I'm with octopus since Bulb went bust, and no issues.
I've been able to mange my monthly payment amount, plus take my credit out without hassle when I crept up.
In some areas, if you are on a smart meter, they give you 'power up' sessions if there had been alot of wind or sunshine. The day before, I get noticed that this session will be 10-12, or 13:00-1530 for example. If I opt in, I get any electric I've used within the session time reimbursed back to me. During these times, I use the washing machine, dishwasher, oven, vacuum and anything else I can.
We've recently renovated, and all our appliances are fairly efficient anyways, so at most, these sessions amount to about £2-3 back to the account. If you had a solar battery you could charge, or a car, then maybe you'd get more money back. The session might be 3 per week, or 1 a fortnight, so not a reliable thing and only in selected areas.
Separately, they also have 'Free Electrical sessions' occasionally, but these only reimburse the additional electric above your average for the past 10days, for that time period. At most, these sessions give me 50p back!