How to choose a solar EPC contractor in Bangladesh: ten questions, and what a good answer sounds like
Ten questions to put to any solar EPC contractor in Bangladesh before signing, the answers that should worry you, the red flags in a quotation, and the handover documents a serious contractor produces at commissioning.
Bangladesh's solar market has grown rapidly, and with it the number of companies claiming to be solar EPC contractors. The quality varies enormously, from experienced engineering firms with certified teams and Tier-1 equipment to operators using substandard panels and unqualified labour. A poorly designed or installed solar system can underperform by 20 to 40%, fail within 5 years, and void your equipment warranties. Here are the ten questions to ask before signing any EPC contract, and what a satisfactory answer actually sounds like.
The ten essential questions
Are you an authorised partner of the module and inverter brands you are proposing? Authorised partners receive factory training, genuine spare parts and warranty support. Non-authorised resellers may use counterfeit or grey-market equipment. Ask to see the letter, not a logo on a website.
Can you show me completed projects of similar scale? Ask for project references with contact details. A credible EPC will have verifiable references from clients you can call. Similar scale matters: a contractor with forty 10 kWp rooftops has not built a 500 kWp plant.
Does your scope include the structural design, lightning protection and net-metering application? Many low-cost quotations exclude these items and add them as extras later. Get the exclusions listed in writing before you compare prices.
What is the module's product warranty and performance warranty? Tier-1 modules offer a 12-year product warranty and a 25 to 30-year linear performance warranty. Tier-3 modules may offer only 5 years. Ask who honours the claim inside Bangladesh and what the process is.
What inverter brand are you proposing, and do they have a service centre in Bangladesh? Inverter failures are the most common cause of solar system downtime, so local service support decides how long an outage lasts. Ask what spares are held in-country.
Will you provide a performance guarantee (PR ratio)? A credible EPC will guarantee a minimum performance ratio of 75 to 80% and accept liquidated damages if it falls below. Ask how PR will be measured and against which irradiance reference.
What is included in your O&M contract? The first 2 years of O&M should be included in the EPC price. Ask for response time SLAs and what is covered, particularly cleaning frequency and whether inverter servicing is inside or outside the fee.
Are your installation teams certified? Ask for evidence of electrical safety training, working-at-height certification and SREDA-registered installer status. On a tin-shed roof this is a safety question before it is a quality question.
How do you handle the BPDB, DPDC or DESCO net-metering application? A full-service EPC handles the entire utility application process, not just the installation. Ask how many approvals they have obtained from your specific utility.
What monitoring system do you provide? A quality solar system should include a cloud-based monitoring platform showing real-time generation, consumption and alerts. Ask specifically whether monitoring is at string level or only at plant level.
Red flags to watch for
Quotation does not specify the module brand, model and wattage.
Inverter brand is unknown or has no Bangladesh service centre.
No structural design or wind load calculation included.
No performance guarantee or PR ratio commitment.
Price is more than 20% below market rate (BDT 60,000 to 80,000 per kWp installed).
Company cannot provide verifiable references from completed projects.
No mention of lightning protection, surge protection devices (SPDs) or earthing.
The price flag is worth explaining, because a low number is not automatically a bad one. Ask what was removed to reach it. In practice a quotation that far below the range has dropped the structural design, moved to a thinner mounting section, used undersized DC cable, left out surge protection, or excluded the net-metering application. Every one of those saves money on day one and costs more than it saved within five years. Undersized DC cable in particular is invisible at handover and shows up only as a persistent yield shortfall that nobody can locate without a string-level test.
What to establish before you go to tender
You will get better proposals, and be much harder to mislead, if you supply these facts to every bidder rather than letting each one guess.
Sanctioned load and transformer rating, from the bill and the substation nameplate. These set the approvable capacity ceiling and there is no point pricing a plant above it.
Twelve months of electricity bills, and daytime consumption if you can extract it. Without this, every savings figure you receive is invented.
Roof construction and age. RCC, corrugated metal on steel purlins, or asbestos sheet. Purlin spacing and remaining sheet life change the mounting design completely, and asbestos changes the method statement.
Roof obstructions and future plans. Water tanks, lift machine rooms, vents, existing plant, and any building work planned nearby that will cast a new shadow.
Tenure. Owned or leased, and how long the lease runs against the expected payback.
Existing generator and any large non-linear load. The generator interface has to be engineered, and harmonics from existing VFDs or induction furnaces affect inverter selection and protection.
The documents a serious contractor hands over
This is the single most useful test in this article, because it is verifiable after the fact and it costs you nothing to specify. Write the handover pack into the contract, tie the final payment to it, and a large part of the quality problem takes care of itself. A contractor who intends to cut corners will negotiate hard on this clause, which tells you what you need to know.
As-built single line diagram and array layout, reflecting what was actually installed rather than what was designed.
String test records: open-circuit voltage and short-circuit current for every string, with the irradiance and temperature at the time of test.
Insulation resistance and earth continuity test results for DC and AC sides, with instrument details.
Earthing and lightning protection test report, including measured earth resistance.
Inverter configuration record: grid protection settings, power factor, export limits where applicable, and firmware version.
Thermal scan report of modules, combiners and terminations at commissioning, which becomes the baseline every later scan is compared against.
Structural design calculation and wind load basis for the mounting system.
Utility approval file: NOC, approval letter, signed net-metering agreement and meter details.
Warranty certificates in your company's name, with serial numbers, plus the O&M manual and monitoring platform credentials transferred to your staff.
If you are a public buyer on e-GP
Public hospitals, universities and government institutions tendering through e-GP face a specific difficulty: lowest evaluated price wins, so the specification has to do the quality work that commercial negotiation would otherwise do. Write the technical requirements so that a substandard bid is non-responsive rather than merely cheap. Specify module tier and warranty terms, require a named inverter make with in-country service, make the structural calculation and wind load basis a submission requirement, require the performance ratio guarantee and the handover pack as contract deliverables, and set installer certification and reference projects of comparable capacity as qualification criteria. Requiring that the net-metering approval is inside the contractor's scope also prevents the familiar outcome where a plant is built, paid for, and then sits unapproved because the application was nobody's responsibility.
Where Vvon fits
Vvon Technologies Limited is a solar EPC contractor: we engineer, procure, build, commission and maintain complete plants, and we do not sell components over the counter. We have commissioned over 7 MWp of industrial rooftop solar across Bangladesh, including the 1,503 KWp Akij Agro Feed plant and the 575 KWp Ahad Jute Mills plant. Our in-house engineering team handles the work from structural design through the BPDB, DPDC and DESCO net-metering applications to post-commissioning O&M. Modules and inverters specified into our projects come from Tier-1 makes including Jinko Solar, JA Solar, Canadian Solar, Sungrow, Huawei, SMA, Growatt, Solis and Schneider Electric, selected per project on yield, warranty and service reach inside Bangladesh.