# Performance and consumption task A detailed guide on the consumption task can be found here. # Where is section C, D and E of the performance report? These sections are displayed in both the **MCS performance report** and the **performance and battery pages of the customer proposal**. You can find the performance report from the 'forms' drop-down or by clicking the **⋯ three dots** in the top corner of the [Performance task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/performance-task "Performance task"). Easy PV will only show these sections in the MCS performance report if the [MCS self-consumption calculation](https://help.easy-pv.co.uk/books/performance-and-consumption/page/performance-task "Performance task") has been completed. The MCS method can only be completed if the generation is less than 6000kWh, the consumption is between 1500-6000kWh and the usable battery capacity is less than 15.1kWh. An alternative method is offered in the [Consumption task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/getting-started-with-the-consumption-task "Consumption task"). As long as the Easy PV or MCS method is selected in the [Financial task](https://help.easy-pv.co.uk/books/financial-task/page/using-the-financial-task "Financial Task"), the equivalent to section C and D (if there is a battery) can be found in the bottom left corner of the performance and battery storage pages of the Customer Proposal. If there is no battery, sections A-C will appear in the bottom left corner of the performance page.

# How are sunpath diagrams automatically calculated in 3D? The sunpath diagrams maps the path of the sun across the sky at different hours in the day for different months of the year. For each point on the sunpath diagram, Easy PV calculates the amount of solar radiation reaching the panels from direct and diffuse radiation. For shaded regions, where direct radiation is radiation is fully blocked, the system calculates how much diffuse radiation still reaches the panels. The shading factor is the proportion of solar radiation that reaches the panels after accounting for these shading losses. # What is self-consumption? Self-consumption is the amount of electricity generated that is then consumed within the property. This could be directly or via a battery. As a percentage, the definition is: **Self consumption = Solar PV electricity consumed within property (kWh) / Solar PV electricity generated (kWh)** Energy that is not self-consumed is then exported to the grid. A higher self-consumption typically means a faster payback period since this reduces the amount spent on energy bills. Read here for guidance on how to [reduce your payback period](https://help.easy-pv.co.uk/books/faqs/page/the-payback-period-is-too-long-how-can-i-fix-this "The payback period is too long, how can I fix this?"). # The MCS self-consumption calculation doesn't work for my project - why? The MCS calculations won’t work for projects with an annual generation greater than 6000 kWh, annual consumption not between 1500-6000kWh or with battery storage over 15.1kWh. For these situations, we recommend using the Easy PV [Consumption task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/getting-started-with-the-consumption-task "Consumption task") to generate accurate system projections and then ensure you select the Easy PV calculations in the [Financial task](https://help.easy-pv.co.uk/books/financial-task/page/using-the-financial-task "Using the financial task"). # Why has the generation not changed after adding optimisers? Adding optimisers in the inverter task will not automatically change the generation. The generation is a product of the kWp of the inverter, the kk value (which itself is based on the pitch, orientation and location of the panels) and the shading factor. If panels remain grouped the same, their shading factors and kk value will not change. With optimisers, you can put panels in separate **shading groups**. This allows Easy PV to factor in differences in the kk value and shading factor for the panels in each group on a single string. Without shading groups the generation will not change because the kk value and shading factor will be the same on the whole string, as it would be without optimsers. # How does the Consumption task estimate self-consumption? Easy PV simulates generation, consumption and battery usage across a full year to estimate how much solar energy is used on site. The [self-consumption](https://help.easy-pv.co.uk/books/faqs/page/what-is-self-consumption "What is self-consumption?") is the proportion of electricity generated that is consumed on the property (directly or via a battery). To determine how much is used in the property, we use the total generation figure from the [Performance task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/performance-task "Performance task") and model this across the year using a PVGIS **generation profile**. This is then compared against the chosen **consumption profile**. Easy PV looks **minute-by-minute over the course of the year** at how much energy is generated and consumed and, if present, how charged the battery is. It then models how the energy would be diverted accordingly. For example, if solar power is being generated and the profile shows they are consuming energy at that time, then this energy will be diverted to consumption. If they are not consuming at that time then it will be used to charge a battery (where present) or discharged to the grid. This factors in forced charge and discharge times, battery specs and export limits. We can then determine how much is used directly, used to charge the battery or sent to the grid. # What are the differences between the MCS and Easy PV self-consumption calculations? There are a few differences between the Easy PV and MCS self-consumption calculations:

	easy-pv.co.uk MCS	Easy PV
Easy PV task	Completed at the end of [Performance task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/performance-task "Performance task"), select `MCS` in [Financial task](https://help.easy-pv.co.uk/books/financial-task/page/using-the-financial-task "Using the Financial task") to use	Completed in [Consumption task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/getting-started-with-the-consumption-task "Getting started with the Consumption task"), select `Easy PV` in [Financial task](https://help.easy-pv.co.uk/books/financial-task/page/using-the-financial-task "Using the Financial task") to use
System size and consumption	Strict limits: - Consumption: 1500-6000kWh - Generation: <6000kWh - Usable battery capacity: <15.1kWh	No limits on system size or consumption. Any consumption, generation or battery capacity
Consumption profile	Domestic profiles only: home all day, home half the day and out all day	Domestic or commercial consumption profiles. Plus the option to upload half-hourly data from customer
Method	Determines self-consumption based on look-up tables specified in MGD 003, using annual generation and consumption totals	Models how generation is distributed using PVGIS data, then calculates usage minute-by-minute across the entire year.
Additional options	Limited since it only compares annual figures and cannot factor in real-time changes.	Minute-by-minute calculation means export limits, inverter clipping, variable tariffs and forced charging/discharging of batteries are factored into calculations