SOLA4012 2024 Commercial PV

SOLA4012 2024

Commercial PV project

1 Scope summary

You are a graduate engineer in a large engineering department of a well-known PV installer (SPREEnergy). The company has received a tender request from a large retailer, for the installation of a non-exporting, grid-connected PV system for their commercial buildings around Australia, with an energy storage option. You will have to find a suitable warehouse from the retailer somewhere in Australia and produce a full system design for the tender response. Your design will be firstly submitted to the Engineering Manager and Compliance Department for review (30%). Once your design has been approved by the Compliance Department you can optimise it for the final Tender submission (15%). A summary of the tender requirements can be found below.

2 Compliance and tender summary

The project incorporates a roof mounted grid-connected PV system, with no grid export, that must comply with all the requirements from the Clean Energy Regulator (CER), to be eligible for the creation  of  Large-scale  Generation  Certificates  (LGCs)  or  Small-scale  Technology  Certificates (STCs) depending on the final size of the system. The layout of the PV array must be designed to:

- Maximise the system capacity (trying to achieve a minimum size of 100 kWdc),

- Maximise the annual yield within the roof space available (avoid self-shading and shading, and good ventilation of the PV modules must be ensured), and

- Minimise the levelized cost of electricity.

You are fully responsible for all design matters of the system and selection of components, including the PV modules, support structures, fixings to existing roof sheeting, DC cabling from PV panels to inverters, cabling to the building distribution boards, earthing, and protections. Easy access to all PV panels is essential, to allow for cleaning and maintenance, by means of clear access corridors. The panel layout also must allow for continuous access to the existing perimeter roof gutter system.

The system must be suitable for connection to the low voltage distribution system of the building (400/230 V, 3 phase, 50Hz). The inverters are to be installed in a suitable room on the ground floor (from now on the ‘inverter room’). The proposed point of grid connection is the building Main Switch Board (MSB), located on the ground level, next to the service area (usually close to loading docks). The existing service riser and cable trays can be used to route the cables from the roof to the MSB. The MSB has available circuit breaker spaces for the connection of the PV system; however, the designer must size and select the circuit breakers adequately.

As this system will  be  installed  by SPREEnergy, your design  must adhere to the  Design and Construction guidelines for PV systems (section E3.5) in the link below:

https://www.estate.unsw.edu.au/sites/default/files/documents/SECTION%203.5%20PV%20SYST EMS%20REV%201e%20-%20Final.pdf

You will receive a year of interval load data for the building. You can use this data to size your   system for both design options (with and without storage). You must scale this load data to achieve an  energy  intensity  of  200  kWh/m2/year  before  using  it.  You  must  fill  any  missing  data  with appropriate methods.

2.1 Battery Option

For the final tender submission, you must provide an additional design option that includes battery storage (this is not required for the compliance report). The storage option might allow the installation of a larger PV system as any excess energy can be used to charge the battery but, the system must not export energy to the grid. Notice that a different selection of inverter might be necessary in order to allow for energy flow between the building, the PV system, and the grid. The preferred battery chemistry is Lithium-ion due to the number of cycles and high DOD levels that can be achieved. You must select the size and model of the battery that provides the best economic benefit to the owner of the system. You must also estimate when a replacement battery is required. Unfortunately, SPREEnergy does not have current battery prices, so you will need to do some cost investigation.

The battery system must comply with all relevant Australian Standards (AS/NZS 5139: 2019) and be  able  to  supply  energy  to  the  three-phase  electrical  system  of  the  building.  The  battery inverter/charger must comply with the same conditions as the solar inverter.

2.2 Economic Assessment

SPREEnergy has asked you to produce a design that offers the lowest Levelised Cost of Electricity (LCOE) and highest Net Present Value (NPV) for each option (with and without battery storage) in order to win the tender. Assume a life span of 25 years for the PV system, but bear in mind that some components might need replacement over that period. The capital investment of the system is important but secondary. The electricity tariff structure for the building is shown in Table 1.

Table 1 – Customer Electricity Tariff

To  calculate the  direct  costs  of your system,  SPREEnergy  has  provided  you with  the values presented in Table 2. The tender specifies an inflation rate of 2.5% and a real discount rate of 6%.

