Home Battery Power Supply

I see a lot of negative comments regarding mains filtering, OK fair enough but so far nothing about devices such as the Tesla Powerwall, a large battery topped up by renewable power supplies such as wind or solar. I’m seriously thinking about getting one in the near future but how would that affect my Naim equipment? There would be no change to the household circuit or the dedicated radials for the HiFi, just a battery and an inverter feeding the consumer units much like a giant UPS

That is an excellent question. I started thinking about this recently for our next house move. With the cost and availability becoming more agreeable I have been contemplating a solar array feeding a power bank. If both solar array and grid power came in ( and fed back to grid) via the power bank then a ‘clean’ supply should be possible.

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A battery back up is a good idea, Tesla have made it into a whole house all day supply size & that has to be good.
But don’t be fooled into believing it’s a low noise supply, DC/AC inverters such as we have for example with PV systems add noise, not that it’s necessarily audible with hifi, but perfect it ain’t.
It needs looking into & will be something goood for the future, but tread carefully.


Just be carefull, inverters are noisy things. Whilst a lot better than say 10 years ago, they chop your dc into ac. Starting with a square wave and then effectively filling in the gaps to approximate to a nice sinusoidal wave.
Whilst this is what happens in wind farms/PV cells, the noise generated by these tends not to travel too far from point of generation. But of course in your house, this means that any noise will not get absorbed by the network.
Of course all a bit odd, as your hifi then turns the ac back to nice smooth noise free dc.
Do your own due diligence. Don’t believe the blurb from salesmen. Get evidence of exactly what the inverter output looks like.
Early ac inverters were horid. The wave was little more than a square wave. Very digital. Any motor supplied had to be significantly derated, to avoid overheating. Strange sound from the motor too.

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As I suspected, not a perfect solution. Maybe I could try and see how it works out but keep the option to feed the dedicated radials direct from the mains rather than the inverter should it get noisy or less than perfect?

Under New Products I suggested around the New Year that maybe Naim should have an alternative PS for boxes which can draw on a DC system because with solar it makes sense to only use AC when needed in the house. Why convert from DC to AC and then back to DC with the Naim PS, lighting, phone chargers etc.

As @ColinP says DC home energy storage is available now. Of course not all Naim owners will have solar, but now is the time for Naim to do the R&D because otherwise regulations may tighten to ban large Transformers.


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I’ve had Solar panels now for 2 years, but no battery backup. They are an absolutely great idea, and in my case will pay for themselves after 10 years. Having Battery Backup is less cost effective until the price of batteries significantly reduce. As an alternative, I divert any unused electricity to my Immersion heater, or a 2KW heater in the hall after that, which means I get free hot water all summer and some in winter, plus often get some good extra free heat via the electric heater to partially heat the house.

I dont have any of the answers but happy to discuss ideas…

I’m guessing that the battery is charged by the Solar Panels, and then feeds into the Inverter, so it will be the inverter generating the electricity. These Inverters cost around £500 and are typically made in China, and certainly wont have the same care as Naim would have in their design.

Now the Voltage produced by the Inverters is designed to match what comes from the grid. So below is a typical day, and makes no difference if you are producing energy or not. As you can see, it is not normalised.

In terms of the quality of the mains Sine Wave, I cannot say, but I do know in my case it makes no SQ difference, or Hum to my setup (282/HCDR/NAP140). Some believe it does effect it. My NAP140 does Hum, and that doesn’t change throughout the day/night.

Running DC current around the house may have some complications. Firstly you wouldn’t be able to use normal sockets in case of someone plugs in the wrong device. Secondly you would have to match 240V DC, otherwise you would have to run much thicker cables as the current running down would increase. This would then still require some step down device to drop it down to a level your HiFi wants.

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It would be interesting to know what effect this all has - we had a wind turbine put up in 2011 and it has more than paid for itself - a shame solar doesn’t have feed in tariffs any more but I want to get battery and solar too. The wind turbine produced power (shared with two family neighbours) gets used in the house first and any excess exported so I would hope we should get particular benefit from battery storage - wind in the winter, sun in summer if we get solar. Though the addition of an air source heat pump last summer, and the everhot range oven coming in April will also compete for power. But battery storage is stupidly expensive - £8k for a Tesla power wall installation that can hold about 2 quid of electricity. Would love to be able to use my electric car for storage for home use, but that seems a way off yet

I didn’t notice any effect from the wind turbine on the quality of sound from the hifi - it (the turbine not the stereo :stuck_out_tongue_closed_eyes:) has been merrily blowing round for the last week or so and it (the hifi) is all sounding very fine. I think the inverter is on the turbine mast so 150m or so away - maybe that helps


All good points. It would be a good area for university research.

