The s/w and s/e array are each meant to be on separate input to the inverter
I take it they are? As I said before, it's tricky troubleshooting when the weather is not optimal - much easier when it's sunny and you know roughly what should be happening.
My money is still on crappy weather.
Managed a measly 1.4kw so far today.
Luxury - 0.35 here!
Was very murky all day, bar about one hour when we generated 0.2 kW.
@Footflaps where are you and how big is your array and what orientation?
The weather has been very patchy the last few days. We've been down in London; some times it's been glorious weather there while our panels back in Telford have been doing nothing, but at other times murky, damp weather there while our panels back home have been doing 5kw!
I can easily believe that the last day or so luck could be the difference between a couple of great solar days and a couple of terrible ones.
I put a 4.2kw array into a shop/flat I own (rented out) around 4 years ago. S/W facing roof. The whole building is electric only so I did it to help lower the tenants bills. I get the FIT which is somewhere around £130/year.
I’ve no remote access and have never bothered tracking how it’s doing apart from submitting quarterly meter readings to the FIT provider.
I recently put the figures I have from the FIT rebate remittances into a spreadsheet, looks like it’s performing reasonably well?
Just to bang on again about the PGVIS model. If you are thinking of solar it gives you a very good estimate of your possible gain. I have been surprised so far as to its accuracy.
Planning? A flat roof would require a ground mount style frame to mount the panels – that’s going to stand out somewhat!
Dug around on the Edinburgh planning portal last night. Neighbours with panels who did apply were told it did not need consent as it was not visible from ground level. So seems ok to crack on from that perspective.
Just out of interest how are the installers going to hold the frames down?
Just out of interest how are the installers going to hold the frames down?
Preferred (and likely) method is to drill through the roof to attach them, but they can use a ballast system if that is deemed not possible.
Preferred (and likely) method is to drill through the roof to attach them
As the son of an architect who's mantra was to never drill into a flat roof, that worries me. What do you think the chances are of all those holes remaining watertight over a period of 10 years?
(See also balustrades fitted onto flat roofs rather than onto the fascia)
Lovely day for generation, but to illustrate the difference between S facing arrays and E/W facing arrays this is the current state of play of my two setups:
4kW E/W Array:
Date - Time - [Total] Energy - Efficiency - [Current] Power
23/02/23 - 11:30AM - 3.200kWh - 0.801kWh/kW - 1,335W
3kW S Array:
Date - Time - [Total] Energy - Efficiency - [Current] Power
23/02/23 - 11:30AM - 6.713kWh - 2.238kWh/kW - 2,325W
!!
What do you think the chances are of all those holes remaining watertight over a period of 10 years?
Not an architect or engineer so to be honest, I've no idea.
Thus far just putting my trust in...
1. Both methods seemingly being established methods for fitting to flat roof.
2. Putting trust in a reputable company to guide me. Many cowboys out there but this one come well reviewed and personal recommendation from people I know.
But still not committed to anything so open to other opinions.
What do you think the chances are of all those holes remaining watertight over a period of 10 years?
If it's done properly with proper seals and cowls then quite high.
A quick google suggest most flat roof system just sit on top and use ballast, which is a lot simpler...
https://www.valksolarsystems.com/en/solar-mounting-systems/kits/flat-roofs/solar-ramp/valktriple
We've always used ballast when installing antennas on flat roofs, but they have blown over in exceptionally windy conditions. Not sure how happy I'd be with a load of sails (solar panels) waiting to be lifted off the roof in the next gale....
We’ve always used ballast when installing antennas on flat roofs, but they have blown over in exceptionally windy conditions. Not sure how happy I’d be with a load of sails (solar panels) waiting to be lifted off the roof in the next gale….
Yeah, we are quite exposed, basically it's downhill for miles until it hits the Forth, and a single story property next door which means we have lovely clear views for miles from 2nd floor, but also really bloody exposed to the elements. I'm not sure I would be 100% on the use of ballast, but again I'd put trust in them. They did say that the ballast option is likely to be more expensive due to the amount that would be needed, it would be harder to get up and weight on the roof may be too much.
I was thinking that if we ever do a roof conversion we'd end up moving the solar panels to a flat roof, so I was thinking of making a frame which bolted into the walls at either end, had feet sat on the roof mid span and then bolt the solar panels to that, so they can lift off without ripping bolts out the walls....
Obvs be a bespoke frame, but fairly easy to make out of galvanised steel.
