100W–700W Solar Module OEM Range: How to Spec the Right Wattage
Key Takeaway
A 100W–700W module range is a catalog of nameplate power at standard test conditions, not one size. Lock the job, the maximum length and mass, and the system voltage first. Choose the wattage bin only on an outline that still fits the rails, the inverter current, and the container.
Table of Contents
When the RFQ Names Watts Too Early
Nameplate power is the DC watts a module is rated to produce at standard test conditions: 1000 watts per square meter, 25 degrees Celsius cell temperature, and the AM1.5 spectrum. A manufacturer that offers about 100 watts through about 700 watts is offering several formats and several power bins. The number on the brochure is the top of a span. The number on the purchase order has to be one model.
Procurement teams often write “550 watts or higher” or “use the highest wattage available” before anyone has measured the roof bay, the purlin spacing, or the inverter input. Two suppliers can both answer 550 watts and still ship different lengths, different power tolerances, and different open-circuit voltages. The cheaper quote then fails at layout, or the higher quote fails because the module is longer than the rail span the structural drawing already froze.
The opposite mistake is just as common. A small off-grid or remote communications load gets a utility-format module because the wattage looks modern. A residential roof gets a module near 700 watts because fewer pieces sound cheaper, then the crew cannot lift it and the long side crosses a fire setback. Watts are an output of cell count, cell size, and binning. They are not a substitute for the outline.
Weltrus manufactures photovoltaic modules across a span of about 100 watts to about 700 watts, including TOPCon construction used from smaller distributed arrays up to longer commercial formats. This page does not list every bin in stock and does not state a price or a lead time. Those answers move with the model and the month. One published factory lot is a useful picture of the high end: model FX-630HT-02, specified at 630 watts, with a pallet label size of 2382 by 1134 by 30 millimeters and 36 modules on the pallet. How that lot was staged is in the 630 W factory shipment note. The lesson for wattage selection is that a high nameplate still carries a long side, a mass, and a container plan.
What Each Power Band Is Usually For
Use the bands below to choose a class of module. They are procurement groups, not a Weltrus stock list and not a rule that every project inside a band uses the same length. Neighboring bins often share one outline and differ only by factory test results. A jump from one band to the next often means a different cell count or a different length, which is a different mechanical and electrical design.
| Nameplate band | Usual job | Check before you write the watts |
|---|---|---|
| About 100–250 W | Small off-grid loads, pumps, remote communications sites, marine use, and replacement of legacy small modules | Battery or controller voltage, connector type, and whether that outline is still in production |
| About 400–500 W | Residential roofs and small commercial roofs that must stay close to an existing rail layout | Length and width versus rail span, mass for a two-person lift, and open-circuit voltage versus the home inverter window |
| About 530–600 W | Commercial rooftops and some ground-mount rows where a mid-length module fits the structure | Operating current versus MPPT rating, row spacing, and the mechanical load stated for that outline |
| About 600–700 W | Large commercial and utility-style arrays that can accept a long module | Container orientation, clamp zones, string current, and rear-side gain only if the design is bifacial |
A residential all-black requirement often lands in the 400–500 watt class because the roof grid and the visual spec were written for that length. What to read on that class of datasheet, separate from frame color, is covered in all-black 445–465 W residential panel checks. Do not treat frame color as a wattage. Do not treat a 630 watt logistics example as the right module for a house roof.
Inside one outline, the factory sorts modules into power bins after the flash test. A 540 watt bin and a 560 watt bin can share dimensions and still be different line items, because the buyer is paying for a minimum nameplate and the energy model uses that minimum. Ask which bin you will receive in volume. A sample from the top bin does not prove the purchase-order bin if the bill of materials differs.
Efficiency is a result of power divided by module area, not a second way to name the product. Two 550 watt modules can have different efficiency if one is larger. When you compare area-limited roofs, ask for efficiency on the full module area, including the frame, and keep the area figure next to the watts. Cell technology still matters for temperature behavior and for bifacial projects. How to separate TOPCon and PERC in a 2026 bid is a different note: TOPCon versus PERC bifacial procurement.
