Article: The Audio Impact of Solar Panels and Battery Backup: Comparing Sound Quality of Panels, Batteries, and the Grid

[austinpop]

View full article

[The Computer Audiophile]

Thanks for the detailed follow up Rajiv!

[bobfa]

@austinpop Thanks for the update.  

 

It would be very interesting to put a commercial power line monitor on the input to your system just to look at the line.

 

Is there a way that you could install a circuit to the PW+inverter to always run that way?  So, a Power Wall powered Audio System?  I am not certain, I want to see the budget estimate for that.

[AudioDoctor]

I wish I had enough open roof space to put that many solar panels on without cutting down trees. Thanks for writing up your thoughts @austinpop.

[Jud]

Why it sounds the way it does I don’t know, but I’m very happy for you, Rajiv, that you have done well audio-wise by doing good for the planet with your solar and battery system.

 

 

[Temporal_Dissident]

Thank you for the great article. Timely, as I am looking into solar myself. In my case, I've thought about a dedicated audio power circuit that was fed this way: Solar Array > Batteries > Dedicated Audio A/C Circuit

 

Question: 

Doesn't the Tesla PW system just continuously charge on-site batteries? And would that not effectively insulate your power supply from the messy interference on the public A/C grid? I figured it would work like a large-scale power regenerator,...since your A/C is being converted locally from D/C it would be very clean and pure. No? 

 

 

[JoeWhip]

Awesome results Rajiv! Solar doesn’t make sense here due to topography as I was in contact with Tesla about this a couple of years ago. I do know that my SQ with our whole house generator sounds identical to the grid which is a plus too. I will have to do a listening test with my new MacBook Oro running off battery power vs. plugged in given the 21 hour battery life!

[austinpop]

 

6 hours ago, bobfa said:

Is there a way that you could install a circuit to the PW+inverter to always run that way?  So, a Power Wall powered Audio System?  I am not certain, I want to see the budget estimate for that.

 

3 hours ago, Temporal_Dissident said:

Question: 

Doesn't the Tesla PW system just continuously charge on-site batteries? And would that not effectively insulate your power supply from the messy interference on the public A/C grid? I figured it would work like a large-scale power regenerator,...since your A/C is being converted locally from D/C it would be very clean and pure. No? 

 

 

 

At least with the Tesla system, and I suspect most other solar+battery installs, the house is fed energy by a smart gateway, which treats each component as follows:

• Solar panels: Power source
• Grid: Power source AND sink
• Batteries: Power source AND sink
• House: Power sink.

I don't see an easy way to bypass the gateway.

 

Here is a little video snippet of the power flow in real time. Notice how the sum of power generated and consumed always match.

 

 

 

[So great]

Thank u, This is a  great article. I've been using a UPS for computer as my AC POWER PURIFIER for a while, it's very close to your ideal using the  POWERWALL DC convert to AC to power supply your  audio equipments. 

[Mike Rubin]

I posted in response to your first article that I hear no differences in SQ whether drawing from the panels during the daytime or from the grid at night, possibly due to the presence of a PS Audio regenerator in the path. Sounds as though my experience isn’t unique.  
 

You make a compelling audio case for batteries, though. Here in San Francisco, with PG&E availability increasingly on a banana peel, solar homes are moving quickly in that direction. In my case, however, the economics for the upgrade to batteries haven’t been compelling and I will have some logistical issues locating them on the premises so I haven’t pressed the issue.  You may have just given me the most important reason to look more closely. :)

[PYP]

Very cool.  I suppose this must be considered the ultimate tweak!  

 

I've read about some audiophiles who unplug the refrigerator so that they can hear their system unimpeded by compressor noise.  Those folks might consider a battery backup as a great upgrade.   They can have their (unspoiled) cake and eat it too (so to speak).  

[MarcelNL]

Great article! We're about to have solar installed and I never gave battery packs a serious thought but now I will (of which we'll also benefit given the current energy issues in Europe)!

 

 

[MarkusBarkus]

10 hours ago, PYP said:

 

I've read about some audiophiles who unplug the refrigerator so that they can hear their system unimpeded by compressor noise.

