LA Solar Group

Solar Panels

Installing Industry's Best

Solar panels differ in manufacturing specifications, shape, color, price and efficiency.

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Solar panels come in many varieties to meet the different cost, performance, size, efficiency, and aesthetic needs of customers. The type of solar panels you obtain will vary based on the solar panel manufacturer.

Solar panels utilize the following major technologies:

  • Polycrystalline Silicon (cheaper, moderate efficiency, usually blue in color)
  • Monocrystalline Silicon (considered “premium,” high efficiency, requires less roof space, typically black in color)
  • Thin-Film (cheaper, low-moderate efficiency, could be flexible, has lower and better temperature degradation)

Solar cells made from these technologies are connected, usually in sets of 60, 72, or 96 cells. Once connected, they form a solar panel or module. In turn, the panel or modules are connected to one another to form arrays (e.g., groupings on different roofs). The arrays are then collectively referred to as the solar system.

Example: Panasonic N330 (VBHN330SA16) panel is composed of 96 N-Type, monocrystalline cells.

Power Rating (watts)

Solar panels are rated by their DC power output in watts (W) under standard test conditions (STC) and real-world test conditions (PTC). The closer the PTC value is to the STC, the better the real-world performance would be to the marketed performance. When looked at as a ratio (PTC/STC), the ideal would be 100%.

Example: Panasonic N330 (VBHN330SA16) panel’s STC rating is 330W, and the PTC rating is 311W, resulting in a PTC/STC ratio of 94% (which is very good for this technology).

Efficiency (%)

A solar cell’s efficiency measures its ability to convert light into electricity. The higher the efficiency, the better (assuming the costs are about the same). Residential efficiencies in the low 20% range are considered excellent. Higher efficiency cells mean that fewer are needed to attain the same panel wattage; thus, less roof space is required. Alternatively, a panel utilizing high-efficiency cells would produce higher wattage in the same area.

The comparison metric is (PTC Watt rating/SF). STC watts could be used as well, but PTC is a more realistic and conservative value. When comparing, the value used needs to be consistent.

Example: Panasonic N330 (VBHN330SA16) panel’ s efficiency is rated at 19.7. Its power is rated at 306 PTC Watts and takes up (41.5″ x 62.6″ = 18sf) resulting in 306W/18sf = 17W/SF.

Efficiencies depend on the cell capability and the number of cells used. Some high-wattage panels use a greater number of lower efficiency cells, at the cost of larger panel size.

The most efficient and best solar panels are considered monocrystalline silicon cell panels, which come with a higher price tag. If you have enough roof space available, it may be better to use more or larger panels with lower efficiency cells.

Doing so will lower your net cost, resulting in a shorter payback period and higher ROI.

Temperature Degradation

Most solar panels’ power degrades with higher temperatures – the hotter the panel, the less it produces. This percentage decrease per each degree of increase over 25°C is referred to as the temperature coefficient. The lower the coefficient, the better.

To keep the panels cool, install them as high as possible above the roof surface (to provide better air circulation), usually at least 6″.

Example: Panasonic N330 (VBHN330SA16) panel’s temperature coefficient is -0.258%/°C. On a 95°F day, it is about 120°F on the roof. 120°F is about 50°C. This is 25°C above the 25°C baseline, so the % degradation is -0.258 * 25 = 6.45%. This leads to a 21W drop in the output of the 330W rated panel. The good news is that for every drop below 25°C, the output increases.

Warranted Tolerance

An average 330W panel may be more or less than 330W. Most solar panel manufacturers provide a warranted tolerance percent that limits this variance. Most premium category panels have only a positive tolerance. This means that the actual output will be between 0% and the warranted tolerance value on average.

Example: Panasonic N330 (VBHN330SA16) panel’s Warranted Tolerance is: +10%/-0%. This means that a randomly chosen panel’s output will be anywhere between 330W and 360W, with an average output of 345W.

Bypass Diodes

When one or more solar cells in a panel does not produce electricity due to failure or shading, the solar panel is negatively impacted.

To reduce this impact, the cells are broken up into groups (usually 20 cells/group in a 60-cell panel, or 24 cells/group in a 96-cell panel), with each group capable of being “bypassed” in case of low producing cells within that group. Therefore, the remaining groups will still perform.

Example: Panasonic N330 (VBHN330SA16) panel consists of 96 cells and are broken up into 4 cell groups of 24 cells each and having 4 bypass diodes.


Bi-Facial panels have a double glass construction that serves to generate solar energy from both the front and back sides of the solar panel. Since the panels are ultra-thin, they can also be frame-less with a plastic back sheet. These are aesthetically attractive options to install on residential roofs, terraces, and carports.

The technology can operate at its fullest potential when installed on a highly reflective roof surface. In this case, the panels can produce 24% more energy than standard mono-facial modules. Bi-facial panels can generate up to 100% AC output vs. 80-85% AC output from conventional panels.

This output change is due to its low thermal and light degradation. Module efficiencies are currently up to 22%, with panel output between 310W – 370W. A 25-year power warranty is offered with 95% efficiency from years 1-5, and 83% efficiency from years 6-25 at 0.6% degradation.


With almost invisible cell lines, their smooth black design will look great on any roof. These panels are manufactured with high-efficiency, thin-film technology that has less degradation than mono or poly modules.

The purpose of the film is to generate consistent power year-round, even during cloudy and overcast days or when the sun is at a low angle during the winter months.

Shading will have little effect on these panels, thus providing better performance when compared to typical crystalline silicon modules. With lower temperature tolerance, thin film performs better in a variety of climates from cold to hot weather.

NREL (National Renewable Energy Laboratory) tested frameless solar modules and found out that they have the same warranty as the mono or poly modules. 

Frameless panels offer the most aesthetically attractive modules in the market. With almost invisible cell lines, their smooth black design will look great on any roof.



The main reason why this happens is when you have a grid-tied solar system, it has safety measures preinstalled to shut down production in case of a power outage so as not to do extensive damage to the grid or the employees working on fixing the outage.

If you’d like to install a battery system to have power during a power outage, you can contact and set up a consultation.

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