Set your Solar system and Battery size

H

Hermes

Last updated on Jul 27, 2026

It's now quite common for solar plans to include stepped rates or capacity limits that impact the feed-in tariff revenue that can be achieved for that plan. For example, a retailer might offer a solar plan available only to households with solar systems rated 10kW or less.

Similarly, some plans are available only for battery-equipped households, and may also feature eligibility restrictions based on battery capacity.

Bill Hero will include or exclude these kinds of solar- and battery-capped plans from your results once it knows your solar system's kW rating. Solar system sizing and battery data information are generally not visible in your bills, so you need to tell Bill Hero the system directly.

You can do this via the Subscriber Portal.

Solar system size refers to the inverter rating

There are two main components in a solar system: the panels on your roof and the inverter that converts the direct current (DC) electricity they generate into alternating current (AC) power for use in your home.

It's common that the aggregate capacity of the panels on your roof will exceed the inverter rating.

đŸ›ˆ Solar Panel Capacity

The rated capacity of a solar panel is the power it will generate under standard test conditions, measured in watts (W). There are 1000 watts in 1 kilowatt (kW).

Under ‘standard test conditions’, a new solar panel rated at 350 W will generate 350 W of power. But in practice, the actual power generated will be less than this, and depends on:

  • climate zone

  • weather conditions

  • time of day and the season

  • location

  • slope of the panel

  • the direction the panel faces

  • dirt, debris or shading on the panel

  • wiring and other system factors.

A home solar system might include 19 x 350 Watt panels, so the system size would be 6,650 Watts or 6.65 kW.

However, the inverter is typically smaller than the panel output. For example, a 6.6 kW solar system will often be paired with a 5 kW inverter.

The panel rating is a 'best case' power output benchmark, and in real life, they will rarely, if ever, actually output power at the full rated capacity, so an 'under-specced' inverter makes sense.