Advice on Energy Tariffs

Hi Everyone - a new joiner here!

Some advice please as I am a novice in the solar world!

I have on order 14 x 415w panels and a 9.5 kw battery with a 5 kw inverter (pending DNO approval) which I hope to have installed in July, providing parts are availabe. So a few qusetions if that ok?

Has anyone had a 5kw inverter approved by DNO or is this a long shot? My installer said that this can be restricted if no DNO approval.

How long does it take to switch to a feed in tarrif - should I switch now or wait till panels are installed?

Who are the best providers and what tarrif is best bearing in mind that theer are just 2 people in the household and energy usage is just below average (as we are very frugal with our usage - but will increase as wont have to watch our consumption if generating our own electric.

Thanks in advance

The DNO approval is based on your maximum panel output, rather than the inverter.

To switch to a feed in tariff, you will need: the application from your installer for DNO approval; the DNO approval to install; the notification from your installer of commssioning to the DNO; and your MCS certificate, all of which should be sent to you after the installation. I think that's it!

Make sure your installer knows in advance that you want all of these as a matter of urgency - in fact make it a coinditon of final payment. Once you have paid in full it becomes more difficult to extract them.

As for which tariff is best, can't help you there, I only decided upon the route to go after a few months worth of data to consider myself (I went Octopus Agile Outgoing).

EDF seems to have kept 4.5p for 5 hours between 00:00->05:00 GMT on an EV tariff with their latest costings.

jd Its not so good on gas though, if thats what you use for heating/hot water!

GDP I have a 5Kw inverter that was approved in only a couple of weeks by Weston power. I think the application is based on your inverter size as this defines the maximum export you can generate, the threshold being delivered over 3.6 Kw for the G99 form you are applying for. It would not make sense any other way as an East west facing property would potentially have many more panels to achieve the same output

I doubt it will be a problem to be honest as 3.6 or less does not even need permission before the work starts and 5 is not a great deal more

I think some installers / sales people just don’t like the hassle of the G99 and waiting in case you change your mind. I personally think you’ve made the right choice, far too many upgrading later and increase cost, I’m glad I went for the largest system I could.

I’m now on Octopus outgoing adgile and averaged 20p / kWh for Feb / March which I think is excellent. Incoming I’m just on there standard variable. Octopus took weeks to contact to the meters, so I would apply in advance. To be fair they backdated my export to when I applied for it so all good

GDP Welcome

The DNO approval is for output to the grid. So while they might not approve the full 5kw some your solar plus battery they will allow 3.68kw output. The output can be capped by giv energy so no issue there. I have 1x 5kw Solis and a 6kw solis going in at the end of May. The DNO will be made away of the second inverter but I do not intend to challenge the previous cap decision. I will have 10kw of panels but my output to grid will be capped at 3.68kw.

You will not be able to switch to a SEG tariff until your solar is installed. Depending on what input tariff you have Octopus offer a 7.5p export tariff. If you have an EV and join their Go tariff you outgoing is capped at 4.1p however.

But basically DNO approval should be fine. Just your output to grid might be capped at 3.68kw. Just to be clear that is only the output to grid that is capped, you will still get the full 14x 415w in your home.

GDP
I think the right tariff depends on whether you are an exporter or importer during Late Spring to Early Autumn.

We have 5.4kWp solar and 8.2kWh battery and go from mid April to mid September without importing any electric (except for the minor inverter balancing import) on probably 95% of the days. As a result our import rate isn't the rate that drives our cost/credit. We are therefore on Agile Incoming because of the low standing charge, which on most days is higher than our cost of electric, and Agile Outgoing Variable as we currently receive quite high rates on the Outgoing Variable tariff.

As a result we have received a credit on our last electric bill of around £50.

However if you continue to import during thIs period this strategy is not going to work as the import rate would be the driver of your selection. If you have an EV, then Go is probably the tariff to choose, but I haven't really worked that out as we don't have an EV as yet.

There is no one size fits all for tariff selection, but the good thing about Octopus is there is no charge to move tariffs if you get your initial selection wrong.

