Civil and Electrical Engineering in Solar PV Power Plant

Initial Preparation

It comes to planning a site for a solar utility project. The money invested in the initial stages can go a long way towards a facility�s successful operation during its 30-year lifespan. The initial planning process requires a great deal of negotiation with local jurisdictions, utility companies, and governing agencies. Our team works through the terms of Conditional Use Permits (CUPs), Power Purchase Agreements (PPAs), and Interconnection Agreements (IAs) while also discussing and making determinations on such issues as: topography and boundary surveys, grading, stormwater mitigation, retention features, fire suppression planning, options for mounting systems, and the need for an Operations and Maintenance building.

Surveys, Studies, and Mapping

As part of the planning process, engineers will conduct a hydrology study with stormwater and flood calculations, and provide a review of the owner-supplied project studies, requesting additional data as necessary. You should be able to assess the status of the topographic, boundary, and geotechnical data and determine what is sufficient for design and what still needs to be conducted for project success. Engineers can assist in managing any sub consultants necessary for project completion, as well as pick up where developers left off in terms of preliminary engineering and project study creation.

Civil Design

Civil design provides the underlying structure of systems within which solar power facilities can exist and operate. You have to be extensive experience with solar racking and tracking products and we foster continual product vendor dialogue to engineer a clean, sensible, and cost effective solar facility. Final construction drawings and documentation will detail the entire civil infrastructure, including the design of project and access roads, the laydown area for the PV array, design and layout of any permanent fencing and PV racking systems, site grading, existing easements, and locations of inverter skid foundations.

Structural Design

PV system�s structural design in conjunction with the civil site development design. Engineering team will design the structural pile foundations, inverter pads, and transformer pads, based on geotechnical parameters, the solar panel manufacturer�s specified design requirements, and all governing codes.

Electrical Engineering Services

Site Surveys

Roof survey: As part of the initial preparation for roof-top projects Engineer will perform a detailed roof survey as the basis for an as-built roof plan. Team will locate the exact coordinates of all rooftop obstructions, and identify surrounding objects�such as trees and power lines�that could potentially shade the solar array and impact annual energy production. The process concludes with a complete CAD as-built site plan for the design engineering team.

Electrical site survey:

To lay the groundwork for interconnection, engineer will complete electrician survey the site's existing electrical system. This includes a switchgear inspection for load-side or line-side taps and documentation of existing switchgear specifications, such as model numbers, BIL ratings and breaker sizes. The electrician will also survey the area for equipment pad locations, wall-mounted equipment locations, and conduit penetrations.

Solar Energy Performance Modeling:

To further model the solar project�s viability, engineer will conduct a weather study to determine available sunlight irradiance for the specific location. The resulting information, along with the system design, will factor into the PV energy production model/software, allowing us to determine appropriate model inputs.

Utility Interconnection Package

Engineers continues the utility interconnection process with a series of comprehensive agreements with electrical utilities and power system regulators

Fundamental Documents

Engineers will provide a Basis of Design (BOD) template for client review and input. Once approved, the BOD will serve as the defining document for the project going forward, determining the design parameters and standards of all work listed in the Engineering Work Order.

Engineers will generate a single line diagram (SLD) that shows the interconnection design. The SLD will clearly illustrate the AC and DC electrical systems, inverters, power/auxiliary transformers, metering, breakers, and disconnects. It will define the overall power collection strategies and outline the plant utility protection scheme.

Array Layout: The final array layout is a culmination of a number of aspects, including topographic and site boundary surveys, and factors laid out in the BOD such as shade analysis, module string size, string-rack configuration, and other efficiency measures which reduce unnecessary costs. At this point we begin populating the solar array with the module layout, honing in on sub-arrays and inverter groups, optimizing inverter loading ratios, establishing preliminary road locations, and other related details.

Low and Medium Voltage Engineering

Solar utility projects are typically a combination of both low voltage DC and medium voltage AC electrical systems. Bridging the design details from DC to AC and creating cohesion throughout the design is one of the unique features. There is an exciting trend towards offering solar array wiring of up to 1500 Volts DC on ground-based systems and 1000 Volts DC on rooftop solar systems. We�re enthused to be at the forefront of this transition as solar facilities become more ubiquitous.

Our DC electrical design incorporates solar source circuit and homerun feeder circuit wiring plans, plus the equipment pad layouts with a detailed wire and conduit entry plan. The process also involves developing a conduit routing or trenching plan, creating a more detailed single line diagram, and the final engineering for the interconnection into existing switchgear.

solar AC medium voltage switchgear and collector system, as well as the ratings for distribution in step-up transformers. The process also requires designing underground and overhead feeders, medium voltage trenching and boring, switchgears (including breakers), and equipment elevations. During the medium-voltage process, engineers will coordinate with utility engineers, sub-station engineers, and other project stakeholders.

Underground Cable Sizing

step of determining optimized underground cable sizing when implementing its solar PV projects. Proper sizing of underground cable requires assessing the cable and conduit spacing based on soil conditions, including during worst-case scenarios such as a flood or a drought.

Additional Solar Electrical Engineering Services

Performance Monitoring and Reporting System design
SCADA engineering and controls
Tracker control system engineering