Grid tie inverter is an innovative concept in solar energy technology that can help today’s homeowner offset high energy costs while protecting the environment. These devices differ from the stand-alone solar inverters that many homeowners use to generate their own electricity in that they tie in to the utility power grid, making it possible for energy to flow in both directions (i.e. to the customer and back out to the grid).


Thus, grid-tied solar inverters don’t limit the power generated by the system to the homeowner’s exclusive use, but rather, by allowing users to reroute unused power back to the grid, they enable consumers to sell that power back to the utility company. This revolutionary concept is the means by which solar technology is putting unprecedented power into the hands of the consumer, in more ways than one.


How Grid-Tied Solar Inverters Work and What They Do.


Grid-tie inverters are the commonly referred to as the brains of a solar system. A photovoltaic module (solar panel) converts sunlight into electricity, using semiconductors that react to the photons in the light. Grid tie inverter systems convert direct current (DC) to alternating current (AC), making the DC energy delivered by solar panels compatible with the rest of the utility grid.


These systems work by using sophisticated tracking technology that senses and adjusts the system’s voltage as needed to ensure that it matches the grid’s AC output voltage, thereby enabling the surplus electricity to flow back to the grid. Without this technology, the power would only be able to flow in one direction: from grid to customer. With it, the vital electricity flows from grid to customer, with the unused power flowing back to the grid again. That way, when the customer’s system generates less electricity than needed, the system draws enough power from the utility grid to make up the difference, and when the system generates more power than needed, the excess is diverted back to the grid.


When a grid-tied inverter wakes up in the morning by detecting a minimum voltage output from a solar array, it then looks to the utility grid to see if it can detect electricity. If it detects the power from the grid, it then looks at the frequency of the AC utility electricity to see if it is pure sine wave (60 Hz) + – a very narrow parameter. If “all is well”, the inverter then turns on and begins converting power from the solar panels and exports any excess power produced in the home onto the public utility grid.


“Power” to the People


Like many other aspects of modern technology, the grid tie inverter lets the consumer play a much more significant role in, today’s marketplace. In addition to allowing homeowners to generate electricity for private use (an innovative enough concept in itself), the inverter also allows the consumer to benefit from the energy that exceeds the customer’s own immediate requirements. This incentive has encouraged many homeowners to consider solar power, lessening their individual and collective burden on the environment, conserving the earth’s dwindling natural resources, and helping to meet our country’s growing energy needs.


Spinning the Meter Backwards


The capacity to deliver excess power back to the utility company through the delivery grid has come to be known as “spinning the meter backwards.” This phrase is an apt descriptor for the bottom-line outcome that grid-tied solar inverters provide, since they actually reduce, or eliminate, the amount of metered power the consumer must purchase from the utility company. Yet, spinning the meter backwards only goes so far, since it can only be used to offset the cost of electricity actually used by the customer. While the utility company is required by law to purchase the excess electricity generated by a grid-tied solar inverter system, once the amount of energy sold to the utility company matches the amount used during a given year, there is no further financial benefit to using the system. In other words, don’t allow someone to oversell you a system that will produce more than you require or it will dramatically reduce your return on investment.


How is “Grid-Tie” Inverters Different?


Most houses and commercial buildings that have a solar array as a source of electricity are also connected to their local power grid. When the electricity demand of the building is greater than what the solar array can provide, the balance can be drawn from the grid, but when the array is producing more power than is needed, the excess electricity can be sent out onto the grid to provide power for other people to use. This connection has to be managed carefully, however. The electricity has to be delivered to the grid in a form and at a power level that the utility’s system can accept. Also, if the utility suffers a power outage, the inverter has to be able to sense the blackout condition and immediately shut off the connection. This helps protect the safety of any utility workers who are trying to repair the grid and get it back into operation; a stray source of electricity can cause injury or even death to a line worker who is working on supposedly shut-down system.


New Technology, More Choices for Inverters?


Modern grid tie inverters are designed to operate with a minimal loss of power in the transfer from the solar array to the utility grid. To maximize power production, main stream inverter companies like SMA, SolarEdge, and Enphase have designed these precisely engineered devices to feed the maximum power onto the grid. Commonly called NET metering, any excess power produced is deducted from the power consumed at night and measured each month by the utility company and reported to you in your monthly bill.


Solar irradiance is dependent on temperature characteristics and the modern inverter must constantly adjust to achieve maximum power point tracker (MPPT) for climate conditions and cloud cover. To do this, inverters adjust the voltage so the system runs at its maximum power output at any given moment of the day. Additionally the inverter in most cases, records the operating data from the system which can be stored and reviewed in either real time or later by calling up the data. The newest trend in grid-tied inverters are high-frequency (HF) transformers in place of heavy coils and “H” bridge used in converting DC to AC power. High frequency transformers have lower efficiency losses and are smaller and lighter.


If you need more information about grid tie inverters, I recommend that you can visit the website of Power Master Technology Co., Ltd. This Company provides power inverter, solar panel, and battery charger etc. For more details, please feel free to send inquiry or contact them directly.



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