President Xi Jinping in April this year, visited the Anhui Jinzhai photovoltaic poverty alleviation project, which caused hot of the PV poverty alleviation. And this new model who combination of new energy and poverty alleviation began to attract widely attention. Per national solar energy planning, the total size of PV-poverty alleviation project during “thirteen five” is 15GW, and the annual construction scale is about 3GW, accounting for 20% new photovoltaic power generation installed capacity.
Clearly we all realized that PV poverty alleviation is a big cake, not only led to increasing income of poor households, but also promote the rapid development of the domestic photovoltaic industry. However, many problems have been exposed in the process of poverty alleviation.
Cutting corners and perpetrate a fraud are not desirable
Since PV poverty alleviation projects tend to be tendered by the government, they usually follow a low-cost competition strategy and have long payment cycle. Therefore, many installers or contractors will save DC isolators in the project in order to save costs.
Another “smart” approach is that when some manufacturers did device selection for the inverter & electric box etc., in pursuit of low-cost, they used the AC breaker in the DC side. The ARC capacity and rated load cut off power are bigger not enough, easily lead to overheating, leakage and sparks, or even caused the power plant on fire. We all know that the working voltage of the DC side in PV system is very high, and the AC current has zero-crossing but DC current hasn’t zero crossing. Therefore, the DC system isolating is much more difficult than the AC system.
The big role of the DC isolators
The following by example, we might as well to talk about the DC isolators protection in the photovoltaic power plant.
In the installation of the solar systems, the installer generally first through switch off the DC isolators to isolate the solar panel and inverter input. DC power is not connected to the DC side of the inverter when wiring and plugging DC terminals after turning off the DC switch. This prevents electric shock and damage to the inverter and back-end equipment. Therefore, in the installation of photovoltaic systems, we need “DC switch.”
In the PV power plant, the inverter is the “core hub”, in order to ensure adequate power generation time, the inverter is no OFF button. As long as there is light (even rainy weather) can generate electricity panels, the inverter that is automatic. However, this also cause a problem that the DC side still has power when the inverter is replaced or repaired, even though the AC side has been disconnected by the installed AC circuit breaker. In this case, if the inverter does not have a “DC isolator” to turn off the DC power from the battery side, it will cause electric shock and equipment damage.
Currently on the market most of the inverters are TL series, that is, no internal electrical isolation, the existence of AC SIDE to DC SIDE inverted possible. In the maintenance, if can physical isolation the AC and DC current, then the PV system can be better protection in each section.
The future of PV-based poverty alleviation will be 100-300kW village-based power plants, basically will use string-type inverter program. Mainly with built-in DC isolator (embedded in the inverter) and external DC isolator (between the panel and the inverter installed separately) two options. Therefore, the solar DC isolator is the most important component of the system security. The reliability and stability of the solar DC isolator is directly related to the photovoltaic power generation & revenue and safe operation of photovoltaic systems.
Therefore, we recommend that users choose well-known brands as a solar system DC isolator: PROJOY and so on. It is reported that, PROJOY PEDS DC isolator is the first Europe patented product and obtain UL certification in China. And also after careful scrutiny and rigorous screening, PROJOY DC isolator was selected by China Guangdong Nuclear Power Supplier White List. It is also the only supplier in the list to focus on high-voltage isolators for solar system.
At the same time, PROJOY ELECTRIC isolators are underwriting by China Ping An Insurance, the total insurance amount up to 1 million US dollars. The huge insured amount provides comprehensive protection of the user’s photovoltaic system.