u/Admirable-Size-4951

This is a typical small commercial solar-plus-storage project designed to provide an uninterrupted power supply while reducing electricity costs for a biological laboratory.
The primary application is to ensure reliable power for a laboratory that stores a large number of temperature-sensitive vaccines and biological samples. These materials must remain in a strictly temperature-controlled environment at all times. However, as AI data centers (AIDC) have rapidly increased in both electricity demand and scale over the past few years, they have placed significant pressure on the local power grid. As a result, power outages have become increasingly frequent, making backup power essential to prevent temperature fluctuations that could compromise valuable laboratory assets.
To address these challenges, the customer decided to install a 50 kW rooftop solar PV system to maximize self-consumption and reduce dependence on the utility grid.
The system consists of a Growatt WIT 55 kW 208 V Three-Phase Hybrid Inverter paired with a Pytes 48100HV SE 61.44 kWh Outdoor Battery Energy Storage Cabinet. During the day, the solar array supplies electricity directly to the laboratory’s loads, while excess solar energy is stored in the battery system. At night, the laboratory is powered by the battery system to further reduce electricity costs. To ensure emergency backup capability, the battery’s maximum depth of discharge is limited to 50%, reserving sufficient energy to provide backup power during unexpected grid outages and maintain stable laboratory operations.

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?

It takes a whole long weekend to install and setup the Sigenergy SigenStor All-IN-ONE system:

- 11.5kW AC output with a peak output 17.1kW wiring 440W * 26 PV system

- 2 Sigen BAT 9.02kWh for total 18.04kWh capacity

- 200A loading hub with 5 double-pole controllable breakers.

this system will cut the electricity bill by about 75% as originally planned. Later, based on the system performance and actual power consumption, plan to expand the current system by adding one or two BAT 9.0 (9.02 kWh) batteries to increase the backup capacity, with the goal of getting close to off-grid operation.