Getting quotes for a solar photovoltaic (PV) system is often the most frustrating step in the adoption process. Different contractors propose different system sizes, brands, and financing models, making an "apples-to-apples" comparison nearly impossible.

Here is a step-by-step guide to standardizing solar bids, spotting red flags, and evaluating contractor quality.

📌 TL;DR: standardizing your solar quotes

• Provide standardised data: give all contractors the same 12 month electricity consumption data and specify a target system size range.
• Ask for price per watt: require the final quote to show the total system price divided by the system size in Watts (DC).
• Standardise key components: request quotes based on an agreed minimum panel efficiency and specify the inverter type (e.g., string inverter or micro-inverters).
• Spot red flags: immediately discard quotes using high-pressure tactics or lacking specific equipment names and full warranty details.
• Verify experience: prioritise local experience, necessary certifications (EMA, LEW), and strong long-term warranties over short-term savings.

Before you request any quotes, prepare a standardized information package that you provide to every contractor. When everyone works from the same information, you get comparable proposals.

What information to provide:

• 12 Months of energy consumption: provide the last 12 months of electricity bills to show annual consumption and usage patterns. This allows the contractor to accurately size the system to your needs.
• Roof plan/layout: provide floor plans or drone images showing the available roof area, existing obstructions (vents, cooling units), and roof material.
• Roof condition: specify the age and material of the roofing (e.g., metal, concrete, tile). This affects mounting and potential structural costs.
• Existing electrical data: mention the current electrical service size, available space at the main switchboard, and any existing Power Purchase Agreements (PPAs) or financing constraints.

A quality contractor will be transparent; a poor one will try to obscure the facts. Be wary of proposals that employ high-pressure tactics, such as claiming the price is only valid if you sign immediately. Reputable quotes should be fixed for at least 30 days. A major red flag is the omission of specific equipment details; insist on the exact Manufacturer, Model Number, and Efficiency for all components, rather than accepting vague terms like "high-quality panels."

Furthermore, reject quotes that offer inflated or unverified savings without first analyzing your past 12 months of bills, or that focus only on monthly financing payments without detailing the total upfront cash price, making a true $/Wp calculation impossible. Finally, ensure the quote clearly addresses the permitting process and explicitly names the party responsible for the SP Group/EMA grid application and the mandatory Licensed Electrical Worker (LEW) submission.

A great solar system is only as good as its installer. To verify a contractor’s quality and stability, ask pointed questions about their operational history and staffing. Inquire about their local experience by asking how long they have been operating in Singapore and requesting two recent commercial references to verify their familiarity with local regulations (BCA/SCDF) and interconnection rules.

Regarding personnel, clarify whether the installation team consists of in-house staff or subcontractors, as in-house teams often ensure better quality control. Finally, probe the contractor's commitment to long-term service by asking for details on their workmanship warranty period, the location of their service team, and the guaranteed response time for repairs, as local support is paramount for maximizing long-term performance and uptime.

🔎 FAQ

Q: Why is the $/Wp the most important metric?

A: The Price Per Watt is the unit price of energy-generating capacity. Since all quotes might have slightly different system sizes kWp, the price per watt is the only reliable way to compare the fundamental cost-to-output ratio.

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Q: Should I choose the lowest price per watt quote?

A: Not necessarily. You must weigh the price per watt against the equipment quality (Tier 1 vs. Tier 2 panels), the installer's local reputation, and the strength of the warranties. A slightly higher price per watt for a top-tier inverter and a proven local installer often offers better value over the 25-year lifespan.

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Q: What information should I demand to see on the warranties?

A: Demand to see the specific product material warranty and the performance warranty. Also, ensure the installer's workmanship warranty is included.

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Q: If a quote promises significantly higher kWh production for the same kWp size, what should I do?

A: Treat this as a red flag. Production estimates are based on highly standardized modeling software. They may be using unrealistic assumptions to make their proposal look better.

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