The Solar Thread

We just had a quote through where the installer mentioned cutting down the boiler flu and sticking a panel above it…every other installer said there was no chance we could have 9 panels on the roof due to the flu, this nut job said it was fine to remove it as there was no repercussion to it.

Told our gas engineer who installed the boiler and essentially thought I was joking at first as someone cant be that stupid.  Told me to run a mile.

He did quote £8k for a 4.2kWh system with a 3.6kw battery – both of the other installers were similar price but with larger batteries and said we’d have to have a south east split between the two roofs.  Located in Norwich

Money is now going towards the mortgage repayments 🙁

Longer days so more generation but peak is lower. Is this to be expected, pitch of roof Vs sun position perhaps?

That’s flux lowering their import and export prices.

The exports coming down a larger % which will skew things slightly

Still better than basically every other export.

muddyjamesFree Member
Longer days so more generation but peak is lower. Is this to be expected, pitch of roof Vs sun position perhaps?

My system loses quite a chunk of generation due to heat. It’s nominally an 10 year-old 2.25 kw system. In short sharp periods of sunshine  I have had 2.4kw out of it, but on longer hot days I get a peak of around 1.8kw.

It doesn’t help that my inverter is in the loft, so that gets too hot as well.

Longer days so more generation but peak is lower. Is this to be expected, pitch of roof Vs sun position perhaps?

the panels will be MUCH hotter which reduces their efficiency.  You’ll be losing between 5-10% of peak power (dependent on how they’re installed), especially on days with lower wind, so less convection cooling.

Mine are in-roof and can lose 10% on VERY hot, still days.  On roof should be lower losses as air can get underneath.

Damn look to have some kind of issue. Checked the app this morning to find the battery empty. Quick flick through the days shows that generation dropped suddenly to 0 at 3:30 in Wednesday. Battery held out to midday yesterday but now pulling from grid! That the battery discharged suggests the inverter can still produce DC.

I’ve become aware of DualSun combined solar leccy and water heating panels. Their own website doesn’t suggest a large deployment in the UK (French company) but does anyone have any knowledge or experience of them? A forum search didn’t return anything to me but I’m bound to have missed something. The marketing fluff seems logical but the reality may be a long way from ideal.

https://dualsun.com/en/

So I have an error code of 18×61 vin buck max at the time production stopped. Sounds rather dead (assuming the text refers to voltage in buck pack). Installer was straight onto logging it with SE and then mentioned 3ishnday response currently and that they (SE) may just supply a replacement. One plus side is we might get to see if the new SE battery management will force charge during the cheap period (assuming it is clever enough to recognise 0 generation).

Silly question, but have you tried turning it all off and then on again after allowing for a discharge period?

I have yes, twice now.

@nixie I tried to fiddle with the new battery profiles in the app but they don’t do what I want. I’m sticking with the custom setup i asked SE to do which force charges the battery at 2 am and maximises export in the evening. One thing I cant seem to get it to do yet is to use the battery for house needs during the 1600 to 1900 peak. At the moment if, eg, I put the oven on, the power is diverted from production so export is reduced, but i’d rather it came from the battery, which can be charged later.

Did all Flux users get the news of reduced rates from July? ~10% drop in payments is disappointing but understandable i guess.

@lodger yeah I’m not convinced by the battery control options. I’m going to run with it for a bit then ask SE to do something custom if it does not do what I want. I’m also looking at seeing what I can do with home assistant.

 One thing I cant seem to get it to do yet is to use the battery for house needs during the 1600 to 1900 peak.

Is this not a limitation of the invertor. On our setup the inverter can only output 3.6kWh. If the oven or any other device is put on then it will use some of that output and therefore reduce the export. The battery cannot be used to to maintain the export level as the power still has to be converted by the inverter. If our inverter has to be replaced I’m going to try and get a bigger model installed (if they will let me pay the cost difference) and just throttle it. Perhaps then I can relax the throttling at points when we won’t be exporting (e.g. when array output is > 3.6 and the car is charging).

Did all Flux users get the news of reduced rates from July?

I did yes.

