I. Policy Tailwinds: Global Subsidies and Tax Incentives Boost the Market

In 2022, governments around the world introduced incentive measures to actively promote plug-in PV systems. The most notable was the US Inflation Reduction Act (IRA) , signed into law on August 16, 2022, which raised the solar Investment Tax Credit (ITC) to 30% and extended it through 2032. This means that households installing PV systems between 2022 and 2032 can claim a tax credit of up to 30% – saving the average home more than $7,500 on installation costs, and an additional approximately $9,000 on electricity bills over the system’s lifetime. Even more significantly, standalone energy storage systems were included under the ITC for the first time – storage devices with a capacity of 3 kWh or more are eligible for the 30% tax credit, opening the door to PV+storage home energy models.

In Europe, local governments were equally active. The German city of Jena launched a dedicated subsidy programme for plug-in PV systems in November 2022, with a total budget of €100,000. The standard subsidy rate was 25% of the purchase price (up to €200), while for low‑income recipients of social benefits the rate was as high as 75% (up to €600). Mayor Thomas Nitzsche said: “Rising electricity prices are worrying many citizens, and generating your own solar power is becoming increasingly attractive to these people. Plug‑in PV systems – so‑called balcony power plants – also give tenants the opportunity to generate climate‑friendly and affordable electricity.” Earlier, in January 2022, Jena had already introduced a basic subsidy of 25% of the purchase price, capped at €200, with higher support for economically disadvantaged groups.

Meanwhile, Cyprus approved a $1.6 million grant scheme in April 2022 for PV‑powered electric vehicle charging infrastructure. The scheme provided a subsidy of €750 (about $818) per kW for installing or expanding PV systems, up to a maximum of €1,500 (about $1,636) per vehicle. The application deadline was December 12, 2022, and the aim was to promote charging infrastructure for category M1 electric vehicles and plug‑in hybrids.

II. Market Explosion: Europe Leads Global Plug‑in PV Growth

At the market level, plug‑in PV systems experienced explosive growth in 2022. According to data from energy consultancy LCP Delta, more than 1.8 million households in Europe installed solar PV systems in 2022 – a year‑on‑year increase of 64%. Plug‑in solar devices were a key driver of this growth.

Germany is the pioneer market for plug‑in PV systems, known as “balcony power plants”, which have been a popular choice since 2021. By the end of 2022, nearly 200,000 plug‑in solar devices were in operation in Germany. According to a study by HTW Berlin, between 2020 and 2021 alone, 128,000 plug‑in solar devices with a total output of 51 MW were added in Germany. A south‑facing, unshaded PV panel on a balcony can generate roughly as much electricity per year as a fridge and a washing machine consume. Due to supply shortages, delivery times for German mini‑PV systems sometimes exceeded one year, but as one energy company employee noted: “That’s still better than roof‑top PV, where you have to wait three years.”

On a global scale, the dynamism of the PV market in 2022 also reflected the growth potential of plug‑in systems. According to Apollo Research, the global solar PV market reached $4.1583 billion in 2022 and is expected to grow at a CAGR of 6.63% to $7.8626 billion by 2032. A report from Lawrence Berkeley National Laboratory showed that by the end of 2022, the US had cumulatively installed about 3.2 million distributed PV systems, accounting for more than 80% of all systems installed to date. The growth of the residential solar market has been driven by favourable regulatory environments, rising electricity prices, and increasing public concern about climate change.

Furthermore, the EU‑commissioned EUKI project actively promoted plug‑in PV panels, advocating for the installation of plug‑and‑play PV panels on balcony railings, building facades or in gardens. Consumer organisations in countries such as Slovakia have initiated procedures to pave the way for plug‑in panels to enter local balcony markets.

III. Technological Breakthroughs: Efficiency Records and Product Innovation Advance Together

In 2022, significant breakthroughs in solar PV technology at multiple levels laid the foundation for improved performance of plug‑in systems.

In the area of high‑efficiency PV modules, Japan’s Sharp Corporation announced in June 2022 that it had achieved a world‑record photoelectric conversion efficiency of 32.65% in a lightweight, flexible solar module. Designed for vehicle applications, the module uses a triple‑junction compound semiconductor structure and weighs only 56 grams per square metre. Its lightweight and flexible nature makes it suitable not only for EVs and aerospace but also opens up possibilities for future plug‑in mobile PV systems.

In the field of perovskite tandem cells, researchers at the Karlsruhe Institute of Technology (KIT) produced perovskite/CIS tandem solar cells with an efficiency of nearly 25%, setting a record for that technology. The lightweight, flexible design makes it particularly suitable for vehicles, portable devices, and foldable/rollable applications. Meanwhile, the École Polytechnique Fédérale de Lausanne (EPFL) reported a certified tandem solar cell efficiency of 31.3% in summer 2022.

