Solar Panel Quality and Use Questions

Technical Guidance - Solar Panels

Our Panels are manufactured especially for us with USA silicon wafers and assembled in China. The panel manufacturer in the larger (180W+) series has compliance to Australian Standards and is certified by the Clean Energy Council of Australia. Approval 25071. We get a test certificate electronically on every panel.

Is the quality of a solar panel purely dependent on the quality of the silicon wafer?

No, although it is partly true. There are global suppliers these days of high quality wafers and this is not the quality bottleneck! The manufacturing challenge is how to capture those minute +ve and –ve charges into current and power.

This is the core activity of a solar panel manufacturer. They buy in the wafers, and then coat them with junction material and screen print the circuits that carry the current. Then the screen printed circuits are “wired” together with a special “foil” current bus. Finally the foils are gathered together and become the electrical output of the panel.

There is significant technology involved in this process. Absolute cleanliness is essential and the lamination of the wafers and the surface materials is important for performance and to prevent moisture getting in.

eco-camper solar panels are built on state of the art production lines with high quality inspection and testing.

What is the difference between Monocrystalline and Polycrystalline Solar Panels?

Firstly you recognise Monocrystalline panels from uniform looking wafers that typically have the corners cut off and so the panel is a sort of octagon. Monocrystalline panels are typically 18%+ efficient in full sun. Polycrystalline are 17%+ in full sun but can be more efficient in partial sun or shade. Monocrystalline panels are generally lighter but more expensive for the nominal watts output.

Are the panels individually tested?

Yes.

PV modules are rated at a well-defined set of conditions known as Standard Test Conditions (STC). In production, PV modules are tested on a device known as a flash simulator. This test equipment contains a flash bulb and filter designed to mimic sunlight as closely as possible. It is accurate to about ±1%. Because the flash takes place in only 50 milliseconds, the cells do not heat up appreciably. This allows the electrical characteristics of the module to be measured at close to 25°

What affects the performance of solar panels? (let’s ignore rain and eclipses…)

Dust (which simply blocks the light), the temperature of the panel and the angle of the panel to the sun have the most affect. To minimise the temperature of the panel, they are kept open in the rear for air to circulate. To seal the rear of a panel would reduce the performance.

Older solar panels are much less efficient and performance does deteriorate with age. Generally, improvement in the manufacture of panels improves panel efficiency by 0.2% every 3 months.

What is the best angle to the sun?

At about the latitude of Mt Isa, 38 degrees is the perfect angle. South of Mt Isa the panels are standing up more. Whereas north of Mt Isa, the panels need to be flatter.

What is the best way to use a solar panel?

As a battery charger! There are regulators that operate like a smart battery charger.  You can use solar panels without a regulator which will keep voltage pressure on the battery but once the panels get large relative to the battery size, the pressure can be too much.

What are the risks of damage to Solar Panels?

They are designed to withstand all of the rigors of the environment including arctic cold, desert heat, tropical humidity, winds in excess of 200kph, and 25mm (1 inch) hail at terminal velocity.

The main risk is from twisting and cracking the panel. For this reason, small panels are preferred. We use multiples of 20W and 40W panels. We store the hinged panels in a padded bad close together. They are best carried upright in the vehicle but it is not essential.

Can you buy Solar Panels without the glass surface?

Yes. The panels can be bonded to Aluminium with a protective layer on top. These are lighter still. We sell these as a flexible portable solar panel. They are not as suitable for the top of caravans as if they are scratched by overhanging trees or otherwise whilst driving,  the surface coat can easily break and instantly ruin the panel.

How many hours per day would someone typically be ably to get from solar panels?

This is key published data called “Peak Sun Hours”. It is published by region by month. Typically this is grouped for summer and winter. Those regions with less average sunny days will have less peak sun hours. The further south for the same weather conditions also reduces the peak sun hours. Generally we use the Peak sub hours to calculate the expected watt hours you may get from solar panels.

Note that Solar modules are usually rated in Watts BUT this is not at a 12V rating and so we have to re-rate solar panels to a 12v nominal use capacity to calculate the size required.