That makes sense – although there are times/days when we are below the inverter peak (ours seems to be 6) when it might be able to take up the slack.

Did all Flux users get the news of reduced rates from July? ~10% drop in payments is disappointing but understandable i guess.

its not so much the 10% drop in payments – you can live with that when the cost of lecky drops similarly.

but they have closed the gap between import and export slightly at the same time – that sucks

I wonder if it will change again in the autumn.  At the moment there’s far more power being generated in Europe through nuclear and renewables than is needed.

I wonder how many people will stay on Flux as we get nearer winter; in summer the high export rate is great, but in winter the import rate matters more, and there are other tariffs with lower night time rates.

Come October or so, when most of our power will come from off-peak import instead of solar, we’ll be switching to Octopus Go or something.

Depends on how much storage you have and if you can fill it in the nighttime rate.

We’ll be grid charging the batteries in December and January – the best we can do in the 3 hour window is 11kw, so £2ish a day.  That means our maximum power cost in the winter months will be £100, probably less.  We’re currently exporting an average of 15kWh a day, so £3 a day at current rates, that’s a net gain of around £500.   Even force charging on flux, we should be approaching cash neutral by year end including the standing charge.  I think it works for us and should continue to do so.

To my suprise our battery fully charged during the cheap period last night. Not as good as having an fully working system but at least it’s taking the sting out of it being down.

With an EV the cut-over for me on Flux will probably be about September. Fortunately I can shuffle across onto Intelligent Octopus.

Overall I’m £240 in credit over the last 30 days on Flux, with a 4.6kW array split east/west. The bulk of the income has been late afternoon on the high rate.

Looks like June with be a record month for solar:

https://www.theguardian.com/business/2023/jun/25/solar-powers-ahead-with-hopes-of-a-renewables-record-for-solstice-month

Overall I’m £240 in credit over the last 30 days on Flux, with a 4.6kW array split east/west. The bulk of the income has been late afternoon on the high rate.

East West splits are king on flux. I can’t have any west facing panels at the moment :/

East West splits are king on flux.

Definitely west facing. Ours is nearly twice that size but because it’s SE facing its output has fallen right off by the time the Flux peak period starts. I keep wondering about adding more panels on the NW facing side so as to generate a bit more later in the day…

Ive had notice of my unit costs decreasing on flux but not my export rate…. whats it dropping to?

Numbers were in the same pdf attachment. This is South coast;

Electricity (Export)                  Current prices      New prices
Unit rate – peak (per kWh)     35.925p                 31.413p
Unit rate – flux (per kWh)      9.111p                      7.177p
Unit rate – day (per kWh)       22.518p                  19.295p

Oh just checked. Im on outgoing octopus so its fixed at 15p

we don’t have an EV so most of the other tariffs are off limits at the moment. We would use the off peak hours to heat water and our ruinously expensive underfloor heating as well as putting 10kwh into the battery. we’d preserve the battery for peak-time which would save a few pounds a day, but a couple of units of sun in the daytime wouldn’t touch the sides in jan/feb.

A longer off peak would be great for the heating, will see what sort of economy 7  plans there are available. Loss of export payment doesnt matter because there will be no excess.

Figures for June and the half year point.

5.4kWp array, south facing, in the SW. 20kWh of storage.

799kWh generated, 357kWh exported, 14kWh imported.

We’ve determined that we can run the electric shower at an 8kW draw without triggering the grid. Almost an equal split between battery discharge and generation. Nice!

Half Year Figures:

3152kWh generated, 926kWh exported, 649kWh imported.

We’ve only just begun getting paid for export, but had we been getting paid for the full year, we’d be almost cost neutral, but would still have had to pay £84 for the standing charge.

We’ve had a very disappointing last few days of June, ending with today with the lowest day of production since early April! The longer days made up for it, but June only just beat the much sunnier May.

What has been great though is Octopus Flux… every day since we’ve been on it our daily bill has been negative, even with charging the car. Hopefully it should continue to be good for another few months before we have to decide when to switch back to a normal off peak rate when generation drops and we start needing heating again.

We’ve determined that we can run the electric shower at an 8kW draw without triggering the grid.

