Specification builder · Tier C
Hybrid solar PV power system (10-30 kVA) with lithium iron phosphate battery storage for essential loads
A hybrid solar system combines solar panels, a hybrid inverter and a lithium (LiFePO4) battery so that a laboratory, ward, cold-chain store or office keeps power through load-shedding and pays less for grid electricity. Hospitals, health departments and drug testing labs in Pakistan buy 10-30 kVA systems (15 kVA is typical) for their essential loads. Good tenders specify performance, certificates and protection in neutral terms, and choose the installer by AEDB certification, references and service.
What this equipment will do
- Loads served (essential-load port): lab refrigerators, incubators, safety cabinets, lights and IT; ward, nurse-station and OT lights and sockets; vaccine, blood-bank and pharmacy cold rooms; office and server-room loads.
- Three-phase 400/230 V, 50 Hz pure sine-wave output of 10 kW or more, able to carry unbalanced single-phase loads (inverter type-tested to IEC 62109-1 and IEC 62109-2).
- Starting of motors and compressors: 150% overload for 10 s on the backup port. (with the optional module)
- Automatic changeover to battery and solar on grid failure and automatic return when the grid comes back, verified by a recorded grid-failure test at commissioning.
- UPS-mode changeover within 20 ms or 10 ms, so most computers and controllers do not reset. (with the optional module)
- LiFePO4 battery storage of 10 kWh usable or more with battery management system (IEC 62619 or UL 1973, UN 38.3).
- Solar generation of 10 kWp or more from certified monocrystalline modules (IEC 61215, IEC 61730).
- Earthing, surge protection, DC isolation and AC protection of the installation (IEC 60364-7-712).
- External lightning protection designed from a risk assessment (IEC 62305-2). (with the optional module)
- Net-billing (prosumer) connection to the DISCO, inverter tested for utility interface and anti-islanding (IEC 61727, IEC 62116, NEPRA Prosumer Regulations). (with the optional module)
- Integration with the existing diesel generator through an interlocked automatic transfer switch. (with the optional module)
- Remote monitoring by app or web portal with alarms for grid failure, faults and low battery. (with the optional module)
Not covered: It is not sized to run air conditioners, water heaters, large pumps or a whole hospital; those stay on the grid or generator, or need a larger solar plant.; It does not give true no-break power to sensitive analysers, OT equipment or servers by itself; those need their own online UPS downstream.; It does not replace the generator for long outages at night or in cloudy weather; backup time is limited by the stored battery energy.; It is not a medical isolated power supply (IT system with insulation monitoring) for operating theatres or ICUs; that is a separate isolation-transformer panel.
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Standards this specification draws on
- IEC 62109-1 Basic safety standard for power converters used in PV systems; the hybrid inverter must be type-tested to it.
- IEC 62109-2 Particular safety requirements for PV inverters (insulation monitoring, residual current, anti-islanding hardware).
- IEC 61730 PV module safety qualification (parts 1 and 2): electrical insulation, fire and mechanical safety of the modules.
- IEC 61215 PV module design qualification and type approval (heat, humidity, UV, hail and mechanical load tests) that predicts long field life.
- IEC 62619 Safety requirements for industrial lithium batteries, including stationary storage (UL 1973 is the accepted North American equivalent).
- IEC 62620 Performance test methods for industrial lithium cells and batteries, used to check capacity and cycle-life claims.
- IEC 61727 Utility-interface characteristics for grid-connected PV systems (voltage, frequency, power quality, DC injection).
- IEC 62116 Test procedure for anti-islanding protection of grid-connected inverters, which DISCOs rely on for line-worker safety.
- IEC 60364-7-712 Wiring rules for PV installations: DC cabling, isolation, protection, earthing and labelling.
- IEC 62305 Lightning protection series; part 2 risk assessment decides whether an external lightning protection system is needed.
- NEPRA Prosumer Regulations, 2026 Current NEPRA rules (replacing the 2015 net-metering regulations) for connecting distributed generation up to 1 MW under net billing.
- AEDB (Certification) Regulations, 2021 Certification of solar installers/vendors in Pakistan (enlistment now handled by PPIB); needed for DISCO connection.
Common mistakes in tenders for this equipment
- Copying one brand's datasheet figures (an exact battery voltage window, bypass current rating, number of MPPTs or parallel units) so only that brand complies; state minimum needs with 'not less than' instead.
- Sizing the system by kWp alone without a load survey of essential circuits, so the battery is drained by air conditioners and the inverter trips on motor starting currents.
- Accepting a vague 'UPS function' claim without a stated and tested changeover time in milliseconds, and assuming the hybrid inverter replaces online UPS units for OT, ICU or analyser loads.
- Ignoring heat: inverters and batteries installed in sun-facing rooms or under tin roofs derate in summer and lithium batteries lose life quickly above 35-40 deg C.
- Leaving earthing, DC isolators, surge protection, lightning protection, cleaning access and the essential-load board out of the bill of quantities, then paying variations or living with an unsafe system.
- Accepting modules or batteries without model-specific IEC certificates, flash-test data and serial-number checks, which lets re-labelled, B-grade or old-stock products in.
- Asking for DRAP medical-device registration: a solar power system is not a medical device, so this demand only confuses bidders; ask for AEDB certification and type-test certificates instead.
- Writing 'net metering' into a new tender without checking the current NEPRA prosumer (net-billing) rules and the DISCO process, so the export benefit is overestimated.