On the product innovation front, Delta launched the world’s first bidirectional inverter (BDI) integrating solar generation, energy storage, and EV charging in April 2022. This all‑in‑one solution combines AC/DC conversion and control for home power infrastructure, rooftop solar, storage batteries, and EV charging into a single device, greatly simplifying system architecture and reducing installation and maintenance costs.

Standardisation work also advanced. In October 2022, the German Association for Electrical, Electronic & Information Technologies (VDE) released the first draft standard for plug‑in solar equipment, opening a consultation period. The standard aims to comprehensively regulate technical safety requirements for plug‑in solar devices, covering pre‑assembled models and products comprising modules, inverters and cables. It provides manufacturers with a unified safety testing standard and gives end users transparent proof of technical safety and quality.

IV. Installation Revolution: DIY Balcony Power Plants Reach Millions of Homes

In 2022, the most notable trend in plug‑in PV systems was the proliferation of DIY balcony power plants. The core advantage of these systems is: no professional electrician required, no need to own a house, not even a balcony – anyone can install them themselves.

A typical balcony power plant consists of one or two solar panels and an inverter. The inverter converts the DC electricity produced by the solar cells into AC, which is then fed via a connecting cable into a standard household socket – the self‑generated green electricity flows directly into the home grid for consumption. In Switzerland, mobile systems with an output below 600 W do not need a permit; they only need to be reported to the local electricity supplier. In Austria, power of up to 800 W can be fed into the grid without a permit – only registration is required.

In September 2022, Austria’s telecom A1 launched its PluginEnergy solar system, offering two models – 380+ COMBO and 760+ COMBO – priced at €840 and €1,450 respectively, with annual power generation of up to 350 kWh and 700 kWh. The system comes with an 18‑year performance guarantee and a 6‑year warranty, and can be used immediately without waiting for grid operator approval.

Indian startup Hartek Solar, meanwhile, introduced a customisable, IKEA‑like plug‑and‑play solar kit. An engineer visits the home and tailors the installation to the user’s needs – for example, users can choose to install a 2 kW or 3 kW system rather than being forced into a standard 10 kW configuration. This customised solution has been installed in more than 500 homes across several Indian states, including Haryana and Punjab.

A portable plug‑and‑play rooftop PV system developed by the Gujarat Energy Research & Management Institute (GERMI) in cooperation with Germany was successfully tested in Gandhinagar in July 2022 and is about to be commercially launched. The system can be easily moved from one location to another, offering a flexible option for users who relocate.

In Ukraine, tech startup WeDoSolar launched a vertical solar panel designed specifically for balconies in February 2022, which can be easily attached with windproof straps. Since launch, it has received thousands of orders, providing a convenient energy solution for European users affected by the war.

V. Storage Integration: PV+Storage Systems Enter a Fast‑Development Track

In 2022, the integration of plug‑in PV systems with energy storage became a key industry focus. With the IRA’s inclusion of standalone energy storage under the 30% tax credit, the economics of PV+storage systems improved significantly. According to a report from Lawrence Berkeley National Laboratory, the attach rate of storage batteries rose steadily, and the median price of PV+storage systems was $0.6–1.6 per watt higher than that of standalone PV systems. For a typical residential configuration, this represents an incremental cost of about $1,200 per kWh of storage, roughly in line with the average storage cost under California’s Self‑Generation Incentive Program.

Delta’s BDI solution goes a step further by integrating solar, storage and EV charging into one unit, achieving a “solar‑storage‑charging” all‑in‑one system. It supports a variety of energy management applications, including storing excess daytime solar power for use at night or during cloudy periods, and storing electricity using time‑of‑use tariff differences.

On the technology side, researchers are also exploring more efficient PV+battery integration. A study conducted at the University of North Carolina at Charlotte in March 2022 developed novel PV‑battery series optimisers that provide optimally designed power electronics converters for different residential solar+storage systems. Research by Anna H. Schleifer and colleagues explored the evolving energy and capacity value of PV+battery systems in the context of grid evolution.

VI. Cost Trends: Structural Adjustments Amid Upward Price Pressure

Although the long‑term price trend for solar PV is downward, supply chain bottlenecks in 2022 had some impact on plug‑in system prices. The “Tracking the Sun” report from Lawrence Berkeley National Laboratory showed that PV system prices in the US underwent structural divergence in 2022: inflation‑adjusted real prices continued to fall, but nominal prices rose.

Specifically, from Q1 2021 to Q4 2022, median installed prices for standalone PV systems increased by $0.1–0.3 per watt (i.e., 4–13%) in nominal dollar terms. However, over the long term, median installed US prices have been falling in real terms by about $0.1–0.2 cents per watt per year since 2013. Industry observers noted that the upward price pressure from supply constraints had not yet fully fed into prices of already installed projects, partly absorbed by inflation adjustments.

In terms of residential PV system size, the median US residential PV system size reached 7.0 kW in 2021, and system sizes continue to trend upward. The market share of module‑level power electronics (including microinverters or DC optimisers) continued to expand, accounting for 94% of