library(tidyverse)
library(plotly)
set.seed(2001)

## make 10 random data series
data <- data.frame(
  t = rep(1:50, 10),
  id = sort(rep(1:10, 50)),
  y = rnorm(500)
 )

## cumulate the random variates by group
data <- data %>%
 group_by(id) %>%
 mutate(y2 = cumsum(y))

## plot
plot <- data %>%
 plot_ly(x = ~ t, y = ~y2, text = ~id) %>%
 add_lines(split = ~id, color = I('gray'), alpha = 0.5) %>%
 hide_legend()
plot