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How to use the MCS calculator

OpenSolar
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Summary:

The OpenSolar MCS Calculator adheres to the official MCS standards for calculating solar PV output, based on:

  • MIS 3002: The Solar PV Standard (Installation) — defines how PV output should be calculated.

  • MGD 003: Determining the Electrical Self-Consumption of Domestic Solar PV Installations (with and without Energy Storage) — details self-consumption methodology for domestic systems.

Note: The MCS calculator is only available for systems designed within the UK. Attempting to use it outside of the UK will result in an error.

 

Setting MCS Calculator as the Default

To enable MCS as the default energy production calculator for UK projects:

  1. Navigate to:
    Control > Design & Hardware > Setbacks & Design Settings

  2. Under Simulation Settings, select:
    MCS (UK Only) in the Energy Production Calculator dropdown.

Note: For all designs created within the UK, the MCS calculator is the default option automatically.

 

 

Enabling MCS Calculator for a Specific Project

To apply MCS to a specific project design:

  1. Go to the Design section.

  2. Navigate to:
    Summary > Advanced Settings > Energy Production Calculator

  3. Choose MCS (UK Only) from the calculator options.

For non-MCS or large systems (typically >50kW), OpenSolar provides alternative calculation models such as System Advisor Model (NREL) and PVWatts.

 

 

Including MCS System Performance Summary & Sunpath Shading Diagram in your Proposal:

You can include both the MCS System Performance Summary and Sunpath Shading Diagram in proposal templates:

  • Go to:
    Control > Purchase Experience > Proposal Template

  • Select or create a proposal template, then access the Proposal Content section.

  • Scroll down to the Disclaimers section.

  • Add the MCS performance summary and sunpath diagram placeholders by:

    • Clicking the placeholder icon.

    • Searching and inserting the relevant placeholders (e.g., under System Performance or System Hardware Components).

  • Save the template.

 

 

You can add the MCS system performance summary table and sunpath shading diagram (Only if using the MCS Calculator) to your proposal template by the following steps:

  • Go to Control > Purchase Experience > Proposal Template and then click on mceclip2.png an existing proposal template (please create a new proposal template if you don't have one created already). You will then need to open up the Proposal Content section.

  • Scroll down to the Disclaimers section in Proposal Content.

Note: The placeholder for the MCS system performance summary table and sunpath shading diagram is only available within the Disclaimers section of the Proposal Template.

  • You can add the placeholder for the MCS system performance summary under any Disclaimer section by clicking on the icon as shown in the image below.

Preview the proposal to confirm both MCS visuals are included.mceclip5.png

Setting up the Occupancy Archetype for MCS Self-consumption Calculations

  • Navigate to:
    Projects > Electricity Usage

  • Choose a usage source other than default.

  • Under Curve Weekday, select an option that maps to one of the MCS-defined occupancy archetypes.

mceclip6.png

 

MCS Calculation Limitations:

MIS-3002 (generation calculations)

  • Applies to PV systems up to 50kWp DC output.

  • Systems must be connected to permanent buildings and typically grid-tied.

 

MGD 003 (self-consumption calculations)

  • Annual household electricity consumption must be between 1,500 kWh and 6,000 kWh.

  • Annual PV generation must be below 6,000 kWh.

  • EESS (energy storage) must:

    • Have ≥80% round-trip efficiency at 25°C.

    • Be charge/discharge capable within 6 hours at rated power.

If these conditions aren’t met, OpenSolar uses its internal self-consumption methodology.

 

Note: MGD 003 defines the maximum self-consumption percentage as 95%. Hence when using the MCS calculator, the self-consumption will never exceed 95%.

 

MCS Self-consumption Table Explainer:

A. Installation data
Installed capacity of PV system (kWp) Total capacity of the solar PV system represented in terms of kilowatt peak power output (kWp). A solar system with a peak power rating of 3.68kWp working at its maximum capacity on a sunny day will produce 3.68kW of electricity.
Orientation of the PV System - degrees from South The orientation of the proposed solar PV system(s) in relation to true south.
Inclination of system - degrees from horizontal The angle of the proposed solar PV modules. Often determined by the pitch of the roof facet or the mounting system.
Postcode region Region as determined by MCS UK postcode zones.
B. Performance calculations
kWh/kWp (Kk) from table

Kk is an MCS factor derived from:

- Solar array postcode location
- The pitch of the solar array (horizontal angle from the ground or roof)
- Orientation of the solar array from South

Alongside KWp (the size of the solar PV array) and the SF (shading factor), Kk is used to determine likely solar panel output.
Shade Factor (SF) A value used to assess the potential impact of shading on a solar PV installation as a result of both near and far objects. The shade factor (SF) is used to modify the amount of electricity that is predicted to be generated by a proposed Solar PV system. Values range from 1 (no shading) to 0 (full shading).
Estimated annual output (kWp x Kk x SF) An estimate of the total annual output
of the system.
C. Estimated PV self-consumption - PV Only
Assumed occupancy archetype Lifestyle factor indicating the length of time a property is occupied throughout a typical day.
Assumed annual electricity consumption The amount of electricity consumed by a property over a typical year.
Assumed annual electricity generation from solar PV system Predicted solar PV generation taking into account system size, location and shading factors.
Expected solar PV self-consumption (PV Only) The proportion of solar PV generation consumed by the property, assuming no electrical energy storage system (EESS) is present.
Grid electricity independence / 
Self-sufficiency (PV Only) The degree of utility independence or “self-sufficiency” gained by adding a solar PV system.
D. Estimated PV self-consumption - with EESS
Assumed usable capacity of electricity energy storage device, which is used for self-consumption The amount of capacity available for storing solar PV energy. Self-consumption is the proportion of solar PV output which is directly consumed by the domestic property. Increasing the expected consumption of electricity generated by a solar PV system enables greater self-sufficiency. Usable capacity of an energy storage device is determined by manufacturer specifications or installation parameters.
Expected solar PV self-consumption (with EESS) The proportion of solar PV generation consumed by the property, assuming an electrical energy storage system (EESS) is present.
Grid electricity independence / 
Self-sufficiency (with EESS) The degree of utility independence or “self-sufficiency” gained by adding a solar PV system alongside an electrical energy storage system (EESS).
E. Additional benefits from PV and EESS
EESS capacity not used for self-consumption The amount of storage capacity not utilised by domestic generation technologies such as solar PV.
Total energy discharged per annum The total amount of energy discharged from an electrical energy storage solution (EESS) per year.
Additional self-consumption for EV, heat pumps, diverters (only when present) Domestic electricity consumption related to technologies such as EV, heat pumps and power diverters.

 

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