EGING PV (Signature Solar) EG Star EG-NT54-HL/BF-DG 440W Bifacial

What these numbers mean for an off-grid build

The table above is what the manufacturer publishes. This section is what those figures imply once the unit is doing real work, worked from this row and from the 22 products in the same table. The arithmetic is shown so you can check it against your own design rather than take it on trust.

What one panel actually produces

Rated output is 440 W, which is what it makes under standard test conditions in a laboratory rather than on your roof. In service, a reasonable planning figure is rated watts multiplied by the peak sun hours at your location and then reduced by around 20 percent for wiring, temperature, soiling, and conversion losses.

On that basis one of these panels yields roughly 1.41 kWh on a day with 4 peak sun hours, and about 0.88 kWh in a location whose worst month averages 2.5. The difference between those two numbers is the whole argument for sizing an array on the worst month rather than the annual average. The site report gives both figures for any address, and the solar calculator turns them into an array size for your load list.

String design, and the cold-morning trap

Open-circuit voltage is 38.9 V per panel. Dividing a controller's maximum input voltage by that figure gives the naive series limit: about 3 panels for a 150 V controller, 6 for a 250 V unit, and 12 for a 500 V unit.

Do not build to those numbers. Panel voltage rises as temperature falls, so a string that measures safely on a warm afternoon can exceed the controller's limit on a clear, cold morning, and exceeding it can destroy the controller instantly rather than gradually. The correction depends on the panel's voltage temperature coefficient and on the coldest temperature your site actually reaches. Work it out for your own design low, which the site report gives for any address, and leave margin on top. Lesson six covers the wider direct-current safety picture.

Current, wiring, and fusing

This panel produces about 14.57 A at its maximum power point. Panels in series carry the same current at higher voltage; panels in parallel add current at the same voltage, which is why parallel strings need combiner fusing and series strings often do not.

Efficiency, and when it matters

Rated efficiency is 22.8 percent, 8 percent above the median for this table (median 21.1 percent). Efficiency describes watts per unit of area, so it matters when roof or rack space is the binding constraint and matters much less when it is not. On open ground, cheaper and larger panels producing the same total watts are frequently the better buy.

Price per watt

At $0.39 per watt, this panel is 57 percent below the median for this table (median $0.90 per watt across 22 panels). Price per watt is the only fair way to compare panels of different sizes, and it is worth remembering that racking, wiring, and labor do not scale down with a cheaper panel. The price index tracks where the market has been.

The closest alternatives in this table

Sorted by the specification that defines the category, these are the units in the solar panels table sitting nearest to EGING PV (Signature Solar) EG Star EG-NT54-HL/BF-DG 440W Bifacial at 440 W. Comparing against near neighbors is more informative than comparing against the whole table, because it isolates the differences that are not simply size.

• Canadian Solar TOPHiKu6 CS6.2-48TM-440H (All-Black TOPCon) · 440 W
• Jinko Tiger Neo JKM440N-54HL4R-B · 440 W
• Aptos Solar DNA-120-MF10-440W · 440 W, $0.41 per unit
• LONGi Hi-MO 6 Explorer LR5-54HTH-430M · 430 W

The full table sorts on every column, which is the fastest way to see whether a difference in price is buying a difference in specification or only a difference in brand.

How this fits with the rest of the system

Panels are chosen against the controller more than against each other. The controller's maximum input voltage caps how many of these can go in series, its maximum charge current caps how many watts the array can usefully deliver at your system voltage, and both limits bite hardest in cold weather. The controller table lists those ceilings for each unit.

Downstream, the array has to be able to refill the bank in the worst month rather than on an annual average, which is a battery question as much as a panel one. The battery table gives capacity and charge limits, and the system planner sizes array, controller, battery, and inverter against each other in one pass instead of one at a time.

Checking these figures against the datasheet yourself

Check whether the quoted power is at standard test conditions or at the more realistic nominal operating cell temperature, since the two differ by a meaningful margin. Look for the temperature coefficient of open-circuit voltage specifically, not only the coefficient for maximum power, because it is the voltage figure that decides your string length in cold weather. Check what the product warranty covers as against the performance warranty, which are different promises.

Two conventions catch people out across every category. The first is that a specification quoted without its test conditions is not really a specification, so where a datasheet gives a number and no conditions, treat it as marketing until you find the conditions. The second is that model names persist across silent revisions, so a sheet downloaded three years ago may not describe the unit in the box. The price index and the observed prices above are dated for the same reason.

