r/EnergyStorage

Every single time I talked about installing my system, the internet "experts" and some of my buddies came out of the woodwork to tell me the exact same thing: "If you don’t get a battery, the whole system is completely pointless."
Well, it’s been up for three months now, and I’m glad I ignored them.
My setup is an 18.6kW solar array with a 17kW Huawei inverter. Absolutely zero battery storage. Instead of dropping thousands on chemical storage just to buffer a measly 4–6 kWh a day for most of the year, I did something else: I put in a public-facing EV charger. It gets used daily by tourists, and I charge 45c per kW.
If you look at the stats from yesterday, you can see exactly why a battery makes zero sense for my use case. That massive green and orange block on the graph is peak production matching my peak consumption perfectly. The EV charger is doing the heavy lifting right when the sun is hitting hardest. I am directly consuming and monetizing the energy the exact second it’s generated.
The numbers from yesterday alone (04/07/2026 in the screenshot):
Total generated: 116.42 kWh
Consumed straight from PV: 69.63 kWh (That means 93.99% of my daily power came directly from the sun)
Fed to the grid: 46.79 kWh
Pulled from the grid: A grand total of 4.45 kWh
I’ve already hit 7.49 MWh of lifetime generation in just three months.
On top of the day-to-day charging, part of my roof faces North-West. In the winter, a battery would just sit there completely empty, acting as an expensive paperweight.
People need to stop treating batteries like a mandatory rule of thumb. If your daytime load matches your peak generation—or if you can actually monetize your solar noon like this—a battery is just a black hole for your ROI.
Change my mind

Upgrading from 18 kWh to 27 kWh storage completely changed how much of our own solar we actually use

We’re in the San Francisco Bay Area, California.

When we first installed our system, we started with 10 kW rooftop solar and 18 kWh of Sigenergy SigenStor battery storage. On paper, it looked like more than enough.

After running the system for a little over a month, the energy data told a different story.

During the day, our 10 kW solar array easily covered the entire household load. It also fully charged the 18 kWh battery by the afternoon. After that, we were still exporting around 10 kWh back to the grid almost every sunny day.

The problem didn’t show up until the evening.

Once our EV came home and started charging, the same 18 kWh battery had to power both the house and the car. That extra demand drained the battery much faster than we expected, and we ended up importing electricity from the grid during peak hours.

Instead of adding more solar panels, we decided to expand the battery.

We simply added one Sigen BAT 9.0 module, increasing total storage from 18 kWh to 27 kWh.

The difference has been surprisingly noticeable:

* Much higher self-consumption of our own solar energy

* Less electricity exported to the grid during the day

* More stored solar available for EV charging at night

* Lower peak-hour grid imports

* Better overall energy independence

One thing I really like about the Sigenergy SigenStor platform is its modular design. Expanding the system was straightforward—we didn’t have to replace the original battery or redesign the system.

Looking ahead, if we add more high-power appliances (or even another EV), we’ll probably add another BAT 9.0 (9 kWh) or BAT 6.0 (6 kWh) module.

With AI workloads, electric vehicles, heat pumps, and increasing household electricity demand, I honestly think home battery storage is becoming less of a luxury and more of a necessity.

Has anyone else here found that adding battery capacity delivered a bigger improvement than adding more solar panels?

Finally got my EcoFlow DELTA 3 Plus working with a third-party 48V server rack LiFePO₄ battery using an expansion adapter.

Initially, I kept getting Short Circuit Protection (4) every time I energized the external battery and thought something was wired wrong.
Turns out the issue was simply that the DELTA was nearly full while the external battery was much lower. Once I got them to a similar state of charge, everything connected immediately.
Now the DELTA recognizes the battery and is charging/discharging it normally.

Pretty impressed with the flexibility this opens up. Instead of buying a proprietary expansion battery, it looks like standard 48V rack batteries are a viable option if you use the correct adapter and match the battery voltages before connecting.

A newly installed Battery Energy Storage System (BESS) in Exeter, UK, experienced a smoke/fire incident on June 22 at around 5:30 pm (BST), according to local reports.

The project, called Battery Box, is operated by Amp Clean Energy and is designed as a compact roadside energy storage solution for local grid support.

According to the company:

Smoke was reported from one cabinet associated with the grid connection point.

The BESS was safely shut down following standard safety procedures.

The battery system will remain offline while the investigation continues.

The company said there is currently no reason to believe the incident was related to the recent hot weather.

Devon & Somerset Fire and Rescue Service responded to the scene, isolated the battery storage unit from the nearby substation, established a safety cordon, and cooled the installation using hose reels.

At this stage, the cause of the incident has not been disclosed, and there are no confirmed reports regarding property damage or injuries.

Since the installation is located in a residential area, the event has renewed public discussion about BESS safety, fire protection, and siting.

Does anyone have additional information about this project or know whether the smoke originated from the battery enclosure itself or from the grid interconnection equipment? Interested to hear insights from people working in BESS or utility operations.

South Australia had a $20k price event on the evening of 21 June. Most batteries weren't ready for it.

Watch the SOC row at the bottom. Every battery starts the day with charge. By mid-morning they're near empty across the board. The price spike doesn't arrive until the evening, by then, many have nothing left to give.

Some seemed to see it coming, recharging through the afternoon and had meaningful SOC heading into the event. The bid heatmaps show positioning shifted through the day while others stayed flat.

Five SA batteries, five different approaches to the same day. The video is built from open AEMO data via NEMPulse.com.au

Would you expect the fleet to be this depleted before a price event?

If you're just getting into batteries this free to download pdf that covers everything in a simple A to Z might really help https://www.batterydesign.net/downloads/battery-a-to-z-glossary/