Thanks Martyn

Sorry for late reply, I set my account up then forgot the password and was expecting an email notification if I had any replies to my post .

My system was commissioned last week so I am back on the forum! We will see what our usage is and have made a good point regarding the standing charge as we are low energy users as its just the 2 of us so I don't think we will be importing anything during late spring and early autumn either so a tariff with a low standing charge would probably be best for us too. I am gong to contact Octopus soon I see that their name is mentioned a lot when I have been researching .

GDP If you are thinking of switching to Octopus getting a referral code is a good thing to do as they give you a £50 credit (the referrer alao gets £50).

Of course, I would be very happy to provide a code as the £50 would always come in useful 🙂

Thanks for that I will bear that in mind as £50 each will be great!

Hi everyone (sorry for not replying individually but all posts read and noted)

Thank you all and apologies for late reply as I have only just logged on again as my 5.8 PV and 5Kw inverter system is now commissioned.

My installer has registered me/my system as a generator and (verbally) said the DNO application was approved and forwarded me a mail from SSE thanking them for the notification for installation of a 5KW PV system. SSE also confirmed that it has met the requirements of the G98 notification process and I have a MPAN number. I spoke to the installer who said that this confirmation email from SSE covers the DNO application and my registration as a small scale generator connection so I hope that's true .

I think I will be going over to an Octopus tariff but I am going to monitor my usage and generation figures in the coming weeks before I choose a tariff. Will also need to see what its generating v importing on a cloudy day.

GDP I suggest you make your application today. The process involves your DNO creating an export MPAN which they will do (as they have to) as and when they get round to it, but only when requested by a SEG tariff company. Whoever you make your application with will process your application, request the Export MPAN and when that's been received, you then have a 14 day cooling off period. If you wait until you know which tariff works best for you, you may well be delayed weeks waiting for the MPAN from the DNO. Personally, I'd just take a punt with Octopus, or EdF or Eon, or whoever looks OK and kick it all off. This will also indicate to you whether the documents supplied by your installer are acceptable evidence for the tariff.

Thanks Tim - didn't realize it took so long so I had better discuss with the wife and get the ball rolling, we will probably go with Octopus as that's what most people mention on forums etc and is recommended by the electrician that installed the system. I will look at the tariff that charges the lowest standing charge I think

GDP You can take your time over your import/supply tariff choice (or just jump). The comment was about your export tariff which can be with a different energy supplier (or none, just give it away). You already have an import MPAN but it's the export MPAN that you will need to move between SEG Tariffs in the future. Once you have it, changing for export should be as easy as changing for import. Once you have your export MPAN, you can cancel during the cooling off period if you're still not sure, as long as you have your MPAN to give to whoever you go with.

For example, we were fortunate enough to change to the EdF GoElectric tariff before it was withdrawn and we are with Octopus SEG for export. Many people are with Octopus for both. They do seem to be more attuned to PV and EV owners.

I have had import and export MPANs since installing solar PV in 2009. In March this year I had the old mains import/export meter replaced with a smart meter. The import MPAN was registered on the smart meter but they neglected to enter the export MPAN. Took a lot of toing and froing with my energy supplier to get the export MPAN loaded and registered. Eventually after a lot of effort I got it set up so that they could read my export remotely (and continue paying me for it). It is worth ensuring that when a smart meter is installed it has both import and, if applicable, export MPANs loaded into it and not just the import.

GDP .
My understanding is that G98 approval only covers 0 to 3.68 kW single phase (0 to 11.04 kW 3 phase), whereas G99 Type A approval covers 3.68 kW potentially all the way up to 1 MW depending on the capacity of the installed generator.

My recent Western Power DNO response letter confirms my planned installation to have a 5kW hybrid inverter with G99 approval, so I assume I could export up to the full 5 kW single phase.

The GE inverters can be programmed by the installer to limit your export value to whatever the DNO approval states.

Thanks for the advice I will remember that - it seems there is a lot of stuff I dont know yet .