£3k would buy you a 6.3kWh Solax lithium battery storage unit suitable for use with solar PV.


The battery I think would make sense for us, we use next to no electricity during the day (other than a fish tank when we get one again) especially during the summer but evenings and night times we do. Currently we have storage heating and I’d like similar in the new house but more up to date, I’m keen to do my bit to get away from burning fuel to power the home. Storing the energy created during the day makes good financial sense also as the heating is charged up using off peak electricity at a time when there is less demand nationally and cheap, it could also charge up the battery making sure it’s got a good day’s worth of power in it. That would leave all daytime electric to be run by solar or wind. I’d forgotten about wind, where we are now we’re not allowed to erect any form of tower but moving a few miles away we would.

Really it’s more about reducing our load on the national grid at peak times rather than purely financial, I was hoping for a degree of isolation from the mains supply too qualitatively for the HiFi and as backup for the fish tank (we get a lot of wind related power cuts on Anglesey during the winter). Looking at GadgetMan’s graph maybe a battery would iron that out?

I have no idea really, just hoping for lots of input, good or bad and try and make some sense of it

Some battery installations now keep you going in a power cut - until a couple of years ago that wasn’t possible. I know the Tesla power wall does and know others can, but don’t know specifics

I believe Toyota were looking into this (or was it Nissan), where you use your car for Battery storage, and release to the house. So may be available soon, and I think is a great idea, so you get the best of your battery investment.

2 Years ago it was about 1K per KWH battery, so looks like prices getting better.

I suspect not, as I think it has to match the Grid voltage, so that it can put it back in the grid without effecting other properties. That said, I dont think voltage fluctuation matters that much providing its with limits.

It would be interesting to see what the electrical quality is like in the scenario. Of course if it was good, it would mean you turning off your grid connection whenever you wanted to listen to your HiFi.

I think the Tesla product has stayed the same price in the last two years - but others seem to have got cheaper (everything I looked at a couple of years ago was more expensive than the power wall but I have seen more recently similar prices).

The vehicle to grid (v2g) / vehicle to home (v2h) is only possible with Nissan Leaf at the moment, and only in a restricted trial. There is also a complication in that doing anything to the grid would mean I lose the feed in tariffs from the wind turbine. Which also means that solar is only any good if I can use it all myself.

The payback on battery storage is 10-20 years. That would be fine as I am never moving from here. The bigger thing holding me back is a concern that, if I bought now, the prices may drop so much in the next 3-4 years as to mean I should have waited. Also very spent up at the moment!

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I’d say if you do it now, ensure you never look up the prices again. If it’s any comparison, my electric bill pretty much halved after getting the panels, then the feed in tarrif covered the other half. So 10 years sounds about right

Fair point - I don’t have the funds at present though. And priority before that is getting the oil fired Rayburn gone (happens April) and getting rid of oil tank in garage. Which of course then means that I will get more benefit from battery. But I cannot do everything at once

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You clearly don’t have a wife like Mrs Bruss.

Can’t you just do ----- :slight_smile:

And the life of lithium batteries may be 15 years max!



Hi Tim,
Funnily enough, we have just ordered a Tesla Powerwall 2 and 8kW solar array. The Powerwall is on limited supply with a 6 month lead time at the moment. Price has just gone up by £500+. We’ve had quotes above £11k for one, including installation and the Tesla Gateway that goes with it so that it can act as a back-up power supply. It can be bought for less though from a Tesla accredited installer.

It’s going to be interesting to see if/how the hifi is affected when this is all installed.

One side effect of looking into this is that we are now much more aware of what uses electricity in the house. The Naim hifi comes out really badly, as it draws over 100 Watts on a 24/7 basis, which makes it as thirsty as the major white goods in the house (e.g. washing machine & tumble dryer), which draw much more when they run but for a far shorter period of time.

Best regards, BF


Payback may be offset in a few years if the price of fossil fuels goes up significantly

If Naim developed power supplies fed by a large lithium battery giving the voltage taps of the various transformers we would not think twice about the cost. One might have a pair so that one was charging while the other is connected to the HiFi.

My Audiophilleo+PurePower usb to spdif is very low noise to deliver superb SQ into my nDAC. The PurePower has a lithium battery which recharges automatically from the nDAC rear USB port when it’s not playing music. I can’t help but think that DC battery technology would delivery better SQ at a lower price. A Naim PS would reduce to DR regulators provided the battery could deliver as much instantaneous current as the big capacitors Naim fits. That’s were the R&D is needed.


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