Sheesh... you really want me to go deeper into the technicalities?!

There is a European-wide specification Requirement for Generators (RfG)

It applies across Europe because we share access to the grid operating at 50Hz.
(Ignore voltages; it's only the frequency component which underpins network stability)

Our EREC G98, G99 and G100 regulations are based on that RfG.

We may not make requirements that are less stringent than RfG, but there are situations where we might need to have a tighter specification.
The Balcony Solar kits come into those variations between G98 and the RfG.

1: Let's note that there's little to prevent a flat owner installing more than one Balcony Kit.
They won't 'know' about each other because there's no mechanism to hand-shake between them.

A qualified installer would know that such an arrangement requires a G99 Application to the DNO.
But a householder is unlikely to understand that regulation or why it exists.

2: EREC G98 is an Annex 1 Document of the Distribution Code and therefore the document is afforded legal weight.

An installation that does not comply with the prescribed requirements of G98 may be disconnected by the DNO due to concerns of interference / safety.

The installation would also have to comply in full with BS EN 7671 (the Wiring Regulations).
Only qualified electricians may work on installations that fall within the scope of the Wiring Regulations.

3: When a device exports to the grid, it does so by raising the voltage.
That causes current to flow from the device, and towards the grid.

In the UK, the grid voltage limits are defined by an Act of Parliament: The Electricity Safety, Quality and Continuity Regulations 2002

Section 27 states:

27.3b defines the single-phase domestic supply to be between 216 - 253v AC.

If a Generation Device senses that the grid voltage falls outside of that range, then it must cease generating (remove itself from the grid).
It may not reconnect until it detects that the mains voltage has fallen back within the supply envelope.

Even then there must be a random delay (typically 1 minute) before it attempts to export again.

Unless the Device has been tested for G98 compliance, then no one knows whether it will correctly perform that voltage stabilisation requirement.

That leaves open the possibility that an engineer working at a local substation could still be electrocuted after it has been isolated from the 11kV supply.

4: All generation devices, especially those which create the 50Hz sine-wave using electronics, will also create harmonics of 50Hz and radio-frequency interference (RFI).

This is much less of an issue for turbines which synchronise to 50Hz using mechanical rotation.

Any device seeking G98 approval must be tested to ensure:

• that the RFI falls below a stated threshold
• that the voltage stabilisation/detection circuitry will still safely disconnect the device from the grid, even if there is RFI and harmonics present

5: Rooftop solar panels cannot be touched by hand whilst in normal operation.

For that reason, most installations 'float' and are not tied to earth.

However, the inverter to which they are connected must still provide adequate surge-protection which is measured with respect to Earth.

A Balcony-mounted (or ground-mounted) solar array can be touched.
The (micro-)inverter itself must be earthed on its mains output,
but it must also provide an earth for the metal casing, the aluminium frame of the panels, and any metal comprising the balcony rail.

The quality of the earth path must be such that a fault-current causes the safety-trip/RCBO to open the contacts within the specified time-frame.

That's an additional problem if the same earth is being used by surge-suppression devices.

G98 testing will check to ensure that the trip opens fast enough when a pre-defined fault current passes through the earthed metalwork.

Since these Balcony Solar kits are not G98 certified, it is unknown whether they will 'fail safe' under the relevant fault conditions.

Is that adequate and detailed enough?

Or do you want me to add more?

@transparent So much drama...  😂

They are not for exporting to the grid. And I have just been told this: 

"They must be hardwired by an electrician (not plugged in to a 3 pin socket)  and the DNO must be notified. They are not usually a problem."

So not quite plug-and-play in the UK but still not complicated for property owners. 

"To get paid for exporting you need an MCS-certified installation which certainly won't be worth it for a small system. And is not what they are designed for anyway." 

-0-

So it certainly is a far cheaper way to have a small battery and solar system but until they have a different way of connecting they will not be able to be used by tenants in the UK.

It is far cheaper to pay an electrician for small scale balcony or garage roof solar & battery system than pay an installer for a full-scale MCS-registered roof system

It really is that simple it turns out.

This was what I needed to know. I guess to be renewables solution for tenants someone needs to invent a different connection system. 

@lucia I suppose ‘A different connection system’ could be based around a small battery (2-4 kWh’s ish) that is charged from the balcony panels and has one or two domestic appliances plugged into it. Maybe a refrigerator and / or other low demand circuit and when there is insufficient power left in the battery, the grid is used to charge it up to a ‘top-up’ level to tide the appliance demand over until some solar energy comes along. Regards, Toodles.

@toodles But the inverter still needs to be hard wired in. That's the electrical connection that makes it impossible for the tenants of rental properties which is the fabulous gap in the renewables tech market that they plug (sorry 🔌😁) in mainland Europe. 

The early starters with these systems have had European Investment Bank support for exactly this reason. The EU has been pushing for renewables developments for the rental sector for a while whereas Britain mostly ignores it. 

But hopefully, someone will get their thinking cap on. 🤞🏻

@lucia There are ‘stand alone’ units such as those used for camping etc. I think the likes of Ecoflow make units that can also plug into the mains to charge the battery - but I may be wrong as I have not researched this at all! Regards, Toodles.

Posted by: @lucia

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They are not for exporting to the grid.

They are 'exporting to the grid' within the EREC definition.

There is no current sensor to prevent electricity from the micro-inverters from being exported when the amount of solar generation exceeds the load imposed by the flat.

If the flat occupants go away on holiday and only keep the power on for a fridge/freezer, then the Balcony Solar system will export.

Posted by: @lucia

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I have just been told this: 

"They must be hardwired by an electrician (not plugged in to a 3 pin socket)  and the DNO must be notified. They are not usually a problem."

And what do you think will happen when the member of staff in your local DNO Connections Team tries to enter the Balcony Micro-inverter into the DNOs system as a G98 device?

There will be no matching device on the ENA database, so they'll respond to the installer with the requirement that the unit gets disconnected.

On the screen in front of me I have the text of the advice given by the senior engineer for National Grid who writes and maintains the standards:
"We would have to seek to instruct the customer to disconnect the equipment as the equipment is deemed to be non compliant with the standards for parallel generation."

That is written by the 'boss' of the guy you've spoken to today.

Generation devices which are not pre-certified to G98 may not be installed in the UK.

It matters not whether they are hard-wired and have the required lockable isolator and dedicated bi-directional RCBO.

The two criteria which differ between G98 and European RfG are these

• Limited Frequency Sensitive Mode (Over frequency)
• Constant active power output