Because the number of hours that is available as forecast is not always the same one the next 8hours are dedicated sensors. But the full forecast is available as sensor attribute, see GitHub - fsaris/home-assistant-zonneplan-one: Unofficial Zonneplan integration for Home Assistant Current Zonneplan Electricity tariff
For usage examples see for instance Finally got the forecast :D ... · fsaris/home-assistant-zonneplan-one · Discussion #47 · GitHub
Thank you for this! I have bought the Zonneplan Nexus and because of this I started using Home Assistant to make a first step in automation ideas. Your script (besides the nicely working api) is the first thing that I actually got working 
(HA has quite a learning curve…)
[update]
I’ve got a small request, I would really like to subtract/add the charging/discharging of the Nexus in the stats/view etc., could someone explain to me how to do this?
Got the same problem, did you already fixed it?