How Battery Storage Works in a Solar PV System

If you're considering solar panels for your home or business, you've likely heard about battery storage. But how exactly does it work—and is it worth the investment?

In this blog, we’ll explain how battery storage integrates with your solar PV system, using a real-world example: a 10-panel (4.4kW) solar system paired with a Fox EP5 battery.

☀️ The Basics of a Solar PV System

A standard solar PV (photovoltaic) system includes:

• Solar panels to generate electricity from sunlight

• An inverter to convert DC (direct current) electricity into AC (alternating current) for use in your home

• A generation meter to track how much electricity your system produces

• Optionally, a battery, to store excess energy for later use

During the day, your solar panels produce electricity. If you're at home and using appliances, the solar power is used immediately. But what happens when you're not home?

🔋 Introducing Battery Storage: Why It Matters

Without a battery, any unused electricity is exported to the grid. While you may earn a small payment for this via the Smart Export Guarantee (SEG), it's usually more cost-effective to store that energy and use it yourself later.

That’s where the Fox EP5 battery comes in.

⚙️ Real-World Example: 10 x 440W Panels + Fox EP5 Battery

Let’s look at a common domestic setup:

• 10 x 440W panels = 4.4kW system

• Estimated generation (London/South East): ~4,200kWh per year

• Battery: Fox ESS EP5 – 5.18kWh usable storage capacity

👉 Here’s how it works:

1. Daytime Generation
   Your 10 solar panels produce electricity when the sun is shining. Let’s say you generate 15kWh on a sunny day.

2. Immediate Usage
   Your home uses electricity as needed—fridge, lights, washing machine, etc. Let’s assume 5kWh is used directly.

3. Battery Charging
   The excess 10kWh is used to charge your Fox EP5 battery. Since it has a 5.18kWh usable capacity, it fills up and stores this for later.
   ✅ Importantly, the Fox EP5 is a DC-connected battery, meaning it charges directly from the solar panels before the electricity is converted to AC by the inverter. This results in greater efficiency, as there are fewer conversion losses.

4. Evening/Night-Time Usage
   Once the sun goes down, your home draws power from the battery instead of the grid. You can run your home into the evening without paying for electricity.

5. Selling Excess to the Grid
   If your battery is full and you're still generating surplus energy, the excess is exported to the national grid. Through a Smart Export Guarantee (SEG) tariff, you’ll get paid for every unit of electricity you sell back.

6. Grid Use (Only When Needed)
   If you use more electricity than the battery can store or deliver, your system automatically draws the remainder from the grid.

💸 How This Saves You Money

• Use more of your solar power (instead of sending it to the grid)

• Reduce your reliance on your energy supplier

• Get paid for excess energy via your SEG tariff

• Protect against rising electricity costs

• Take advantage of time-of-use tariffs (charge the battery with cheap overnight grid electricity in winter months)

With a system like this, it’s common for homes to become up to 75% self-sufficient in electricity across the year.

🔌 Why We Recommend the Fox EP5

The Fox EP5 battery is a sleek, modular lithium battery with:

• 5.18kWh usable storage

• DC connection for higher round-trip efficiency

• Long lifespan (6,000+ cycles)

• 10-year warranty

• Seamless integration with Fox inverters

• Remote monitoring via app

It’s ideal for homeowners looking to dip into battery storage without overspending, with the option to add more capacity later.

🏡 Is a Battery Right for Your Home?

If you:

• Use electricity in the evenings

• Want to make the most of your solar panels

• Plan to future-proof against rising energy costs

… then a system with battery storage, like the Fox EP5, could be a smart long-term investment.

✅ Need Advice or a Free Quote?

We install solar PV and battery systems across London and the South East. If you’re curious about how a battery could benefit your home, we’re happy to help.