# NEW: Add a battery to an existing solar system

**URL:** https://forum.cleanenergyreviews.info/t/new-add-a-battery-to-an-existing-solar-system/3551
**Category:** Photonik
**Tags:** feature, pro-feature
**Created:** [January 23, 2026, 5:29pm UTC](https://forum.cleanenergyreviews.info/t/new-add-a-battery-to-an-existing-solar-system/3551 "2026-01-23T17:29:37Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Marty](https://forum.cleanenergyreviews.info/user_avatar/forum.cleanenergyreviews.info/marty/32/4032_2.png) [@Marty](https://forum.cleanenergyreviews.info/u/Marty)
#### Post date: [January 23, 2026, 5:29pm UTC](https://forum.cleanenergyreviews.info/t/new-add-a-battery-to-an-existing-solar-system/3551/1 "2026-01-23T17:29:37Z")

</div>

# Calculate the payback of adding a battery to an existing system

With the new STC battery rebate in Australia, adding a battery to an existing solar system can make a lot of sense.

Now, using Photonik design tool, you can model the savings and payback period of adding batteries to an existing system.

 ![Add existing panels to a project to model total solar generation](https://perform.discoursehosting.net/uploads/db8135/original/2X/0/083453e03e6bd2b5d94bf307c20fff53d2a1b15b.png)  
 ![Add batteries to an existing installation to model payback](https://perform.discoursehosting.net/uploads/db8135/original/2X/4/4023e0a65530f34da54f9203b823dcae4665a94f.png)

## Adding a battery can save you nearly $1000 a year and make you 86% self sufficient

The results are quite surprising. The ROI for adding a battery to a system is comparable to adding solar panels. This is a dramatic change from a few years ago when battery prices were higher, and even from before the battery STC rebate, which has made a huge difference in the financial viability of a home battery.

Below is an example of a project in NSW (STC zone 3).

- 🔋 Adding: 9.6kWh battery to an
- 🔆 Existing: 6.8kW solar system

The payback is just over 4 years. Until recently the payback of adding a battery was longer than the expected life of the battery itself. Without the STC rebate, the payback would be twice as high.

 ![ROI for adding a battery to an existing solar system](https://perform.discoursehosting.net/uploads/db8135/original/2X/9/99b9cb002e75753a901ea15ec62f5618f9b1f989.png)

 ![image](https://perform.discoursehosting.net/uploads/db8135/original/2X/8/84f444714e954cc0450596e8ac33d90b420260ae.png)

Check out the feature, and lets us know what you think.

Marty

> **[Free Solar Savings Calculator — Costs & Payback | Photonik](https://www.photonik.solar/)**
>
> Free solar planning tool. See your system size, costs, savings and payback for your home in 2 minutes — no signup required. Plan solar, batteries and EV upgrades.