Simon_C

Hi - I wa not aware of G98 and G99 differences till you pointed it out. I mentioned this in a mail to my installer and also queried wether the DNO application for 5kw inverter was submitted and approved - they say that it has been approved and everything is as it should be fo for my system. I have just sent an email to SSE about that so I hope they will confirm this. Maybe the fact have a 9.5kw battery has a bearing on the approval?

With the GE 5 kW hybrid inverter, the maximum a/c output power in to your household is 5 kW, regardless of what proportion is coming from the solar PV and what from the battery.

The inverter then has an EM115 electric meter that monitors the household grid feed and reports the live import or export power as well as accumulated energy over time.

If your DNO has limited your maximum export power to 3.68 kW (16 Amps at 230 Vac) then your inverter could be outputting at 5 kW, but if your household consumption at the time is 1.4 kW, then the grid export will be 3.6 kW which is within the allowed limit.
If your household consumption then drops off to say 0.4 kW, then the inverter will automatically back off its output to maintain the limit of 3.68 kW export, so the inverter output would be (3.68 + 0.4) = 4.08 kW.

The inverter response time is a few seconds, so as your solar PV output or household consumption changes there can be brief periods above the limit which is allowed.

The normal configuration for the inverter is 'ECO' mode where it attempts to maintain the grid import/export at 0 kW, which it can do until the battery is fully charged from the solar PV. Any further solar PV generation that is in excess of your household consumption will have to be exported as there is nowhere else for it to go.

Simon_C so I assume I could export up to the full 5 kW single phase

Might be worth clarifying. We have two HY5 which our DNO approved but we are limited to 3.68kW. The installers "forgot" this and I had to ask Givenergy to change the export limit to suit.

Simon_C GE 5 kW hybrid inverter, the maximum a/c output power in to your household is 5 kW

This is so, but the inverter itself, given sufficient PV, can handle 5kWac + 2.5/3.6kW DC (Gen1/Gen2) to battery concurrently.

Thanks for that. Hopefully SSE will get back to me and confirm but it sounds likely that DNO may have restricted my output to the grid to 3.6 kw - hence the G98 approval

wilfleek Wrong!!! DNO approval is base on ac output from you inverter.
G98 is for approval up to 3.68kw and can be done after your instalation. It's 100 guarantee it will accepted. If you inverter is over 3.68 kw AC output then G99 must be applied and your instalation must be on hold till application will be approved. In most cases its OK.

Tim .

My recent Western Power DNO response letter confirms my planned installation to have a 5kW hybrid inverter with G99 approval, so I assume I could export up to the full 5 kW single phase.

My DNO letter confirms the inverter rating at 5 kW AND G99 approval, hence my assumption as it does not specifically state what the maximum allowed export is.

You may have 2 x 5kW inverters, but if you only got a G98 approval for them then you are limited to the maximum of 3.68 kW export.

Simon_C No with >3.68kW inverter capacity, we had to apply for G99. We paid for a G99 survey which came back about ten days later and they said we could export as much as we liked up to 3.68kW. The DNO letter quotes: "Maximum Export Capacity 3.68KW" and plant capacity at 10kW with battery storage. I was suggesting that it might be helpful if your DNO was explicit about your export capacity rather than you assuming. Hopefully it is the 5kW rather than 3.68kW. :

Tim , but did your reply letter state your installation had to comply with G98 even though you applied for G99?

Here is the main content of my letter, forwarded via my installer.

WPD Generator Response Letter
Please retain this letter – The electricity supplier may require proof
of our approval to connect the generation unit to our distribution system

Dear Installer

5kW PV Installation with Battery Storage at:-

Installation - Full address

(MPAN No. 1100018xxxxxx)

Thank you for providing an Application for Connection Form requesting permission to connect
generation in parallel with our distribution system at the above location.
The generation unit/s may be connected and remain connected to WPD’s distribution system subject
to the following:-

1. Providing it complies with the requirements of The Electricity Safety, Quality and Continuity
   Regulations 2002 (as amended from time to time).

