Case study: making a profit off-grid

We recently completed a commercial off-grid solar PV & battery storage installation for one of Jackson’s Civil Engineering’s sites. This case study details the opportunity, solution and results of the project.

The business

Jackson is a regionally structured civil engineering firm that operates nationally. Established over 65 years ago, they currently operate out of seven regional offices. The firm has a wealth of experience in various sectors, designing and developing innovative solutions. They have a massive concentration in infrastructures like highways, bridges, ports and buildings.

The job

Due to the size of Jackson, they have various contracts and act as an umbrella company when undertaking projects. We completed the installation for one of their sites, Jackson’s Frameworks, located near the M11 (East England, UK).

The site consists of offices, workshops, bedrooms, showers and a canteen. At any time, there can be six to 20+ employees on-site. The team are constantly performing on-going maintenance work, including throughout the night to make highway work more convenient.

When the site was established two/three years ago, the firm was unable to gain a grid connection. The local district network operator provided a quote for gaining a grid connection but due to the surrounding forest and roads, the figure was far too expensive to make financial sense. Like most sites across the UK, they chose to power the off-grid premises using a diesel generator instead. The firm plans to be on-site for at least 10 years, in total.

The opportunity

The site was relying on a 70 kVA diesel generator 24/7. On average, a diesel generator costs 50p/kWh. This is in comparison to if they got a grid connection and were paying, on average, 15p/kWh. And for a business, this doesn’t make financial sense. Especially, if they were going to endure those running costs for 10 years.

Due to the size of the generator, it was an inefficient source of energy because the on-site energy consumption fluctuates constantly. At times, they will only be using a few hundred watts to power lighting and computers but at other times, they would be using up to 30 kW if a team on-shift is showering. The generator’s massive capacity meant that a large amount of fuel was being constantly burned even if the demand was low.

For a business, they concluded this was unviable because it was a waste of long-term capital.

The solution

Ian Hewson, the head of our Off-Grid Solar Department, liaised with several members of Jackson’s Frameworks for almost 12 months. During this time, Ian visited the site three times before the installation date.

Due to limited space being available on-site, the containers that act as offices were the only place available to install solar PV panels. However, the roof is made of plasterboard so we wouldn’t have been able to penetrate for installation nor would the roof have been able to support the weight.

We designed and developed a bespoke system for Jackson’s Frameworks, which diverted the weight of the system from the centre to the edges of the roof. This meant it was safe for the installation to be completed as the steel frame is strong enough to hold the weight.

This is a common construct for commercial set-ups that have containers as offices. This case proves there is a solution available as normally, a roof like this would be treated as a normal flat-roof installation but couldn’t due to the plasterboard.

The installation consists of:

  • 30 x 325 watt Q-Cell solar PV modules (9.75 kWp)
  • 3 x 8 kVA Victron inverter chargers (three phase supply)
  • 2 x 100 amp DC-coupled charge controllers
  • 3 x BYD B-Box Pro 13.8 kWh batteries
  • 40 kVA diesel generator
  • 200 amp changeover switch
  • Victron virtual display

The Result

Their previous generator was only <50% efficient whilst the new one we are using as backup is <90% efficient. This means that the site is getting more for their energy and reducing their carbon footprint too. Data has shown the environmental benefits from ditching diesel for solar PV. The site has seen a reduction from 600 litres of diesel used per week to only 90 since installation. One litre of diesel produces around 2.68 kg of CO2. If this rate continues, the potential reduction of CO2 emissions this year would be just over 26.5 tonnes. This is the equivalent of what 10 UK households emit per year.

Thanks to data collection, the firm will benefit from a few factors: Setting accurate trigger points for when the generator should turn on and monitoring their three-phase loads. Like most sites, the firm had split different sources of energy consumption into three different phases. As their old generator just continually operated, they never knew what was using the most energy. The display now shows the three phases of the premises separately so there is total transparency. This means the firm or ourselves can highlight what is consuming the most energy and can find solutions on how to make further savings. For example, the site’s electric convection heaters are using/wasting a high amount of energy and could be replaced with an infrared heater.

Energy consumption, renewable energy generation plus statistics on the BYD battery bank performance are now monitored around the clock via the Victron VRM on-line monitoring portal which is continually monitored by Solar Plants’ dedicated off-grid solar department We are also considering retrofitting AI technology which can use previously collected data and predicted solar PV seasonal output data to automatically set adjusted trigger points. This can provide intelligent continuous automated adjustments to the system to further reduce Jacksons CO2 footprint.

Thanks to the components used, this will be a low-maintenance and long-term energy solution for the site. As well as our own 10 year workmanship warranty, the manufacturer warranties for both parts and labour have provided the firm with 5, 10 and 25 year warranties for the Victron components, BYD batteries and the Q-Cell solar PV modules, respectively. As we are BYD’s UK service partner, we were able to provide an extended 10 year/6,000 cycles warranty for the batteries.

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