Posted by: @blizzardgreen

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3. Standalone Off-Grid / EPS Mode:
The unit can be plugged into a wall socket solely for AC grid charging, using its dedicated off-grid EPS sockets to directly power isolated appliances without any back-feed into the home wiring.

Forgive me if I'm getting this wrong but it's all new.

As I understand it this is true, but (3) is an alternative mode of operation (eg for camping) not the unique mode of operation

Put simply (to my understanding)

• it has both a plug (*male connector) and a socket (female connector).  You plug the plug into a socket on your house wiring.  It also has separate DC connections for directly connected solar panels.
• it can charge at up to 3kW though the plug from the mains and/or through directly connected solar panels which plug into the DC connections.  If you already have solar connected to your house circuitry via an inverter, it sees this as 'mains'
• it can discharge at up to 800W (through the same plug as it uses to charge), but only if the grid is connected.
• it can discharge at up to 3kW (provided you have an expansion battery) through a dedicated socket on the back.  Without an expansion battery the max discharge rate through the socket on the back is less.  This can occur whether or not the grid is connected.  If the grid is connected the discharge can (but does not have to) occur simultaneously with 'charging', so it acts as a 'pass through'.
• there are several options to control whether it charges or discharges at any point in time, including responding to some ToU tarrifs

Does that help, @indevolt-tech may be able to clarify further

What I am unclear about is how it determines the energy flowing to/from the grid (which I think it needs to know in some control modes) as it appears not to have a CT clamp.  I think this may be through a linked Shelley device but this is unclear from the website nor, is it clear which Shelley or other devices can be used (and in particular whether the most common Shelly-EM qualifies).  Nor is it clear whether the device has to be dedicated to the Indevolt or can also be polled by other systems (eg Home Assistant).  @indevolt-tech please can you clarify this matter.

Posted by: @jamespa

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Posted by: @blizzardgreen

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3. Standalone Off-Grid / EPS Mode:
The unit can be plugged into a wall socket solely for AC grid charging, using its dedicated off-grid EPS sockets to directly power isolated appliances without any back-feed into the home wiring.

Forgive me if I'm getting this wrong but it's all new.

As I understand it this is true, but (3) is an alternative mode of operation (eg for camping) not the unique mode of operation

Put simply (to my understanding)

 

• it has both a plug (*male connector) and a socket (female connector).  You plug the plug into a socket on your house wiring.  It also has separate DC connections for directly connected solar panels.
• it can charge at up to 3kW though the plug from the mains and/or through directly connected solar panels which plug into the DC connections.  If you already have solar connected to your house circuitry via an inverter, it sees this as 'mains'
• it can discharge at up to 800W (through the same plug as it uses to charge), but only if the grid is connected.
• it can discharge at up to 3kW (provided you have an expansion battery) through a dedicated socket on the back.  Without an expansion battery the max discharge rate through the socket on the back is less.  This can occur whether or not the grid is connected.  If the grid is connected the discharge can (but does not have to) occur simultaneously with 'charging', so it acts as a 'pass through'.
• there are several options to control whether it charges or discharges at any point in time, including responding to some ToU tarrifs

Does that help, @indevolt-tech may be able to clarify further

What I am unclear about is how it determines the energy flowing to/from the grid (which I think it needs to know in some control modes) as it appears not to have a CT clamp.  I think this may be through a linked Shelley device but this is unclear from the website nor, is it clear which Shelley or other devices can be used (and in particular whether the most common Shelly-EM qualifies).  Nor is it clear whether the device has to be dedicated to the Indevolt or can also be polled by other systems (eg Home Assistant).  @indevolt-tech please can you clarify this matter.

It comes supplied with an indevolt smart meter and CT clamp.

But I think according to Aug 26 regs you are not permitted to export from a battery.

Posted by: @blizzardgreen

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It comes supplied with an indevolt smart meter and CT clamp.

 

Oh, I didn't spot that anywhere in the manual!

Posted by: @jamespa

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Posted by: @blizzardgreen

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It comes supplied with an indevolt smart meter and CT clamp.

 

Oh, I didn't spot that anywhere in the manual!

It's on the offer page preselected

Posted by: @blizzardgreen

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Posted by: @jamespa

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Posted by: @blizzardgreen

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It comes supplied with an indevolt smart meter and CT clamp.

 

Oh, I didn't spot that anywhere in the manual!

It's on the offer page preselected

 

The smart meter looks like a DIN module, designed to fit in a CU.  If so its hardly compatible with the idea of 'plug in'.  So unless you can throw that away and use the CT clamp stand alone (plugging into what - the manual doesnt show a CT connection on the back?) then something is 'missing'.  @indevolt-tech please clarify!

Posted by: @blizzardgreen

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But I think according to Aug 26 regs you are not permitted to export from a battery.

 

that's correct as set out above.  The interim product spec issued by the Govt expressly excludes batteries.  However its a fair (I would say almost certain) bet that the final spec (for which we don't yet have a confirmed timescale) will include them given that the major hurdle namely established industry objections to the very concept of plug in (based IMHO on pure self-interest) has now been firmly overruled!