Table 2 - Approximate costs of components and installation

The final cost are the direct costs plus the profit margin. As part of the tender, you must prepare a project installation plan including timeframe, activities, and milestones (a Gantt chart is preferable).

2.3    Model, Assumptions, and Drawings

When preparing both reports (compliance and final tender) you must explain all your decisions (for example component selection, design  parameters and selection),  list all your assumptions (for example module degradation) and quote all your reference sources (for example data sheets). The objective of this project is to present a comprehensive design of the system to submit a good tender, which must include ‘workshop drawings’ containing the full design of your system (panels per string, strings  per  MPPT,  protection,  switches,  cable  lengths,  voltage  drop,  etc.).  In  other  words,  a contractor should be able to build the system if you give them the report.

The compliance report will focus on the correctness of the design in terms of matching and selection of components, safety, estimated costs, and agreement with the Australian Standards. You must provide calculations showing how your design adheres to the Australian Standard.

The tender submission requires the techno-economic optimisation of your original design. For this purpose, it is recommended to use one of the software options such as System Advisory Model (SAM),  Rated  Power  and  PVSyst.  SAM  is  free  and  offers  good  accuracy  and  functionalities, including storage options and economic analysis of grid connected systems. We are also given free subscription to Rated Power software which is new and offers additional functionalities.

The workshop drawings consist of PV system design outline drawings and single line diagrams (SLD). Compliance report only requires the outline drawings. SLD is not required for the compliance report, however if you deliver SLD with the compliance report, you may be eligible for bonus points (i.e., if you miss points for the respective Appendix section – check rubric for more details). You must deliver SLD for the for both with and without battery designs with the Tender Report.

2.4 Performance Guarantee

The design must include a guarantee of the yield output for the first five years. You must include an estimation of the expected the  power output over the  lifetime of the system (25 years) and a methodology  to  compare  the  expected  output  to  the  measured  output.  You  must  specify  the metering and monitoring option, including weather conditions if necessary.

3 Format

3.1    Compliance Report

The submission of the  report to the  Engineering  Manager and Compliance  Department of the company is due on week 5. The main body of the report should have a maximum of 6 pages plus appendices. This report is only for design option 1 without storage.

Your system design must include all the aspects required for a system compliant to Australian Standard:

• Selection of components (PV, inverter, frame, protection, etc.)

•   Sizing of all components including cables and protection, and calculation of voltage drops (this will be delivered as an excel input sheet).

•    Lightning protection assessment.

•   Wind load assessment.

•    Drawing with the physical layout of modules, inverters, wiring, switching and protection gear required by AS/NZS5033, including earthing and lightning protection.

The report must include the following sections:

1.   Context and site assessment

2.   System design and calculations (includes Excel Design Spreadsheet to be submitted separately)

3.   Lightning and wind load assessments

4.   Estimated cost and performance

5.   Estimated project plan

6.   Appendices (workshop drawings and reference datasheets)

3.2    Tender Report

The submission of the final tender is due on week 6. The main body of the report should have a maximum of 8 pages plus appendices. The appendices should include a full set of drawings and data sheets for all the components used in the design.

Your system design must include all the items included in the compliance report plus the system techno optimisation (for both design options: with and without battery) as well as the complete single line diagrams of both design options.

The report must include the following sections:

1.   Executive summary (1 page max)

2.   Context and site assessment

3.   Summary of system design with and without battery

4.   System optimization based on economic assessment

5.   Project plan

6.   Performance guarantee

7.   Recommendations and conclusions

8.   Appendices

a.   Tender return forms (see this document appendices)

b.   Workshop drawings (single line diagrams and system layouts)

c.   Data sheets and warranties.

Note: The Engineering Manager is very strict with the number of pages and will not review any information beyond the specified limit. The purpose of this is for you to decide what’s relevant and to show your work and results in a concise way.

Appendix 1 – TENDER RETURN A: SCHEDULE OF PRICES

The following schedule is to be completed and returned and will be used in the assessment of tenders and administration of the contract.

Appendix 2 – TENDER RETURN B: PERFORMANCE METRICS

The following schedule is to be completed and returned and will be used in the assessment of tenders and administration of the contract. Please list all your assumptions for your calculations.