A credible solar provider must do more than quote panel capacity: it must prove that the design fits your roof, electrical system, operating pattern and backup needs. Use the checks below to compare providers, identify weak proposals before signing, and confirm that the promised support continues after commissioning.
Key takeaways
- Ask for a site-specific design signed by a named electrical professional.
- Require module, inverter, battery, protection and warranty details in every quotation.
- Check commissioning records, test results, approvals and interconnection responsibility.
- Agree on monitoring, response times and performance support before signing.
Can the company prove it can design for your property?
Ask for a site-specific design prepared by a named electrical professional, not a sales estimate based on roof area alone. Verify the company’s solar design capability, relevant project experience, electrical credentials, and responsibility for approvals, interconnection and commissioning.
1. Require a documented rooftop survey recording roof dimensions, orientation, tilt, usable area, obstructions, access routes, roof age and waterproofing details. The report should also state sanctioned electrical load, connection type, daytime consumption and the proposed point of interconnection.
2. Demand a structural assessment covering dead load, wind uplift, snow or other imposed loads where applicable, attachment spacing, rail spans, corrosion compatibility and roof-warranty restrictions. It must explain every penetration and waterproofing treatment; certified modules and rails do not prove that the assembled array suits your roof.
3. Request a shade analysis based on site measurements or a three-dimensional model, with monthly or hourly loss estimates. The design should explain whether it will exclude shaded areas, alter string layouts or use module-level electronics, including the added failure and replacement points.
4. Check the calculations at the site’s lowest and highest expected temperatures. Confirm string open-circuit voltage stays below the inverter and module limits, while hot-weather voltage remains inside the inverter’s MPPT range; request a DC and AC single-line diagram showing fuses, isolators, surge protection, earthing, inverter ratings and interconnection.
For solar lighting, ask for a photometric file and calculations for maintained illuminance, uniformity, spacing, operating hours and battery autonomy. Battery sizing must include worst-season solar resource, efficiency losses, temperature derating, allowable depth of discharge, ageing and cloudy-day recovery.
Which documents make a solar quotation comparable?
A low price is meaningless if one quotation covers 10 kW of panels and another covers 10 kW of inverter capacity. Compare the design basis, equipment, expected output and scope before comparing totals.
Request these documents before signing:
- A site-specific single-line diagram showing string fuses, DC and AC isolators, surge protective devices, earthing conductors, inverter ratings and the grid connection point.
- A generation estimate stating system size, orientation, tilt, shading assumptions, degradation, losses and expected monthly and annual yield.
- An equipment schedule listing manufacturer, model number, rating, quantity, warranty term and compliance documents for modules, inverters, batteries, cables and protection devices.
- Structural drawings showing module layout, rail spans, attachment spacing, dead load, wind uplift, roof penetrations and corrosion-compatible materials.
- The protection scheme, installation scope, warranty terms, commissioning report and maintenance plan.
Use the same comparison fields for every quotation:
| Item | What to record | Why it matters |
|---|---|---|
| System basis | Module kWp, inverter kW, battery kWh and usable kWh | Exposes different system sizes |
| Energy result | Annual kWh, monthly output and loss assumptions | Separates production from nameplate capacity |
| Property assumptions | Roof area, shading, orientation, sanctioned load and grid limit | Shows whether the design fits your site |
| Price scope | Equipment, structure, cabling, approvals, testing and taxes | Prevents omitted work appearing as a later charge |
Ask the supplier to reprice a common system size or provide cost per installed kW and cost per estimated annual kWh. Reject comparisons that omit shading analysis, roof-load responsibility or battery autonomy assumptions.
Does the proposed system match your power and equipment needs?
Choose the architecture from your load profile, outage requirement and property limits, not from the panel count alone.
| Option | What it means | When it applies |
|---|---|---|
| On-grid solar | Solar supplies daytime loads and exports surplus; it shuts down during a grid outage unless separate backup equipment is installed. | Reliable grid, daytime consumption and a suitable interconnection. |
| Hybrid solar system | Solar, grid and batteries work together, with selected circuits operating during outages. | You need backup but want to limit battery size and retain grid support. |
| Battery-backed system | Solar and substantial batteries serve loads with limited or no grid dependence. | Unreliable grid, critical loads or a requirement for longer autonomy. |
Ask for battery capacity in usable kilowatt-hours, not only the battery’s nameplate figure. Confirm the design covers night-time demand, outage duration, allowable depth of discharge, ageing, temperature, round-trip efficiency and cloudy-day recovery.
Require the equipment schedule, manufacturer datasheets, serial numbers and warranty-registration process. Match every proposed substitution by electrical and mechanical performance, not wattage or connector appearance. Check module short-circuit current, inverter MPPT voltage limits, maximum series-fuse rating, connector type, cable insulation, racking metal and surge-protection ratings.
