@simonstengineer, we had to apply for DNO approval for the larger array. I recommend that everyone that can afford an array (and has a property facing the right way) should put one in. Let us know if you are able to convince him.

In my own case, JoJu Solar filed a G99 form application for me with my DNO for 8.61kWp. (Though due to shortage of first choice of panel, I ended up with 8.1kWp.) This application included a Tesla Powerwalland after some 11 weeks, was granted.

Regards, Toodles.

Posted by: @simonstengineer

We also have selv and pelv ac low voltage supplies so you see there are many iterations and therefore standards need to be set or confusion and incompatibility will follow.

For the sake of others reading this, I'm posting here a definition of SELV/PELV which comes from Electrical Safety First's website:

I'm in agreement that we need standards. However, sometimes the standards organisations don't help themselves or 'us'.

I'm currently evaluating a relatively new style of DC Power Connector for domestic use. There are three manufacturers known to me.
However, to gain its CE mark, its connection points inside the plugs and sockets are marked L, N and the earth symbol.  Aagh!

There is a lot more than 'talk of 48v battery storage'. Several of us here on the forum already have (or about to install) just such storage, using LiFePO4 battery technology.

I already have 24v DC wall sockets in locations around my house.

My office/workshop areas also have 12v and 19v DC supplies.

What would help here @simonstengineer is for you to state whether you believe that such in-home domestic DC supplies require installation and tests by qualified electricians such as yourself. It's the professional opinion which is valued here, even if the situation isn't entirely clear.

For others reading this who are not electricians(!), can I point out that the UK has many off-grid supplies amongst the 'crofter community' which fall outside legislation. This has been the case for decades. A good example is the wind-turbine initiative on Scoraig, led by Hugh Piggott.

I am in communication with my MP on such issues, and he has visited on-site to evaluate the situation for himself. This is a lot more than just a swift exchange of emails!

In the present energy crisis, Parliament needs to understand what the wider public can and cannot do to provide themselves with electricity. Imposing legislation on energy generation and storage where there is no demonstrated requirement would cause a public backlash. It would also set back and delay progress towards three issues which are current government policy:

1. development of world-class renewable-energy technologies on which the future UK economy and export markets can be based
2. achieving Nett-Zero carbon emissions by 2050
3. incentivise rapid expansion and investment in community energy initiatives (as laid down in the Ofgem RIIO-ED2 contracts, which come into force April'23)

Posted by: @simonstengineer

I was told then the max I was allowed was 4kw I see yours is over 6, did you need special permissions for this or is that normal now?

I've written a comprehensive explanation of what permissions are required from your DNO over on the OVO Forum.

The ensuing discussions are also very informative. So don't stop reading after you reach the end of my lead-article!

Thank you all for your responses, I too am against regulation that is restrictive, generally regulation should be about protecting or standardising, never stifling new and emerging technologies.  My original solar install was working very well, I didn't have a south facing roof but was determined to have solar, I ended up buying a load of joists from a certain auction site and built a two car carport on the side of my house south facing. I then had a 4KW array fitted by an MCS approved supplier, within 3 months I had a local councilor complained about being able to see my solar panels and I then got a letter from the council telling me I had move move or remove the offending panels. I hope this would never happen today, I now have my panels moved to between the houses out of site from the offended but my winter generation is now awful due to shading. The councilor sold his house and moved away. Did he really think it would affect his sale price or was he anti-green? This was almost 11 years ago

@transparent As far as I am aware there are no regulations restricting the use of any Low voltage installations, as general rule of thumb the lower the voltage the higher the current for a given wattage so be extra careful as to the sizing of your cables and connections. Another point about different voltages is conversion losses, whenever you change from one voltage to another there are constraints and efficiency losses. If you already have a hybrid inverter and low voltage batteries then these are negated as the conversion has already taken place. Use of DC power directly from the batteries is more efficient that converting back to mains via an inverter for use. Another benefit is the supply from the batteries is immune to power cuts and noise.

That's an interesting story about the position of your solar panels.

I'm a frequent contributor to planning applications in my area, with a pretty good idea of what constitutes a genuine reason for an objection. So I'm very surprised that your council could 'issue enforcement' on the basis of the PV panels, whilst the carport itself was regarded as acceptable.

