Lines <- "Hour,PF
0,14/01/2015 00:00,0.305
1,14/01/2015 01:00,0.306
2,14/01/2015 02:00,0.307
3,14/01/2015 03:00,0.3081
4,14/01/2015 04:00,0.3091
5,14/01/2015 05:00,0.3101
6,14/01/2015 06:00,0.3111
7,14/01/2015 07:00,0.3122
8,14/01/2015 08:00,0.455
9,14/01/2015 09:00,0.7103
10,14/01/2015 10:00,0.9656
11,14/01/2015 11:00,1
12,14/01/2015 12:00,0.9738
13,14/01/2015 13:00,0.9476
14,14/01/2015 14:00,0.9213
15,14/01/2015 15:00,0.8951
16,14/01/2015 16:00,0.8689
17,14/01/2015 17:00,0.8427
18,14/01/2015 18:00,0.6956
19,14/01/2015 19:00,0.6006
20,14/01/2015 20:00,0.5056
21,14/01/2015 21:00,0.4106
22,14/01/2015 22:00,0.3157
23,14/01/2015 23:00,0.3157"

library (zoo)
library (strucchange)

z <- read.zoo(text = Lines, tz = "", format = "%d/%m/%Y %H:%M", sep = ",")

bp <- breakpoints(z ~ 1, h = 2)

plot(z)
abline(v = time(z)[bp$breakpoints])
fit <- zoo(fitted(bp), time(z))
lines(fit, col = "blue", lty = 2, lwd = 2)

fits <- lapply(seq_len(nrow(breaks)), function(x) {
  idx <- index(z)>=breaks[x, 1] & index(z)<=breaks[x, 2]
  fit <- lm(z[idx]~index(z[idx]))
})
sapply(fits, coefficients)