If your customers intend to maximize the returns of their solar systems, they may prefer the advantages of hybrid inverter-based photovoltaic cell systems and AC coupled systems.

Hybrid inverters are designed to replace AC coupled systems. If your customer, like most other customers in North America, has very little energy demand during the day (especially two or three hours before and after noon), then having a string inverter or multiple micro inverters may not be able to achieve your customers Since the local utility company only allows customers to use the credit line for future electricity consumption at the same time, or hardly pay any fees (2 cents to 4 cents per kWh) at the end of the 12-month period Excessive power credits (real), customers should be advised to store power in the battery first, and use it during peak hours. Adjusting the hybrid inverter (or PCS) will help your customers achieve their goals and reduce energy costs in the most cost-effective way.

If we examine the energy flow, the AC-coupled system may lose a lot of energy due to repeated multi-level conversion, even though most of these string inverters or micro-inverters do have extremely high PV to AC conversion efficiency. The direct current energy from the solar system is first converted to alternating current, and then the bidirectional inverter usually built into the AC coupled ESS is used to rectify the energy back to direct current. For many AC-coupled ESSs designed with low-voltage 48V battery packs, an additional two-stage DC/DC conversion is required, which may lose up to 4% of energy before the energy can be used to charge the battery.

The energy use at night will reverse the previous path to meet the needs of the home communication network. This is why some ESSs lose up to 13% of their energy due to these repeated conversions. On the other hand, hybrid inverters, especially those designed with 400V battery packs, store energy directly from the solar array and only convert direct current to alternating current during peak periods of demand. Compared with AC coupled systems, energy flow only loses one-third of the energy.

But now many of us work from home, which means a significant increase in power consumption during the day. Although hybrid inverters are usually equipped with enough photovoltaic capacity, you can choose to convert part of the solar energy directly into AC power to meet demand immediately. If local demand is less than production, the excess energy will flow back to the battery or the grid. Here hybrid inverters are once again popular, because it is hoped that the energy used at night will be stored directly in the battery, and AC-coupled photovoltaic power generation systems can be used to meet additional needs. The string inverter or micro-inverter used in the AC-coupled photovoltaic power generation system can also be used to meet the surge demand when sunshine is sufficient, such as AC power.

Given that solar subsidy programs across the United States are coming to an end, such as net energy metering (NEM), rooftop solar will be mainly used for self-sufficiency. Many people will soon own an all-electric car, and some will use heat pumps instead of water heaters. Although we may expect that our utility company can upgrade the distribution network to meet our growing demand for electric energy, adding hybrid inverters and energy storage systems will put our energy future in our own hands and may reduce costs . If we can produce our own energy even while sleeping or buy energy at a lower price, then it may be time to reduce our dependence on utilities.

Andy Li is the CTO of POMCube Inc.

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