Councillors themselves must be particularly careful when raising an objection. Any matter where it can be shown that they have personal interests needs to be dealt with according to a publicly-open procedure. If not then they risk being reported to the Local Government Ombudsman. The Council itself could be liable for a fine.

Have you considered asking your local planning office now whether you would be required to obtain consent to place solar panels on the carport?

The general rule/guidance is that it can't be refused unless it conflicts with other planning constraints, such as the property being within a designated conservation area.

So don't just make a Planning Application. It's not even certain that consent is required.

I wrote to my MP about the very restrictive nature of the siting of garden mounted PV panels complaining that unless one has a garden of at least 12 metres wide, there is no possible way of putting any panels in a back garden without infringing the rules under permissible development. His reply did not help as he just chanted out same wording as contained in ‘permitted development’ and of course nothing has changed yet. I have 10 panels ‘placed’ in my garden but not fixed down to the ground - but at 205 kilos for the panels and about a further 60-70 kilos for the aluminium frame plus ballast blocks, I doubt they will be going far! Another 11 panels are placed on the roofs providing an array of 8.1 kWp. If the man on the Clapham omnibus is to contribute towards renewable energy projects then I think the rules need reviewing!

Regards, Toodles

@transparent It might be useful to members to be aware that if you have 48V available do not be tempted to tap into the battery for different voltages. I have had to remedy a situation for a friend who did this recently, he had two 24v outlets from his 48v pack. The problem was it unbalanced the pack, most decent batteries have a battery management system, in fact it can be dangerous not to have one on most lithium batteries even the safer lithium Phosphate (LIfepo4) these management systems usually manage the balancing of cells in a relatively small way and cannot cope with the unbalancing of loads placed differently across the cells. You might not notice it for some time but it will reduce the life of your batteries. Also most tend to be the resistive top end type balancers that waste a lot of power balancing them.  The only way to safely get 24v or 12v from your 48v pack is to use a DC to DC converter and these are rated and use power in themselves. I hope I made that clear. Feel free to contact me for any advice.

Posted by: @simonstengineer

whenever you change from one voltage to another there are constraints and efficiency losses. [...] Use of DC power directly from the batteries is more efficient that converting back to mains

That point is well made.

I'm presently building a(nother) computer with DC input... in this case auto-ranging between 16-60v 😎 

I'm also a member of a commercial design team of engineers working within this topic of hybrid on/off-grid domestic electricity supplies. So I have a wide array of DC-DC converters 'under test' both in my home and also office/workshop areas.

I could write a whole book on this subject, including cable-sizing, losses due to connector oxidisation, arc suppression, fuse characteristics and over-current trips. The problem with me stating this on the open forum is that @editor will reply here and immediately request that I start another topic where such technical issues can be discussed! 😜 

most decent batteries have a battery management system, in fact it can be dangerous not to have one on most lithium batteries [...]

There are as many differing views on BMS units as there are about cable-sizing!

I have four BMS units here from a very well-known company which do not even provide the feature which was first requested when I communicated with the manufacturer. They are 'not fit for purpose'! In the last 8 weeks the manufacturer has been unable to provide me with a specification of which features are actually present on each of the 15-odd variants they offer for sale!

Balancing cell voltages isn't the most critical feature, although it is often cited. I feel that the safety features are somewhat more important.

It is unfortunate that most sellers still offer BMS units by referring to their ability to 'protect the battery'. I take issue with that. The overriding concern must be to protect the devices connected to that battery in the event that a fault occurs.

The battery itself is quite happy to deliver several thousand amps when offered a near-short-circuit through which to send that current. That's a direct consequence of its chemistry, and it is very likely to survive.

The connected inverters and DC-DC converters meanwhile will be busy setting fire to the house!

@transparent Thank you for that, like I said I hope it would never happen today and people are used to seeing panels now. The planning regs have changed quite a bit and I am sure if I was applying now I wouldn't have a problem. I am getting paid by the FIT and they are the reason I can't put them back. I had to inform them of the move and was told I couldn't move them again without risk of loosing the FIT. It has been pointed out to me that I can raise them up to the max permissible height of the lean to but it would then obscure my only south facing window in the bathroom.