Inverter clipping on my Tesla solar: what per-string data shows about DC/AC ratio

People often complain about their inverter output versus the size of their system. In other words, they get clipping. A common setup behind it: an installer puts in, say, an 18 kW array but only one Powerwall 3. Until recently I couldn’t say much about my own system, because the Tesla app only shows the total. On October 24, 2026 that changed. I set up per-string sensors in Home Assistant, so I can now see every string, every inverter input and every inverter’s output. That data only started that morning, so this article combines it with almost three years of 5-minute history from the Tesla app, and I’ll update it once I have a spring and summer of string data.

What clipping is, in plain terms

Panels make DC power. An inverter turns it into AC for the house and the grid, and every inverter has a maximum AC output. When the panels could make more than that, the inverter simply holds its output at the limit and the extra is lost. That flat top on the graph is “clipping.”

The number that predicts it is the DC/AC ratio: panel kW divided by inverter kW. Ratios above 1 are normal and deliberate, because panels rarely make their full nameplate (heat, dirt, sun angle). NREL’s cost benchmarks model residential systems at about 1.15–1.21 (2017, 2023, ATB 2024). Tesla allows up to 1.7 on its 7.6 kW Solar Inverter and on the Powerwall+ (the model I have) (inverter specs, Powerwall+ datasheet), and the Powerwall 3, rated 11.5 kW AC, accepts up to 20 kW of panels (datasheet), a ratio of about 1.74. So an 18 kW array on one Powerwall 3 (about 1.57) is within the manufacturer’s limits. Whether it’s a good design is the question.

How my system is wired

My 58 panels are spread across three separate 7.6 kW solar inverters: one inside each of my two Powerwall+ units (datasheet) and one standalone Tesla Solar Inverter (datasheet). That’s 22.8 kW of inverter for 24.65 kW of panels. Here’s how the strings are wired:

Each inverter has four inputs with their own maximum power point tracker (MPPT), so strings facing different directions don’t drag each other down. Two of the big strings are split in half and the halves are jumpered onto two inputs. Which Powerwall+ is “#1” and which is “#2” was inferred from the panel layout, but the per-inverter panel counts (19, 18 and 21) are what matter here. The standalone inverter is the interesting one: it has the most panels (1.17 ratio) and they all face the same way.

One thing worth knowing: my Tesla plan set doesn’t print my actual DC/AC ratio anywhere. It lists the 24.65 kW array, the string table (panels per string and per inverter) and the 7.6 kW inverters, and the datasheet pages attached to it give 1.7 as the allowable maximum for both the Powerwall+ and the Tesla Solar Inverter. The 1.06, 1.01 and 1.17 above (about 1.08 overall) are my own math: panels on that inverter × 425 W ÷ 7.6 kW. If you’re getting a quote, ask your installer for the ratio on each inverter, because it may not be printed on your plans either.

Powerwall+ vs. Powerwall 3: my older model vs. the current one

Most clipping talk today is about the Powerwall 3, but my two units are the older Powerwall+. A Powerwall+ is a Powerwall 2 battery (13.5 kWh) with a Tesla solar inverter attached (Tesla’s service manual removes it as two parts, the solar assembly and the Powerwall 2); Tesla’s datasheet describes it as “two separate inverters, one for battery and one for solar.” The solar side is a 7.6 kW inverter with 4 MPPT inputs. Tesla released the Powerwall 3 in September 2023 (Tesla); it combines the battery and an 11.5 kW solar inverter in one box. Here’s how they compare on the things that matter for clipping and output:

From the Powerwall+ datasheet (2024), the Powerwall+ install manual specs, the Powerwall 3 datasheet (2025), Tesla’s Powerwall 3 DC sizing guide and the Powerwall page. Tesla lists 13.5 kWh as nominal energy for both. The Powerwall+ figures are at 25 °C. The 12.9 kW is just 7.6 kW × 1.7; Tesla doesn’t publish a kW figure.

What this means for my roof: I have three 7.6 kW solar inverters (two Powerwall+ units plus the standalone inverter), so 22.8 kW of inverter capacity. A single Powerwall 3 has 11.5 kW. My 24.65 kW of panels wouldn’t even fit on one, since Tesla caps it at 20 kW of solar. The catch with my setup is that the inverters don’t share. Each Powerwall+ inverter only sees the strings wired to it, so spare capacity on one can’t absorb a spike on another. That’s why the west inverter can clip while the other two have room, and why the per-inverter ratio matters more than the whole-system one. A Powerwall 3 has the same limitation between units, but with 6 inputs and 11.5 kW each, more strings share one bigger limit.

Two more differences. The Powerwall 3 can push up to 5 kW of solar straight into its battery on the DC side, or 8 kW with an Expansion, while it’s already sending 11.5 kW to the house (Tesla). I couldn’t find a matching figure for the Powerwall+, so I’m not claiming one either way. And Expansion units only work with Powerwall 3 (datasheet), so they’re not an option for me.

