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

The Audio Impact of  Solar Panels and Battery Backup:

Comparing Sound Quality of Panels, Batteries, and the Grid

Introduction

I recently got solar panels and a battery backup system installed at my house. While this was a decision driven by many factors, as I described in my previous article, The Audio Impact of Solar Panels and Battery Backup: Introduction, Installation & Initial Listen, one of the important concerns was whether it would have a negative impact on the sound quality of my audio system. At the time of that article, the system had just been installed, and was pending PTO (permission to operate) from my local utility.

The main audio impact finding from that stage of the install was that the addition of the Tesla Gateway in the formerly-direct path from the grid to my main panel did not degrade sound quality in any discernible way. This was a huge relief, as it guaranteed that I could always use grid power to keep sound quality at the pre-install level, just in case solar panels and/or the batteries degraded sound significantly.

The evaluation of the SQ benefits or degradations due to panels and battery would happen after PTO. This is where I am now, so this article will continue the saga!

System Progress Update

To recap: the installation is a 12.33kW system, with 29x 425W panels, along with 3x PowerWalls, with a total capacity of 40.5 kWh. Here again is a diagram of the installation:

As is typical of these installs, the next steps to PTO did not go perfectly smoothly! The system failed the utility inspection scheduled about 2 weeks after installation. The inspector could not register any voltage (signifying production) on one of the panel strings. While I was glad he was being this thorough, the Tesla tech later told me he thought the inspector’s multimeter was set to AC volts, not DC volts. Who knows! In any event, it did cause Tesla techs to conduct a couple more testing sessions, which in the grand scheme is not a bad thing. The second inspection another 3 weeks later went without incident.

SInce Austin Energy mandates a PV meter that they install to measure panel production, it meant that prior to PTO, I could not run my panels at all, as without the PV meter, there was an open switch between the panels and the gateway. This meant that for 5 weeks, I went without any way to use my panels and batteries. On the plus side, AE’s definition of PTO is once they install the official PV meter after the passing of the inspection. At least in this phase, I lucked out, and an AE tech came by early the day after inspection and installed the PV meter. I was up and running! As it was a glorious sunny late fall day, here’s my first production day:

It felt so good to return more than half the production of that day to the grid!

After a few days of observing the system in operation, it was time to do some listening tests.

My Listening Setup

Here is a diagram of my listening setup.

Review Playlist

Fall 2021 Review Playlist on Qobuz (US)

To enable you to listen to the same tracks that I did, I have created a public playlist on Qobuz USA. This playlist includes the tracks mentioned in this review, as well as some of the others I listened to in the course of this evaluation. Please note that in some cases, the Qobuz track will not match the mastering I listened to, especially since all my listening was with PGGB-upsampled files. Still, this gives you a sense for the music I listened to for evaluation.

Listening Tests

In operation, the Tesla Gateway manages the flow of energy required to both meet the instantaneous demand from the home, and the production from the panels. This means at any moment, my audio system could be receiving energy from the grid, the panels, the batteries, or some combination of all three.

My goal was to understand the sound quality of each energy source in isolation. To this end, I needed to do some configuration, either through policy settings in the control software through the Tesla app, or by flipping breakers. More on this later.

Here is what the path for each energy source looks like:

• Solar panels -> inverters -> gateway -> main panel -> dedicated audio circuit,
• Powerwalls (builtin inverters) -> gateway -> main panel -> dedicated audio circuit, and
• Grid -> gateway -> main panel -> dedicated audio circuit.

Solar Panels vs. Grid Comparison

To conduct this test, I started on a clear sunny day, and I minimized the loads in the home to ensure that during the listening, power would come solely from the panels. Here’s the app view. The panels’ instantaneous production is 8.9kW, of which 1.7kW is going to satisfy the house demand, with the remainder of 7.2kW charging the Powerwalls, as their current charge of 23% is below my setting of 80% backup reserve.

Since there isn’t a software-driven way to turn off the solar panels, I had to go to the Gateway box and physically switch off the solar panel breakers. With the solar panels switched off, the picture shows no production from the panels and no energy to the Powerwalls. In the US, utility regulations require that batteries can only be charged from panel power, and never from the grid, other than during weather events. The 1.0kW demand from the house is being satisfied from the grid.

Solar Panels vs. Grid Results

In a word, these two configurations were indistinguishable.

Keep in mind there were logistical challenges here. If A is panels and B is grid, it was possible to go from A to B within seconds, if you had a helper to flip the breakers outside for you. However, going from B to A was a 5-minute endeavor. Once solar panel power has been disrupted, it takes the Tesla Inverters about 5 minutes to reboot and start producing again.

I tried this experiment on multiple days, and while on some days I could detect small differences, I would be hard pressed to identify them with any certainty. Let’s just say that the difference, if any, was miniscule.

Could this have been the effect of my Sound Application TT-7 Reference power line conditioner? Impossible to say without more testing. Were I much more motivated, I would assemble a collection of PLCs and power regenerators, and assess this difference on each of them. I’m not motivated to do this comparison.

All I can say is that on my system, with my gear, running off a dedicated circuit from the main panel, through the TT-7 Reference PLC, panel power and grid power were indistinguishable to my ears.

This was a welcome result, and meant I didn’t have to do drastic things like turn off solar panels for critical sunny-day listening!

Powerwall Batteries vs. Grid Comparison

This was a comparison that was possible to do without leaving my listening chair, so it was easy to go back and forth within a few seconds per transition. To ensure purely grid consumption, my reserve threshold had to be set as shown:

Conversely, to go to battery power, I just had to set the backup reserve down to well below the current battery level:

Battery vs. Grid Results

Unlike the panels vs. grid comparison, these results were conclusive, and quite delightful! Consistently, the Powerwalls sounded better than the grid. What do I mean by better?

