Designing for solar PV

Sunlight shines through a solar carport constructed using panels with a clear backsheet, filtering the light and providing cell visibility from below. All photos courtesy VCT Group
Sunlight shines through a solar carport constructed using panels with a clear backsheet, filtering the light and providing cell visibility from below.
All photos courtesy VCT Group

by Taylor Weber, BID

Gone are the days when architects needed to hide bulky solar panels from view to preserve their vision for the design of a building. Today’s panels and racking solutions have created a world of limitless possibilities where solar photovoltaic (PV) technology becomes a feature and can be integrated into the building design instead of added as an afterthought.

Building considerations

The earlier a solar expert is brought on board, the better. Each building is unique, and through co-operation between architects, engineers, and solar designers, one can arrive at the best possible outcome. Design considerations include the size of system required, the space available for installation, and where solar power use and visibility fits into the project’s priorities.

System size

When considering solar PV for a new or existing building, the first concern is sizing the system to match energy production to building consumption or take full advantage of any incentives or contracts available. The system size will depend on the electricity market in which the team is operating.

In a feed-in tariff scenario, all electricity produced is sold to the grid at a contract price. The size of the system is determined by the contract secured with the local electrical authority. In this situation, installing the largest system for which a contract is available typically results in the quickest payback, as there are efficiencies when installing solar PV at scale. A larger system also provides more flexibility down the road when the contract expires and the production model shifts to net metering, where electricity can be used to offset consumption.

A flat roof with torch-down membrane. Black slipsheets have been placed under the ballasted racking for extra protection.
A flat roof with torch-down membrane. Black slipsheets have been placed under the ballasted racking for extra protection.

In fact, for net metering installations, production is expected to offset consumption. Any electricity generated is used to power local loads first, with excess sent to the grid. Electricity sent to the grid earns credits that can be used to pay for electricity when consumption exceeds solar production. Sizing a system too small in this situation can leave money on the table, as the owner will not produce enough electricity to completely offset consumption. Too large a system ends up giving electricity to the grid for free. Consulting a solar designer and analyzing the client’s electricity usage, or projected usage, is the key to a financially viable solar solution.

Once the desired output of the system has been determined, architects are free to get creative with panel size, style, and placement. A myriad of options will offer similar power outputs. It is up to the architects and engineers to balance this need with the state of the building and client opinions.

Available space

The second consideration when designing for solar power is the space available for and required placement of components. Although solar installations are typically situated on roofs, there are opportunities to take advantage of unique or underutilized spaces to add panels for either production or design requirements. Penthouses, awnings, and parking lots are just a few areas that can be used to expand systems.

Attention must also be paid to the location of other electrical equipment. Inverters to change the direct current (DC) electricity generated to alternating current (AC) for use in the building can be housed outside or inside the structure. A transformer may be needed, depending on the installation. Each of these components requires placement, as well as the ability to run wires connecting the system. Placing everything to ensure minimal distance between components and work to run wire is best done in the building design stage. It is easier to provide conduit and locations for systems at that stage than it is to trench cables and move components down the road.

Design priority

As solar PV technology matures and design options expand, it is possible to specify a unique esthetic for a solar installation. Everything from the colour of frames and backsheets to the tint of the glass or colour of the cells can be selected. This has given rise to the use of solar panels as a design feature instead of simply a generation option, although they may not generate as much electricity as a purpose-built system. Using solar arrays to create awnings, clad a wall, or build shade structures is one way to brand the building and broadcast the green initiatives being undertaken.

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