Request a site-specific DC and AC single-line diagram showing strings, fuses, isolators, SPDs, earthing, inverter ratings and grid connection. The design must test string voltage at minimum and maximum site temperatures.
Confirm in writing that the installer owns responsibility for dead load, wind uplift, attachment spacing, rail span, corrosion compatibility, roof warranty and sealed penetrations. For solar lighting, demand a photometric file, maintained illuminance, uniformity, spacing, operating hours and end-of-life battery capacity; lumen claims alone prove little.
What installation and commissioning controls should be non-negotiable?
A plant is not complete because panels are bolted down and an inverter screenshot exists. Demand installation records that prove safe current paths, weather-tight penetrations, correct protection and successful commissioning under IEC 62446-1.
- Require a site-specific DC and AC single-line diagram showing string fuses, DC and AC isolators, inverter ratings, interconnection points, earthing conductors and surge protection devices.
- Inspect cable routing: connectors must be compatible and fully engaged, cables supported clear of the roof, bend radii respected, and exposed cable ends sealed. Require flashing or approved glands for every roof penetration; poor waterproofing causes leaks and intermittent faults.
- Check that earthing and lightning protection match the building’s existing system, cable routes and utility exposure. DC and AC SPDs need suitable voltage ratings, short-circuit withstand, backup protection and visible replaceable-status indicators.
- Require commissioning results for polarity, continuity, protective conductors, insulation resistance, string open-circuit voltage and current, inverter settings, isolator operation and monitoring. An inverter screenshot alone proves little.
- Control substitutions by electrical and mechanical equivalence, not wattage or connector appearance. A different module current, connector, cable insulation, racking metal or SPD rating can invalidate protection calculations.
| Control | Evidence at handover | What failure looks like |
|---|---|---|
| Roof penetrations | Photos, gland details and leak-test record | Water ingress and corrosion |
| Protection | Tested SPD status and earth-continuity results | Damage during surges |
| Strings | Recorded voltage and current for each string | Hidden mismatch or reversed polarity |
| Lighting batteries | Autonomy calculation including losses, ageing, temperature and depth of discharge | Seasonal night-time failure |
How will the company support performance after commissioning?
Do not accept “25-year panel warranty” as an after-sales plan. Secure separate obligations for the product and workmanship warranty, inverter repair, and the performance guarantee, because a failed optimizer, surge-protection device, connector, monitoring gateway, or roof penetration can stop production without invalidating the module warranty.
Put these terms in the contract:
- State the warranty period, covered parts, labour, freight, site access, roof-repair responsibility, claim documents, response time, and replacement or restoration deadline.
- Require a named contact, local spare-parts arrangements, fault-alarm triage, and escalation contacts for unresolved failures.
- Define who owns the monitoring portal, checks data quality, investigates underperformance, restores communications, and applies firmware updates.
- Set the performance guarantee against an agreed annual kWh model, with stated assumptions for irradiation, shading, availability, degradation, grid outages, and exclusions. Specify compensation or corrective work when the target is missed.
- Attach an O&M plan covering inspection frequency, cleaning criteria, thermal scans, torque checks, vegetation, corrosion, protection testing, and annual reports.
A portal screenshot is not maintenance. Ask for alarm thresholds and restoration targets for inverter trips, low string current, missing data, and abnormal generation. Make the installer responsible for roof attachment, corrosion compatibility, and weatherproofing defects.
For solar lighting, require a photometric file and maintained illuminance, uniformity, spacing, mounting height, operating hours, dimming profile, autonomy, and end-of-life battery-capacity calculation. The battery model must include temperature, losses, allowable depth of discharge, ageing, and cloudy-day recovery. Rupribha Electricals (OPC) Private Limited should be assessed against these written deliverables, not catalogue claims.
Frequently asked questions
What proves that a solar company can design for your property?
Ask for a site survey, shading assessment, electrical load review, single-line diagram and a design prepared by a named electrical professional. Check comparable project references and the company’s electrical credentials.
Which documents make solar quotations comparable?
Request an itemised bill of materials, system capacity, equipment model numbers, energy estimate, scope of work, exclusions, payment terms, warranties, approval responsibilities and commissioning deliverables.
How do you check whether a proposed solar system matches your needs?
Compare the design with your load profile, roof constraints, supply phase, backup requirements, battery needs, inverter capacity, protection equipment and future expansion plans.
What installation and commissioning controls should be required?
Require documented mounting and cable checks, earthing and protection tests, inverter configuration, insulation-resistance and polarity tests, monitoring setup, approval records and a signed commissioning report.
What after-sales support should a solar company provide?
Get written terms for monitoring, fault reporting, response times, preventive maintenance, warranty claims, replacement responsibilities, performance reviews and access to system data.