One track on Wagner Overtures & Preludes, Andrés Orozco-Estrada, Frankfurt Radio Symphony (Sony Classical, 24/48) illustrates this well. On Tannhäuser Overture, the piece opens with a soaring hymnal melody on the horns. With battery power, these horn notes soar higher, hang longer, and convey a more spacious image. Going back and forth, the battery source was very reminiscent of a PSU upgrade. I’ve heard a similar improvement going from a stock SMPS to a Farad Super 3, or from the latter to a Paul Hynes SR-7 DR. There is an opening up of the soundstage, allowing the music to breathe and feel effortless. Instruments sound richer and more fleshed out. Very soft passages have a greater clarity, suggesting a lowering of the noise floor. Most importantly, all these improvements did not come at the expense of dynamics, a common complaint with battery supplies.

I’ve done this comparison now over many days, with many different pieces of music. I have yet to have an instance when I favored the grid over the Powerwalls. What about time of day? Granted, these tests were conducted during evening hours (no panel production), but this still spanned between 6pm and 2am across listening sessions. Even late at night, during a season when HVAC usage was minimal, the grid source never even approached the sound quality of the batteries.

Of course, this still leaves many questions that are practically difficult to answer. What is the explanation for this effect? If the batteries are presenting a lower output-impedance power source than the grid, is that measurable? And, how is this effect related to the number of batteries in the installation? I have 3 Powerwalls effectively delivering power in parallel. Could I increase the advantage by going to 4 batteries? 5? What about the other direction? Does this effect disappear with one or two batteries?

I’m not equipped to answer these questions, but it’s something on which we can seek empirical data as more audiophiles install these battery backup systems along with their solar panels.

Conclusions

I approached this entire solar + battery project with some trepidation about its impact on audio sound quality. My rather pessimistic expectation was that I would need to be on the grid for optimal SQ, and my fear was that even grid SQ would be degraded by the introduction of the additional infrastructure, especially the Gateway.

I am therefore delighted with the results. The quick listening test in Part 1 dispelled my misgivings about the effect of the Gateway. Comparing solar panels to the grid, I was pleasantly surprised to find essentially no difference in SQ between the two, perhaps helped by my Sound Application power line conditioner. And finally, the superior SQ of the Powerwalls was an unexpected bonus!

I now know that to achieve the best SQ in my system, I must configure power to be flowing from the batteries. This is trivial at night, but challenging during solar panel production during the day. If I really need the ultimate SQ during the day, I will have to switch off my panels and forego production. Shh, please, no one tell my wife and daughters!

This has been an 8-months long odyssey, from initial order to PTO, but I am so glad we now have an operational solar panel and battery backup system in place. It is very gratifying to see days where solar production far exceeded the house consumption. The fact that I got an SQ boost out of this project just makes it all the sweeter!

Primary System

Music Computer:          Taiko Audio SGM Extreme Music Server, Taiko USB upgrade

Headphone Amplifier:  Cavalli Liquid Gold

Headphones:                 Meze Empyrean, Abyss AB-1266 CC, Sennheiser HD800 (SD mod)

DAC:                                Chord DAVE

USB to dual-SPDIF: Audiowise SRC-DX bridge

Ethernet Switches:        SOtM sNH-10G, Uptone EtherREGEN,

  Buffalo BS-GS2016 (modded for LPS)

Power supplies:             Paul Hynes SR7MR3DRXL (dual regulation, 3-rail)  for switches

                                         Sean Jacobs DC-3 for DAVE

Power Details:               Dedicated 30A 6AWG AC circuit,

Sound Application TT-7 Reference Power Conditioner

Power Cables:               Sablon King (wall to TT-7), Sablon Prince (Extreme),

  Cardas Clear Beyond (DC-3, SR-7),

                                         Cardas Clear for all other components

USB cables:                   Sablon Reserva 2020 USB

BNC cables:                   High Fidelity Cables CT-2 in Schroeder config, JSSG360’d (DIY)

Ethernet cables:            Sablon 2020, SOtM dCBL-Cat7, Supra Cat 8

DC cables:                      Neotech OCC (DC-3), Paul Hynes fine silver (SR-7)

Interconnects:               Cardas Clear XLR balanced

Headphone cables:       Transparent Ultra cable system

Accessories:                  Synergistic Research Tranquility Base XL UEF with Galileo MPC

  Synergistic Research MiG 2.0 footers

  Taiko Audio Daiza Isolation Platforms

Acknowledgments

Many thanks to the following companies for supplying cables and accessories to aid in this evaluation:

• Cardas Audio, for a full loom of Cardas Clear cables.
• Transparent Audio, for the Transparent Ultra headphone cable with a full complement of headphones leads and source terminators.

About the Author

Rajiv Arora — a.k.a. @austinpop — is both a computer geek and a lifelong audiophile. He doesn’t work much, but when he does, it’s as a consultant in the computer industry. Having retired from a corporate career as a researcher, technologist and executive, he now combines his passion for music and audio gear with his computer skills and his love of writing to author reviews and articles about high-end audio.

He  has "a special set of skills" that help him bring technical perspective to the audio hobby. No, they do not involve kicking criminal ass in exotic foreign locales! Starting with his Ph.D. research on computer networks, and extending over his professional career, his area of expertise is the performance and scalability of distributed computing systems. Tuning and optimization are in his blood. He is guided by the scientific method and robust experimental design. That said, he trusts his ears, and how a system or component sounds is always the final determinant in his findings. He does not need every audio effect to be measurable, as long as it is consistently audible.

Finally, he believes in integrity, honesty, civility and community, and this is what he strives to bring to every interaction, both as an author and as a forum contributor.