`.

## Author(s)

Oscar Perpiñán Lamigueiro.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37``` ```BTd <- fBTd(mode = 'serie') lat <- 37.2 fSolD(lat, BTd) fSolD(lat, BTd, method = 'strous') fSolD(lat, BTd, method = 'spencer') fSolD(lat, BTd, method = 'cooper') lat <- -37.2 fSolD(lat, BTd) #Solar angles along the year SolD <- fSolD(lat, BTd = fBTd()) library(lattice) xyplot(SolD) #Calculation of the daylength for several latitudes library(latticeExtra) Lats <- c(-60, -40, -20, 0, 20, 40, 60) NomLats <- ifelse(Lats > 0, paste(Lats,'N', sep = ''), paste(abs(Lats), 'S', sep = '')) NomLats[Lats == 0] <- '0' mat <- matrix(nrow = 365, ncol = length(Lats)) colnames(mat) <- NomLats WsZ <- zoo(mat, fBTd(mode = 'serie')) for (i in seq_along(Lats)){ SolDaux <- fSolD(lat = Lats[i], BTd = fBTd(mode = 'serie')); WsZ[,i] <- r2h(2*abs(SolDaux\$ws))} p = xyplot(WsZ, superpose = TRUE, ylab = expression(omega[s] (h)), auto.key = FALSE) plab <- p+glayer(panel.text(x, y, NomLats[group.number], pos = 2)) print(plab) ```

solaR documentation built on Oct. 19, 2021, 9:06 a.m.