2. Providing it complies with the requirements of National Engineering Recommendations G99:
   ‘Recommendations for the Connection of Generating Plant to the Distribution Systems of
   Licensed Distribution Network Operators’ (ERG99) and G100: ‘Technical Requirements for
   Customer Export Limiting Schemes’ as amended from time to time
   Please note: over and under voltage protection settings should be based on 230V

3. This agreement to connect the generation unit/s is only valid for 90 days from the date of this
   letter. If you do not provide confirmation that the installation of the generation unit/s is
   proceeding, WPD may release the export capacity to other customers and you will need to
   re-apply for permission to connect generation at this location. This action could result in the
   customer having to fund some or further reinforcement in order for WPD to accept the
   connection of the generation unit/s.
   We have examined the information submitted and concluded that WPD’s Engineer is not required to
   witness protection testing and the first synchronizing run of the generator.
   Please note once the generation unit is installed and commissioned the protection settings shall only
   be altered following written agreement between us.
   If WPD receive a separate application for a connection which makes use of the same part of our
   Distribution System as the Customer’s Installation(s) and, due to network constraints and the amount
   of capacity available on the Distribution System, WPD determines that it cannot accommodate the
   Customer’s Installation(s) without a material impact on the terms of the connection offers made
   (including, for example, an increase in the Connection Charge to account for additional reinforcement
   works) this Connection Offer may become "Interactive" and acceptance of your Connection Offer may
   become conditional upon other customers with interactive connection offers not accepting their
   connection offers first.
   If this Connection Offer becomes interactive WPD will notify you in writing and will provide details of
   the process for accepting your interactive connection offer. Further information in relation to
   interactivity is set out in WPD's Statement of Methodology and Charges for Connection, which is
   available from WPD's website www.westernpower.co.uk.
   The customer should discuss with their electricity supplier whether they wish to purchase any
   electricity which is surplus to the customer’s own requirements and agree the necessary
   arrangements for the metering. The supplier must ensure the import meter is of a type that will not
   subtract the number of units exported.
   In the event the generation unit is de-commissioned and will no longer operate as a source of
   electrical energy in parallel with our distribution system the customer must notify us in writing.
   Yours sincerely,

Simon_C I think this is above my pay grade and I don't work any more! I was just saying that assuming something is different from knowing. Should we just chill in this marvellous sunshine?

WELL - I put my trust in the installer (who havent been brilliant regarding communication). They initially said that they were going to apply for the 5kw inverter system and said its been appoved and forwarded me a mail (which states 5Kw PV)from SSE as follows:

Good morning

Generation Connection at MPAN 20000xxxxxxxxxxx At.........................

Thank you for your recent notification regarding the installation of 5 kW PV.

I have reviewed the documents you have provided, and I am pleased to confirm that the information you have provided for the installation of new Integrated Micro Generation and battery storage System meet the requirements of the G98 notification process. Our records have been updated to reflect this. If you require any changes to your electricity meter or electricity tariff as a result of installing this new equipment, please contact your electricity supplier to request this.

Please forward this email to your client which can be used to notify their supplier of this installation

So I assume that my installer may have just applied for the G98 and not the G99 but no point asking them as I dont have alot of confidence in them ? I have emailed the person at SSE about this but no reply as yet.

Tim . Understood, and in need of a cold drink.

Just trying to understand what happens when a G99 application is submitted but the DNO insist on limiting to a maximum of 3.68 kW export.

Does the DNO respond with:-
1/ A G99 approval, but with a stated limit of 3.86 kW.
2/ A G98 approval, which by definition is limited to 3.68 kW.

May be someone else has had experience of this.

Simon_C See graphic.

This is from a presentation which I presume was put online when G98 and G99 came in. Elsewhere in the presentation it shows that Type A is from 800W to 1MW, so all the Givenergy inverters. One of the G99 technical changes from the previous standard was to have a logic interface to allow DNO to constrain output. It looks to me that if your inverter is capable of more then 16A output, the appropriate application should be G99. The DNO then decides whether to limit or not.

From what my installer said, with a 5kW inverter, if you volunteer to limit output to 3.68kW, it can go on a fast track G99 process but if you would like a greater output (as we asked for), you need to submit a full application and await the outcome of their survey (which limited us to 3.68kW anyway).

Does anyone else know the definitive answer? We are making assumptions here.