Jinglish

Snap, and with IOG you can "charge" your car during peak times at 7p and everything else is at that rate. Strangely my car always needs charging at dinner time, washing time and hot water time

With the age of your property IMO you are limited with what you can do given your goal is to reduce your overall heating bill with the potential of being off grid. You could spend a fortune retro fitting insulation, windows etc. with almost no return in your lifetime. I'm all up for saving energy but some properties are just not fit for this purpose. As attractive as a GSHP or ASHP sounds your property don't have the fundamentals in place to support it. I think you will need to look at each measure independently and chart up a cost vs saving vs timeline in a table. 280mm loft insulation if you don't have is probably the lowest hanging fruit. Your biggest heat loss will be from your walls and I don't think there is any sense here in trying to mitigate your single skin without major cost and compromises. If you do overhaul your heating system then I suppose the main choice would be radiator feed by OIL/LPG/Bio Mass OR go for electric all round traditional or even infrared based. If going with electric then you can work out if Solar can offset your usage. Either way your choices are expensive and as said earlier doubt you will ever see a return. Have you tried what grants maybe available? https://ukem.co.uk/ (You be surprised what you can get if you call, ignore the benefits your house should be very low EPC so would likely qualify)

@Tom Maybe you got your wires crossed (no pun intended) or we are taking about the same. Your smart meter is your export meter also. So from the grid it should go… Grid > DNO fuse > Smart Meter > Main Fuse box > generator meter > Inverter > PV Array The CT clamp i’m referring to sits between the smart meter and the main fuse box. The generator meter should measure the output of your inverter before it’s consumed by your dwelling load. The CT clamp will measure surplus feed back to the grid and your export meter will tally up with that so your supplier can pay you accordingly. Your wiring maybe different i.e. your Inverter goes directly to smart meter via Henley block instead of through the main fuse box but this still yields the same result

@joe90 Good point so ASHP gets tank to say 55C but need immersion to kill the Legionella at 65C+ @Tom The CT clamp should be fitted before the export meter so it knows how much to divert and when.

Shoot me down here but... Don't you get paid more to export the surplus than you would if you used it via an inefficient immersion heater? Why wouldn't you use the excess solar to make the heat pump heat the hot water which is much more efficient?

What is your primary motive? Is it.. >ROI (Return of investment) >Go "green" no matter what it costs >Live off grid Depending on what you prioritise would help factor the choice of renewables.

Fox do a triple MPPT invertor I would consider this... https://theecosupermarket.co.uk/product/fox-k-series-7-0kw-hybrid-inverter-kh7/ It is on the DNA register so could be applied for via G99 "fast track" which should be very quick to get DNO approval (7.36kW is the limit for fast track) Polar brand doesn't appear to be listed on the DNA so either of your options you might have to jump through a lot of loop with a G99 "standard" application. Strongly consider the payback for 5 x 5.2kWh batteries. IMO V2G or V2H is a only a few years away of becoming more mainstream which will almost supersede the need for house batteries.

Just out of interest when your installer did the G99 application was it the SGI-3 fast track? Since your inverter is registered as "Compliant" this should have been the route taken. If you go down the G98 route then you're only loosing out on 1.32kW during peak generation. I suggest you model this up in something like OpenSolar which can give you a good indication of cost vs reward but in any event sounds like this is the only sensible route forward. Keep up posted and good luck!

My understanding of the above is as follows... >Part P (Electrical) just means that you/your installer follows the regulation set out in this document: https://assets.publishing.service.gov.uk/media/5a802da7ed915d74e622ceed/BR_PDF_AD_P_2013.pdf >Part P certification can only be issued by either "registered competent person" or "registered third-party certifier" or "building control body" If you want to do the work yourself then it is notifiable to BC therefore...To get a BC certificate (which covers Part P) your install would need to meet Part P and any another other Parts requested by BC You do not need to be qualified or registered you just need to be "competent" and sign to say you are via a BS 7671 certificate (you can buy these and sign yourself) to BC https://www.expresselectrical.net/electrical-installation-certificate I have done this myself for other electrical work e.g. minor works and BC don't have a problem.

To help others expand their system themselves it was very easy. If you hunt around on selling sites you can grab unbelievable bargains I got the following all brand new (except panels) Solax G4 boost 3.6kW invertor £200 BYD 10 x S/H 410W panels £150 Clenergy rails, hooks, clamps, screws etc.. £234 Electrical Cabelling, isolators, fusebox, MC4, ducting etc... £217 TOTAL £801 I used free OpenSolar software to do the design and SLD which was approved by National Grid via G99-SGI3 (aka fast track) process. This expansion adds another 4.1kW peak (estimated 2,617kwh per year) to the existing 4.1kW bringing me to a total of 8.2kW peak but clipped to 7.36kW (estimated 5289kW per year) Octopus have no need to be told I have expanded, I'm already on their outgoing plan (15p) + intelligent go from the original system's MCS. Going by the OpenSolar calculation this predicts a payback of the £801 in around 1.5-2 years

So I’ve gone full circle. I’ve decided to keep the second 3.6kw Solax and install it in the garage. 9 x 410W panels will fit on the West facing roof. Giving me the option in the future to fit another 9 on the East facing roof to max that inverter out throughout the whole day. The existing Solax in the main dwelling with 10 East facing panels can be expanded with an additional 3-4 South facing panels in the future. So for now I will have 19 panels with scope to expand to 32 panels split across 2 inverters across different directions. I’ve applied for G99 fast track and supplied the SLD so just awaiting approval before I fit.

