Maximising Self-Consumption on a 171 kWp Rooftop Solar PV System

System Capacity	Annual Generation	Performance Ratio	CO₂ Savings
171 kWp	167,521 kWh	87.92%	78.7 t/yr

Project Overview

This case study covers our design of a 171 kWp rooftop solar PV system built to reduce electricity costs, improve energy self-sufficiency, and support the site’s sustainability goals. 

The system spans multiple roof areas across the facility, making the most of available roof space while keeping solar generation in step with the site’s electricity demand. 

The challenges

The site was consuming around 199 MWh of electricity a year, almost entirely from the grid. With strong daytime operational loads that line up well with solar production hours, the conditions were right for rooftop solar. 

But simply generating energy wasn’t enough. The design needed to actively align output with demand, so as much of that energy as possible could be used on-site rather than exported. 

The system needed to:

• Maximise on-site consumption of generated solar energy.
• Reduce grid electricity imports and associated costs.
• Improve energy self-sufficiency.
• Minimise carbon emissions.
• Optimise long-term energy savings.

Design Approach

Highlights

• Self-consumption-led design, using site energy data to determine the optimal system capacity.
• Incorporated multiple roof areas with varying orientations to make the most of available space.
• Used multi-orientation layout to balance energy production across different times of day.
• System capacity sized to match solar generation with daytime operational loads.

Energy Consumption Analysis

We carried out a detailed review of the site’s electricity consumption profile to understand how solar generation and building demand would interact. Annual consumption stood at approximately 199 MWh, with significant daytime loads that closely match solar production hours. That load profile meant a strong foundation for high self-consumption performance.

System results

System Summary

Key Engineering Achievements

• 167 MWh of renewable electricity generated annually.
• 81 MWh of solar energy utilised directly on-site each year.
• 48.5% self-consumption ratio. Nearly half of all the generated energy used on-site.
• 87.9% performance ratio, reflecting a well-optimised system design.
• 78.7 tonnes of CO₂ emissions avoided per year.
• 40.7% solar fraction, reducing the site’s dependence on grid-supplied electricity.

PV*SOL Performance Results

PV*SOL simulations of the completed design produced the following annual performance projections:

Self-Consumption & Energy Utilisation

The system was designed specifically to maximise self-consumption and reduce reliance on grid-supplied electricity. Here’s the energy utilisation breakdown below:

Metric	Value
Solar Energy Consumed On-Site	81,252 kWh/year
Energy Exported to Grid	86,268 kWh/year
Self-Consumption Ratio	48.5%
Solar Fraction	40.7%

The installation was expected to offset over 81 MWh of annual grid electricity consumption directly. That translates to real operational savings and a significant reduction in carbon emissions each year.

The Outcome

This 171 kWp rooftop solar PV system shows what’s possible when detailed energy analysis drives the design. By matching system capacity to the site’s actual demand profile, the project delivered strong self-consumption performance, reduced grid dependency, and a meaningful cut in carbon emissions. All from a roof that was previously doing nothing.

Environmental Impact

• 167 MWh of renewable electricity generated annually.
• 78.7 tonnes of CO₂ emissions reduced per year.
• Improved site energy independence.
• Long-term reduction in operational energy costs.

The result here is a reliable, scalable renewable energy solution that works on both financial and sustainability fronts. Less grid reliance, lower bills, and a smaller carbon footprint, every year the system runs.