Installing it, and living with it afterwards

At around 45 lb each, panels of this class are a two-person lift onto any structure, and the mounting has to carry wind uplift as well as weight. Ground mounts are easier to build, clean, and clear of snow, and they keep penetrations out of the roof; roof mounts save land and are harder to service. In snow country, a steeper tilt sheds better and a mount low to the ground will be buried in the month the array matters most.

Wiring is where the yield is quietly lost. Keep voltage drop on the array run small, since a few percent lost between panels and controller is a few percent of every kilowatt-hour the system will ever make. Use connectors rated for outdoor direct-current service, crimp them properly with the right tool, and support the cable so it is not hanging on the connectors. Bond the frames and give the array surge protection: on an exposed rural site it is frequently the tallest metal object for some distance.

Warranty, and what it is worth

The published warranty is 15 years. Off grid, the length of a warranty matters less than the mechanics of claiming on it: who pays freight on something heavy, whether a replacement ships before the failed unit is returned, whether the seller or the manufacturer handles the claim, and whether an owner installation voids anything.

Ask those questions before you buy rather than after a failure, and keep the purchase paperwork, serial numbers, and installation photographs with the systems binder. Where the unit is a single point of failure for something critical, the honest planning assumption is that a warranty replacement takes weeks, which is the argument for a spare or a second path rather than for a longer warranty. Lesson ten covers deciding which of those is worth paying for.

What separates one panel from another

Panels have become a commodity in the sense that most current modules from established manufacturers perform close to their ratings and degrade slowly. What differs is the arithmetic around them and the assumptions a particular module forces on the rest of the design.

Physical size and voltage class are the first fork. Small 12 V-class panels suit vans, sheds, and tiny systems where the array is a handful of modules and simplicity matters. Larger residential modules give far better price per watt and demand a controller with a higher input voltage, more careful string design, and two people to carry each one. Choosing across that boundary changes the controller you can use.

Cell technology moves the temperature behavior and the low-light response more than it moves the headline efficiency. Bifacial modules can add yield on a ground mount over a reflective surface such as snow or light gravel, and add nothing on a roof. Higher efficiency buys watts per unit of area, which is worth paying for when space is the constraint and not otherwise.

Then read the two warranties separately. The product warranty covers the panel failing; the performance warranty covers it producing less than a stated fraction of its rating after a given number of years. They are different promises with different lengths, and a long performance warranty from a manufacturer that may not exist in fifteen years is worth what you would expect.

Mounting, tilt, and the winter case

A panel's output is set as much by where it is pointed as by what is printed on the back of it. In an off-grid system sized on the worst month, that means designing the mount for winter rather than for annual average.

A steeper tilt catches a lower sun, sheds snow, and narrows the gap between the worst month and the annual figure, which is exactly the gap that sizes the array. A shallower tilt favors summer, when most off-grid systems already have more energy than they can use. Where the mount can be adjusted seasonally, two positions a year capture most of the available benefit for the price of an afternoon.

Ground mounts are easier to clean, clear, and service, and they keep penetrations out of the roof. Roof mounts save space and are harder to reach in the month they most need clearing. The tilt calculator works the angle for your latitude, and the site report gives the worst-month sun figure that makes the case.

What the table cannot tell you

Every figure above comes from a published datasheet, and datasheets describe a unit under test conditions rather than in your building. They do not tell you how a manufacturer behaves when something fails inside the warranty period, whether spare parts will still be available in ten years, how the firmware behaves in an edge case, or whether the support line is answered by someone who knows the product. Those things decide as much of the ownership experience as the specifications do, and the place to learn them is from people running the equipment: the forum is a reasonable place to ask.

Nor does a datasheet describe the installation. Most off-grid equipment that disappoints its owner was undersized for the real load, wired with conductors chosen by eye, protected by fusing selected on price, or sited somewhere too hot, too cold, or too awkward to service. The equipment rarely fails on its own terms. Lesson six is the one to read before buying anything on this page, and the system planner puts the whole design together so the components are chosen against each other rather than one at a time.

Specifications here are recorded from the manufacturer datasheet or a primary retailer page on the date shown, with a confidence flag on every row. Manufacturers revise datasheets, and models are superseded without changing name. Check the current sheet before you spend money, and if you find a figure here that no longer matches the source, the corrections page is how to tell us; corrections are logged publicly rather than quietly edited. How this site researches sets out the rest.