As for support: Tesla’s Powerwall warranty (effective May 6, 2026) still covers the Powerwall+ for 10 years (warranty PDF). Tesla’s service manual also has a procedure for replacing a single Powerwall+ with a Powerwall 3 that’s set to 32 A (7.6 kW) output to match the old unit (Tesla service manual). I couldn’t find a Tesla page that says plainly whether new Powerwall+ units are still sold, so I’ll leave that open.

Direction and time of day are the whole story

On a clear day, a west-facing panel peaks in mid-afternoon, an east-facing one late morning, and a south-facing one around 1 PM (daylight time). If an inverter has a mix of faces, they never all peak together. Here’s a clear mid-April day for my three inverters, modeled from sun position and my real panel layout:

The west inverter peaks at about 7.2 kW around 3:25 PM, close to its 7.6 kW limit but under it. Powerwall+ #2 (mostly east) peaks at about 5.8 kW just after noon, and Powerwall+ #1 (south, east and north) at about 5.5 kW after 1 PM. Their peaks are hours apart. The whole roof tops out around 18–19 kW on a clear spring day, split three ways, so no inverter is near trouble. Across the year the pattern holds:

The west inverter reaches 7.2–7.5 kW from March to September and 5.2–5.9 kW in winter. The other two never get above about 6.2 kW. On a truly clear day, none of my inverters clip.

So where does my clipping come from?

Clouds. When the sun shines through a gap next to a bright cloud, the panels get the direct sun plus light reflected off the cloud edge. My highest 5-minute reading ever is 22.18 kW, at 12:35 PM on June 8, 2026: 12–25% above what my model says a clear sky could produce at that moment. Here’s a day like that:

That afternoon the whole system hit 21.6 kW, and I estimate the west inverter briefly “wanted” about 8.7 kW, so roughly 1.1 kW was clipped for a few minutes. Add up every spike like that and here’s what I get:

That’s about 10 kWh a year as a central estimate, almost all between 2 and 4 PM from April to August. Because I had to estimate how the total splits between inverters, I ran the numbers with different assumptions, and the plausible range is about 3 to 50 kWh a year. Against the 30,900 kWh the system made from October 2025 through September 2026 (Tesla app), that’s about 0.03%. At my top-tier FPL rate of 14.61¢ per kWh with tax (here’s why), it’s worth about $1.70 a year, somewhere between $0.40 and $7 (as of October 2026). Five-minute data smooths out the shortest spikes, so the true number is probably a bit higher (NREL on sub-hourly clipping), but it’s still a few dollars a year.

A side finding: my panels make only about a third of the modeled clear-sky output at 7 AM, and about half at 8 AM in March and October, because of trees and low sun. From 9 AM to 4 PM they match the model within a few percent. Morning shade costs me more than clipping does, roughly 1.8% of clear-day energy at most, and that’s an upper bound.

What if the same panels were on less inverter?

Here’s the useful part for anyone looking at a quote. I took my measured 5-minute output from October 2025 through September 2026 (real Florida weather, clouds and all), reshaped it for panels facing a single direction, and calculated how much would be clipped at different DC/AC ratios:

Three things jump out. Up to about 1.2, clipping is a rounding error in every direction. It climbs fast after 1.4. And direction matters as much as ratio: south-facing panels all peak together and clip the most, while a mixed roof like mine clips much less at the same ratio, because its faces take turns. My estimates line up reasonably with Enphase’s published Miami numbers (0.4% at 1.30, 1.4% at 1.39, 5.7% at 1.61), which are hourly and so expected to read a little low. I couldn’t find a published clipping study specific to Florida beyond those tables, so treat mine as one house’s estimate.

The 18 kW on one Powerwall 3 example

An 18 kW array on a single Powerwall 3 is a ratio of about 1.57. Using the curves above, valued at 14.61¢ per kWh (my FPL rate as of October 2026), here’s the estimated loss:

Two fair caveats. Panels lose a little output each year, which reduces clipping over time, and rates will change, so the 25-year column is just the first year times 25, not a forecast. More importantly, the Powerwall 3 can send some solar straight to its battery on the DC side, about 5 kW more, or 8 kW with an Expansion unit, according to Tesla’s DC sizing guidance. That rescues clipped energy, but only while the battery has room. On a sunny spring afternoon a battery that charged all morning is often full by 2 PM, right when a west or south array clips hardest. So the real loss is somewhere between zero and the table, and it depends on how the battery is used. My numbers don’t model that.