As someone with a battery that will do a mere 2.6kw I am quite jealous…

We are a week and a half down at the moment and that’s not going to change till at least the 10th. Very frustrating but nothing I can do about it. Supplier won’t fit a bigger inverter if the current one is found to be dead.

I got £300 this month from flux, also with an ev. Only problem is it makes you neurotic about using electricity because you’re paying at least 20p/kWh for it.

I’ve largely stopped worrying about it now. The system seems to be well enveloped and covers 95-97% of our use case without significant thought. Only occasionally when cooking (hob, oven, dishwasher, etc) will I consider and stagger use. In the winter this will likely be more of an issue, but so far, very pleased.

I’m really happy that it looks like the system will generate more in a year than we use and thus has a slightly positive climate effect rather than just a neutral one.

If we ever have the money to replace my aging BMW Touring with an EV, I might have to also consider expanding the system. We have a quote in place to take it to 12kWp, but 50% of that increase would be north facing. By my estimates, that 6.5kWp system would generate about 3500kWh a year vs. 6000kWh from the south facing array.

It’s a far cry from the 14000kWh we’d need currently for heating but might just do an EV and partial heating.

Prices of panels are tumbling – just seen 500W for £150 inc vat.

I’ve got a flat-roof garage that could take a frame and maybe 6 south facing panels. They’d be sheltered morning and evening though. I’m already limited by the inverter at peak times in the summer so we’d need a new (bigger? additional?) inverter to get the full benefit. However, in the winter, the east-west split of the main array is pretty useless so these could make a big difference. Hard to work out the payback time with so many unknowns.

Anybody had my scenario pls: an existing PV array (on a FIT agreement) where I want to add a 2nd entirely separate PV array?  Did it impact your FIT agreement?

The reason I ask is I’ve had 2 quotes from what appears to be two very competent contractors: Contractor 1 had no issue with this.  Contractor 2 said categorically there was no way to have 2 arrays at one property and I would need to come to terms with the FIT agreement being ripped up.  Everything I can find online sides with Contractor 1 but wondered if anyone else had this, or can guess at the driver as I don’t see that it benefits Contractor 2 to take this stance.

Thanks in advance

you can do it physically – but you cannot have two MPANS

Your new solar would have to feed in past the existing generation meter for the FIT payments.

You wont be able to sign up for SEG payments on the new install as your MPAN is assigned to the FIT payments

ooh just had the total export value to the grid surpass my import valve for the first time since i got the panels. i dont know why this makes me happy but it does.

Also turn down and save on loop coming again but not sure how ill make anything this time as im not using much.

Anybody had my scenario pls: an existing PV array (on a FIT agreement) where I want to add a 2nd entirely separate PV array?  Did it impact your FIT agreement?

I’m looking to do this.

You are not allowed to change the array linked to the FIT in any way – i.e. add to it or change panels.  But you can have a completely separate array that does not touch the FIT array until after the generation meter. So the generation of array 2 can be fed into the same consumer unit as array 1 as the CU will be after the generation meter of array 1.

I doubt you can claim any payments from a second array – just benefit from the generation.  So I would say that installer 1 is correct and installer 2 is kinda correct if he thinks you want the second array to feed into the house before the generation meter of array 1.

Thanks @trail_rat and @sharkbait, amazingly helpful.  That’s a shame but at least a constraint I can understand and work around (I didn’t really expect much exporting anyway).  I will put it down to me not articulating myself correctly.

While I have you! 🙂 – any views on installing pre-G99 approval (by throttling the export to below the current permitted limit) just to get the system up and running quicker?

I’m not sure you can do that.  I think if the total of your potential panel generation is more than 3.9Kwh (or whatever it is that’s allowed regardless) then you must go for approval – I presume your existing array is just under 3.9kwh so almost anything more would require approval.

(Obvs having 2 x 3kwh arrays could potentially put 6kwh into the network in the same way as a single 6kwh array could)

Its the inverter that is the limiting factor G98 = 3.6kw above that G99 is required, not the array. Not sure if its ever checked to be honest. Not so sure clipping is allowed as its easy to override