Posted by: @editor

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Thinking about this, at the point where electricity enters the household circuit, I struggle to see a meaningful distinction between 800W arriving directly from a solar inverter and 800W arriving from a battery inverter. In either case, it is approximately 3.5A flowing into the same socket circuit. The cable, socket, consumer unit and local network do not know whether those electrons came straight from a PV panel or were stored in a battery for several hours first.

They could, and should have allowed storage on the DC side, say upto 5kWh to start with, but then we wouldn't be feeding free power back into the grid and energy companies will loose a chunk of their profits. 

Posted by: @dansus

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Posted by: @editor

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Thinking about this, at the point where electricity enters the household circuit, I struggle to see a meaningful distinction between 800W arriving directly from a solar inverter and 800W arriving from a battery inverter. In either case, it is approximately 3.5A flowing into the same socket circuit. The cable, socket, consumer unit and local network do not know whether those electrons came straight from a PV panel or were stored in a battery for several hours first.

They could, and should have allowed storage on the DC side, say upto 5kWh to start with, but then we wouldn't be feeding free power back into the grid and energy companies will loose a chunk of their profits. 

 

They have done exactly the right thing because they could not have permitted (at this stage) what you suggest without further delaying plug in solar, and there is are very good tactical and strategic reasons not to delay plug in solar any more than is absolutely necessary.   Don't blame the government for this situation, blame the established installation industry (MCS, IET etc), which has tried its very best to prevent any plug in from being allowed, all it would seem out of pure self-interest.

If you look back through the history (or indeed this thread) you will see that the Government have taken a very sensible pragmatic approach to getting the concept of 'plug-in' over the line in the face of the objection s raised by the installation industry.  This was (a) to announce it was going to happen (b) to commission a report to prove that the industry 'safety concerns' are largely trumped up and can realistically be dealt with (c) to permit the quickest and easiest thing to permit, which at the same time has the effect of overruling the key industry objections, thus paving the way to expand the range of permitted products to batteries, whilst at the same time effectively dismissing the industry's self-interested representations as soon as realistically possible.  Had the Government not followed this course not even plug in solar would become legal by August 27th, the way would not have been paved to expand the range of permitted products to batteries, and the industry would have continued its battle to prevent it from ever happening.

This is a clear case where the Government has done the most sensible thing in the circumstances, with a clear short and long term objective and despite the self-interested representations from the industry.  The Government is to be congratulated, the installation industry should hang its head in shame for putting forward largely unsubstantiated objections which have forced the Government through this process and thus delayed the introduction of technology which has been available in continental europe for some while.  

Posted by: @jamespa

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Posted by: @old_scientist

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I think that's the issue with 'plug-in' batteries ...  inverter ratings up to 800W, which is of limited use in a battery product or appears woefully under-specified, at least in today's EPS type battery systems.

I profoundly disagree, but it is of course use case dependent. 

A plug in limited to 800W output (with, in this case, a 3kW inverter), provided it supports 2-3kW charging (input) is very useful, at least for me (see below what kit I have).  I intend buying 10kWh or thereabouts as soon as its legal.   Charge to 10kWh at cheap rate (6 hrs currently), discharge (during the heating season) at 800W when I would otherwise pay peak rate (currently 18 hrs), result = 10kWh at cheap rate that would otherwise be at peak rate. 

That's not what I said (or at least what I meant). I said 'plug-in' batteries [with] inverter ratings up to 800W. It is not clear if the government would hard limit it to an 800W inverter (not a 3kW inverter software limited to 800W output at the plug) or would take a more flexible approach an Indevolt do with their example herein.

I suspect the government (or rather the DNO) will want to limit it to 800W inverter rating (same as plug-in solar) as software limitations are all too easy for the end user to override. If you have a product like the Indevolt which is designed to be capable of both G98 hard wired installation by an electrician and 'plug-in' operation with software limitation should that ever be approved, then inherently there is the possibility an end user can change (increase) the inverter output in software (or by firmware update) even though they are operating it as a plug-in device.

I hope I'm wrong. We will see if the government decide to carry out a consultation and carry it forward.

Posted by: @dansus

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Posted by: @editor

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Thinking about this, at the point where electricity enters the household circuit, I struggle to see a meaningful distinction between 800W arriving directly from a solar inverter and 800W arriving from a battery inverter. In either case, it is approximately 3.5A flowing into the same socket circuit. The cable, socket, consumer unit and local network do not know whether those electrons came straight from a PV panel or were stored in a battery for several hours first.

They could, and should have allowed storage on the DC side, say upto 5kWh to start with, but then we wouldn't be feeding free power back into the grid and energy companies will loose a chunk of their profits. 