I do *not* unplug the fridge. Those charges are unfounded. I turn off the furnace. 😉

[austinpop]

23 hours ago, Mike Rubin said:

In my case, however, the economics for the upgrade to batteries haven’t been compelling and I will have some logistical issues locating them on the premises so I haven’t pressed the issue.  You may have just given me the most important reason to look more closely. :)

 

6 hours ago, MarcelNL said:

I never gave battery packs a serious thought but now I will (of which we'll also benefit given the current energy issues in Europe)!

 

I'm sure this is understood, but I want to be clear that I am not advocating getting Powerwalls (or equivalent home battery backup solutions) solely for the purposes of sound quality. That's quite a cost to pay — although if you look at high-end battery AC supplies like Stromtank, they're not cheap either! Also, how much of this better SQ relates to the number of Powerwalls? Does parallelism matter? Hard to say.

 

As I wrote in the article: The fact that I got an SQ boost out of this project just makes it all the sweeter!

 

What I am suggesting is that this is a potential area of exploration, for which I don't have answers, but do have a lot of thoughts. In essence:

• Is it possible to build a DIY battery-based AC power solution for one's audio system, at a more approachable cost?
• My experience suggests that the quality of inverter used in the Tesla Powerwall and Inverterr is good enough from a noise perspective, given a decent PLC. More evidence would help, but looking at the comments to this and the previous article, this seems to be a widely shared experience, where the SQ of the panels and the grid and hard to distinguish.
• What characteristic of the battery matters the most for the better SQ I heard? 
  • The fact that what I heard sounded so much like a DC PSU upgrade was telling. One key metric that changes, the better the PSU gets, is lower output impedance.
  • Could the same be the case here? Could the batteries' internal resistance (seen from the audio system as output impedance) be the key?
  • Stated another way, could the path forward relate to curating batteries with a high C rating?

I'm suggesting these as hypotheses, at best, because I'm not much of a DIY guy, but I know a small group of ASers who are experimenting here, and early indications are that these hypotheses have some merit. Hopefully, there will be a thread on this at some point.

[Mike27]

Great pair of articles. I’m thinking measuring source impedance might be, ah, “non-trivial.” But if you have access to an oscilloscope, you could *very carefully* observe the AC waveform for noise in both conditions. A DSO could capture both waveforms for comparison, null test, etc. Might or might not tell you anything useful. 
 

But don’t electrocute yourself! We want to read part 3!

[jeffhenning]

Are you doing this as a hoax or just for really stupid people that think that great audio equipment can't deal with power line grunge?

 

When John Atkinson tests equipment for Stereophile, he plugs it straight into the wall with the supplied cable.

 

In testing Benchmark's AHB-2 amp and LA4 pre/amp, he found them to have less distortion and noise than any similar products ("Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered.")

 

Hey, having a cleaner power supply will improve the sound of your system by reducing noise 3dB or so cumulatively. That's it. Also, having the power conditioner take the hit from a lightning strike is good.

 

If your equipment is so poorly designed and built that a power conditioner or the power source drastically changes its audio quality, there is something seriously wrong with it.

 

Either that or your preconception bias has gone into overdrive. Regardless, this article is of no value.

[The Computer Audiophile]

17 minutes ago, jeffhenning said:

Are you doing this as a hoax or just for really stupid people that think that great audio equipment can't deal with power line grunge?

 

When John Atkinson tests equipment for Stereophile, he plugs it straight into the wall with the supplied cable.

 

In testing Benchmark's AHB-2 amp and LA4 pre/amp, he found them to have less distortion and noise than any similar products ("Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered.")

 

Hey, having a cleaner power supply will improve the sound of your system by reducing noise 3dB or so cumulatively. That's it. Also, having the power conditioner take the hit from a lightning strike is good.

 

If your equipment is so poorly designed and built that a power conditioner or the power source drastically changes its audio quality, there is something seriously wrong with it.

 

Either that or your preconception bias has gone into overdrive. Regardless, this article is of no value.

 

Hi Jeff, thanks for the opinion, I think. 

