Tesla Powerwall not charging from solar?

Tesla Powerwall not charging from solar? Run these checks before you call Tesla

Battery troubleshooting · UK homes · Updated 3 November 2026 · Checked against Tesla’s owner manuals and the current Ofgem price cap

It’s a bright Tuesday, the app says your panels are making 3.1 kW, and your Tesla Powerwall is sitting at 18% doing absolutely nothing. I’ve looked at that screen in a lot of UK kitchens, and the battery is rarely the guilty party. Usually something upstream has gone quiet, or a setting nobody has touched since last winter is doing exactly what it was told.

Here’s the order I work through when a Powerwall isn’t charging from solar, before anybody picks up a phone. Settings first, Gateway readings a few steps later, and everything in between. Work down it properly and you’ll either fix the fault yourself or give Tesla (or your installer) such a clean description of it that the call takes ten minutes instead of an hour.

First, split the problem in two

Every “my Powerwall won’t charge from solar” call comes down to two questions, and you need an answer to both before anything else:

1. Is solar power actually arriving? Not “are the panels fine in principle”. Is power flowing right now, through the inverter, past the Gateway’s metering and into the consumer unit?
2. Is the Powerwall currently allowed to accept it? Mode, temperature, grid status, firmware and recall flags all get a veto.

The priority order inside the system never changes: solar feeds the house first, then charges the battery, then exports whatever’s left. So a Powerwall on standby in sunshine means either there’s no spare solar (question 1) or it’s been told not to take it (question 2). Everything below is just working out which.

If your battery isn’t a Tesla, the logic overlaps but the culprits don’t. My guide to why your solar battery isn’t charging covers other brands, tariff windows and inverter clock errors.

The 60-second checks in the Tesla app

Open the app and look at the power flow screen, not the energy totals. Four readings tell you most of the story: the Powerwall’s status line, solar kW now, home kW now, and grid kW (import, or export when you’re sending power out). Read them together and the fault usually narrows itself down.

Check 1: backup reserve and operating mode

This is the single most common “fault” I find, and it isn’t a fault. Open Settings in the app and look at two things: the operating mode and the backup reserve slider.

Mode matters just as much. This is how the three behave with solar on the roof:

While you’re in there, check the grid-charging option and any schedule. If a clever tariff set-up has been quietly working against you, I’ve written up that exact scenario in is Octopus Energy draining your solar battery?. The symptoms overlap heavily with this one.

Check 2: is your solar actually producing right now?

Now the question people skip because it feels too obvious. On a Powerwall 2 install the battery is AC-coupled. Your panels feed a separate solar inverter, and the Powerwall only sees what’s left after the house has taken its share. If that inverter is off, faulted or isolated after some work, the Tesla app shows solar at zero and the battery does nothing. Check the inverter’s own display or app, not just Tesla’s. On a Powerwall 3 the panels wire straight into the battery’s built-in inverter, so PV faults show up in the Tesla app itself.

And be honest about the season. Here’s what a typical 4 kWp UK roof delivers across the year:

Do the base-load sum on a grey January morning. Fridge, freezer, router, standby gadgets and a heat pump cycling add up to 0.7 to 1.0 kW easily. If the panels are making 0.6 kW, there is nothing left to charge a battery with, and “Standby” in the app is correct behaviour, not a breakdown. A 4 kWp array might only harvest 2 to 3 kWh across a whole December day. A cloud band rolling through does the same thing in summer for a few minutes at a time.

If production looks weak even allowing for weather, say half what an identical sunny day gave you last year, that’s a separate problem. My piece on solar panels underperforming walks through shade, degradation and string faults, and solar panels producing nothing gives you a ten-minute check if the app shows a flat line. Cross-checking the inverter’s own monitoring against the Tesla app is also where a lot of metering faults get caught. This rundown of the best solar monitoring apps lists what each platform will and won’t show you.

Check 3: Gateway status and CT clamps

The Backup Gateway is the meter and the brain. It measures what the house uses, what the panels make and what crosses the boundary with the grid, using current clamps (CTs) on the cables. The Powerwall decides whether to charge or export from those numbers alone. Get them wrong and a healthy battery behaves badly.

Two failure patterns dominate:

• Gateway offline. The app says “Not connected”, or the flow screen freezes on stale numbers. The usual triggers are a new router, a changed Wi-Fi password or a weak signal in a garage. A wired Ethernet connection is the steadiest fix. While the Gateway is down, solar charging can stall and export readings go nonsense.
• CT clamps misread. The classic symptom is your inverter’s own app showing 3 kW of solar while the Tesla app shows 0.0 kW and everything exports. Usually the solar CT is missing, on the wrong cable or facing backwards. The trigger is often innocent third-party work, such as an EV charger install, a consumer unit swap or loft cabling moved about, months before the “battery fault” appears.

