When powered by an AC power supply, an expensive driver is a mandatory component of a lighting fixture. But what if the fixtures are powered by direct current (DC) at voltages below 50V? This approach has both advantages and disadvantages.
Main advantages
- Instead of a complex driver, it is sufficient to install a resistor in series with the LED chain
- There is no need to have expensive smoothing capacitors in each fixture
- High level of electrical safety
Main disadvantages
- Requires separate wiring for lighting, since most types of electrical equipment are powered by AC
- For the same power consumption, thicker wires are required
Standalone Power from Solar Panels
Off-grid solar power systems are not connected to the utility grid. The energy generated by the solar panels is stored in batteries. The solar panel provides DC power, and the battery charges and discharges with DC as well. The most common voltage is 48V. Most household appliances require 120V AC (in the US) or 230V AC (in European countries), so an inverter is necessary.
If all electrical equipment in the house, including lighting, is powered by 48V DC, an inverter is not needed. The voltage can be supplied directly from the battery through a circuit breaker. The main issue is the mass production of household appliances that operate on 48V DC. For this to happen, electrical networks with such parameters must first be standardized. This has already been done in India.
India’s Experience
Until recently, the main standard for electrical power in India was 230V AC. Since 2014, a program to electrify remote villages in the Himalayas through the installation of off-grid solar power plants has been implemented. In connection with this and several other solar development projects, India adopted the IS 16711:2017 standard for 48V DC networks. The current in a single line is limited to 5A, but the number of lines that can be connected to one consumer is not limited. Standard wire sizes are 1.5, 2.5, and 4 sq. mm. The choice of wire size depends on the rated current and transmission distance.
The 5A limit per line means that an electrical device cannot consume more than 240W. For most cooking appliances, this is insufficient. However, wood-burning stoves are already common in villages. For charging mobile devices, and laptops, and powering LED lighting fixtures, 240W is more than enough.
Power from the Grid
If the building is powered by the utility grid, a compromise is possible. One or more power supplies can be installed in each room, with each supplying a group of lighting fixtures. This approach saves on drivers while minimizing the need for separate DC wiring. This solution is also recommended for rooms that require enhanced electrical safety.