 

You have some serious bias on this one and preconceived ideas about this stuff. 

 

Appealing to an authority, to support your belief, has been used for eons. Imagine the kerfuffle if JA used something like a Shunyata or 512 Engineering power unit while measuring everyone else's gear. That wouldn't fly in anyone's book. Plus, measuring gear as standalone devices is a pretty benign way to do it.

 

Do you have any evidence that only poorly designed equipment can benefit drastically from clean power? In fact, do you have any evidence even poorly designed equipment can benefit from clean power? Or, how do you define poorly designed?

[Jud]

So international standards for electric current supply quality, given the force of law by state and local regulations, are worthless, or audio equipment is the sole exception among all electrical equipment in the home?

[MarkusBarkus]

...I dunno. I rarely listen intently to my microwave unless Sweetie is making popcorn. Again. 

[bbosler]

10 hours ago, jeffhenning said:

Hey, having a cleaner power supply will improve the sound of your system by reducing noise 3dB or so cumulatively

 

and you know this because .... ???????

 

BTW 3dB of power is a factor of 2, as in twice as much or half as much,  so that seems to me to be significant, but I'm thinking you just pulled that number out of thin air

 

A-POP, I am curious what the specifications are for the output of the Tesla inverter. What is the distortion spec for it? Does it produce a significantly cleaner 60 Hz or eliminate some other noise coming in off the grid or ??? What is the output impedance of the inverter versus the grid? I know you didn't say this, but some may assume because it starts from a battery it must be cleaner, but that depends on the design of the DC to AC inverter, not just the fact it runs from a battery.

 

It is possible it is actually more distorted than the grid and adds something to the sound that you perceive as an improvement? PSAudio had (maybe still has) a MultiWave option on their regenerators which basically produces a distorted 60 HZ instead of a clean one, and many report feeding this distorted wave to their equipment improves the sound. 

 

I believe you hear what you hear, but to explain it there must be something significantly different about the grid versus the inverter. Just curious what that difference is

 

And if using DC batteries to produce AC to feed to components which take the AC to make DC, seems like the next logical step is just run everything straight off the batteries and skip the DC to AC to DC. I realize that will take some modification of the components and a way to regulate the DC down to the level needed by the device, but if you've gone this far....................

[KingRex]

Hello Austinpop,

I have a couple comments. 

Its unfortunate you have no way to bypass the gateway and feed your main panel direct from the utility.   Your installation is a similar in design to how generators are installed now.  The utility is in essence routed through a transfer switch that decides if the power is sourced from the utility or a secondary source.  When I design a system for generator use such as I did at Fremer's home, I separate the secondary power from the utility power to reduce the amount of conductor and termination points in the path of the audio power supplies. 

Did they use aluminum wire for the service connections or copper is also a question I would ask.

 

What you did is interesting in that it has given you the opportunity to listen to  battery vs utility.  I begun investigating this myself.  I never got to building out a system as battery makers who have worked with audiophile doing as such did not receive positive feedback.  You on the other hand did. 

 

I am not sceptical of your perception of battery bettering utility.  I have used a Fluke 125 scopemeter on many houses and I always see about 2.4% to 4.5% THD measured to voltage on the 3rd and 5th.  Sometimes out to the 7th and 9th.  Utility power is never clean as your sharing the transformer with 4 or 5 neighbors.  

 

Your test also appear to be performed with very low power headphone amplifiers.  Your perception of battery and wall could be very different if you were driving a high power amplifier connected to power hungry speakers.  In the most general sense, I see most audiophile enjoy their front end gear feed via a filter/regenerator of some kind.  I only know 2 people who likes their amps through a filter.  All others like direct to the wall.  

 

I would like to PM with you and be put in contact with others investigating the battery solution.  If indeed it is a good solution, I would like to know.  Although Stromtank is a excellent turn key solution for those in apartments with poor utility power.  Most audiophile don't want to purchase $5k in lithium, a charger and $2k inverter,  then wire it all up.  It would be a dangerous mess behind your rack unless enclosed in a safe storage container. 

 

I appreciate your review, but it leaves many questions unanswered.

