I presume you will be on the 50% deemed export rate? If so, this is applicable to you (taken from the Octopus energy blog:

"50% Deemed was one option under FiT for getting paid for your export. This is often the case where an export meter wasn’t fitted and so it is was assumed that 50% of the solar energy generated would be exported (the other 50% being consumed). This is calculated from the installed potential output of the solar panels at the time of install. You may find you are still better off keeping the Deemed 50% than switching to Outgoing Octopus - for example if in fact you are exporting only 20%, or if the solar panels aren’t optimally oriented to supply the potential output or have deteriorated over several years. As the FiT Export rate is now 5.38pence and our flat rate is 5.5pence then you are better off with Outgoing Octopus if (average over the year) you export more than around 50% of the installed capability".

Perhaps think carefully about this, especially if your panels are not south facing?

Thanks Jeff,

I'd seen that and suspect it's wrong in degraded panels effecting the choice. FiT deemed export is 50% of your metered generation ( i.e. if I look back over my statements export is always exactly half of generation). So if the PV was were performing badly this wouldn't make any difference in the choice to switch.

Our Generation was 3729kWh in 2020 and we imported 1300kWh, I don't know what our self use was (another reason it would be nice to have an export meter) but looking at January electricity usage I suspect self use is less than 25%.

Outgoing agile also appears to pays circa 10p / kWh after 4pm so with our west facing array we'd be double winning from metered time of day export.

I'm pretty confident it's the right financial decision (if I've understood it correctly) but was hoping someone had already been through this. My main worry is that I inadvertently get opted out of FiT generation as well as FiT export which would be bad! Energy company blogs that don't seem to understand the system don't help this worry.

Posted By: jms452Thanks Jeff,

I'd seen that and suspect it's wrong in degraded panels effecting the choice. FiT deemed export is 50% of your metered generation ( i.e. if I look back over my statements export is always exactly half of generation). So if the PV was were performing badly this wouldn't make any difference in the choice to switch.

Our Generation was 3729kWh in 2020 and we imported 1300kWh, I don't know what our self use was (another reason it would be nice to have an export meter) but looking at January electricity usage I suspect self use is less than 25%.

Outgoing agile also appears to pays circa 10p / kWh after 4pm so with our west facing array we'd be double winning from metered time of day export.

I'm pretty confident it's the right financial decision (if I've understood it correctly) but was hoping someone had already been through this. My main worry is that I inadvertently get opted out of FiT generation as well as FiT export which would be bad! Energy company blogs that don't seem to understand the system don't help this worry.

3729 kWh for a west facing array sounds amazing. I don't know where you are located but on a good year we get 3300 with a south-southeast array and 3000 on average (we are in Pembrokeshire). Like Philedge above, I'm not convinced that it is worth changing for the sake of a few hours worth of decent generation after 4pm but maybe I'm missing something! Might be worth contacting Octopus directly and checking this out.

Posted By: Jeff B3729 kWh for a west facing array sounds amazing

Generation last year was higher than normal. We got 4022 kWh from our slightly-too-horizontal south-facing array, versus 38xx kWh for each of the previous three years (xx = 22,35,84).

It should be possible to work out what the payments will be given some historical data. I'm sure John has done his sums correctly :)

Hi Phil, I'm in Suffolk so quite a bit closer to John in Cambridge. I think cloud cover is a lot more important than latitude (at least within the UK) but I am quite surprised by Jeff's lower numbers. I suppose he has 4 kWp like the rest of us?

The difference between your figures and mine does indicate the importance of differences in local weather. For completeness, my full figures are:

2016 3,963.86
2017 3,822.45
2018 3,884.38
2019 3,835.84
2020 4,022.27

Posted By: Jeff B3729 kWh for a west facing array sounds amazing

2.25kWp west and 1.75kWp south both at 45 degrees (too steep) located just south of Cambridge.

Posted By: Jeff BI'm not convinced that it is worth changing for the sake of a few hours worth of decent generation after 4pm

Main reason is that I think we export most of it and only get paid for 50% of it. After 4pm generation is the icing on the cake.

Posted By: djhDon't you need a smart meter for an agile tariff? If so, that should be able to tell you how much you're actually exporting (that's how they measure what to pay you for after all!) and so you can calculate your self-consumption.

Yep - I was going to do them both in the same process to ensure I get the right smart meter for outgoing PV. Maybe paranoia but I don't fully trust the processes at big organisations to get edge cases right.

Posted By: Ed DaviesThey're pretty clear that you can still receive the FiT generation payments. From that FAQ page: https://octopus.energy/blog/outgoing/ with my emphasis:

Thanks Ed.


Nice to see no significant major in GBF PV arrays!


Starting the process to join outgoing agile (and get a suitable smart meter) the next step is to get a letter confirming our PV is grid tied from UK power networks!

https://www.ukpowernetworks.co.uk/electricity/distribution-energy-resources/need-help-with-an-existing-solar-panel

I have signed up to Agile Outgoing, been on it for the last 12 months.

