solar2Local.R

library(solaR)

## Download data from NREL (see help(calcG0))
NRELurl <- 'http://goo.gl/fFEBN'

dat <- read.table(NRELurl, header=TRUE, sep=',')
names(dat) <- c('date', 'hour', 'G0', 'B', 'D0', 'Ta')

##B is direct normal. We need direct horizontal.
dat$B0 <- dat$G0-dat$D0

##http://www.nrel.gov/midc/la_ola_lanai/instruments.html:
##The datalogger program runs using Greenwich Mean Time (GMT),
##data is converted to Hawaiin Standard Time (HST) after data collection
idxLocal <- with(dat, as.POSIXct(paste(date, hour), format='%m/%d/%Y %H:%M', tz='HST'))
idx <- local2Solar(idxLocal, lon=-156.9339)

NRELMeteo <- zoo(dat[,c('G0', 'D0', 'B0', 'Ta')], idx)

lat=20.77

## Compute irradiance on a tilted plane
gefNREL <- calcGef(lat=lat, modeRad='bdI', dataRad=NRELMeteo, corr='none')

## Extract result as a "zoo" time series. Use complete to obtain all the variables
zNREL <- as.zooI(gefNREL, complete=TRUE, day=TRUE) 

names(zNREL)
##  [1] "w"        "aman"     "cosThzS"  "AlS"      "AzS"      "Bo0"     
##  [7] "rd"       "rg"       "decl"     "eo"       "ws"       "Bo0d"    
## [13] "EoT"      "G0d"      "D0d"      "B0d"      "Fd"       "Ktd"     
## [19] "kt"       "fd"       "G0"       "D0"       "B0"       "Ta"      
## [25] "Beta"     "Alfa"     "cosTheta" "Bod"      "Bnd"      "Gd"      
## [31] "Dd"       "Bd"       "Gefd"     "Defd"     "Befd"     "Bo"      
## [37] "Bn"       "G"        "D"        "Di"       "Dc"       "B"       
## [43] "R"        "FTb"      "FTd"      "FTr"      "Dief"     "Dcef"    
## [49] "Gef"      "Def"      "Bef"      "Ref"     

## Change the time index and use the local time
zNRELlocal <- zoo(zNREL, idxLocal)

xyplot(zNRELlocal[,c('Gef', 'G0', 'Bo0')], superpose=TRUE)

oneDay <- window(zNRELlocal,
                 start=as.POSIXct('2010-11-01'),
                 end=as.POSIXct('2010-11-01 23:59:59', tz='HST'))
## Display results: lattice will display the time index paying attention to the local time zone
Sys.setenv(TZ='HST')
xyplot(oneDay[,c('Gef', 'G0', 'Bo0')], superpose=TRUE)
Sys.setenv(TZ='UTC')