Used Longi generators, ups & solar in Islamabad & Rawalpindi
Is a used Longi generators, ups & solar worth buying?
Longi modules are imported from China, and the badge covers several quite different constructions. A Hi-MO 5 is a conventional gridded module on the larger 182 mm wafer; a Hi-MO 6 is back-contact, with no gridlines visible on the front at all; and dual-glass bifacial versions replace the polymer back sheet with a second pane. Wafer size changed between generations too, so similar wattages are not interchangeable.
Imported
Parts usually have to be imported or sourced from the grey market, so a repair takes longer and costs more — which matters more on an older unit than the build quality does.
Nothing on a module is serviceable except the junction box and its leads, and those are matched by connector pattern rather than by brand — solar shops across Islamabad and Rawalpindi stock MC4-pattern connectors, though mating two different makes of connector is the usual cause of a hot joint. The performance warranty stays with the original installation, so a used Longi is sold on measured output rather than on paper.
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Checking a used Longi generators, ups & solar
These are specific to Longi. The general generators, ups & solar checks apply too and are on the generators, ups & solar page.
Read the type code
Longi's rear label carries a type code beginning LR with a generation digit, not the Hi-MO marketing name. That code is what a datasheet is looked up against for the exact current, voltage and dimensions.
Look for front gridlines
A front face with no visible gridlines is a back-contact module; a gridded front is the conventional construction. The two are not interchangeable within one array, because footprint and electrical figures both differ.
Check the rear pane
Dual-glass bifacial modules replace the back sheet with a second pane, which adds weight and fixes where the frame may be clamped. A hairline crack in that rear pane does not show from the front, so look across the back face in raking light before grading a lot.
Match the wafer generation
Longi changed wafer format between generations, so an older module and a Hi-MO 5 can sit at almost the same wattage while differing in size and in current. A series string follows its lowest current, so match the generation rather than the wattage.
Ask how it mounts
A bifacial module fixed flat against a roof sheet has nothing to reflect off its rear face and works as a single-sided one while still carrying the extra glass. It earns its premium only on a frame or ground mount with clearance behind.
What Longi generators, ups & solar are worth
- A module whose LR type code can be matched to a datasheet places more easily than one known only by a marketing name, because the buyer needs its exact current and dimensions before wiring it into an existing string.
- Back-contact modules are the hardest to replace like for like, since nothing else on the market shares their footprint and figures — so a matched set is wanted while a single orphan is not.
- Dual-glass panels weigh more and specify where they may be clamped, which suits structures built for them and makes them awkward on rails set up for framed single-glass modules.
- A bifacial module holds its premium only where it can be mounted with clearance behind it, because the rear face is the entire reason for the premium.
Model lines you will see second-hand
- Hi-MO 4
- Hi-MO 5
- Hi-MO 6
- LR4 series
- LR5 series
General generators, ups & solar checks
These apply whatever the badge on the front says — the generators, ups & solar page covers them in full.
Start it from cold
Ask that the generator has not been run that morning. A healthy engine catches within a few pulls, or on the first turn of the key, and settles to a steady note. Long cranking, a haze of unburnt petrol or blue smoke that will not clear after a minute points at worn rings or a carburettor that has been standing.
Run it under load
No-load running proves very little. Plug in something substantial, an iron or a heater, and listen. The engine should take the load with a brief dip and then hold. Lights that dim and brighten, or an engine hunting up and down, suggest a tired governor or a failing AVR.
Check the oil and smoke
Pull the dipstick before anything is started. Oil that is milky, thin or smells of petrol tells you more than any test run. Under load, black smoke is a fuelling problem and blue smoke is oil getting past the rings, and both are easier to spot before the engine is warm enough to hide them.
Inspect the battery bank
On a UPS or solar setup the batteries carry much of the value. Look for the manufacture date on the case, bulging sides, powdery corrosion at the terminals and low electrolyte in a tubular cell. A bank that charges full and then runs a couple of fans for minutes rather than hours is finished.
Watch the changeover
Switch off the main breaker with a fan and a light running. A sound inverter takes over without the fan stopping and without loud relay chatter. Note also whether it is a pure sine wave unit or a modified wave one, which makes fans and motors buzz and is wanted less.
Hold panels to the light
Look across a panel face at an angle. Cracked glass, hairline crazing across the cells, brown snail trails and bubbling of the plastic back sheet all mean output that will not come back. Check the junction box cover is sealed and the MC4 leads are not perished, and read the rating plate rather than trusting a quoted figure.
Longi generators, ups & solar — questions
What does the LR code on the back of a Longi panel mean?
Are used Longi bifacial panels worth more?
Other generators, ups & solar brands
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