Some buildings suit solar because of how they are used rather than how big they are. Boston College is one of them.
We commissioned a small but carefully designed solar PV array on the Mayflower building at Boston College. At 32 kWp it is one of the more modest systems in our back catalogue, and it is also one of the neatest examples of why sizing matters more than scale.
Why the numbers work
Teaching spaces, offices and facilities run predominantly during daylight hours. That is exactly when a rooftop array is generating. When demand and generation line up that closely, most of what the system produces is used on site rather than exported, and the return arrives sooner.
The headline figures:
- 32 kWp rooftop system
- 3.7-year payback
- 31% internal rate of return
- 38% of the building's electricity bill offset
- 6.1 tonnes of CO2 saved each year, equivalent to around 290 trees
- £158,000 in lifetime bill savings
A 32 kWp array will never make headlines. It will quietly take more than a third off an electricity bill for the next twenty-five years, which is rather more useful.
The wider point
Education sites are a natural fit for on-site generation. The pattern of use is predictable, the roofs are usually uncomplicated, and the business case does not depend on optimistic assumptions about export income.
When energy is consumed at the same time it is produced, solar stops being a sustainability gesture and becomes a straightforward part of running the building.
Wondering what your own roof could support? We will model it against your half-hourly data and tell you straight.
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