It looks like the updated G98 regulations for Plug-in Solar come with a new B2 Form for the specific purposes of notifying the DNO about your 'plug-in' solar post installation (plugging it into the wall) which would then allow you to register for export with your electricity provider. They cannot hold out on an MCS certificate as it's a plug-in device that requires no installation, so only the G98 notification is required.

Hopefully they may even include the B2 form in the box together with a note that it is mandatory to fill it in and notify the DNO of your purchase.

I see nothing in the legislation or regulations specifically prohibiting export or SEG payments for said export.

Posted by: @old_scientist

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I suspect the government (or rather the DNO) will want to limit it to 800W inverter rating (same as plug-in solar)

It hasn't , at least so far as I can see, limited the plug in solar inverter to 800W.  It has limited the export 'at the point of connection to the fixed electrical installation' to 800W and the maximum connected PV to 2kWp.  I cant find in the spec limit on inverter capacity.  Furthermore this is per circuit, so if you have two rings you can have 1.6kWE in total, albeit that this requires a G99 application at present I believe.  

I don't think that there is any prospect at all that the 800W export figure will change, because it is EU-wide (we may not be a member, but we are on the same grid and use pretty much the same regs).  That does not prevent the inverter from being able to charge at a higher rate or to discharge at a higher rate to a socket that is not grid connected.  In fact plug-in equipment that discharges to one or more sockets that are not grid connected at a higher rate than 800W (and thus must include an inverter with a capacity >800W) already exists - its called a UPS (see eg this, but there are many)

The 800W limit on export could be a hard limit on an inverter capable of charging at a faster rate, it does not have to be a software-configurable parameter.

I can see no reason that the UK Government would want to do anything other than what the EU has done, ie allow the type of flexibility that the Indevolt equipment has.  Unless of course the installation industry comes forward with even more trumped up reasons to prevent progress in order to protect their lucrative monopoly and the Government is unable to overcome them in much the same way it has done with plug in solar.

Posted by: @jamespa

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Posted by: @old_scientist

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I suspect the government (or rather the DNO) will want to limit it to 800W inverter rating (same as plug-in solar)

It hasn't , at least so far as I can see, limited the plug in solar inverter to 800W.  It has limited the export 'at the point of connection to the fixed electrical installation' to 800W and the maximum connected PV to 2kWp.  I cant find in the spec limit on inverter capacity.  Furthermore this is per circuit, so if you have two rings you can have 1.6kWE in total, albeit that this requires a G99 application at present I believe.  

I don't think that there is any prospect at all that the 800W export figure will change, because it is EU-wide (we may not be a member, but we are on the same grid and use pretty much the same regs).  That does not prevent the inverter from being able to charge at a higher rate or to discharge at a higher rate to a socket that is not grid connected.  In fact plug-in equipment that both charges from the mains and discharges to one or more sockets that are not grid connected, in both cases at a higher rate than 800W, already exists - its called a UPS!

The 800W limit on export could be a hard limit on an inverter capable of charging at a faster rate, it does not have to be a software-configurable parameter.

I can see no reason that the UK Government would want to do anything other than what the EU has done, ie allow the type of flexibility that the Indevolt equipment has.  Unless of course the installation industry comes forward with even more trumped up reasons to prevent progress in order to protect their lucrative monopoly and the Government is unable to overcome them in much the same way it has done with plug in solar.

That's not how I read the interim product specification published this month:

See section 4.1 Power and Current Limitation which states maximum apparent power of 800 VA, and 5.3 specifies that EMC testing shall be conducted at the maximum power that the inverter is capable of delivering (Smax <= 800 VA). If the inverter is capable of delivering more than 800 VA and is then restricted to 800 VA for the UK market, it is not compliant.

Same with the legislation signed into law:

https://www.legislation.gov.uk/uksi/2026/848/made

(b) has a maximum rated alternating current output not exceeding 800 watts;

@old_scientist 

4.1 says this

Plug-in solar devices shall be designed such that the maximum apparent power Smax supplied
to the mains installation does not exceed 800 VA and the maximum current does not exceed
3.5 A.

That specifies the maximum supplied to the mains installation.  Furthermore it defines the term Smax as being the maximum power supplied to the mains installation.  The term Smax is subsequently used in 5.3 to define the test condition.

This does, as I read it, prohibit an inverter from being hardware capable of more so long as the limit is somehow applied at the point of connection to the mains installation.

I haven't yet worked out whether or not a unit with an auxiliary output socket is permitted by the interim spec, but there wouldn't be much point at this point given that the spec is expressly solar only.

Posted by: @old_scientist

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If the inverter is capable of delivering more than 800 VA and is then restricted to 800 VA for the UK market, it is not compliant.

by which clause (although the use case is unlikely to occur given that the EU has exactly the same 800W limit, and in practice the units are built for the EU market not for the UK only market) 

The legislation says 'rated'.  Nothing so far as I know stopping a manufacturer forcing a hard rating limit in hardware, software (provided it isn't user configurable) or firmware.  In fact that is, so far as I am aware, common practice and who would anyway want to buy (or design) a product that is operating just at its 'burn-out' limit?