Check the Gateway’s status in the app. If it’s offline, or the numbers have frozen, start there. If anything has been touched electrically in the house since the system last worked properly, tell whoever calls out exactly what and when. That one detail saves a diagnostic visit. If your export readings look odd too, my guide to a smart meter not sending export readings covers the supplier side.

Check 4: high grid voltage and the midday cut-out

This one is very British. Your network operator (the DNO) has to keep the supply at your cutout between 216.2 V and 253 V, which is 230 V minus 6% and plus 10%. Your inverter has its own limits under the G98/G99 connection standards. It trips when the voltage at its terminals averages above 253 V over ten minutes, and within about a second if a spike reaches roughly 262 V. On a sunny, low-demand day your own export current pushes the voltage at the inverter above the voltage at your meter, and the rest of the street is doing the same thing. A perfectly legal supply can still trip a perfectly healthy inverter.

The signature is a battery charging fine at 10am, then a sawtooth of charge-stop-charge-stop between 11 and 3, with export spikes in between and a “grid overvoltage” or “Vac high” entry in the inverter’s event log. The wording varies by maker. After each trip the inverter waits at least 20 seconds, then runs its own checks, so it normally restarts within one to five minutes. That’s why the sawtooth looks the way it does. On a Powerwall 3 the same trip shows as PV production dropping to zero, because the inverter is inside the unit.

The fix starts with evidence. Log the AC voltage at the moment of each trip and ask your installer to raise it with the DNO. You can find your DNO free on 105. The cheapest cures are often on your side of the meter, such as an undersized AC cable or a tired joint, or a modest export cap. If the network itself is above 253 V with your solar off, a transformer tap change is the DNO’s job and cost. Don’t let anyone nudge the trip limits in the installer menu on a whim, because they’re part of your connection agreement. My full piece on solar inverters tripping on high grid voltage covers who pays and what each fix costs.

For today’s purpose, just know this: if the event log shows voltage trips at the times your battery “went faulty”, the Powerwall is a witness, not a suspect.

Check 5: temperature limits

Batteries are chemistry, and chemistry has opinions. Tesla rates both Powerwall generations to operate from −20°C to 50°C, but rated to operate isn’t the same as charging at full speed. The Powerwall 2 owner manual says it may limit charge or discharge power at the extremes and gives 0°C to 30°C as the optimum range. Tesla’s Powerwall 3 Heat Mode white paper shows charging limited once the cells drop below 10°C and stopped below 0°C, which is why the Powerwall 3 heats its own cells. Discharging holds up longer than charging, which is why the symptom looks so odd. The battery runs the house fine but turns solar away.

In the UK that means two seasons of grumbles. The first is January, in an unheated garage or on a north-facing external wall, where cells sit cold overnight and morning solar gets rejected until the unit warms up. Most lithium home batteries behave this way around 0°C, as I explain in the cold section of my battery not charging guide. The second is high summer, in a plant room or dark corner with no airflow. Tesla says Powerwall 3 performance may be reduced above 40°C, so a heatwave can tip an enclosed unit into derating.

If the timing of your “fault” matches a cold snap or a heatwave exactly, you’ve probably found it. Snow sitting on the lower half of the array does the rest, halving production while the app insists it’s a clear day.

Check 6: after a power cut

If your complaint started the day after an outage, stop here. During a cut the Powerwall runs your backed-up circuits from the battery. Whether solar keeps topping it up depends on how your system was wired and whether the inverter sits on the backed-up side. A standard grid-tied inverter drops out within a second of the cut, because anti-islanding rules say nothing may feed a dead network. It can restart on the Powerwall’s supply once it sees a stable voltage. What the Powerwall can’t do is charge from the grid, because there is no grid.

When power returns, nothing snaps back instantly. Under G98/G99 the inverter must wait at least 20 seconds with voltage and frequency inside its limits, then run its own checks. In daylight that normally means one to five quiet minutes. Past 15 minutes, the usual suspects are a latched fault code, a tripped RCBO or isolator, a battery stuck in backup mode, or grid voltage too high for the inverter to reconnect. Sometimes a component comes back in the wrong state, such as a Gateway that still thinks it’s off-grid. My walkthrough of what G99 reconnection actually does after a power cut covers the timers and the tell-tale signs.

Check 7: Powerwall 2 recall limits

If you own a Powerwall 2 that went in between roughly November 2020 and December 2022, check this before you touch anything else. The recall started with an Australian notice in September 2025. The US Consumer Product Safety Commission followed on 13 November 2025 with recall 26-092, covering about 10,500 units sold between November 2020 and December 2022, after a faulty batch of cells from a third-party supplier. The UK hasn’t issued its own recall notice, but a small number of UK units sit inside the affected batch, and Tesla’s free replacement programme applies to flagged units regardless of country. Powerwall 3 isn’t part of it.

