Solar Photovoltaic and Batteries

You can model the impact and benefit of Solar Photovoltaic (PV) systems along with Batteries within your project in the Solar and Batteries section of the Appliance View.

Solar systems in Hero are considered as 3x separate components: Solar Arrays, Inverters and Batteries, all of which can be added separately from each-other and in any quantity required.

Solar PV & Battery Calculations in NatHERS WoH

Solar PV and Battery Systems will supply any electricity demand of the house prior to any Grid Electricity being supplied on a hourly basis. This is the PV Supply result value shown throughout Hero.

If the hourly solar production exceeds the inverter capacity, then the excess solar power will be curtailed and lost/dumped (this counts towards the PV Curtailed value in Hero).

If there is still excess solar PV power beyond the home's electrical demand, and if there is a battery that still has storage capacity, then the PV power will be supplied to the battery to charge it (we call this the PV Battery Charging value in the Hero hourly results viewer) based on the battery's characteristics as explained below.

If there are no batteries or the batteries are fully charged, then any excess solar PV electricity will be exported to the grid with a feed-in tariff cost credit received for that energy, and the electricity is treated as a net-negative energy or emission value. This is called PV Export in the results areas of Hero.

There are limits on export capacities for most electrical networks in Australia on a per phase basis (and some sites may even be completely prevented from exporting any excess PV power). If the excess solar power exceeds this export capacity, then this energy is also curtailed (this counts towards the PV Curtailed value along with any inverter curtailment). 

If there is insufficient solar power to supply the electrical demand but there is available battery capacity, then the battery will meet the load according to it's battery characteristics (see below). This is called the Battery Supply value across Hero.

Any further electricity beyond this will then be supplied by Grid Electricity.


1 - Regulated Load

Solar and Batteries are Regulated Loads that contribute to the NatHERS Whole of Home rating if added, but are not required to achieve a WoH Rating.


2 - Add new Solar System group

You can model multiple separate Solar Systems (a system being a combination of arrays, inverters and batteries) as required for your project, such as where various solar systems are being installed across different dwellings in a multi-dwelling project. 


3 - Group Label

If you have multiple Solar groups you can rename the group label to make it clear what the group represents.


4 - Add Solar PV Array, Inverter, Battery, Remove Group Buttons

You can add multiple Solar PV Arrays, Inverters and Batteries into a group using these buttons, or remove the group entirely using the delete button.


5 - Array Section

Inside each Solar PV Array section you'll enter the information on each Solar PV array that is installed in a different orientation or pitch. An array is a collection of individual solar panels, with multiple arrays being possible for any system.


6 - Array Capacity

Enter in the total rated capacity of the panels included in this array in kilowatts peak. This may be higher than than the inverter capacity but you should be mindful of oversizing limits of solar inverters that may apply to your project (e.g. a maximum oversizing ratio of 1.5 or 150% is common however you should confirm your solar inverter supplier).


7 - Array Area

As an alternative to entering the array capacity, you can enter in the proposed area or pitched area, which will then provide an estimate of solar PV potential based on a area rate of 6.8 m2 per 1 kW of panels (currently this is fixed but this will be variable in future).

The "Area" value is the flat area as might be calculated from PDF floor plans, whereas the "Pitched Area" would be the true area of panels required on the roof depending on their pitch, both of which are of value.


8 - Array Azimuth

Enter the Azimuth of the PV array (i.e. the orientation the panels face) in degrees, which will then show the orientation value (i.e. N, NE, E etc.).

The Azimuth is the direction the panels facing in a normal direction, i.e. where the solar radiation is coming from. E.g. in Australia, the most solar productive azimuth is for panels to face north.


9 - Array Pitch

Enter the pitch of the PV array in degrees. A pitch of 0 degrees would be a flat panel, a pitch of 45 degrees would be . If you enter a pitch beyond 90 degrees, Hero will flip the Azimuth 180 degrees and reset the pitch to within 0-90 degrees to avoid confusion (i.e. a 135 degree pitch facing North is more properly just a 45 degree pitch facing South).


10 - Array Shade Factor

This not a NatHERS Regulatory requirement that assessors should estimate the shading factor over any arrays, however you can optionally enter in a simple shading factor that will reduce the solar array production by that proportion on a hourly basis, which can help to produce more accurate assessments of true solar PV production.


11 - Second Array example

This section shows how a second PV array has been added into the project, with a different orientation. 


12 - Inverter Section

This section shows the inverter of the system.


