Understanding the Consumption task (WIP)

How does the consumption task estimate self-consumption?

The consumption task compares the output of the modelled PV system with the consumption. To do this we take the total generation figure from the performance task and model this across the year using a PVGIS generation profile. This profile is based on the number of panels, where they are in world and which orientation they are facing. We then compare this against the selected consumption profile.

Using these profiles Easy PV then looks minute by minute over the course of the year at how much is being generated, how much is being consumed and how charged the battery is and diverts the energy accordingly, factoring in the charge rate of the battery.

The self-consumption is then calculated based on the proportion of electricity generated that is consumed on the property (directly or via the battery).

Whats the difference between MCS and Easy PV self-consumption calculations?

	MCS (UK only)	Easy PV
Easy PV task	Completed at the end of Performance task, select MCS in Financial task to use	Completed in Consumption task, select Easy PV in Financial task to use.
System size	Consumption: 1500-6000kWh Generation: <6000kWh Usable batter capacity: <15.1kWh	Any consumption, generation or battery capacity
Consumption profile	Domestic profiles: home all day, home half the day and out all day	Domestic, commercial consumption profiles or half-hourly data from customer
Method	Compares annual generation and determines self-consumption based on look-up tables.	Compares generation and consumption profiles minute-by-minute across the year to determine self-consumption
Additional options	Limited since it only compares annual figures.	Minute-by-minute calculation means export limits, inverter clipping, variable tariffs and forced charging/discharging of batteries are factored into calculations

For IE users, only Easy PV method is available.

Understanding consumption data

Once you have configured the Consumption task inputs and submitted them, you can explore the calculated information.

The left-hand side shows the full results of the consumption task calculations with interactive graphs and detailed insights. For each section, the top graph gives you the annual figures in kWh and the bottom graph gives daily figures in kW.

All graphs use the following key to help you understand the generated data:

Generation

This shows the estimated annual generation of the system and whether the generated energy is used directly in the house, used to charge the battery or exported to the grid.
It will also show inverter and export limitation clipping if you've turned this on.
Bottom graph can help understand export rates, export clipping or inverter clipping, with figures given in kW

Consumption

This shows the total annual energy consumption of the property and where this energy will come from.
It shows how much energy is expected to be supplied directly from the solar array, via the battery or imported from the grid.
Top graph useful to see how consumption is being met at different point in the year

Import and export

This shows the likely flow of energy to and from the grid over the course of a year.
It's likely that there will be more energy exported during summer when the solar array is generating more energy, and more energy will be imported from the grid during winter months.

Financial benefits

This shows the money spent and earned on electricity flowing to and from the grid over the course of a year based on selected tariffs.
It allows you to see the total money earned from export payments versus the money spent on imports, and how would compare to having no solar installed.

If you would like to use the Easy PV self-consumption calculations as the basis for your financial projections in the customer proposal, make sure it is selected in the financial task.

Battery utilisation

This helps you understand the modelled utilisation of the battery over the course of the year based on the amount of the the available battery capacity that is actually charged and discharged each day.
Utilisation of over 100% is possible at times where a battery is charged and discharged more than once during a day.

Low battery utilisation can be due to either insufficient PV generation to charge the battery (often the case in winter, or on cloudy days), or because loads are small overnight and the battery does not fully discharge. If you have low battery utilisation you may want to reduce the size of the batteries or recommend forced charging of the batteries on an overnight tariff to the property owner.