@old_scientist 
Good news, at least some revenue was rescued this year.
I had a similar result, my May nett usage was within a percentage of my July nett usage and yet my nett revenue is 70% higher than on octopus outgoing. 
Yes the AI doesn’t seem able to predict solar generation at all, it also can’t predict the impact my export limit has on the my system optimisation, it lost me about 10% potential generation compared to me tweaking the system. 

Looks increasingly like high energy prices are coming over the winter, going to need this revenue to cover it. I’m starting to think about a fix, probably cosy, but last year OE put applied an early exit penalty. Ideally I’d stay on flux until end September, but I need to check when the next price cap will be set. 

Using percentages to explain measurements can confuse alot of people

you said your net income (excluding standing charges) on Flux is around 170% of self consumed.

This can be interpreted 2 ways

The amount is 100% if its the same, so you made an excess of 70%
or you actually made 170% in excess of the amount you made.

politicians love percentages as they can hide the true costs

in actual numbers, the first interpretation of your percentages would be a £70 profit on £100, the second a £170 profit on the £100

A better way is to compare the 2 values, im guessing, as i don't have your figures, but your incoming was 1.7x your outgoing, using the second example incoming/outgoing would be 2.7x which would be remarkable that Gregg would set up Octopus to provide such a spectacular profit margin.

@agentgeorge 
I believe my use of percentages was correct, the nett revenue for May was £100 whilst on outgoing octopus, the nett revenue for July was £170 on flux. Both months had near identical generation and usage (+/-3kwh). £170 is 170% of £100. 
This time last year the nett revenue was £350 on OEF, it’s because I export 90% of what I generate in these months. 

Yes, the payments were very generous and don’t make good business sense, I guess that’s why they have stopped. But I have a large winter usage with the bloody heat pump, so over the entire year my annual nett profit will only be a few hundred pounds this year, or less if the import prices go crazy.

@papahuhu yes your use is correct, i was referring to the way you can interpret the results. 
politicians always spin things. A change from 100 to 150 is a 50% increase, but 150 to 100 is a 33% decrease. Same actual £ change but different headline % change.

i use cosy tariff which suits my houses usage. Having PV and battery to time shift power during the 4pm-7pm expensive period.

ive been renovating my house past 3 years and went thru the first winter with the Cosy6 unable to cope with the heat loss, used spot heaters to supplement.

ive been insulating every cavity, double insulation the loft eves, and ceilings, all floors and all exterior walls are now 150mm insulated. The difference year on year is significantly lower bills and energy unit usage.

I dug the floors out to install the UFH which has worked well with the Heat Pump

If your rooms are large enough, adding 50mm of insulation to the exterior walls with batons and insulated plasterboard is a good first step.  Doing this to a window wall is harder as you'll need a larger window board 

@agentgeorge 

You do know that you can flip tariffs with octopus, daily if you wanted to. I use cosy in the winter, but if you have any excess generation you would be better financially to use flux in the summer. You get, if I recall correctly, 35p/kWh vs 11p on outgoing. It’s a click of the mouse to flip. 

Yes, insulation is important. We had several vaulted ceilings and added 120mm PIR board, it made a huge difference. Watch out for condensation though, we added Small DMEV fans into all “wet” rooms and trickle vents into at least one window in every room. The RH came down about 20% as a result, if we hadn’t done that I’m sure we’d have had mould, as anything above 60% is likely to cause issues. 

But if octopus fitted an undersized unit then they should be liable to replace it for you, it’s their error.

I thought they stopped that as people were getting to the end of they day then flipping to the cheapest tariff for that day as it took effect on the day you changed ?

@papahuhu it was the other way round. Octopus tried to install a huge unit to cope with the losses at installation; i had already done real heat loss calcs of around 5kW so didnt want an over sized power hungry HP. With UFH the house has comfortable all over heating, not localised radiator heating. I run my cosy6 low and quiet, barely breaking 45C flow temps. Its not quick at heating the house, if i need to beat the tortoise, i bring out the supplemental halogen heaters; also gives a nice warm red glow to the room.

@papahuhu @toodles do you take advantage of tariff switching suggested by papahuhu

@agentgeorge That sounds a bit mad from a financial perspective, the radiant heat source will have an efficiency of less than a boiler. But perhaps you enjoy to bask under the heat lamps, lizard like?!

@etchedpixels I don’t flip everyday, but was making the point that it was a possibility. But there’s nothing in the terms and conditions to stop you doing so, or at least there wasn’t when I checked 6 weeks ago. I changed 4x last year, they never questioned or challenged me.

@agentgeorge As yet, I have stuck with Cosy. My export is on Outgoing at 12 pence. Regards, Toodles.

@agentgeorge As long as you don’t have an EV and have excess PV generation, there’s no situation in which flux won’t outperform cosy/outgoing in the summer months. It will be in the region of +70% revenue. It’s 35p vs 11p, do the calculation for your personal situation. But you do need to change back in October.