Rex

[bbosler]

2 hours ago, KingRex said:

 

What you did is interesting in that it has given you the opportunity to listen to  battery vs utility. 

 

that statements gives the impression that one is listening to battery power, when in in fact you are listening to power from a DC-AC inverter powered by batteries. I know you know this, but like you said this all raises questions one of which goes back to my question above..... how clean is the Tesla  inverter power? I have no idea , but given that the purpose of the device is to power refrigerators, furnaces, AC units, etc. they may not have been overly concerned about the purity of the output.

 

just curious

[austinpop]

6 hours ago, KingRex said:

I would like to PM with you and be put in contact with others investigating the battery solution.  If indeed it is a good solution, I would like to know.  

 

I would suggest waiting until they have anything workable, as they said they would start a discussion thread here. As you correctly noted, the trick is to find a solution that is practical, in light of the challenges of safety and cost.

 

6 hours ago, KingRex said:

 

I appreciate your review, but it leaves many questions unanswered.

 

Indeed it does, and I hope I was clear that I was not asserting otherwise. I went into my solar+battery install without any expectation of SQ gain. Indeed, my only hope was not to lose SQ, based on Michael Fremer's report with the transfer switch. That I found a configuration that gave me an SQ benefit was truly a bonus.

[KingRex]

2 hours ago, bbosler said:

 

that statements gives the impression that one is listening to battery power, when in in fact you are listening to power from a DC-AC inverter powered by batteries. I know you know this, but like you said this all raises questions one of which goes back to my question above..... how clean is the Tesla  inverter power? I have no idea , but given that the purpose of the device is to power refrigerators, furnaces, AC units, etc. they may not have been overly concerned about the purity of the output.

 

just curious

I 100% agree.   And I believe regenerator such as PurePower, PS Audio and Stromtank are also an inverter of sorts.  I believe some equipment can function better on clean power.  And some equipment may be less bothered by it. 

 

I am not sure the issue is so much the switching power supply noise with audio.  As in, backfeed pollution to the audio branch circuits.  I have spoken to others with micro inverter solar, which Austinpop's is not.  They do not have batteries and there system is not routed through a Gateway.  They can disconnect the solar from the utility power.  They do not notice and degradation in sound with the solar connected.  Again, its a different inverter system and a different wiring scheme.  

 

Rex

[austinpop]

Article Followup - How to configure battery power during the day without foregoing any panel production
Jan 8, 2022

As you may recall, the key conclusion of my article was that my system sounded best when my house was being powered by the Powerwall batteries. I also showed how I could use the Tesla app settings to configure battery power during a listening session at night. But what about during the daytime?

Gateway Settings for Powerwall Power during the Day

 

When I wrote the article, I was still finding my way around the configuration settings, so at the time I achieved this in a brute force way, by flipping off the PV panel breakers. This is inelegant, to say the least, not to mention that you're foregoing PV panel production during your selfish listening session! Now I have a better solution, which is to use the so-called Time of Use Control. This setting is meant for use with utility plans with varying rates based on time of day. By specifying peak and off-peak times, the gateway routes battery power to the house during expensive peak times. It also routes all the solar production to the grid, to earn the peak rates for solar production. We can exploit these two characteristics.

In my case, I don't have time-of-use rates, but instead I use this control for battery power during listening sessions, especially during the day. I tend to do my critical listening either in the late afternoons, or late at night. So I defined a rate plan with fictitious pricing like this:

 

 

 

 

 

Here is an energy flow view during that 4-6pm window:
 

 

 

Here, the house demand is driven by the batteries, while any solar production gets sent to the grid. Here's another scenario, at the peak of production on a sunny winter day:

 

 

 

Was the SQ with battery power in this scenario as good as at night, when solar production is 0? In other words, does the cross-traffic at the gateway (solar panels --> grid) interfere with the home traffic (batteries --> home)? To check this, I compared the SQ of the above case, with 8.3kW solar production, with turning off the PV breakers to halt solar production completely. I didn't hear a notable difference.

So there you have it — a way to use the Powerwalls for daytime critical listening, without interrupting solar production!

I hope this was helpful.