How to Compare Solar EPC Offers Beyond the Price per kWp

Price per kilowatt-peak can help you organize solar proposals, but it is a weak basis for awarding a project on its own. Two offers can show similar installed capacity while including different works, predicting different energy output and leaving different responsibilities with the owner.

A useful comparison makes those differences visible before negotiations begin. The aim is to understand what you will receive, what remains outside the price, and how the finished plant will demonstrate that it meets the agreed requirements.

1. Put every offer on the same scope

Start with a common comparison sheet. Record DC module capacity and AC inverter capacity separately. Identify the equipment models, quantities, connection point, monitoring system and design basis. Confirm whether taxes, transport, installation, civil works and commissioning are included.

Then work through interfaces: roof strengthening, waterproofing, switchgear, transformer upgrades, utility coordination, communications, access equipment and construction shutdowns. Mark each item as included, excluded, provisional or unclear. Ask bidders to close unclear items in writing.

For example, an offer excluding a required electrical upgrade should not be compared directly with one that includes it. Add a clearly identified owner allowance until the missing scope is priced. Keep that allowance separate from the contractor's quoted amount.

On an Egyptian project, verify the implementing contractor's current NREA qualification, registration and capacity category before award. Check the certificate against the proposed plant rating rather than accepting a generic claim of approval. The four categories and published capacity limits are listed in the EgyptERA article in this collection. [4]

2. Reconcile the energy estimates

Ask each bidder for the model assumptions behind its predicted annual output. Compare the weather dataset, shading assessment, orientation, soiling, temperature effects, electrical losses, inverter clipping, availability and degradation assumptions.

Make sure the estimates refer to the same measurement point and period. Separate generated electricity from electricity the facility can consume or sell under its actual arrangements. A higher production forecast is not automatically a better design; it may reflect a more optimistic assumption.

Request a brief explanation of the main differences between models. Where the commercial decision is sensitive to output, independent technical review can help distinguish genuine design benefits from inconsistent inputs.

3. Read warranties as operating obligations

Separate equipment product warranties, module performance warranties, installation workmanship cover and any plant-level performance commitments. For each, identify the responsible entity, duration, exclusions, remedy and claims process. Clarify whether labor, transport, removal and reinstallation are covered.

A module performance warranty does not automatically protect the owner's total annual electricity savings. Ask what evidence a claim requires and who collects it. Review whether proposed maintenance duties are practical for your site and are reflected in the operating budget.

NREL's PV and storage O&M guide treats performance tracking, maintenance and contractual responsibilities as connected parts of managing a plant. Availability alone is insufficient to establish whether energy performance meets expectations. [1]

4. Agree on testing and acceptance before award

Do not leave the acceptance process to a handover meeting. Define the inspections, test procedures, measurement conditions, instruments, reporting format and responsible parties before construction starts. Distinguish safe energization, commissioning, performance verification and final acceptance.

Require a practical handover package: approved as-built drawings, equipment records, test reports, settings, manuals, monitoring access, warranty documents and operator training. Agree how defects are recorded, classified and closed, and how any outstanding items affect acceptance.

DOE recommends carrying technical specifications through procurement, design, installation and commissioning, and enabling third-party inspections before acceptance. [2] Your project documents should translate that approach into clear, site-specific deliverables. These are technical procurement considerations; legal advisers should review contractual remedies and enforceability.

5. Compare operating support and how SPP can help

Request a priced O&M scope rather than a general promise of support. Confirm preventive maintenance, cleaning responsibilities, fault response, monitoring, reporting, spare parts, warranty administration and exclusions. Distinguish remote acknowledgement from arrival on site and restoration of service.

Ask who will review performance reports and act on alarms once the EPC team leaves. PNNL recommends planning and budgeting for maintenance and tracking system performance so potential problems can be identified. [3] A monitoring platform is useful only if someone is accountable for using it.

Build the final recommendation around compliant scope, technical quality, credible energy assumptions, acceptance arrangements and lifecycle obligations, alongside price. Record any residual risk and who accepts it.

SPP can support owners through engineering review, technical due diligence and owner's engineering, including review of EPC submissions and testing requirements. This creates a traceable basis for clarifications and award decisions without substituting for the contractor's responsibilities.

Send SPP the proposals, site requirements and available drawings for a structured technical comparison. The first useful output is a focused clarification list, not an automatic choice of the cheapest bid.