I did it because I have two solar pv systems, one is FIT and the other isn't. I had to show that both systems were MCSE compliant and also move my FIT to Octopus which was a bit of a hassle.

I now get paid for all exports based on Agile rates but I still get the FIT payment they said the export element would stop but I think I still get that too.

If you only have one FIT eligible system I don't think its worth doing.

Posted By: Jeff Bdjh/philedge: yes I have a 4 kWp system, however the max it has ever delivered on a typical blue sky day is approx 3.2 kW.

You seem to have much lower output than Phil or myself. I wonder why?

- I have microinverters, so shouldn't suffer so much from shading problems. Do you have any intermittent shadows on your array?

- what does PVGIS say about expected output where you live? It's usually quite good.

Posted By: djh
You seem to have much lower output than Phil or myself. I wonder why?

I think Pembrokeshire should be a fairly good area, certainly as good as us according to the irradiance map, so I guess the lower output is down to panel performance with older panels or not having optimisers??? Im sure the 2011 FIT rates will be ample compensation�

Posted By: Jeff Bdjh/philedge: yes I have a 4 kWp system, however the max it has ever delivered on a typical blue sky day is approx 3.2 kW.

How do these compare with your outputs?

We see around 3.5kw max on a good day but I think that is a touch lower peak than it could be with having our panels split across 2 roof pitches and a chimney partially shading the 1kw SW facing array.

The daily averages I have show much the same good months as yours with May being the best followed by June then July and April not too far behind

Posted By: jms452Did you need to get connection confirmation from your network operator?
Did you leave the FiT generation payment elsewhere and just ask to cancel the FiT deemed export and move this to Octopus?

Yes i had to get the DNO to approve the second system, I have a 3kW and a 4.2kW array but I had to have a max output of 6kW so I have 2 x 3kW inverters.

My FIT is now with Octopus, you have to transfer it to them if you have agile Outgoing.

Overall our production over the year almost exactly matches domestic consumption including running an EV.
I am paying £30 a month for my electricity and I get about £500 a year in FIT so overall running cost is negative.

Posted By: nigelMy FIT is now with Octopus, you have to transfer it to them if you have agile Outgoing.

That doesn't seem to be the case based on what the previously quoted page says?
From https://octopus.energy/blog/outgoing/ :

"When you sign up to the Outgoing Octopus, you will be required to opt out of your deemed export payments from your existing FiT supplier (but there’s no requirement to switch your FiT contract to Octopus.)"

Posted By: djh

Posted By: Jeff Bdjh/philedge: yes I have a 4 kWp system, however the max it has ever delivered on a typical blue sky day is approx 3.2 kW.

You seem to have much lower output than Phil or myself. I wonder why?

- I have microinverters, so shouldn't suffer so much from shading problems. Do you have any intermittent shadows on your array?

- what does PVGIS say about expected output where you live? It's usually quite good.

I've had a look on the PVGIS website and put in some figures. I know the roof slope is 49 degrees but how do I determine the azimuth? If the panels are facing south-east does that equate to an azimuth of 45 degrees?

Posted By: Jeff BI know the roof slope is 49 degrees but how do I determine the azimuth?

If this is a query about the azimuth when using PVGIS then when you 'visualize the results' to the right of the bar chart there is a (sort of) compass rose which if you hover the cursor on the perimeter and move it around the perimeter this will show you the azimuth that PVGIS wants relative to the compass point. (south is 0, west of S is +degrees and east of S is -degrees )
Also shown on the rose is the sun height for June and December along with the presumed horizon height for your location

Thanks for the many comments and the azimuth figure. I have run the PVGIS routine using a roof slope figure of 49 degrees and azimuth angle of -45 degrees and it calculates I should be achieving 3792 kWh p.a. The average figure we have achieved in 10 years is 3099 (range: 2896 to 3374). Out of interest I have calculated the difference in outputs per month between my actual average data and PVGIS calculated data - see attached spreadsheet.

The largest differences in percentage terms are for the months of Jan, Feb, Mar, Oct, Nov and Dec. I think the explanation for this is that the sun is quite low on the horizon during those months and my neighbour's trees effectively block the sunlight even though they are bare at those times. I do have micro-inverters so if I didn't I think the figures would be much worse. From April to September the sun is higher in the sky and for most of the day is well above the trees. It is noticeable though that after about 1pm the PV output starts to drop significantly as the sun moves around to the SW and W.

We have had thoughts about moving some of the PV panels from the SE facing roof and putting them on the SW facing roof. There would only be room for 6 panels on the latter though, leaving 15 on the main roof so may not be worth the hassle/expense. Also not sure if this may be an issue with the FIT i.e. altering the system layout?

P.S. Apologies to jms452 for hijacking the thread.