THE EDDLINGTON CENTRE

EDDLINGTON LANE

EDDLINGTON

DONCASTER

DN12 1PL G59 APPROVAL FOR A 25,000W GRID-TIED PHOTOVOLTAIC ARRAY

THE BRIEF

DAS Solar undertook the feasibility study on the site of a converted Junior school on the outskirts of Doncaster. The site is now home to a resource and learning centre run by an independent charity. The site was made up of one building centred on a large open courtyard. Built in the 1930s its structure and composition were the first priority when assessing the site. The roof is of traditional construction with flat roofed areas covering entrance halls and of later construction the main joining corridor within the quadrant. The tiled roof was covered with handmade rosemary type tiles original to the building. Sarking felt under these tiles was absent and there was evidence of damage on all roofs. The basic structure however was in good condition with no evidence of water ingress, damp or structural fragility.

The site is in use every day and gets very busy at times. Special attention was going to have to be given to protection of the general public and staff within. The project would have to go ahead while the centre was still in use.

Return on investment was paramount to the funding of the project. We calculated the system would pay for itself in less than seven years, a terrific investment for our client.

The electrical system with in building is brand-new with several sub-metered distribution boards scattered throughout. The three phase supply continued to all these boards and lent itself perfectly to the retro fit PV array proposed.

PROPOSAL ACCEPTED

The office based team swing immediately into action. Planning applications, G59 applications and an Energy Performance certificate are standard requirement of the project. These are made along with the instruction of Charted Structural Surveyor, Access Contractor and Health and Safety Assessor. These reports are received and findings reviewed. These are then discussed with the client and fixes and alternatives agreed.

THE EPC ARRIVES

It’s not good news. The boiler and main source of heating is coal fired. This fact alone means the property will never reach the required D band needed to qualify for the top rate of financial return without spending in the region of ten thousand pounds. We adjust the figures to compensate analysed the costing and maintain the overall return on investment would be almost identical if we scaled down the installation to just 12 kW. We chose the north roof as access, safe working and electrical connection are considerably more cost effective.

With PV Installed Without PV Installed

SOME QUICK MATHS, IT STILL MAKES SENSE.

STRUCTURE

On this occasion the roof needed significant structural work. The calculations are made and the correct methods employed to ensure this will never become an issue. Over 120 lm of timber along with heavy gauge nuts, bolts, and washers are used to pin the roof fabric together following the structural reports instruction to the letter.

REMEDIAL WORKS

King trusses, perlins and rafters not strong enough?

We strengthen and brace the entire roof structure. Available roof space will allow a 12kW array to be installed on each of the two main south facing roofs. The total weight of each array is well over a ton.

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ELECTRICAL DESIGN

Main three phase cabling within requires no upgrade. Arrays can be fed directly into sub-distribution boards within 3 meters of the loft mounted inverters.

Each array is separately metered ensuring the most accurate production figures are available. Use of two independent GSM modem units means this information is available at the touch of a button and in real time. All this adds up to minimal voltage drop losses and an excellent efficiency for the client and the environment. Our specification included the market leading SMA Tri-power TL Inverters. Two units were required as the arrays were on opposite edges of the site.

The electrical drawings and calculations are completed and distributed to the relevant network connection authority for consideration.

FINE TUNING

We produce 3D animations of the suns path over the site. This allows our engineers to select the best possible module configuration. All shading issues are overcome to allow optimum operation. These calculations are checked and double checked by our electrical engineers.

PLANNING APPLICATION ACCEPTED

We get the go ahead from the local authority.

DISTRICT NETWORK OPERATOR APPROVES CONNECTION

At long last we can proceed to site.

ESTABLISH SITE AND ERECT SUITABLE ACCESS

The fun part starts and our highly skilled installation crews arrive on site. Our scaffolder is on site the same day. An exclusion zone is created beneath the work area and maintained throughout the installation. Notices are placed and safety briefings given. The premises general manager is briefed on the schedule of works and works with us to ensure a safe working site at all times.

Measurements are checked and the installation begins.

THE INVERTER

We position the inverter in the centre of the loft directly above the distribution board. A dwarf support wall is chosen to mount the inverter. The existing loft hatch is too small to accommodate the large unit. It’s stripped out and reinstated with a larger diameter hatch to allow future removal of the unit if required.

DC isolation switches are fitted to the reverse of the wall and channelled through to feed the inverter. Once inverted the AC power then runs back through a separate channel to the main isolation switch. Everything is labelled and is easily identified. The new loft hatch is made and fitted by our joiner’s onsite.

THE ROOF

Known as “pigs” in the solar industry, the reputation of these roof tiles is well known. Normal Rosemary tiles are difficult to work with but the tiles on this roof were handmade, much larger than the modern Rosemary and almost impossible to match.

Repairs were made to ensure roof integrity beneath the array; we give a water tight guarantee on all our projects.

THE ARRAY

We install 48 modules in landscape orientation. This maximises the potential of the roof space and array. Each row is a single string of 12 making any future string diagnostic issues straight forward.

Anchors are set at the very edge of the array giving complete stability during heavy winds and periods of prolonged winter weather. We test every module as it comes up on the roof and check this against the factory flash tests.

COMMISSION

The most important part of the installation is the testing of the entire electrical system. We label up all distribution boards, isolators, wiring runs, MCBs and meter positions. We test all the existing hard wiring within the building before connecting our installation.

Each string is tested and checked before connection into the inverter. All AC testing and earthing arrangements are double checked, tested and recorded as needed for the installation certificate and also to satisfy the DNO’s requirements. On this occasion a representative from BRE attends site on behalf of the client and inspects the works.

HANDOVER

Having fulfilled our obligations and satisfied the inspection the site is cleared and handed back. All paperwork is completed and handed over in the operation and maintenance manual. Wiring schematics are finalised and published. All relevant authorities are made aware of the installation as prescribed in engineering recommendation G59-1.

MONITORING AND MAINTENANCE

DAS solar will monitor and maintain this installation for the next 25 years. The Estler A1100 GSM meter gives us instant access to array performance in real time. The system is monitored remotely and can be accessed online by both ourselves and the client. The data is recorded and assessed on a daily basis to maintain the highest possible yield and operational performance. All components are tested periodically and by our skilled electrical engineers ensuring optimum production. We recommend cleaning the modules, as a minimum, once a year and is part of our inspection.

This 12kW system will exceed our expectations by a minimum of 20% paying back the initial £22,000 investment fivefold and continue to produce clean renewable electricity for the next 40 years.

It will produce over 300,000 kilowatt hours of sustainable electricity saving over £££££££tons of co2.

THE OPS TEAM

THE EDDLINGTON CENTRE

BRAD “UGLY” KIRKBRIDE

LEE WOODS NIGEL”DUMBLEDOR”WHITE STEVE SPENCER

WAYNE “WIGGY” CLARK DARREN GRAHAM