Any recommendations for some simple guidance on solar PV please?
I want to get a better idea of what may (or may not) be feasible at home before I obtain quotes. So not too simple, but I think that the Code of Practice might be too detailed and technical.
A simple question, but Uncle Google does not help.
I gather that there is normally an a.c. isolator means of isolation adjacent to the inverter. What sort of cable is normally used to connect that to a CU please? T&E?
I ask simply because I want to get my installation "solar-ready" as far as possible.
I thought the other aspect was being able to secure the isolation, rotary isolators can typically be secured with a pad-lock to prevent unintended switching. Plus they're highly visible and operable by unskilled people, when immediately next to the inverter, that makes them better for emergency switching.
But regarding the battery location, have you checked PAS 63100:2024 Fire Protection Battery Storage Systems, I think this is freely available from BSI but you need to register, it gives guidance on location. I've not seen the latest amendment of BS7671 but I understand that now has more requirements on battery storage, which I expect will be aligned with the PAS.
On your original topic about cabling, if you're thinking about running in cables, it's also worth thinking about the need for additional cables for current transformers, or RS485 comms to meters/monitoring at the main consumer unit.
I thought the other aspect was being able to secure the isolation
CU components (MCB, RCCBs, Switch disconnectors etc.) are in theory lock-offable - otherwise we'd not be able to use them for isolation when working out of sight of the CU. Granted you usually need a suitable bit of kit, but anyone working on such systems should have that.
- Andy.
CU components (MCB, RCCBs, Switch disconnectors etc.) are in theory lock-offable
I have very little confidence in those dolly locks. I could, I think, install a 2-pole MCB, but then I'd have to shorten the busbar.
Or of course I could open the main switch, but then the lights would be off on that floor. (I can, and often do, wear a head torch.)
Plus they're highly visible and operable by unskilled people, when immediately next to the inverter, that makes them better for emergency switching.
Good point! (Even if it is hidden behind Mrs P's boxes of shoes.)
But regarding the battery location, have you checked PAS 63100:2024 Fire Protection Battery Storage Systems
Yes. "6.5.1 Where practicable, storage batteries shall be installed outdoors. Where it is not practicable to
install storage batteries outdoors, batteries shall only be installed indoors at a location: ... "
It seems to me that the ideal place is under the roof which bears the panels, or at least close by, but although the loft space is prohibited, the store room on the other side of the wall is not.
There is a small section of wall outdoors, but 2 storeys up is poorly accessible (a cherry-picker gets there nicely), even if it may be possible.
I've not seen the latest amendment of BS7671 but I understand that now has more requirements on battery storage
Less than you might have expected.
570.6.7.203 Stationary secondary batteries in dwellings shall be installed in a suitable location taking account of manufacturer's instructions and PAS 63100.
if you're thinking about running in cables, it's also worth thinking about the need for additional cables for current transformers, or RS485 comms to meters/monitoring at the main consumer unit
Yes, I have thought about that. There is no prospect of running a cable from the attic to the origin, but I think that a CT could be squeezed into the middle DB.
Many thanks for your advice, folks.
CU components (MCB, RCCBs, Switch disconnectors etc.) are in theory lock-offable - otherwise we'd not be able to use them for isolation when working out of sight of the CU. Granted you usually need a suitable bit of kit, but anyone working on such systems should have that.
It doesn't look like that would comply with G99 which stipulates there has to be lockable points of isolation, now a rotary isolator is almost certainly compliant because you can snap a pad lock through it to lock it in position. And bear in mind the person doing the isolation could be someone from the DNO who is following their safety procedures.
But an MCB is not directly lockable, as you discuss it needs another adaptor device to be fitted, which may or may not be available dependent on who is performing the isolation. As such, you'd be getting into a debate about whether it was lockable. I would suggest that it is not lockable, certainly not directly lockable.
G99 Requirements:
15. Common Compliance and Commissioning Requirements for all Power Generating Modules
...