Not sure how happy I’d be with a load of sails (solar panels) waiting to be lifted off the roof in the next gale….
a wind load survey would quickly force you to use solar ballast buckets such as the renusol console
These enclose the back of the panel from the wind reducing sail effect
As Doug points out though cost and weight quickly mount
so I was thinking of making a frame which bolted into the walls at either end, had feet sat on the roof mid span and then bolt the solar panels to that, so they can lift off without ripping bolts out the walls….
quite sure Doug will want an mcs certificate which a home brew mounting system won’t get
quite sure Doug will want an mcs certificate which a home brew mounting system won’t get
It's not any different to how the installer we used mounts panels on gable ends etc, they just knock up bespoke frames out of square section steel tubing on site to mount the panels as required...
Plus in our case, which is what I was talking about, we already have all the certificates....
quite sure Doug will want an mcs certificate which a home brew mounting system won’t get
Yup and got to be supplied and installed by them to get the Home Energy Scotland grant and loan. Plus I hate heights so no chance I'm going up on the roof.
We've got a flat garage roof in Glasgow (approx 5.5m x 4m / 23m2) that gets sun most of the day, effectively our only potential for south facing. The house is E/W and North facing and is Victorian semi so wouldn't be appreciated by neighbours... Looking at option of putting 10/12 panels on the garage and rear extension, or 9 on garage and 3 on a frame next to the garage out of sight...
Would be going over a 2 year old sika liquid plastic roof - looking at the plastic trays for ballasting or else knock up a frame with pads to spread the load. There is a small ~300mm parapet upstand around the roof so shouldn't be "too" exposed to wind...
Is there a go to DIY package on the web, or a go to panel type that is considered the best value for money for this type of setup? There seem to be loads to choose from.
My facebook feed is now full of firm after firm offering 12 panels + inverter + battery deals from £5k to 13k... Plenty of DIY kits come up in google but it would be good to have a real recommendation from someone who has done something similar.
Electric company car coming in May will change our usage / might be looking at car charging point and a house battery setup too? Hard to know which way to go.
Sale of our existing car may provide some of the funds for this project. Looking for a bit of energy future proofing but will only do it if numbers work. I appreciate Glasgow and flat roof aren't perfect.
We consumed 7783kWh last year, = 21kWh per day. Expecting this to go up next year with car charging.
Any help would be greatly appreciated, thanks.
Any help would be greatly appreciated, thanks.
Run the numbers first to see what you could generate from the available area.
Looking at option of putting 10/12 panels on the garage and rear extension
Again, check that you don't need planning as a panel on the garahe roof is going to add probably 1m to the height .
ideal thanks
If putting panels on a single storey building check they won't be shaded.
A home battery will pay for itself quite quickly if you make use of the Octopus Go tariff which you should consider anyway when the EV arrives.
Although using 21 kWh a day, that's going to be a large & expensive battery!
Although using 21 kWh a day, that’s going to be a large & expensive battery!
Unless he uses 21kWh at night it doesn't have to be that large. Its not good economics to size a battery to cover you in December as it will take an age to get payback. Most of the year solar will cover 20-100% of your requirements so size the battery accordingly.
Although using 21 kWh a day, that’s going to be a large & expensive battery!
Logical thinking would be to think of a battery as a capacitor.
Remove the export since rates are derisory (without being able to control when it's exported)
Going "off grid " is expensive ....how ever removing a large chunk of your import is reasonably cheap by comparison
We consumed 7783kWh last year, = 21kWh per day. Expecting this to go up next year with car charging.
If it helps with your working out, we produced 4000kwH in Glasgow last year (feb-feb). From all accounts that was a good year. We were quoted to expect approx 2500-3000kwh based on location/aspect. That’s a south facing roof with 4.6kw panels tied in to the standard 3.65kw inverter. No battery.
Be advised though, 70% of the production occurred feb-august. August-Feb sporadic at best in Glasgow. Our biggest saving comes from the iboost to heat the water.
I finished installing the second battery today along with all of the associated wiring and ducting - just in time too. Even given the power off time whilst I wired it up, it was a 17kWh day! Saw a new peak power from the array of 4.89kW, but only briefly as it’s intermittently cloudy.
There’s now ~19kWh of storage on the side of the house, which should do us even on very busy days.
I wish there was more information from
The BMS about how it’s doing its job between the packs as they’re quite different in size to one another, but I can’t find anything through the inverter. I’ll try to ask LG.
New peak for us ...from a 4.14kWh array plugged into a 3.6 inverter.
Never saw that in the last 18 months. Peaked at 3.8kWh last April with the last 3.6 inverter. Summer sun never gets close to that with the excess heat.
