In @homonid''s case the wiring can be right first time because it's a renovation project.

But it's also possible to use existing 1½mm² lighting cabling to deliver 24v power to dedicated LED fittings without lifting floorboards!

Obviously, you need to completely remove the relevant wires from the mains MCB in the consumer unit before doing anything else! 😯 

Personally I don't like downlighters recessed into a ceiling.
They create shadows and you also end up with a 'dark ceiling'.
A matt white ceiling should be used as a significant asset when considering the illumination of the whole room.

There was a post here from @homonid  about LED lighting which got 'lost' in the ether when posts about Smart Meter issues were relocated here. 😥 

Fortunately it's still fresh in my mind, so I can answer both points!

1: I recommended installing 24v DC LED lighting (not 12v).
For the same power output, the wiring will be half as thick when using 24v, which saves needless expense on copper.

To obtain 24v from a storage battery I use DC-DC converters like this:

This steps down from a nominal 48-60v to 24v DC

A typical 20-Amp unit will cost about £30 from Amazon UK, and will probably be enough to supply all lighting in the home.
However, I prefer to buy direct from a reputable seller on AliExpress.

Ask if you need help to buy direct from China.
AliExpress has thousands of 'stores' but you can usually identify the better ones by the number of that product which they've sold.
Their reputation on AliExpress is important to them, whereas anyone can set up a store on Amazon and you don't really know who they are.

I use multiple DC-DC converters and have 24v power outputs around the home.

The assembly in this photo delivers 12v which runs

• broadband router
• WiFi remote Access Point
• external door entry lock
• alarm system

The 19v DC-DC converter supplies a monitor.
It used to do my (older) laptop, but my current one uses a USB Fast-charger input (USB Power Delivery system).

I also use the 'raw' 52v from the storage battery to an Ethernet Switch and a CCTV system, both of which have PoE (Power over Ethernet)

If there's a power outage to the house, then I wouldn't notice it.

2: If you're considering an 'interim' inverter prior to building a whole-house 'off-grid' battery storage at some later date, then I would still suggest that you consider a SunSynk inverter.

I don't (yet) have any here, but I have gained lots of insight into which companies provide inverters that are properly designed.
They key point is that they need to offer features which the householder would actually find useful!
That includes inputs from solar and grid to charge a battery, and the ability to operate in parallel with either single-phase or 3-phase configurations.

At some point, I would hope that the British company, GivEnergy, are also able to deliver a well-designed hybrid inverter.
But they are currently concentrating on the software changes required to get their All-in-One (combined inverter/battery) units operating as they should.

(I think we've also lost a post here from @judith  which was a comment on ELV (24v) LED lighting.
But I don't recall it being a question which needed an answer)

@judith My understanding is that in the commercial luminaires Leds are often overrun (source is Big Clive videos) so they burn out more quickly though I also take @transparents point that the circuit boards are in tiny spaces and overheat and die. Having said that my mains led bulbs are lasting far better now but they are not Gu10. The first low voltage ones I had in my boat years ago were rubbish dying after only a few hours. I am no electronic expert just a hobbyist.

@transparent Thanks again for the useful information. So much food for thought. Last nights Panorama made me think it would be best to leave smart meters until the communication problems are resolved. This rather simplifies my plans for battery backup systems as the more sophisticated setups require smart meters to take advantage of smart tariffs.

Posted by: @jancold

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My understanding is that in the commercial luminaires Leds are often overrun

I've discussed the issue with LED chip manufacturers.

They point to the fact that LED wafers have lower temperature tolerances than silicon chips.
Ie LEDs should run 'cold'.

Within LED bulbs the heat comes from the electronics behind the LED emitters.
Due to tight price margins, bulb manufacturers use less-efficient circuitry to -

• convert from AC mains to low-voltage DC
• deliver a constant current through the emitters (LEDs don't use constant voltage)

Too often, the bulb manufacturers use the same aluminium body to act as a heat-sink for both the emitter elements and the electronics.

You can buy some LED bulbs that use higher efficiency electronics, such as these GU10 LEDlite ones from TLC.

But to evaluate the efficiency the customer needs to compare the input watts against the output brightness in lumens.
Anything greater than 100-lumens per watt is worth considering.

Remember also that white-light LEDs use a phosphor to create the wide spectrum.
That deteriorates over time, for which manufacturers' specifications have a L-code.

A white light source marked L70 means that the luminous intensity drops to 70% of the specified value within however many years they state (typically 5 years).

Any manufacturer quoting an L90 specification is therefore telling you that there is a lower decrease in illumination over time for his product.
Typically these bulbs will be using emitters made by the likes of Cree or Epistar, who are the world leaders in this phosphor technology.