Solar basics

Derived from the Greek word “phos”, meaning "light," and from volt, which was named in honor of the Italian physicist Alessandro Volta, photo-voltaic (PV for short) describes materials with the property of producing electricity when exposed to sunlight

The most common and most efficient photovoltaic products are made from crystalline silicon, representing over 95% of the market.

Cell Types

Mono – Crystalline

The solar cells in monocrystalline panels are slices cut from pure drawn crystalline silicon bars. The entire cell is aligned in one direction, which means that when the sun is shining brightly on them at the correct angle, they are extremely efficient. So, these panels work best in bright sunshine with the sun shining directly on them. They have a uniform blacker colour because they are absorbing most of the light.

Pure cells are octagonal, so there is unused space in the corners when lots of cells are made into a solar module. Mono panels are slightly smaller than poly panels for the same power, but this is only really noticeable on industrial scale installations where you may be able to fit a higher overall power with monocrystalline.

he cost of producing pure silicon wafers is a little more than for polycrystalline cells but generally there is not much difference in price these days.

Poly Crystalline – (Multi-Crystalline)

Polycrystalline panels are made up from the silicon offcuts, moulded to form blocks and create a cell made up of several bits of pure crystal. Because the individual crystals are not necessarily all perfectly aligned together and there are losses at the joints between them, they are not quite as efficient. However, this mis-alignment can help in some circumstances, because the cells work better from light at all angles, in low light, etc. The appearance is also different – you can see the random crystal arrangement and the panels look a little bluer as they reflect some of the light.

Since they are cut into rectangular blocks, there is very little wasted space on the panel and you do not see the little diamonds that are typical of mono or hybrid panels. Some people prefer this more uniform appearance, others like the diamonds. The choice is yours because the overall size and cost is very similar to monocrystalline.

Advantages of Mono - Crystalline Cells

• Monocrystalline solar panels have the highest efficiency rates since they are made out of the highest-grade silicon. The efficiency rates of monocrystalline solar panels are typically 15-20%.
• Monocrystalline silicon solar panels are space-efficient. Since these solar panels yield the highest power outputs, they also require the least amount of space compared to any other types.
• Monocrystalline solar panels produce up to four times the amount of electricity as thin-film solar panels.
• Monocrystalline solar panels live the longest. Most solar panel manufacturers put a 25-year warranty on their monocrystalline solar panels.
• Tend to perform better than similarly rated polycrystalline solar panels at low-light conditions.

Why you should consider solar energy?

• Solar energy provides a healthy return both environmentally and financially.
• Solar PV electricity generation does not emit poisonous air pollutants into our atmosphere such as CO2, SO2, NOx, VOCs and PM. These pollutants contribute to global warming as well as a wide variety of adverse health effects, particularly with children.
• PV installations are low maintenance and most generate power for many years with minimal intervention. Ongoing operating costs are extremely low compared to existing power technologies.
• Solar PV is a renewable and domestically harvested energy source, lessening our dependence on fossil fuels and foreign energy sources.

DETAILED EXPLANATION OF OUR PRODUCTS AND REASONS FOR USING THEM FOR OUR PROJECTS

Why we use Mitsubishi and Hyundai panels, when there are numerous Chinese products in the market?

Mitsubishi Electric has been in the solar electric field since its infancy in the 70s, when they made the first solar panels to provide power to satellites. They continue to lead the industry with their photovoltaic modules, designed for both commercial and residential grid-tie applications. Mitsubishi solar panels offer both high performance and reliability and meet the requirements of international quality standards. (UL 1703, IEC 61215, TÜV Safety Class II).

Hyundai Heavy Industries started its solar business in 2005 with production centers in “Eumseong”, as part of a plan to bring new business to the table. In December of 2006, the company acquired ‘CE Mark’, an international safety mark recognized in 28 countries of Europe and the safety/quality marks of the ‘International Electro technical Commission (IEC)’ recognized in 43 countries around the world.

Why do we use Mono-Crystalline modules instead of Poly-Crystalline?

Monocrystalline solar panels have the highest efficiency rates since they are made out of the highest-grade silicon. The efficiency rates of monocrystalline solar panels are typically 15-20%.

Monocrystalline silicon solar panels are space-efficient. Since these solar panels yield the highest power outputs, they also require the least amount of space compared to any other types. Monocrystalline solar panels produce up to four times the amount of electricity as thin-film solar panels.

Monocrystalline solar panels live the longest and they come with a 25-year warranty.

Perform better than similarly rated polycrystalline solar panels at low-light conditions.

Monocrystalline solar panels tend to be more efficient in warm weather and the performance decreases as temperature goes up, but less so than polycrystalline solar panels.

Why don’t we use optimizers or micro inverters for module level optimization?

So far all the major Inverter manufacturers who are leading the inverter market such as SMA, KACO and Fronius still use the traditional technique of “String Inverters” as the system is very efficient, simple to operate and also for its durability. Very few solar companies use this module level optimization which is expensive and the system layout is fairly complicated compared with string inverter due to is wiring system.

Conventional String inverters use MPPT – Maximum Power Point Tracking method and the inverter does the optimization at the inverter itself. Module level optimization technology has been tried and tested by all the inverter manufacturers but the system does not really work out financially as they have not seen a considerable amount of power or efficiency increase compared with the extra cost involved.

Module Level optimization is considered more suitable for the places with shading (shadows from trees, adjacent buildings and etc.) which is not the case in our applications in Sri Lanka where we have open rooftops and flat un-shaded areas for panel installations.

Why you should consider solar energy?

• Solar energy provides a healthy return both environmentally and financially.
• Solar PV electricity generation does not emit poisonous air pollutants into our atmosphere such as CO2, SO2, NOx, VOCs and PM. These pollutants contribute to global warming as well as a wide variety of adverse health effects, particularly with children.
• PV installations are low maintenance and most generate power for many years with minimal intervention. Ongoing operating costs are extremely low compared to existing power technologies.
• Solar PV is a renewable and domestically harvested energy source, lessening our dependence on fossil fuels and foreign energy sources.
• Tend to perform better than similarly rated polycrystalline solar panels at low-light conditions.

Source credit: http://ges.lk/pv-tech.php