Remove the export since rates are derisory (without being able to control when it’s exported)
I buy at circa 18p a kW on Eco7 then if I do export any I get circa 15p per kW. I dont buy any at the expensive rate since early Feb so the export works ok for us.
Trailrat what app is that? 😁
Solis numberjumbler app
Remove the export since rates are derisory (without being able to control when it’s exported)
We've just signed up to Octopus' dynamic export rate, although not yet seen the prices they offer.
Not sure if it's the same as their "Agile" tariff, where the unit price varies every 30 mins.
If doing a smart plug immersion solution to excess generation, can I stick a dimmer switch rather than an on off after the fuse spur
to scale down consumption? Problem is the inverter can only push 5kw so if i boil the kettle then I’m drawing power from the grid.
Will that shorten its life?
I buy at circa 18p a kW on Eco7 then if I do export any I get circa 15p per kW. I dont buy any at the expensive rate since early Feb so the export works ok for us.
hence the my brackets in your original part quote - what you are doing would not be possible without the ability to control when the export happens ( IE batteries)
f doing a smart plug immersion solution to excess generation, can I stick a dimmer switch rather than an on off after the fuse spur
to scale down consumption?
that sounds like a really shonky and quite probably dangerous way to solve something where an off the shelf qualified product exists already to perform that function.
worth noting that few smart plugs are rated to an immersions draw on continuous current. most will do it peak but not continuous.
Problem is the inverter can only push 5kw so if i boil the kettle then I’m drawing power from the grid.
The immersion shunt unit should sense that you're pulling current from the grid and back off the current to the immersion whilst the kettle is boiling.....
Plus, how long do you boil a kettle for? 1 minute tops?
Yes having done a quick google, lighting doesn’t run at 13 amp so a high current rheostat is needed and it needs a heat sink too.
If there’s a dimmer will the smart plug need to do 13a - theoretical question. I’ve discounted as not a very practical idea.
Footflaps- I don’t have an I boost or similar so immersion just runs at full tilt when on
Footflaps- I don’t have an I boost or similar so immersion just runs at full tilt when on
doing that manually will get boring very fast
Yes having done a quick google, lighting doesn’t run at 13 amp so a high current rheostat is needed and it needs a heat sink too.
Normally dimmers just chop the 230v using triacs so the on period is less than 100% (or at least the ones I used to build). I assume someone would make a 13A version...
A rheostat sounds like a very old school solution.
might it be easier to run two small immersion heaters off two plug switches?
Footflaps- I don’t have an I boost or similar so immersion just runs at full tilt when on
You could automate it - I have a system [that uses a Pi, IFTTT and a Warmup wireless thermostat] to switch the electric underfloor heating on and off when there's enough generation which works pretty well.
But that's 'only 800w so if there's an overlap of a few minutes when the generation has dropped but the floor is still on then it's not the end of the world, but 3kW is another matter. And the times when your panels are producing more than 3kW + your house background usage are going to be fairly limited.
You're much better off stumping up for a diverter - it's the best solution for water heating.
might it be easier to run two small immersion heaters off two plug switches
That assumes two immersions in the tank - and still a PITA.
You’re much better off stumping up for a diverter – it’s the best system for water heating.
Or not worrying about drawing off the grid for 30 secs when you boil the kettle....
Although I realise it becomes quite obsessive. I worry about sequencing kettle, microwave and grill when cooking, so as to never exceed our 3.8 kW inverter limit. Totally pointless in the grand scheme of things, but I do 'get it'!
We’ve just signed up to Octopus’ dynamic export rate, although not yet seen the prices they offer.
Not sure if it’s the same as their “Agile” tariff, where the unit price varies every 30 mins.
Been on the agile since install, just moved onto the 15p tariff as we were consistently below this threshold very rarely above 15p.
what you are doing would not be possible without the ability to control when the export happens
Not really. My batteries dont allow me to choose. Excess solar goes to my batteries, then my solar diverter then back to the grid. It happens sporadically during the day when none of the others have any demand.
Anyway I am looking to extend the PV I have from 5.6kW (5kW inverter) to around 8kW to provide for the increased draw that my future EV will demand. If I didnt export to the grid (at around 15p per kW) then each kW would provide around 3 miles (dependent on several factors of course) of range (of course I give up the export benefit so its not free) but in Feb alone I have estimate around 180 miles so far. Thats roughly half our car monthly mileage.
If I add 2.8kW (assuming I can) then should I add another inverter or feed into the current one??? Tempted to add another as even in Feb I have seen bursts of >5kW so I would be giving quite a lot of free energy away...
Been on the agile since install, just moved onto the 15p tariff as we were consistently below this threshold very rarely above 15p.