Thanks for sanity checking, I didn’t think about counting the cells. Looks like I’ve narrowed it down and based on what I’ve tested I believe they are the 410W versions. But either way I think I got enough info to plan the string and inverter I want to use with them.

So I moved one of these panels to face the same direction as my existing array of 10 x 410W which currently reads 2.93kW from the Solax app / 10 so 293W each (underload) This unknown panel reads 46.7V & 9.23A but NOT underload so 431W I was told drop it by 25% to get the underload wattage so 323W. Since my existing setup of 293W is 1.4 times away from its maximum of 410W if I apply the same 1.4 multiplier to this panel that makes it 450W. (323 x 1.4) I know these are rough calculations but at least I’m in the ball park of the output it generates?

Arr that seems to make sense, I was told they were imported from Morocco. I think the stickers were intentionally removed. I did find evidence of a faded impression on one that seems to read BYD but they do a few variations it could be so i’ll do some electrical testing later

I got as far as this… but no datasheet yet https://www.htc-lb.com

Can anyone help identify my panels there are no markings other than numbers on the side and front? They are 1m x 2m and 40mm deep Spits out around 50V dc on a cloudy day.

So my inverter details are on the left, min voltage is 40V My new expanded is 10 stringed array in series to creates the left Vmp (Optimal Operating Voltage) against worst case ambient temperature of 30.8C gives me 287V Current in series is approx. 10.5A Typical 4mm2 cable is 0.005ohmes per m so with a cable run of 40m (round trip of 80m) I make it a 3.57v drop if I upgrade to 6mm2 (0.003ohms/m) this reduces to 2.38v using this caculator: https://midsummerenergy.co.uk/voltage-drop-calculator What is an acceptable voltage drop? (I guess green text is good and orange text is border line) Appears to be 3% as previously suggested So again thanks all for the help 6mm2 seems to be the way forward as I'm likely less than 40m anyway probably more towards 30m

Thank you for your advice; on reflection and crunching some numbers I’m going to wire in the extra 10 panels to the unused second MPPT on my existing 3.68kW inverter (it can handle the over sizing) All i need to do is run two 4mm MC4 cables from the garage to the main dwelling approx 40m. The overlap area is not worth chasing for the extra cost and headache. Reckon I can do this for less than £500!!.

Thanks. That was the who point in this post to take caution and ask others. How would they know if I did a non-MCS expansion? Did you tell them or did they discover yours? The likely hood of me generating over 3.68kw which isn’t self-consumed is probably quite low. This is due to Solar iboost and possibly my EV. I guess worst case is I can fit a form of limit of 3.68kw back to the grid so I wouldn’t benefit selling back at 15p over 3.68kw but gives me self consumption headroom up to 7.36kW. Yes correct about the red clipping, this was just a quick mock up in paint. I’ll run it through the MGD 003 when I get more time but your feedback is noted.

You make sound points. Just to double check your suggestion I expanded my new proposed array from 8 to 10 panels (as I can actually fit 10). Took a clearer day, and inverted the current SE profile to roughly represent the proposed SW roof; overlayed them which yields the graph below. The overlap area in red would exceed the 3.68kW rating which you can see is a significant area to miss out on. I know this is under optimal conditions which is a lower occurrence rate in the UK but I managed to get a new same model inverter for £200. Looking at S/H panels I found 10 x 400W for £200 then brackets and fitting/wiring myself will cost about another £300. So looking at £700 total to expand up to the SGI-3 limit. I have a solar iboost which will heat the hot water for surplus generation before selling it to the grid for 15p I’ll put all this into OpenSolar software and see what that yields. I don’t have a battery as I think in a few years time V2G will become more mainstream. I’ve got an EV but using Intelligent Go until bidirectional chargers support CCS2 and the motor industry allows this use. Basically I wouldn’t see a return in a house battery by the time V2G is mainstream.

I get what you’re saying however the current inverter nearly maxes out close to 3.6kW at noonish with the 10 panels I have so adding more would clip my generation at the overlap. Plus the other facing roof is actually on a detached garage so wiring would be very difficult and cost more to use the same inverter even if i replaced it with a larger capacity and two MPPTs.

Thanks that’s what my plan was, notify DNO but not Octopus. What information do I need to provide once the G-99 SGI-3 work is completed?

Fast track it is then 😉

That’s what I thought. But do I do a G99 fast track or keep quiet from DNO also?

Hello, I’ve just had 10 x 410W panels fitted to my SE facing roof. I’ve got a Solax Boost G4 3.68kW inverter and this has been professionally installed with MCS certificate and G98 DNO. I’m on Octopus outgoing. I want to expand my system by fitting a further 8 panels to another SolaxBoost G4 3.68kw on a SW facing roof so that we have generation throughout the whole day rather than mostly in the mornings. However I want to fit this expansion myself…. So my questions are: 1) Since both devices qualify for G99 fast track I can do the DNO myself but do I need to provide an MCS certificate afterwards? 2) If the answer to Q1 is no then since I’m already exporting to Octopus then I don’t feel that I need another MCS or to tell them i’ve expanded. I mean how would they know? Even if I go over 3.68kW the DNO is happy so who cares? J