The reason it belongs in a not-charging guide is that Tesla can limit charging on affected units, or remotely discharge them for safety, until the replacement is fitted. UK owners report “Powerwall Disabled” alerts. If that’s what you’re seeing, a reboot won’t fix it.

What I’d do:

1. Keep the system online. Recall notifications and the remote safety discharge only reach connected units, so switching it off “just in case” blocks the fix.
2. Open the Tesla app and look for a recall alert. Then check the model and serial number on the nameplate on the side of the unit.
3. If you’re inside the window but have no alert, email Tesla support with your serial number and ask in writing whether your unit is in the programme.
4. Expect to be pointed to your original installer to book the swap. Owner reports through mid-2026 describe two to three months between the discharge and the replacement, so don’t plan around the battery being back next week.

Lost savings while you wait are considered case by case, and it pays to log them from day one. My Powerwall recall guide has the full serial check, and the Powerwall 2 compensation claim guide shows what you can realistically claim.

The safe reboot sequence

Half of all comms gremlins clear with a proper ordered restart, done once and calmly. Screenshot your settings first. If Tesla support or your installer has given you a different sequence for your install, use theirs. Otherwise this is the order I use, and it only touches switches you already use day to day:

1. Switch off the solar PV isolator (usually near the inverter or in a loft or hallway box).
2. Switch off the inverter at its isolator or its own on/off switch.
3. At the consumer unit, switch off the Powerwall breaker and the Gateway or battery spur.
4. Wait a full 60 seconds. Longer is fine. Impatient is not.
5. Reverse the order: Gateway or battery spur on, Powerwall breaker on, inverter isolator on, PV isolator on. If your inverter manual gives a different order for AC and DC, follow the manual.
6. Leave it alone for 5 to 10 minutes. The Gateway boots, finds the network and re-reads the metering, and the Powerwall rejoins the app. Rushing this and “testing” at minute two causes more false fault reports than anything else I see.

Do it once. Cycling the isolators repeatedly just restarts the self-checks and wears the relays. If a lockout-type code comes back after the restart (earth fault, arc fault, RCD or contactor), stop resetting and book the fault in. If the symptom survives one clean reboot with correct settings and confirmed solar production, you’ve earned your phone call, and you now have a precise story to tell.

Powerwall 2 vs Powerwall 3: same symptom, different suspect

Generation changes where you look. Powerwall 3 launched in the UK in August 2024, with the first installs that September, and Tesla stopped selling new Powerwall 2 units soon after. So an install from late 2024 onwards is almost certainly a Powerwall 3. An earlier one with a separate solar inverter on the wall beside it is a Powerwall 2. The model name is on the label and in the app.

The deeper comparison, including whether an upgrade makes sense, is in my Powerwall 3 vs Powerwall 2 head-to-head. If you’re weighing a replacement rather than a repair, current installed prices are in my Tesla Powerwall UK cost guide for 2026.

What the downtime actually costs you

Worth knowing, because it stops the panic. A Powerwall that isn’t charging doesn’t usually waste your solar. It exports it, so you get your SEG rate instead of saving the full unit rate. The Ofgem price cap puts imported electricity at 26.32p per kWh (national average, direct debit) until 31 December 2026, and a new cap starts on 1 January. SEG tariffs run from about 3p to 32p a unit depending on the supplier and tariff, with most open-market fixed rates nearer 13p. I use 7p in my own sums across the site.

So a day when 5 kWh that should have gone into the battery is exported at 7p instead of offsetting 26.32p units costs you about 97p. Annoying over a month, but this is a leak, not a haemorrhage. It’s also why I’d rather you spend an hour diagnosing properly than pay for a panic call-out, which typically runs £80 to £150 for a diagnostic visit.

To put real numbers on your own export, my SEG income estimator does the sum from your tariff and generation. If your export readings look as broken as your charging, the metering fault in Check 3 is very likely the shared cause.

Who to call, and when

Hardware does fail, and these are the signs I’d never ask you to live with:

• Explicit system errors or battery warnings in the app, such as contactor faults, BMS errors or a “Powerwall unavailable” message that survives a clean reboot.
• A unit that’s hot to touch, swollen, noisy in a new way or smells of burning. Isolate if it’s safe to reach and call immediately, with no diagnostics.
• Capacity that has collapsed far beyond normal ageing, or a unit that won’t hold charge off-grid at all.

Then the question of who:

Your Powerwall warranty is Tesla’s, not your installer’s. It runs for 10 years, with a 70% capacity guarantee on the Powerwall 3, and it carries on if your installer goes bust. The installer’s workmanship cover is separate. It’s at least two years and commonly five to ten, and MCS is moving certified installers to approved financial protection of at least six years by 31 March 2027. Installers certified under the MCS scheme should put configuration faults inside that window right for free. My guide to what solar warranties actually cover explains the exclusions that catch people out, and what to do if your installer has gone bust covers the rest.

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