Is Photovoltaic-coupled Water Electrolysis Hydrogen Production Technology Suitable for Residential Applications?

“Generate hydrogen using solar energy, then produce electricity when needed—freeing yourself from the grid and achieving zero-carbon independence.” This vision sounds appealing. As a technical team with years of experience in the energy sector, we must caution residential users with such aspirations: applying wind-solar hydrogen production technology to home settings is not only unlikely to save costs at this stage but may become one of the most expensive household energy options.

Let's examine the practical challenges of photovoltaic-coupled water electrolysis through a concrete example.

1. “Photovoltaic + Hydrogen Power Generation” Technology

Using a water electrolysis unit rated at 1Nm²/h (standard cubic meters per hour), 55 kWh of electricity is fed into the electrolytic cell. Through complex electrochemical reactions and system losses, electrical energy is converted into chemical energy, ultimately yielding 1 kilogram of hydrogen. This hydrogen requires further conversion for effective utilization.

Subsequently, this 1 kg of hydrogen is fed into a household hydrogen fuel cell for power generation. Through a series of chemical reactions, the chemical energy stored in hydrogen is converted back into electrical energy. In practice, the hydrogen fuel cell can only produce 12-15 kWh of usable electricity. This yields a total cycle efficiency of approximately 21.8% to 27.3%. This indicates that over 72% of the original electrical energy is lost as heat and other forms of energy during the “electricity-hydrogen-electricity” double conversion process.

2. Photovoltaic + Lithium Battery Technology

Using the same 55 kWh of photovoltaic power generation, the charge-discharge cycle efficiency of a lithium battery system typically exceeds 85%. This translates to approximately 46.75 kWh of usable electricity from 55 kWh. Compared to the photovoltaic + hydrogen power generation scenario, the maximum usable electricity for a household is only 15 kWh.

Why such a significant gap?

1. Electrolytic hydrogen production and hydrogen fuel cell power generation fundamentally involve converting energy from one form to another. Thermodynamic laws dictate that such conversions inevitably incur losses, with unavoidable theoretical energy depletion at each stage. In contrast, lithium battery charging/discharging follows a more direct “electricity-chemistry-electricity” pathway, featuring fewer conversion steps and consequently lower energy losses during storage and release.

2. From a technological maturity perspective, lithium batteries have established a complete, mature industrial chain. Their system efficiency has been optimized over the long term and is approaching its engineering limits. Conversely, hydrogen energy technology for residential applications remains in its early developmental stages. The system comprises multiple complex components—electrolyzers, compressors, purification units, fuel cells—each requiring additional energy consumption. The overall efficiency of the integrated system consequently lags behind that of lithium batteries.

3. Cost differences also emerge between PV+lithium storage and PV+hydrogen generation. Hydrogen production equipment manufacturing and hydrogen storage itself consume substantial electricity. To achieve equivalent household power goals, hydrogen solutions often require larger solar panel installations. From a full lifecycle cost perspective, current residential hydrogen systems struggle to compete economically with traditional energy storage methods.

For household users prioritizing environmental sustainability and energy autonomy, efficient utilization should remain central. Channeling clean solar power into less efficient conversion systems incurs substantial costs for residential applications. It's important to recognize that hydrogen, as a strategic energy source, should primarily focus on industrial applications, grid-scale energy storage, and heavy-duty transportation systems.

For residential energy scenarios, we recommend: At this stage, opt for the technically mature and economically viable “PV + lithium battery” solution to maximize the value of every kilowatt-hour of sunlight. Only when hydrogen energy achieves breakthroughs in residential technology and demonstrates significant economic improvements should its integration into home energy systems be considered a prudent approach.