Introduction to Photovoltaic Panels (Solar Panels)

 

This is a very brief overview of photovoltaic panels. I do urge you to read more detail, and here is a link to start you on your journey of understanding.

https://www.alternative-energy-tutorials.com/photovoltaics/photovoltaic-panel.html

There are typically Polycrystalline and Monocrystalline panels. All PV’s we supply are monocrystalline, as it has the most efficient conversion rate. The conversion rate for our PV’s is equal to, or greater than 21%. This conversion rate is an indication of the panel’s ability to convert sunlight into power. In other words, about 21% of sunlight captured is converted into energy. Polycrystalline panels have a lower conversion rate.

One should consider placement of the PV’s. Behind glass, PV’s cannot reach their maximum efficiency, as glass reflects light, which means less light reaches the PV. Partial shade shall also affect efficiency, as does cloud cover.

It may sound counterintuitive but heat also diminishes the efficacy of PV’s. One would find in the heat of summer, the PV is less efficient than a sunny winter day. Optimal temperature is around 25° C.

When using our USB ports, bear in mind that the temperature of the battery in the device being charged also has bearing on efficiency. A phone in a hot car, would not charge efficiently. This is the reason why we suggest the use of a longer cable, so that whilst the PV is in the sun, one can keep one’s device in the shade. It can be tricky to find the perfect position for your PV and your device, as the length of the USB cable also affects the efficiency of current. I shall add another blog about USB cables, as that is also a complex subject.

This is not a physics class and I do not pretend to be an expert. My wish is merely to create an interest in the hope that you shall do more research and reading on the matter, but, as a starting point, I shall try to show some examples that may help you understand solar panels, and aid you in selecting the right option to suit your needs and your budget.

  • Watts – potential power is considered in watts. So, a 60W panel does not provide 60W when in the box, but it has the potential, when placed in perfect conditions, to generate 60W of power. In a formula, it would be denoted as (P)
  • Volts – the force at which the generated power is transmitted, is referred to as Volts. (V)
  • Amps – the speed at which power is transferred, is measured in amps. (A) When there is no load connected, there is no flow of current. But when a load (e.g. your cell phone) is connected, current flows, and in a formula is denoted as (i). Why i? From the French phrase intensité du courant, (current intensity).

Take, for example, our 75W mobile PV, the voltage is 18V. It can transfer current at 4.2A. The formula is:

P = V x i.      So, 18 x 4.2 = 75.6  – and there you have your 75W panel!

Should you wish to charge a battery, let’s assume a Sealed Lead Acid Battery (SLA). The battery is usually 12V (24V is not used in this example). The capacity of the battery is denoted as Amp Hours (ah). The general rule of thumb, is that the charger (panel) should have the capacity to transfer current at rate at least 20% of the battery ah.

Let’s assume you have a 12V – 20ah battery. You would require at panel that can generate a flow of current at least 4A (which is our 75W option.

I shall do a separate blog on batteries. You will note that I do not yet have batteries for sale. I am investigating solutions and hope, soon, to have batteries available.

Be Safe.

Anne

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