Do they use the same value for import and export on Agile?
Or does the export have a lower dynamic value?
True!
As you said, doing it manually is going to get old very quickly - you could switch it on then go out and it cloud over leaving the immersion on, or just forget to switch it off!
If I add 2.8kW (assuming I can) then should I add another inverter or feed into the current one???
I have wondered how this works, I assume they talk to each other (I think the Huawei ones do anyway). Otherwise the whole backing off thing might be a bit random as each thinks it is the only inverter in the system. Or maybe they co-exist fine. Pretty sure with Huawei all the inverters link via Ethernet so act as one.
That assumes two immersions in the tank – and still a PITA.
you can (I think) get dual element immersion heaters for exactly this purpose - the original purpose was one of them run off the economy 7 timer and one for boosting. No idea if they'd be too powerful when both run together
its worth noting that immersion heaters should be run off dual pole switches, which I doubt any remote control plug hack would achieve.
I assume they talk to each other
I'm pretty sure the Foxess ones work alongside each other and have seen screenshots of the software supporting that. Quite pleased with the vendor so far (battery and inverter) so no need to change I suppose but as the roof is low it is borderline DIY.... Obvs with an expert to make the final connections.
export is way lower than import for obvious reasons orherwise many would just load shift back to grid when prices above import. i was on the dynamic agile export averaged 10-13p, so a flat 15p is better for me. Im still on E7 for import, want to move onto tracker but there is now a 6 month wait as they are only doing 50 applications a day. Flat rate will have to do meantime
http://mysmartenergy.uk/ gives you the details
If I add 2.8kW (assuming I can) then should I add another inverter or feed into the current one???
This is what I want to do and I'm going to add another inverter for a couple of reasons:
1) Existing array is on two strings and the inverter accepts two strings, so there's no room for a third string [extra panels would be ground mounted]
2) My existing FIT does not allow any alterations to the equipment and I'm not going to risk the [substantial] income that provides!
Two questions..... will your existing inverter take the potential generation from a combined 8kW array and will your DNO allow an increased generation (or are you not going to tell them?
Not really. My batteries dont allow me to choose.
I think your misunderstanding.
With batteries you have a choice.
Without you have no choice
@sharkbait Good questions I will have to check the spec in detail of the inverter. My setup also already has 2 strings. I am waiting for a call from my installer and happy to be open with them and see what they suggest.
Solis numberjumbler app
Ah - fellow tea leaf readers.
I think your misunderstanding.
How so?
I think your misunderstanding.
How so?
I have absolutely no idea.
If you are upping generation (and the new inverter is linked to the grid) You will still need to advise your dno with a gn99 or whatever the form is.. might be worth checking they view this as “not a change”
Two questions….. will your existing inverter take the potential generation from a combined 8kW array and will your DNO allow an increased generation (or are you not going to tell them?
I’m pretty sure that risking the payments on the FIT scheme is the least of your concerns, as OFGEM monitor individual trends and can not only demand a full repayment of anything paid to you under the scheme, but then cheerfully pass the entire case over to the police.
A system diagram is placed on record when the system is installed, so it’ll be immediately obvious if anyone visits to read the meter (or because your generation trend has doubled) if it’s been modified.
It’s honestly not worth fiddling. Any new system needs to be completely independent from the existing install. That’s not to say that you can’t do it, but you need to be very careful about how it’s done.
It’s honestly not worth fiddling.
Agree. Thats why I said this
I am waiting for a call from my installer and happy to be open with them and see what they suggest.
It’s honestly not worth fiddling. Any new system needs to be completely independent from the existing install.
That's certainly my feeling.
I’m pretty sure that risking the payments on the FIT scheme is the least of your concerns, as OFGEM monitor individual trends and can not only demand a full repayment of anything paid to you under the scheme, but then cheerfully pass the entire case over to the police.
A system diagram is placed on record when the system is installed, so it’ll be immediately obvious if anyone visits to read the meter (or because your generation trend has doubled) if it’s been modified.
It’s honestly not worth fiddling. Any new system needs to be completely independent from the existing install. That’s not to say that you can’t do it, but you need to be very careful about how it’s done.
Fairly sure that surfer doesnt get FIT payments - in which case im not sure why anyone would be handing anything to the police.
as for the system diagram - you over estimate the system -- ive seen whats on record for my system at DNO level and it amounts to a piece of paper that says ive installed solar and i wont export more than 3.6.
The MCS which is not a legal requirement has a kit list and a schematic but no one will be chasing based on that
My original question seems lost. Im shocked...