15.3. Commissioning Tests / Checks required at all Power Generating Facilities
15.3.1. The following checks shall be carried out by the Installer at all Power Generating Facilities and on all Power Generating Modules irrespective of whether they have been Fully Type Tested or Type Tested:
(a) Inspect the Power Generating Facility to check compliance with BS7671.
Checks should consider:
Protection
Earthing and bonding
Selection and installation of equipment
(b) Check that suitable lockable points of isolation have been provided between the Power Generating Modules and the rest of the installation;
I would suggest that it is not lockable, certainly not directly lockable.
In which case how is isolation from the grid achieved? BS 7671 462.3 has a very similar requirement that isolation devices "prevent unintentional or inadvertent closure" - e.g. by locking out if not located directly adjacent to the equipment to be isolated. If CU components don't do that, we've got bigger problems...
- Andy.
The definitions are different:
Lockable: "able to be locked" or "that can be locked" i.e. can I apply a lock to it.
"prevent unintentional or inadvertent closure" - this is a much broader definition which could be achieved by many different means or methods, of which locking is one but other methods could be used which do not use a lock and do not require the device to be 'lockable'.
462.2 gives "examples" of:
- Located within a lockable space or lockable enclosure
- Padlocking
- Located adjacent to the associated equipment
Presuming the installation extends beyond the immediate area where the CU is installed, the 3rd option is out. So while BS 7671 always leaves the door open to ingenious other solutions, what other practical options are open to the domestic electrician?
- Andy.
what other practical options are open to the domestic electrician?
There are locks and there are locks.
Suitably skillful thieves can overcome almost all of them.
A good bash with a fist would overcome a dolly lock. A hammer might be required for one of those yellow rotary things. You would need a good hacksaw or a disc cutter for an Eaton Glasgow.
The point is that all of them prevent inadvertent closure of the switch: there has to be a deliberate act to achieve it. The only difference is the amount of effort. But doesn't the same apply to the lock on your shed?
my inverter (and battery) will be in the same store room as the top floor's DB
Worth looking at PAS63100 for battery placement
According to the PAS 63100:2024 standard for home battery storage in the UK, batteries should ideally be installed outdoors, such as in a garage, outbuilding, or in a dedicated external cabinet. This is now depedant of battery chemistry type/makeup
It is probably advisable to have an EICR/Periodic inspection and test to check on the current condition of the install first and ask to check if you have
RCBO or Bidirection MCB for the dedicated circuit you plan to use for the Solar PV/Battery?inverter setup
Is there an SPD type 2 present and in good working order. (Not all flag colours are the same meaning)
On a side note if you are going to have Solar PV/Battery/Inverter installed please check your smoke/heat alarms and positions. 10 years is normal replacement date for domestic dwelling but the alarm/sensor should normally advise of replacement date on a sticker on the unit. Additional alarms maybe required due to the proposed extra kit (Solar PV/Battery/Inverte) and they should be inter-linked
It is probably advisable to have an EICR/Periodic inspection and test to check on the current condition of the install first and ask to check if you have
RCBO or Bidirection MCB for the dedicated circuit you plan to use for the Solar PV/Battery?inverter setup
Is there an SPD type 2 present and in good working order. (Not all flag colours are the same meaning)
Sergio, thank you. The installation is < 10 years old and in good order.
There will be an MCB for the inverter circuit in a 4-way DB nearby. That has a 16 mm² distribution circuit from an MCB in the main house board. All the final circuits are on RCBOs. SPD is fitted.
There will be an interconnected smoke alarm in the store room.
So, plug and play for the solar installer. :-)
It is probably advisable to have an EICR/Periodic inspection and test to check on the current condition of the install first and ask to check if you have
RCBO or Bidirection MCB for the dedicated circuit you plan to use for the Solar PV/Battery?inverter setup
Is there an SPD type 2 present and in good working order. (Not all flag colours are the same meaning)
Sergio, thank you. The installation is < 10 years old and in good order.
There will be an MCB for the inverter circuit in a 4-way DB nearby. That has a 16 mm² distribution circuit from an MCB in the main house board. All the final circuits are on RCBOs. SPD is fitted.
There will be an interconnected smoke alarm in the store room.
So, plug and play for the solar installer. :-)
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