Part 4 of 4: Solar Inverter? What the heck is that?

In this 4-part series of articles Greg Shaw, Managing Director, Solar Shop Hua Hin, explains by KISS (Keep it Simple): The difference between DC and AC power; The difference between 1 and 3-Phase; How do Solar PV Panels Work?; and What is a solar inverter? Stay tuned as there will be more articles to come to help you (and our customers at Solar Shop Hua Hin) understand solar systems. If you take the time to read this 4-part series you will be rewarded with a real-life practical conclusion which you will more fully understand. And that will brighten you day because knowledge is power!

PART 4: What is a Solar Inverter and what is it used for?

written by: Greg Shaw, Managing Director, Hua Hin Solar Co., Ltd.

A Solar Inverter (or converter or PV inverter) converts the energy (and power) gained from the sun through a solar panel system into a usable power source that can be fed into an electrical network. Put another way, solar inverters convert variable direct current (DC) into an alternating current (AC).

High quality solar inverters, such as those sold by Hua Hin Solar, are designed to precisely match the frequency and voltage level of the grid they are connected to. In our Grid-Connected solar systems solar power is first consumed in the building, then any surplus electricity is fed to the utility grid. Inverter systems up to a power of 5 kW are generally built as a single-phase system. For larger systems (5kW or greater) the inverter output feed is generally connected to a three phase system. 3 Phase inverters have a relatively simple design and distribute load to all three phase equally – leading to better quality output and higher efficiency. Conversely, a single-phase inverter can be used for each of the 3 single phase lines of a three phase system. However using 3 separate inverters to supply power in this way may exceed acceptable cost of the solar system.

Hi-end inverters also feature maximum power point tracking (MPPT) to get the maximum possible power from the solar panel PV array. They repeatedly sample the output of the solar cells to obtain the maximum power for the given environmental conditions – namely solar irradiation, temperature and total resistance. Put another way, since the solar panel module’s peak voltages and currents vary considerably depending on the weather conditions, an electronic circuit in the inverter continuously adjust voltage so that the inverter’s working point matches the PV arrays maximum power. This way maximum power fed into the house and utility grid is achieved.

Safety First! Grid-tied solar inverters are also designed to shut down when they do not detect the presence of the grid. This is built-in safety system is known as “anti islanding protection.” This is important as if the inverters continued to work in the event of a power blackout, their energy output could harm any line workers sent to fix the power grid.

Solar Inverters commonly used in a domestic or workplace setting are known as a “Micro Inverter” (or miniaturized inverter). Micro inverters are used by home owners who wish to save on the cost of electricity by generating their own source of power. Those people living in geographical regions with high exposure to sunlight are often those that purchase solar energy systems.

Solar micro-inverter is an inverter designed to operate with a single PV module. The micro-inverter converts the direct current output from each panel into alternating current. The micro-inverter design allows for parallel connection of numerous, independent units in a modular way.

Micro-inverter advantages include;

• single panel power optimization
• independent operation of each panel
• plug-and play installation
• improved installation and fire safety
• minimized costs with system design
• stock minimization

A 2011 University study reported that an individual integrated inverter setup (with micro-inverters connected in parallel) yielded about 20% more power in unshaded conditions. In terms of shaded conditions, the inverter generated 27% more power compared to solar panels connected to a single inverter. Both setups utilized identical solar panels.

OK! So here it is! A real-life practical-application conclusion to the 4-part series of articles you just read….

One of our clients recently asked, “If we are on vacation and we are not using any electricity, will it be easy to switch off the panels? What happens to the electricity from the panels if the system is switched off?

My reply:

Dear [Customer],

Great question!

We install a DC switch between the solar panels and the solar inverter. All you do is flip the switch like a circuit breaker. The current cannot flow from the panels and the system stops. As there is no DC current to convert to AC electricity there is also no power produced by the inverter.

At this time a worker can do works on the panels as they are not generating DC current.

I hope that helps!

Kind Regards,

Greg.

Hua Hin Solar Co., Ltd., is Hua Hin’s largest and most dependable solar energy company. We provide exceptional products and services at affordable prices and we offer long-term customer care. Our Team is committed to using green solar and wind energy to help our retail customers and residential/business partners make the necessary transition towards energy independence. “We design and install affordable solar systems with the highest yields. For your free consultation contact us today at huahinsolar@gmail.com. If you have anything less than a great experience with Solar Shop Hua Hin please call my cell.” Greg, Managing Director, +66(0)89 824 1963.