You are right @trail_rat I dont get FIT.
I'd be genuinely amazing if anyone is checking up on installed systems and also amazed if the records were correct for most installed systems....
It's probably all stored on a access database somewhere.
My G99 cert was far more comprehensive and the paperwork from the DNO arrived back from them with all of my system diagrams, etc embedded into the sign off paperwork.
Another shout out for the accuracy of the PGIS Database. Its not totally clear how many Kw my system would generate in February from the graphic but I read that as being 280kW (28 day Feb) As it stands (its cloudy here so may get another kW or so today) I have reached 279.08kW which seems an incredibly accurate estimate...
Its not totally clear how many Kw my system would generate in February from the graphic
If you hover over the graph in the original web page it tells you the actual value for each bar.
@footflaps Cheers. I never noticed that and the above was a screengrab that I embedded in a Spreadsheet alongside other numbers.
This was our prediction:
[url= https://live.staticflickr.com/65535/52437382441_babd24d272_z.jp g" target="_blank">https://live.staticflickr.com/65535/52437382441_babd24d272_z.jp g"/> [/img][/url][url= https://flic.kr/p/2nTHhUH ]Solar PV output[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
But we seem to have done much better (over double)....
[url= https://live.staticflickr.com/65535/52717211431_54ddfecd67_n.jp g" target="_blank">https://live.staticflickr.com/65535/52717211431_54ddfecd67_n.jp g"/> [/img][/url][url= https://flic.kr/p/2ojrujt ]Feb 2023[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
which seems an incredibly accurate estimate…
Pot luck, it will just have numbers in for 'average cloud cover' for each month for a given region, but no two years will be the same in reality....
@sharkbait, you mention a few posts up you get FIT payments. Do you have a generation meter fitted between inverter and your mains supply?
Similar musings here to add another system on the E/W garage roof, but would be separate and not connected to the generation meter ony FIT paying setup.
Do you have a generation meter fitted between inverter and your mains supply?
With a smart meter, they can just read your generation on the fly as it measures import and export....
We also have a 'non smart' generation meter.
@sharkbait, you mention a few posts up you get FIT payments. Do you have a generation meter fitted between inverter and your mains supply?
Oh yes. It counts all the 65p's I get (or whatever it is per kWh generated now)
🙂
If I add more PV the panels will feed another inverter (and meter just 'cos) and then connect to the existing PV feed after the generation meter and before the consumer it in the stable.
Okay - partially in response to the above posts about location/capacity, February's figures are in!
5.4kWp array - SSE Facing at an inclination of 30deg. 14x385W panels, no optimisers, little>no shading from late Jan, but some in December, 12kWh battery now expanded to ~19kWh of battery storage.
In February we generated 282kWh of power and used 92% of it. We imported 165kWh from the grid and exported 21kWh to it. This export was largely due to 2-3 sunny days where generation exceeded storage/usage and is one of the reasons I've added the second battery. The battery allowed us to store and use ~190kWh we would otherwise have lost. The array has rarely exceeded 3.4kW of generation.
To compare. December was 140kWh, January was 200kWh, Feb was 280kWh.
That's interesting @daffy and I need to look at those numbers to calculate the addition of another battery module which I suspect will be very helpful. Trouble is they are £2500...
Like many others, I sized our battery on what our average (80-100%) daily usage is/should be. I think this is a mistake. The weather in the UK is rarely consistently sunny, so having more capacity to store on the good days often gets you 1.5>2 days which might just get you through a cloudy day, etc. Also, in winter we tend to use more power as the boiler pumps are running more often laundry is dried inside, we eat more hot meals etc, so average usage might be better planned based on winter usage with a plan to charge the packs off-peak.
I also couldn't afford the second pack at the time of install as it was £4500 (for just the pack!), but managed to get one for £1600 brand new on ebay and fit it myself with the pairing kit from LG. Total cost was £2150 for the battery, RESU plus, cables, tools, ducting, etc for an additional 6.5kWh. Whether it pays off...that's another matter, but I thought it might be worth a shot.
Simialr figures to Daffy here in SE Wales
4.8 KW array on south facing 38 degree roof with no shading
1.1 Kw on south facing 5 degree roof with some shading at this time of year.
Run through 2 MPPT controllers in a Victron system with 14 KW Pylontech LiFePo batteries. Grid tied on ESS settings with export not enabled. Running 2 households and a farm workshop and sheds (which are quiet at present)
February figures are:
Consumption 328 kWh
Solar generation 275 kWh
Imported from Grid 88 kWh
Exported 0
For comparison December gave 111 kWhs and January was 203 kWhs
