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Resolving Tesla’s Delayed Grid Charging Problem
Recently, we encountered an issue with Tesla's time-based control feature. Here’s what happened, how it affected customers, and the steps we took to resolve it.
Written by
Dean Dunning
Published on
August 25, 2025
Introduction
At Think Solar, we believe in being open with our customers. We celebrate the good stories about our installs, but we also talk about the challenges we face. More importantly, we explain how we fix them. This transparency builds trust.
Recently, we encountered an issue with Tesla's time-based control feature. Here’s what happened, how it affected customers, and the steps we took to resolve it.
What Is Time-Based Control?
Time-based control is a smart mode available on Tesla Powerwall 2 and Powerwall 3 batteries. Its purpose is to help households save money on power bills.
You enter your electricity plan into the Tesla app, and the system analyses your plan alongside your household’s energy use. Based on this, it decides the most efficient way to draw from the grid, battery, and solar power.
For example:
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In summer, it may export solar power first if rates are high, then charge the battery later.
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In winter, it often charges overnight at lower rates.
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It adapts to your habits over time, such as reduced heating use, and adjusts accordingly.
This intelligent management helps shift costs to lower rates, providing ongoing savings.
Can It Avoid Peak Periods?
Most peak periods in New Zealand last around four to five hours, depending on your power provider.
With a 13.5 kWh battery, many homes can avoid drawing power from the grid during those peaks. This leads to significant cost savings.
The Problem With The Firmware Update
Tesla regularly updates its software to improve performance. However, a recent update designed for the US market was rolled out to New Zealand and Australia too. It introduced a feature called delayed grid charging.
This feature did not align well with local power plans.
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Before the update: Batteries began charging at the start of off-peak times (for example, 11pm to 7am), reaching the needed levels overnight. At 7am, they discharged to cover the morning peak.
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After the update: Charging began much later, often just before the peak period. Batteries were not fully charged, forcing homes to use grid power during the tail end of the peak.
What Customers Experienced
The change meant customers paid peak rates for some of their power when it could have been charged off-peak. This added around 60 cents or more per day to peoples bills and while the difference may sound small, over a month, this amount adds up.
Customers were the first to notice something had changed. Through the Tesla app, they saw batteries charging differently and peak coverage dropping. Calls and emails started coming in, and soon it was clear the problem wasn’t isolated and we soon recognised a pattern across the Think Solar Group.
How We Fixed It
Every support query we receive is logged in our ticketing system. This process gives us a full record, escalates issues to our technical team, and ensures nothing gets overlooked. As reports came in, the pattern confirmed that this was a widespread issue.
As an accredited Tesla installer, we could escalate the problem directly with Tesla support, a channel not available to many providers in New Zealand.
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We provided detailed examples, showing before-and-after behaviours.
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Tesla initially issued one-off fixes, but with more than 1,000 systems across our fleet, we pushed for a large-scale solution.
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We escalated the case to their fleet manager and engineers, sharing data on the customer impact.
As a result, Tesla overrode the delayed charging function for all our sites.
Once in place, we ran spot checks on both reported and unreported systems. The results confirmed that Powerwalls were once again charging at the start of off-peak hours and covering peak periods in full. Normal service was restored.
What We Learned And Our Advice
This experience showed how even a small software change can have big consequences, especially when rolled out across different international markets.
Our key lessons were:
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Clear communication is essential when explaining customer impacts.
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Direct relationships with manufacturers, like Tesla, are invaluable.
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Having those links allowed us to fix the issue across our entire fleet quickly.
If you are not a Think Solar customer but own a Tesla Powerwall, we recommend checking your Tesla app. Look to see if charging is delayed or if peak coverage has dropped. If it has, contact your installer and mention the delayed grid charging bug. Tesla is aware of the issue and has a solution ready to apply.
Our Promise To You
We give peace of mind. When issues arise, we take ownership and work until they are solved.
It may take time, but we ensure your system performs as it should. If you ever have questions about your solar or battery system, please get in touch. We are here to help.
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