Lines That Must Match Across Quotes
Fair comparison starts when every bidder fills the same fields for the model they will ship. If a field is blank, the wattage is not yet comparable. Put these lines in the RFQ so a lower price cannot hide a different product.
| Datasheet line | Why the wattage quote fails without it |
|---|---|
| Nameplate power and tolerance | 550 watts with a tolerance that allows power below the nameplate is not the same delivered floor as 550 watts that may only test at or above the nameplate |
| Test condition | Standard test condition watts are not a yield figure and are not interchangeable with a rating taken at another irradiance |
| Dimensions and weight | Racking, labor, and containers follow the outline and the mass, not the wattage printed on the label |
| Open-circuit voltage, operating voltage, short-circuit current, operating current | These four numbers set series length and whether the MPPT can take the string |
| Temperature coefficients for power and voltage | Cold sites raise open-circuit voltage; hot sites cut operating power. The coefficient is model-specific |
| Maximum system voltage and series fuse | A 1000 volt design and a 1500 volt design do not share a string length even at the same wattage |
| Mechanical design load and the clamp note | A load number without the clamp zone cannot be checked against the rail layout |
| Cell type and rear construction | Glass-glass, backsheet, and a bifacial factor change weight, handling, and energy. They are not implied by watts |
| Datasheet revision and model code | Quotes on two revisions are two products, even when the marketing wattage is unchanged |
Certificates follow the model code, not the band. Before the purchase order, match IEC 61215 and IEC 61730, or the local equivalent, to the exact model. The document list is in the IEC 61215 and IEC 61730 verification checklist. A certificate for a shorter module in the same family does not cover the longer one you are about to buy.
Warranty language also has to name the model. A 30-year linear power warranty is a curve and a claim process, not a sentence you can copy onto every wattage. Read the first-year limit and the annual rate on the warranty for that revision. Product warranty for workmanship is a separate term from power warranty. Keep them in separate columns on the comparison sheet.
Module Count, Cold Voltage, and Current
Module count is arithmetic, and it is the easy part. It is also the part teams finish before the electrical check. For a 100 kilowatt DC target, 222 modules at 450 watts deliver 99.9 kilowatts, so 223 modules reach 100.35 kilowatts. At 630 watts, 158 modules deliver 99.54 kilowatts, so 159 modules reach 100.17 kilowatts. The 630 watt choice uses fewer modules. That saving is real only if each 630 watt module fits the bay the 450 watt layout was drawn for. These counts are an illustration. They are not a Weltrus design and they are not a bill of materials.
Connectors, clamps, and home-run cables fall when the module count falls, and only under the same stringing rules. If the longer module forces an extra rail, a different ballast layout, or a second inverter because of current, the piece-count saving is spent. On a roof, add the module mass to the structural check before you accept the higher bin. A heavier module on the same area can raise the design load even when the wattage per square meter looks better. The roof-side list is in the commercial rooftop structural load checklist.
Cold open-circuit voltage decides how many modules you may place in series. Use the open-circuit voltage and the voltage temperature coefficient from the datasheet you will buy. Here is the method with assumed numbers, labeled so they are not copied onto a purchase order. Assume 50.0 volts open-circuit at standard test conditions, a voltage coefficient of −0.26 percent per degree Celsius, and a minimum cell temperature of −10 degrees Celsius. The temperature difference from 25 degrees Celsius is 35 degrees. Voltage rises by 0.26 percent times 35, which is 9.1 percent. Cold open-circuit voltage is about 50.0 times 1.091, or 54.6 volts. On a 1500 volt maximum system voltage, a first series limit is 1500 divided by 54.6, which is 27 modules, before the extra margin your inverter manual or local code requires. On a 1000 volt design the same module gives 18. A different wattage usually has a different open-circuit voltage. Copying a string length from a 450 watt sheet onto a 630 watt sheet is how arrays trip on the first cold morning.
How 1500 volt strings change balance-of-system parts, beyond this single-module check, is in 1500 V string design and balance-of-system cost. Run that note after you have a real datasheet, not instead of it.
Current is the other gate. Large-format modules often operate in the mid-teens of amps. If one MPPT input is rated below the short-circuit current of a single string, the inverter is the wrong class for that wattage, even when the kilowatt total looks fine. Parallel strings add current. Write operating current and short-circuit current beside the MPPT limit, and write the number of strings that will land on that input. Leave headroom for the tolerance the manufacturer states, not for a round number you prefer.
