Most warehouses fulfil the two most important criteria for benefiting financially from rooftop solar installations: they have plenty of unused but accessible rooftop space, and consume significant quantities of power during day-to-day operation.
In just over 80 years, Knowles Transport has grown from a single vehicle, delivering agricultural produce from the Cambridgeshire countryside to the London markets, into one of the UK’s largest and most well-known warehousing and distribution companies, with over 1.5 million square feet of warehouse space. Knowles offers a 24-hour delivery service for any palletised product, still focussing chiefly on the foodstuffs and agricultural sectors.
Like others in the industry, Knowles finds itself under constant pressure to reduce both operating costs and the company’s carbon footprint — and, in particular, to perform well in energy audits.
Solar electricity is much cheaper than that supplied by utility companies, and attracts a government-backed renewable energy feed-in tariff (FiT) per kWh produced, even when it is used on site. In effect, the operator is paid twice for the same solar energy: once in savings on electricity bills and again in FiT revenue. Once initiated, FiT payments are guaranteed for 20 years and linked to the retail index price (RPI), so can be expected to increase each year. Excess electricity that cannot be consumed on site is fed into the grid, attracting both export tariffs and FiT revenue.
Installing warehouse solar panels
Following a tender process, BELECTRIC UK was asked install solar panels at Knowles headquarters and warehouse in March, Cambridgeshire. Data analysis indicated that a 200 kWp (kilowatt peak) rated project would be the best fit with the site’s on-site energy use profile. The 200 kWp capacity was divided into two separate systems — 150 kWp to feed into the warehouse and 50 kWp to power the HQ offices — to take fullest advantage of the scaled FiT scheme in place at the time.
Phased installation and commissioning of the two systems took around three weeks in total and was completed to schedule, with no disruption to the facilities’ operations. The two solar rooftops used REC multicrystalline silicon cells due to their tolerance to harsh environmental conditions and high energy conversion efficiency. The mounting and cabling systems were based on BELECTRIC’s in-house developed technology.
After the system was commissioned, Knowles saw an immediate and dramatic reduction in energy costs of around 50%.
Pre-installation, the two systems were expected to produce a total of 192,000 kWh of clean solar electricity per year, resulting in estimated utility cost savings of £21,000 and combined FiT and export revenues of £21,500. In the first year of operation the solar rooftops have performed even better than this, producing energy yields, savings and revenues around 5% higher than estimated.
Knowles opted to finance the entire solar installation itself, so receives all electricity, FiT payments and export revenues directly. The company can expect to recover its initial investment from these receipts in less than five years, while the system itself is projected to continue producing energy over a 25-year period.
Alex Knowles, Director of Knowles Transport, commented:
“From the first meeting, BELECTRIC UK showed professionalism and in-depth technical knowledge, setting aside any concerns we had about investing significant expenditure into a new area. The project was completed efficiently and effectively in the timescale originally proposed by our BELECTRIC project manager. After installation the customer care was and continues to be exemplary.”
For warehouse operators reluctant to invest upfront, alternative financial arrangements are available.
Almost all the energy generated at Knowles HQ has been used on site, with only about 5% exported to the grid. Because on-site energy cost savings are significantly greater than export tariffs for excess energy production, this represents the most cost efficient way of operating the facility. While the Knowles warehouse is a largely ambient temperature facility, operators of chill storage warehouses with higher on-site energy use could expect to gain greater financial benefit from installing larger-capacity solar systems, subject to local grid capacity availability.