What Is a Solar Inverter and Why Do You Need One?
Your solar inverter converts the direct current (DC) power produced by your solar panels into alternating current (AC). They’re also the brains behind your solar-plus-battery system, enabling you to generate electricity on-demand.
Microinverters electrically isolate each panel from the next so that small amounts of shading, debris or snow lines on one panel don’t reduce output across the array. This improves MTBF & increases reliability.
Reliability
Inverters are the operational heart of solar plant and therefore need to be robust. According to a report by kWh Analytics, 80% of PV array failures occur at the inverter level. That is why a high-quality inverter with a reliable manufacturer and solid support and maintenance programs is so important for both short and long term reliability.
The most critical components in inverters are the insulated-gate bipolar transistor (IGBT) and capacitors, all of which need to be properly designed, rated, and matched to the inverter environment. Inverter manufacturers also need to minimize the number of parts prone to failure such as fans and LCD screens which will typically wear out over time.
MTBF is often quoted to be an indication of inverter life, however this can be misleading because it does not take into account how the product will be used and the environmental conditions that are likely to be experienced. A better example is the death rate of 25 year old humans – they have an MTBF of 800 years but we all know that they can die at any time!
Many leading inverters are backed by a 5-year warranty with a 10-year extension option available. Some inverters like Fronius and SMA are renowned for their reliability with local service and support, while others such as Goodwe have excellent reputations for quality and value. SolarEdge inverters are also highly regarded by installers for their microinverter-based design which allows individual panel-level optimisation.
Flexibility
Inverters convert direct current (DC) electricity produced by solar panels into alternating current (AC) so that household appliances and equipment can use it. They also connect to the power grid if approved in your area, contributing energy to the utility system.
A microinverter is a small device that can be installed under the roof of a photovoltaic panel, connecting to it with a single wire. It optimizes each individual panel’s output by separating the DC connection from the AC. This allows each panel to operate independently, without affecting the others in the row.
Compared to central and string inverters, which can have multiple components and are more complex, microinverters reduce overall cost SOLAR INVERTER by reducing the number of parts. This, in turn, improves installation and fire safety. Microinverters are modular, which means that in the event of a problem, one component can be replaced with another.
Smart string inverters, also known as power optimizers, are a form of hybrid solar inverter that can work with both off-grid and grid-tie solar systems. They can integrate with battery storage outdoor pathway solar lights or AC coupled batteries. They also feature MPPT technology, allowing them to identify and track the most optimal point in changing environmental conditions. As a result, they can achieve high conversion efficiencies, making sure that most of the captured solar strength is converted to usable energy.
Efficiency
A normal power inverter converts the uneven DC (direct current) output of your solar panel into alternating current (AC), which your home is wired to receive and consume. A solar inverter does the same, but also takes into account your home’s energy consumption patterns to ensure that you are capturing as much of your own electricity as possible.
Solar inverters must be sized to withstand the maximum power your panels produce on a good day. This means that the system size should be about 1.2x larger than the inverter’s max power rating. This helps avoid any power-limiting conditions such as shade or mismatching.
The efficiency of a solar inverter is proportional to the power it produces over its full output range. Typical efficiency curves are shown in Figure 4.
Some solar inverters, such as the Enphase micro-inverter, do panel-level maximum power point tracking and have high efficiency. However, their design is often complex and requires multiple electronics, which can increase your installed costs and reduce reliability. String inverters are simpler and cheaper, but don’t offer the same level of efficiency. They can have a higher level of degradation, and require more regular maintenance, such as cleaning their cooling fans. This can reduce their lifespan and performance. This is particularly true for older models. They use electrolytic capacitors, which can degrade over time and need replacement on a regular basis.
Savings
Inverters help maximize the solar energy your household can generate, and therefore the savings you can realize. Calculating the savings potential of your solar power system starts by determining how much electricity you consume each year (typically 10,632 kilowatt-hours, or kWh). Next, you need to determine your average electricity rate – which is found by adding up your state’s annual cost of utility power, according to the U.S. Energy Information Administration, or EIA).
Then, divide your annual electricity consumption by your average electricity rate, and that’s how much a residential solar panel system can save you per year. Keep in mind, the climate and amount of peak sun hours in your area can also play a role in how much you can save by going solar.
String inverters (also known as central inverters) work by converting DC power from multiple solar panels to AC power at one large device. They can reach a maximum efficiency of 99%, which is pretty impressive, but they do lose some power production due to “inverter clipping,” which occurs when the system hits its max electricity production.
Microinverters, on the other hand, convert DC power directly at each solar panel and electrically isolate each panel from each other. This allows individual solar panels to harvest optimum power, and simplifies stock management for a solar system. Additionally, microinverters allow for individual solar panel monitoring.