Logistics closes the same loop. The published 630 watt pallet uses an outline of 2382 by 1134 by 30 millimeters. That long side is longer than the internal width of a typical 40-foot high-cube container, so the loading plan has to run the long side lengthwise. A wattage choice near the top of the range is therefore a packing choice. Ask for pallet count, pallet mass, and the allowed orientation before you book the vessel. A module in the 400 watt class with a shorter long side can pack differently and still be the right buy when the site is a house.
How to Spec the Wattage
Work in this order. Skipping to step five is how the RFQ collects prices for modules you cannot install.
- Name the job and the voltage. Write small off-grid, residential roof, commercial roof, or ground array, and write 1000 volts or 1500 volts as the maximum system voltage the design will use.
- Write the physical limits. Maximum module length, maximum width, maximum mass the crew and the rail can take, clamp zone if the racking vendor already published one, and the container type you will ship in.
- Shortlist outlines that fit those limits. Reject a format here even if its nameplate is higher. A module that crosses a setback or a purlin is not a candidate.
- Read the power bins on the surviving outlines. Pick the bin you will actually receive in volume. Record tolerance and the model code.
- Run cold voltage and current with the coefficients on that datasheet. Set the series count and check MPPT current, including parallel strings. If the string does not fit, go back to the outline. Do not “solve” it by hoping for a warmer site than the design temperature.
- Compare suppliers only on a full row. Tolerance, dimensions, load, rear construction, revision, and certificate model code have to match. Then compare price on a defined Incoterm and a defined quantity.
- Qualify with a pilot lot of the purchase-order revision. A showroom module from a higher bin does not qualify the bin on the order.
Keep the comparison sheet. When a supplier offers a substitute “same watts, new size,” return to step two. Same watts with a new length is a new module. The energy model, the structural letter, and the certificate all move with it.
What a Wattage Choice Does Not Decide
- It does not mean you should buy the top of the catalog. Specify near 700 watts when the long outline fits the structure, the inverter, and the container. Specify a lower band when the roof, the lift, or the existing rails say so.
- It does not make a small module the safe choice for a large roof. A 100–250 watt class on a commercial roof multiplies connectors, clamps, and labor. Use that class for the small loads it was built for.
- It does not choose the cell technology. TOPCon and PERC can both appear inside a wide wattage span. Compare them on the procurement points in the TOPCon and PERC note, not by assuming the higher wattage is the newer cell.
- It does not replace a certificate or a structural check. Match the test reports to the model. Put the module mass and the clamp zone into the roof or ground design.
- It does not publish Weltrus stock, price, or lead time. The span is about 100 watts to about 700 watts. The model you can buy is the one on the datasheet we send against your limits. Send target kilowatts, maximum length and mass, system voltage, and destination market if you want that revision named.
Send the Limits, Not Only the Watts
Share the target array size, the maximum module length and mass, and whether the design is 1000 volts or 1500 volts. Weltrus will answer with the datasheet revision inside the 100W–700W span that fits those limits.
Frequently Asked Questions
What does a 100W to 700W solar module OEM range mean?
It means the manufacturer builds more than one nameplate power, from about 100 watts to about 700 watts at standard test conditions. It is a catalog span, not one module. The wattage on your purchase order is a specific model, outline, and datasheet revision inside that span.
Does a higher wattage always mean fewer modules and lower balance-of-system cost?
Only when the larger outline still fits the rails, the roof or ground layout, the crew lift, and the inverter current. If the long side forces a new racking grid or the current exceeds the MPPT rating, the higher nameplate can raise cost. Count modules only after the format fits.
Which datasheet lines must match before two wattage quotes are comparable?
Match power tolerance, test condition, dimensions, weight, open-circuit voltage, operating current, temperature coefficients, maximum system voltage, mechanical load with the clamp position, cell and rear construction, and the datasheet revision. A shared wattage number without those lines is not the same buy.
How do I check that a wattage bin fits the inverter?
Use the open-circuit voltage and the voltage temperature coefficient on that datasheet to estimate cold open-circuit voltage, then divide the maximum system voltage by that figure to set a series count. Compare operating current and short-circuit current with the MPPT current limit, including parallel strings. Do not copy the string length from a different wattage.
Does Weltrus stock every watt from 100W to 700W?
No. The 100W to 700W figure is the span Weltrus manufactures across, not a promise that every integer watt is a stock model. Send the target kilowatts, maximum module length and mass, system voltage, and market. Weltrus will reply with the datasheet revision that fits, including power bin and outline.
