Full DC Communication Power Supply of Photovoltaic Systems

From photovoltaic power generation, energy storage to electricity consumption, all adopt DC form, reducing the need for AC-DC conversion. They have their own applicable characteristics and application logic in industrial (such as communication field) and solar EV charging system.

Ⅰ、 Industrial scenario (taking the communication field as an example)

Industrial scenarios such as communication base stations and data centers have extremely high requirements for power stability and continuity, and the equipment is mostly DC loads (such as servers, base station equipment, switches, etc. usually use -48V DC power supply). At the same time, they need to address the problem of insufficient power grid coverage in remote areas.

Application characteristics of full DC architecture

1. High load matching degree

Communication equipment itself is mostly driven by DC power (such as RF modules in base stations, optical transmission equipment, etc., all of which rely on DC power supply). The full DC architecture can directly interface with photovoltaic DC output and energy storage batteries, eliminating the multiple conversions of "DC → AC → DC" in traditional AC systems, reducing conversion losses by about 5% -10%, and improving energy utilization efficiency.

2. Ensure power supply continuity

Combining energy storage systems (such as lithium iron phosphate battery packs, usually designed with high-voltage direct current) can achieve direct current coupling of photovoltaics, energy storage, and loads. When the power grid is cut off or the photovoltaic power supply is insufficient, the energy storage battery can quickly switch to load power supply, and the response time can be controlled in milliseconds to avoid communication interruption (traditional AC switching may cause short-term power outages due to inverter delays).

3. Adapt to harsh environments

Remote communication base stations (such as mountainous areas and deserts) often rely on photovoltaic independent power supply. The full DC architecture simplifies system design (without the need for AC inverters, transformers, and other equipment), reduces equipment failure rates and maintenance costs, and DC equipment has better resistance to low temperatures and humidity, making it suitable for harsh outdoor environments.

4. Scale and modularization

Large data centers can achieve flexible power expansion by connecting multiple photovoltaic DC subsystems in parallel, combined with high-voltage direct current (HVDC) distribution technology, to meet high load demands and facilitate centralized monitoring of the power generation, energy storage, and consumption status of each module.

Ⅱ、 Family scene

In household electrical equipment, the proportion of DC loads is gradually increasing (such as LED lighting, refrigerators, air conditioners, smart home devices, etc.), while pursuing energy conservation, cost control, and electricity convenience. Application characteristics of photovoltaic full DC architecture:

1. Adapt to DC household appliances to reduce conversion losses

The traditional household power grid is AC, and DC loads (such as DC variable frequency air conditioners and DC fans) need to be converted through built-in rectifiers, resulting in approximately 3% -5% loss. Under the full DC architecture, photovoltaic DC output can directly supply power to DC household appliances, coupled with DC energy storage batteries (such as 48V low-voltage systems), reducing intermediate conversion links, especially suitable for small apartments or newly installed residences (with pre installed DC lines).

2. System simplification and cost reduction

The household full DC system does not require a large capacity inverter (only a small DC-DC converter is needed to regulate the voltage), and the equipment cost is 10% -20% lower than that of the AC system. It is also easier to install and maintain (reducing AC distribution switches, leakage protection equipment, etc.). For example, a 48V DC home system can be directly connected to photovoltaic panels and energy storage batteries to provide power for lighting, television, small household appliances, and more.

3. Safety and flexibility

Low voltage direct current (such as 48V) provides higher human safety and eliminates the risk of high voltage electric shock, making it suitable for home environments; At the same time, it can be flexibly expanded, such as when adding photovoltaic panels or energy storage batteries, simply parallel them without adjusting the AC distribution system.

4. Limitations: Compatible with AC loads

There are still some AC loads in the household (such as microwave ovens, electric water heaters, etc.), and a full DC architecture requires the configuration of small DC-AC inverters (only for these devices), which may increase the cost slightly, but efficiency can be optimized by prioritizing the use of DC loads and limiting the power of AC devices.

Ⅲ、 Common advantages and challenges of all DC architecture

-Common advantages: reducing AC/DC conversion losses and improving energy utilization efficiency; Simplify system structure and reduce equipment failure rate; Naturally matched with the DC characteristics of photovoltaics and energy storage, suitable for the integration of new energy.

-Common challenge: Need to unify DC voltage standards (currently different equipment voltages are inconsistent); The compatibility with traditional communication loads needs to be optimized; During long-term operation, it is necessary to address issues such as DC arcing and corrosion.

In summary, the all DC architecture focuses more on reliability and high-power adaptation in industrial (communication) scenarios, and more on cost and safety in household scenarios. Both can achieve efficient energy consumption by reducing conversion links, which is an important direction for the future development of photovoltaic systems.