Most solar AMC agreements we are asked to review are a cleaning schedule with a more impressive title. They specify how often someone visits and what they will wipe. They say almost nothing about the equipment that actually takes plants offline, and nothing at all about how you would know whether the work was done.
The gap most contracts leave
A solar plant has three failure modes that cost money. Soiling reduces output gradually. Electrical faults — usually inverter-side — take output away suddenly. And structural or cabling problems do nothing for two years and then do a great deal all at once.
A cleaning-only contract addresses the first and ignores the other two. That is fine if you have someone else covering them. Most owners do not, and discover this during the first inverter fault, when the cleaning contractor correctly points out that inverters were never in scope.
Scope: the eight items
A contract worth signing names all of these, and says who owns each one:
- Module cleaning — with a stated method, water source and quality standard, not just a frequency.
- Visual module inspection — cracks, delamination, discolouration, hotspots, junction box condition.
- Inverter maintenance — filter and ventilation checks, error log review, firmware status, terminal torque.
- String and DC-side checks — open-circuit voltage and current per string, connector condition, insulation resistance.
- Structural inspection — mounting integrity, fastener torque, corrosion, ballast position.
- Earthing and lightning protection — continuity and resistance, measured and recorded.
- Cable management — UV degradation, rodent damage, sagging, conduit condition.
- Generation monitoring — measured output against an expected curve, with someone named as responsible for looking at it.
If an item is genuinely out of scope, that is a legitimate commercial decision. It should be a decision, though, not a discovery.
Evidence and reporting
Ask what you receive after each visit. The honest answer from a lot of the market is “a WhatsApp message saying done”, and if the technician is good that is probably true. It is simply not something you can audit, hand to a buyer during due diligence, or use to argue a warranty claim.
What a defensible visit record contains:
- Date, time in and time out, and who attended
- The checklist actually completed, item by item
- Photographs before and after, from fixed positions so they are comparable
- Readings taken, with the instrument used
- Anything found that was not fixed, and what it needs
- Generation for the days either side of the visit
Response times
Scheduled visits are the easy part. The clause that matters is what happens when something breaks between them. A contract should state:
- How a fault is detected — monitoring alert, or you noticing the bill
- Acknowledgement time, and by which channel
- On-site response time, split by severity
- Who pays for parts, and what the mark-up is
- What happens when the fault is a manufacturer warranty item — who files it
“Best effort” on a plant of any size is not a service level. It is a way of avoiding one.
Read the exclusions first
Genuinely: read that section before the scope section. It is where the contract tells you what it really is. Common exclusions worth pushing back on are inverter repair of any kind, anything requiring scaffolding or a boom, module replacement handling, and — our favourite — “damage caused by environmental conditions”, which on a rooftop in Maharashtra is doing a remarkable amount of work.
Questions to ask before signing
- What does a completed visit report look like? Show me a real one, redacted.
- How will I know output has dropped — will you tell me, or will I?
- Who exactly attends: your employees, or a subcontractor you will not name?
- What water do you use, and what is its hardness?
- What is in the exclusions, and what would it cost to bring the important ones in?
- If I leave, do I take the maintenance history with me?
That last one catches people out. Your plant's service history is an asset — it affects resale, warranty claims and the next contractor's learning curve. Make sure the contract says it is yours. Ours does, and any record we hold in Earth360 is exportable on request.
Related: What OneEarth O&M covers · What cleaning should cost