Comparison of Solar Panel Types

Technical Guidance - Solar Panels

For your reference, Photo-Voltaic Solar technology is improving in efficiency by around 0.1% per quarter for Monocrystalline cells. Efficiency of 10% means 1 sq.m panel in full sun will generate 100W of electricity. So, 2010 Panels should be 1-2.5% more efficient than 2005 generation cells!
There are 4 Major Types of Solar Technology available for the Camping Market:

Panels made from polycrystalline cells are the most common and cheapest.( Typically BP, Solarex, Sharp and Kyocera). Their conversion efficiency 13% to 15% (sunlight to electricity). However, under elevated temperatures of 50 degress C panel temp, the efficiency drops by around 20%.

Panels made from monocrystalline cells are used in high reliability applications such as telecommunications and remote power. (Typically BP, Siemens and ECO-CAMPER). Their conversion efficiency is typically 14-17.5% (higher than the polycrystalline cells). However, at elevated temp, the efficiency only drops by 10-15% so they are more consistent in output.

Panels made from amorphous cells have been used in portable items for many years (UniSolar).
Their conversion efficiency of sunlight to electricity is 5-7%, about half that of the other panels but unlike the other types, their output does not decrease in elevated temperatures.

Panels made thin film cell CIGS technology. (Copper, Indium, Gallium, diSelenide) are flexible, durable, and provide slightly higher efficiency than other flexible solar cells. (SUNLINQ, Global Solar, P3). Typical sizes less than 60W.They can be mounted to curved surfaces and any backpack, tents or jackets

The critical item that delivers the current to charge the batteries is the solar controller. There are 3 major types of controller: Standard single phase controller, Multistage controller, and Maximum Power Point Tracking Controller (MPPT). Only the latter provides close to the maximum power of the panels. The first 2 controllers provide roughly 70% of the panels power to the batteries as they reduce the voltage of the solar panels but do NOT increase the current. MPPT Controllers are true “State of the Art” technology with 96%+ output.

The final critical factor is the location of the controller. Inexperienced suppliers mount the controller on the back, or close to the solar panels. This means that the long cable from the panel to the batteries is AFTER the power reduction by the controller and will have great difficulty getting the batteries fully charged. The experienced suppliers mount the controller at the battery end of the solar panel cable.

In summary, the way to compare the relative output capacity of panels is by the current output charging batteries at around 13.5V. The absolute power in kW is a nominal maximum cell output. You should look at a table of $price per delivered amp to the batteries at 13.5V.
Inexpensive Asian packaged solar kits will typically have simple controllers mounted to the back of panels for a relatively per performance in output. The 30-50% lower price is then matched by performance.

Benchmark Price per Delivered Amp at 13.5V (using ECO-CAMPER prices):

Output at Batteries at nominal 13.5V	80W Portable Solar Panel	120W Portable Solar Panel	125W Flexible* Solar Panel
Super Charged MPPT Controller	$120/ Amp	$112/ Amp	$173/ Amp

(* = Bonded Monocrystalline Cells on Coated Flexible Aluminium Strips, super lightweight)

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