By Vvon Engineering Team | Published | Updated
What actually degrades a rooftop solar plant in Bangladesh, how often to clean and with what water, how to read string-level data, and the scope an annual maintenance contract should contain before you sign it.
Solar EPC & street lighting RFQ checklist (TXT)
Maintenance should preserve safe operation and help identify avoidable losses. Set it around the actual equipment, roof environment and performance records rather than promising a service life or a fixed rate of loss without maintenance.
Generic advice about dust misses what is happening on most industrial roofs here. Brick kiln and cement dust binds to glass and does not wash off with a light shower. Fine lint settles on arrays above RMG floors. Feed and grain dust coats panels at agro processing plants. Roadside sites in Dhaka, Gazipur and Narayanganj accumulate a greasy traffic film that behaves quite differently from loose dust and needs contact cleaning.
Splash deposits, persistent moisture, algae and bird fouling can create uneven soiling. Localised shading may cause mismatch or hot spots, but its electrical effect needs investigation rather than a fixed diagnosis from appearance.
Set cleaning from observed deposits and performance, adjusted for seasons and access. Rain may remove some loose dirt but is not proof of a clean array. Use the selected manufacturer's limits for water quality, tools, pressure and any approved detergent.
Water quality matters more than most operators expect. Much of Bangladesh's tube-well water carries high iron and dissolved solids, and washing with it leaves an orange or chalky residue that scatters light as effectively as the dust you removed. If your supply is hard or iron-rich, use filtered or low-TDS water for the final rinse, or you will be cleaning the panels and dirtying them in the same operation.
| Task | How to set the interval | Responsible person |
|---|---|---|
| Cleaning and visual condition | Soiling evidence, seasons and manufacturer method. | Trained personnel under the safe access plan. |
| Electrical inspection and tests | Equipment guidance, risk and previous findings. | Competent electrical team. |
| Inverter cooling and firmware | Manufacturer instructions and a controlled update decision. | Qualified/authorised service provider. |
| Surge and earthing checks | Approved design, inspection plan and storm events. | Competent electrical team. |
| Thermal survey | Risk, baseline and suitable operating conditions. | Qualified thermography team. |
| Performance review | Defined monitoring and alarm response. | Owner and O&M provider. |
| Structure and roof | Designer's schedule and significant events. | Responsible structural/roof professionals. |
Confirm the monitoring platform, data granularity, owner access and support included in the contract. Investigate unexplained output changes using fault logs and appropriate measurements.
Compare strings only after accounting for module count, orientation, shading, tracker arrangement and measurement conditions. A bypassed substring within one module does not normally remove one third of a whole multi-module string's output. Common or isolated losses can have several causes; use logs, irradiance and qualified electrical tests to distinguish them.
A thermal survey can identify abnormal heating in modules and connections. Interpret findings with loading, irradiance, weather and electrical evidence; an image alone does not establish the cause or severity of every defect.
Follow the applicable thermography procedure and record irradiance, loading, wind and sky conditions. Compare results with a suitable baseline. Do not present one weather threshold as sufficient for every inspection method.
Review temperature, cooling, ingress and fault history. Service filters and fans using the manufacturer's safe procedure and planned isolation; no alarm is not proof that the unit is operating at full capacity.
Inspect seals and terminations at the agreed interval. Evaluate firmware changes with the authorised provider and preserve approved protection settings. Confirm spare and repair arrangements before purchase.
Review new obstructions and vegetation using safe inspection access. A revised string or tracker arrangement may reduce mismatch but requires electrical checks and cannot recover sunlight physically blocked by a permanent obstruction.
Most annual maintenance contracts on offer are a cleaning schedule with a service visit attached. Before you sign one, check it contains all of the following, and make the reporting obligation explicit rather than assumed.
Consult the relevant edition and the documents for the exact equipment and site: IEA PVPS: operation and maintenance in different climates; JinkoSolar: model datasheets, certificates, installation manuals and warranties; NREL: photovoltaic and energy storage operation and maintenance; HSE: planning work around fragile roofs.
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