WHO THIS GUIDE IS FORHomeowners with an existing grid-connected solar system who want to assess a battery retrofit.
Identify the inverter—not just the panel brand
Find the inverter model, installation date, original proposal and warranty records. “Battery-ready” in an old brochure is not proof that a particular battery can be connected today. Ask the installer to verify the exact equipment combination against current manufacturer documentation.
Include fault history and monitoring access. If the inverter is unreliable or the solar array also needs attention, make that a separate part of the brief so you can distinguish a necessary repair from an optional upgrade.
Photograph labels only from a safe, accessible position. Missing records are a reason to arrange an assessment, not to open an enclosure or climb onto the roof.
Check what you export and buy after sunset
For a household focused on evening use, compare daytime exports with evening and overnight grid imports across seasons. Ask whether your current array produces a recurring surplus and how much of the proposed battery could reasonably be used.
If the goal is backup rather than bill savings, state that first. A reserve for outages changes how storage is operated. A payback estimate should explain the tariff, reserve, charging assumptions and losses; it is not a guaranteed outcome.
- A year of consumption and export data, where available.
- Typical evening loads and any overnight EV charging.
- Backup priorities stated separately from savings goals.
- Planned changes to the existing solar system.
Compare the three retrofit conversations
AC-coupled systems use a battery inverter alongside solar equipment; DC-coupled arrangements use a compatible hybrid inverter. Neither description proves suitability for your existing installation. The proposal should identify the actual products, controls and required works.
| Possible approach | What to confirm | Why it matters |
|---|---|---|
| Retain the solar inverter | Can a separate battery system operate with the existing installation? | Avoid assuming that a battery enquiry requires a full solar replacement. |
| Use an existing hybrid inverter | Which batteries and firmware does this exact model support? | A hybrid label does not establish universal compatibility. |
| Replace the inverter as part of an upgrade | Which scope is needed for storage, and which is an optional solar upgrade? | Compare the combined works and support responsibilities, not an isolated battery price. |
What the retrofit quotation must make explicit
Ask for a retained/replaced/added equipment list. Have the installer describe switchboard work, cable routes, proposed battery location, connection approval and commissioning. Do not assess a location from a promotional photograph; siting and clearances require a professional check.
Request one clear support pathway for faults in the combined system, plus the warranties that apply to each retained and new component. If backup is included, the circuit list and operating limits belong in the written scope.
A retrofit should answer “what changes to this home?” A product sheet alone answers only “what can this product do under its specified conditions?”
Sources & further reading
General information, not a site-specific design, installation instruction or financial recommendation. Equipment suitability, approvals and project outcomes require an individual assessment. Never work on electrical equipment yourself.
