Electrical Conversion
There are two main types of electricity used today: Direct Current electricity (DC) and Alternating Current electricity (AC). When electricity is generated in a solar cell, it's in DC form. AC electricity, however, is much cheaper to transport than DC is, so immediately after it's generated the electricity produced by a solar cell is passed through something called a solar inverter. Simply put, solar inverters change electricity from DC to AC.
There are two types of solar inverters that are commonly used today. Large central inverters act on the current produced by entire solar arrays, while smaller micro inverters function specifically on the electrical current of one solar panel.
A central-inverter manufactured by the Chinese power-electronics company KSTAR.
Image: PV Tech
The advantage of micro inverters is that if one solar panel or its solar inverter has a problem, it will have no effect on the rest of the array. An easy way to think about this is with a water analogy. Imagine it’s a hot summer day, and a soccer team is thirsty after playing the first half of their game. The only water they have is in one big jug. When someone accidentally knocks over the jug, all of the water spills out, and nobody gets to drink any. As a result, the whole team is dehydrated during the second half, and they lose.
Vocab
Direct Current Electricity (DC)
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When electrons flow one way in a looped current.
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Ex: Electricity flowing in a loop from a battery to a light bulb then back to the battery.
Alternating Current Electricity (AC)
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When a flow of electrons is constantly switching direction at regular intervals.
Solar Inverter
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A device that converts the DC electricity generated by a solar panel into AC.
Central Inverter
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A solar inverter for an entire solar array.
Micro Inverter
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A solar inverter for an individual solar panel.
A 1200W micro inverter.
Image: Risin Energy
The next game, every player brings their own water bottle. In their haste to drink water at halftime, the team klutz drops his bottle, and it spills all over the ground. Since only his water supply was compromised, however, the rest of the team still has water. All the players drink from their own bottles, the team enters the second half hydrated (except for the klutz, of course, the poor guy's wheezing), and they win the game. The water bottles in the soccer scenario are comparable to micro inverters. Even if one solar panel or micro inverter fails to function properly, all of the other panels will produce AC electricity. This way, we can minimize the damage a problematic solar inverter will have on the net electrical product of a solar array.
The main problem with micro inverters is their cost. It is much more expensive to purchase and install multiple micro inverters than it is buy one large central inverter. If micro inverters can be made cheaper and more accessible to consumers, electricity production should increase worldwide.
References
Gd-Admin. “1200W WIFI Micro Inverter Solar Grid Tie Solar Panel Smart Inverter.” Https://Www.risinenergy.com/, www.risinenergy.com/1200w-wifi-micro-inverter-solar-grid-tie-solar-panel-smart-inverter-product/.
Stoker, Liam. “KSTAR Targets European Market Following Spanish Central Inverter Certification.” PV Tech, 6 Feb. 2021, www.pv-tech.org/kstar-targets-european-market-following-spanish-central-inverter-certificat/.
“What Is Alternating Current (AC)?: Basic AC Theory: Electronics Textbook.” All About Circuits, www.allaboutcircuits.com/textbook/alternating-current/chpt-1/what-is-alternating-current-ac/.