13 - Inverter Capacity

Enter the maximum capacity of the installer inverter(s) in kW. Any Solar PV generation that exceeds the inverter capacity will be curtailed (and dumped) and presented in the Curtailed section of the Solar Results. Hero will show a warning alert if the oversizing ratio exceeds 150%.


14 - Battery Section

This section shows any batteries that have been added to the system.


15 - Battery Types

There are currently three types of batteries that can be added to a project, each with different charging and discharging efficiencies and characteristics. 

Battery Characteristics:

  • Depth of Discharge (DoD): The DoD is the measure of much of the battery's capacity can be safely depleted on a cycle before potentially damaging the battery. E.g. a DoD of 0.9 means that a battery can safely discharge 90% of it's overall capacity, with 10% of the capacity always being kept in reserve. 
  • Charge Limit: The Charge Limit (c rating) is how much of the battery's capacity can be charged in one hour. E.g. a charge limit of 0.5 would mean that half of the battery's capacity can be safely charged in one hour.
  • Charge Efficiency: The charging efficiency represents how much of the input solar electricity is stored into the battery, with the remainder being losses. E.g. a charging efficiency of 0.92 would mean that 8% of the solar PV energy supplied to the battery is lost to heat and other losses.
  • Discharge Efficiency: The discharge efficiency is the proportion of output battery stored energy that will be delivered as useable electricity to the demand load. E.g. a discharging efficiency of 0.87 would mean that when the battery depletes it's capacity by 1kWh it would only deliver 0.87kWh of power to the demand load.

Available battery types:

  • Lithium Ion:  Lithium ion batteries have become one of the most popular battery technologies in recent years and come in many varieties and configurations such as micro-batteries up to larger systems. They are typically lighter than lead acid batteries, with higher charging efficiencies and greater depth of discharge and charge rates, however come with some downsides such as fire risks and recyclability. 
  • Lead Acid: Lead acid batteries have been historically the most common battery technology for solar. They tend to be heavier than other battery technologies, and cannot be discharged as far, have slightly lower charging efficiencies and charge limits, however still represent a feasible option.
  • Zinc Bromine: Zinc Bromine batteries are a less common type of battery technology with a greater depth of discharge capability and potentially greater lifespans., albeit with slightly lower charging/discharging efficiencies and charging rates than Lithium Ion. 

Battery characteristics in NatHERS WoH:

At this stage you cannot vary the characteristics of batteries under NatHERS WoH.

Battery Type Depth of Discharge Charge Limit Charge Efficiency Discharge Efficiency
Lithium Ion 0.9 0.5 0.92 0.92
Lead Acid 0.5 0.2 0.895 0.895
Zinc Bromine 1.0 0.25 0.87 0.87


16 - Battery Capacity

Enter in the maximum storage capacity of the battery in kWh (kilowatt hours). Depending on the Battery Type, this capacity will be depleted to a maximum depth of discharge of this total capacity.


17 - Solar Results

As per all Appliance categories, the individual results of the Solar & Batteries are shown in each section along with the percentage impact of Solar to the overall Operational Energy, Running-Cost and Operational Emissions of the Project. You can hide this Category Result in the Settings section of the Appliance View.

The Solar Results section however has a range of additional results that can provide additional information to the user including:

  • PV Supply: Amount of Solar PV power directly supplying electricity demand (excluding batteries) after any inverter curtailment has been calculated.
  • PV Export: Amount of Solar PV power that has been exported to the grid after export curtailment has been calculated.
  • Battery Supply: Amount of Battery power directly supplying electricity demand in the home after charging losses have been calculated.
  • Utilisation: The Utilisation rate is the proportion of Solar Power that is used on-site be it directly supplying power or charging batteries. Given feed-in tariffs are consistently being reduced across Australia, utilising the most of your produced solar power on-site allows you to maximise the benefit. By shifting demand patterns (such as hot-water heating and other appliances) we can increase the on-site solar utilisation rate. Adding a battery to a solar system can therefore drastically increase the utilisation rate by reducing the amount of electricity exported.
  • Sufficiency: The Sufficiency rate is the proportion of overall electricity demand of the house that is met by solar or battery power. A theoretical fully renewably powered home would have a self sufficiency rate of 100%.


18 - Solar Comments

As per all Appliance categories, you can add your own comments, description, recommendations or explanations to the Solar section to include in your report exports. You can hide this Comments section in the Settings section of the Appliance View.


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