Asymmetric solar inverters
What exactly is asymmetry capability, and which inverters possess the ability to reduce energy asymmetrically? Let's delve into it.
When delving into the realm of solar systems, we often encounter perplexing terms, one of which being "asymmetric" energy output in inverters. But what does this entail in practicality, and is it even necessary? In the context of apartments or small detached houses, a single-phase network might still suffice, but the importance of asymmetry capability arises with a three-phase network. To grasp the significance, let's dissect what three phases entail: In essence, the electrical network supplying an average family home is segmented into three phases. Physically, this manifests as four cables entering the property from the mains, with three of these cables conducting current (the fourth being neutral, and a fifth for grounding), constituting the three phases to which various consumers are distributed. This distribution varies from property to property, typically factoring in safety considerations, electrical equipment specifications, and personal requirements. Accurate consumer distribution holds paramount importance, as an imbalance could lead to circuit breaker tripping, thereby preventing overcurrent and safeguarding both electrical devices and the network. But how does this translate concerning an average family's consumption habits? Let's consider a typical three-phase electricity network prevalent today in family homes. On these three phases, consumers and sockets are distributed separately. To illustrate:
- Phase 1 (L1): Kitchen appliances (fridge, oven, microwave)
- Phase 2 (L2): Lighting and bedrooms
- Phase 3 (L3): Living room and garage
Single-phase networks are now primarily relegated to apartments and small family homes. For properties with heightened electricity demands, a three-phase setup is imperative. However, achieving equal consumption across all three phases is nearly unattainable. Thus, when installing a solar photovoltaic (PV) system in such properties, which will be integrated into the gross metering framework from 2024 onward under the Solar Plus Programme, the capability for phase symmetry in inverters assumes pivotal importance. Under the erstwhile net metering system, the presence of an inverter capable of managing phase imbalance wasn't a pressing concern, as utility companies bought grid-connected solar generation at nearly the same price as it was sold to them. Therefore, instances of simultaneous solar generation consumption and grid purchase due to symmetrical inverters posed no issue. However, with Hungary transitioning to gross billing from the onset of 2024, the scenario alters significantly. Under gross metering, electricity purchased from the grid costs approximately 38 HUF per kWh, whereas electricity fed back into the grid fetches a mere 4 to 5 HUF per kWh from the supplier. Upon installing a solar system, the utility will substitute the existing electricity meter with a new one to separately monitor grid consumption and grid-fed electricity. While the meter employed for gross metering mirrors its predecessor used for annual balance metering, it tracks electricity flow across each phase individually. Consequently, bill reconciliation via simultaneous recharging and purchasing becomes unfeasible, as both transactions are distinctly recorded on the meter. This is where asymmetric inverters come into play. Consider an example featuring a 5 kW symmetric inverter:
Example for a 5 kW SYMMETRIC inverter:
As depicted, with total consumption at 5 kW, distributed asymmetrically across phases, and solar production also at 5 kW, the cost isn't zero due to the inverter's symmetrical energy output. Purchasing 0.84 kWh of electricity from the grid costs about 31 HUF, whereas feeding back 0.82 kWh yields only around 4.1 HUF. Thus, with 5 kW consumption and 5 kW solar production, the bill amounts to approximately 27 HUF, which is disadvantageous. Conversely, let's examine the operation of an asymmetric inverter:
Example for a 5 kW ASYMMETRIC inverter:
In the case of inverters equipped with phase asymmetry capability, the inverter adeptly manages varying consumption per phase, obviating the need for grid transactions. Consequently, consumption is entirely sourced from solar generation, eliminating utility costs. Granted, this represents a momentary example, as consumption fluctuates throughout the day, but asymmetric inverters handle such fluctuations more efficiently. It's worth noting that most asymmetric inverters on the market operate at 50% efficiency per phase, meaning they can deliver half of their rated power per phase. For instance, a 5 kW inverter can deliver a maximum of 2.5 kW per phase. Nevertheless, efficiency can surpass that of symmetric inverters, as power is distributed across phases optimally. Moreover, inverters capable of 100% power output per phase are slated for release soon, as early as 2024, according to manufacturers' preliminary datasheets. So, which inverters boast asymmetric power output capability? With gross metering instituting a heightened emphasis on inverter asymmetry capability, it's prudent to inquire with contractors about compatible inverters. At Solar Kit, we endorse several manufacturers' products capable of phase asymmetry. Here are a few examples:
Huawei: Huawei's MAP0 series inverters represent a significant advancement in solar inverter technology, particularly concerning phase-symmetric operation. Scheduled for release in 2024, these inverters are anticipated to set new standards in efficiency and performance. Key Features of Huawei's MAP0 Series Inverters:
- Phase Symmetry Capability: One of the standout features of the MAP0 series is its ability to achieve perfect phase symmetry, allowing for optimal power distribution across all phases of a three-phase network. This capability ensures efficient utilization of solar energy and minimizes reliance on grid power.
- 100% Power Output per Phase: Unlike traditional inverters that may operate at reduced efficiency per phase, the MAP0 series boasts the ability to deliver 100% of its rated power output per phase. This means that each phase receives its full share of solar energy, maximizing overall system performance
- Advanced Monitoring and Control: Huawei's MAP0 series inverters are equipped with advanced monitoring and control features, providing real-time insights into system performance and enabling remote management and troubleshooting. This ensures optimal operation and facilitates proactive maintenance, minimizing downtime and maximizing energy yield.
- High Efficiency and Reliability: Built on Huawei's cutting-edge technology and engineering expertise, the MAP0 series inverters deliver exceptional efficiency and reliability. With robust construction and Deye and SolaX: Deye and SolaX inverters can deliver a maximum of 50% of their rated power in one phase. Additionally, when connected to a battery, these inverters seamlessly transition to island mode within 4 milliseconds, ensuring uninterrupted power supply akin to an uninterruptible power supply (UPS). Furthermore, these inverters feature a built-in backup output, enabling uninterrupted operation of electrical consumers during power outages, contingent upon critical customer circuit deployment. This sustainability is viable during sunny weather with solar generation or until battery energy is depleted.energy available in the battery lasts.
*(subject to critical customer circuit deployment)