My opinion: design for production, not just the quote

This part is my opinion, so I want to be fair about it. Putting more panel than inverter is not a scam. It’s standard engineering: a second inverter costs real money, and losing 1–2% of a year’s energy to save that money can be the right trade. For a sense of scale, NREL’s benchmarks put residential inverter hardware at about $0.15 per watt AC for string inverters (2017) and $0.34 per watt DC for microinverters (2023). Going from 1.6 to 1.2 on an 18 kW array means adding about 3.75 kW of inverter. At the 2017 string-inverter benchmark that’s roughly $560 of hardware (3,750 W × $0.15), before labor, permits and markup. I couldn’t find a published price for a second Powerwall 3 or a standalone Tesla inverter, so treat that as a rough benchmark-based estimate, not a quote.

Where I think buyers get a bad deal is when the ratio is pushed high because it makes the quote look good, and nobody tells them what it costs. Quotes are compared in dollars per watt of panels. Less inverter per watt makes that number look better, while the clipping cost shows up later on your bill. On a mostly south roof at 1.57, my estimate is close to $300 a year. On a mixed roof it’s about $55. Those are very different answers, and the installer has the software to give you yours. Ask for it.

One piece of history here: Tesla offered a solar price match from 2020 (Electrek, May 2020) through at least March 2025, when its support page still listed the terms (archived copy). The terms compared price per watt for a comparable system size, and required the competing quote to include an inverter and a warranty of at least 10 years. It appears to be discontinued: the page now redirects to Tesla’s general support page, and a January 2026 owner post says it’s no longer offered (Reddit). I haven’t seen an official announcement. Either way, per-watt price comparisons say nothing about how much inverter you’re getting.

String inverters vs. microinverters

My system uses string inverters: panels wired in series into an inverter input, with Tesla’s Mid-Circuit Interrupters for rapid shutdown (up to five per string, per Tesla’s install manual). Microinverters put a small inverter on every panel. For clipping, the difference is:

• A string inverter shares its limit across all its panels. Mixed directions on one inverter help a lot, as my table shows. All-south on one inverter is the worst case.
• A microinverter’s limit is per panel, so mixing directions doesn’t help; the ratio is just panel watts over micro watts. Enphase’s IQ8M is rated 325 W continuous and the IQ8A 349 W (tech brief). A 425 W panel like mine on an IQ8M is about 1.31; on an IQ8A, about 1.22. Enphase sets no maximum ratio and says clipping is small next to other losses.
• Microinverters handle shade panel by panel, which a string can’t. Separate MPPT inputs on a string inverter get you part of the way.

Neither is automatically better. What matters is the effective ratio and direction of whatever is behind each limit.

My son’s system

My son lives in Fleming Island, which Tesla doesn’t service, so his isn’t a Tesla solar install: it has non-Tesla panels, one Powerwall 3 and a Powerwall 3 Expansion. I don’t know his array size yet. That Expansion matters for clipping, because it raises the DC-to-battery headroom. I plan to look at his data in a follow-up.

Questions I’d ask an installer

• What’s the DC/AC ratio, per inverter? Not for the whole system: for each inverter, or each microinverter.
• Which roof faces are on which inverter? All-south on one inverter clips the most; mixed faces clip the least.
• How many kWh a year will clip, and at what hours? Their design software can model it. Ask for the number in writing.
• What would one more inverter (or a second Powerwall) cost, and how many kWh would it recover? Then do the math at your own rate.
• How much clipped energy can go to the battery? On a Powerwall 3 (the current model), ask about the DC-to-battery path and whether an Expansion changes it.

What I’ll update

The per-string sensors started on October 24, 2026, so they haven’t seen a single spring or summer afternoon. Next year I’ll replace my estimated inverter split with measured numbers, check how often each inverter actually hits its limit, and see how much the morning shade really costs on each string. I’ll update this article after the spring and summer 2027 data is in.

Related: what my east, west and north panels really produce and my production vs. Tesla’s estimate.

— Rick

Sources

• Tesla Powerwall 3 datasheet (11.5 kW AC, 20 kW max solar, 6 MPPTs)
• Tesla Powerwall 3 system design: DC sizing
• Tesla Powerwall+ datasheet
• Tesla Powerwall+ install manual: specifications (battery 5 kW in / 5 kW out)
• Tesla Powerwall page (Powerwall 3 release date, specs for Powerwall 3, Powerwall+ and Powerwall 2)
• Tesla Powerwall Limited Warranty (USA), effective May 6, 2026; Tesla service manual: Single Powerwall+ to Powerwall 3 upgrade
• Tesla Solar Inverter datasheet and install manual specifications (DC/AC up to 1.7)
• Enphase: PV module and inverter ratings, IQ8 Series tech brief (March 2022)
• NREL: PV and storage cost benchmarks, Q1 2023; NREL: PV system cost benchmark, Q1 2017; NREL Annual Technology Baseline 2024, residential PV
• NREL: sub-hourly modeling and inverter clipping
• Electrek: Tesla solar price matching (May 9, 2020); Tesla price match terms, archived March 16, 2025; r/TeslaSolar, January 2026