Ref: https://agileprices.co.uk/
You should select your region at the top.of the page.
Yes, this is a potential problem, with a huge variance in price between the 4 slots.
First pass
01:00 - 15.4p
01:30 - 22.1p
Second pass
01:00 - 24.0p
01:30 - 16.9p
With this data, I want to set the first 01:00 slot, and the second 01:30 slot, but WonderWatt is only showing first occurrence
SolarAssistant apparently has no concept either, so as others have said, they will skip tonight's 01:00 and 01:30 slots entirely to avoid getting expensive KWh's
For safety, I am selecting 02:00 and 02:30 only to carry the battery thru the night. It's due to be sunny all day tomorrow, so I will run dishwasher and washing machine during glorious sunny hours.
In answer to your concern, WW 02:00 and 02:30 slots match the agile pricing correctly, so should be safe.
However, I am no expert and I am just sharing my hope/opinion and as such I accept no responsible for making incorrect assumptions.