Different types of photovoltaic systems
Photovoltaic systems have a very wide range of applications and can be used to generate electricity wherever the sun shines.
Five different types of photovoltaic systems
Self-generation and residual power online
This photovoltaic system mode is the most common one for everyone, and generally distributed photovoltaic power generation systems mainly use this mode.
The power sent by the PV system can first meet its own load use, excess power can be sold to the grid company to avoid waste; if the power generated by the PV is not enough for the load, that is, the power supply from the grid to supplement. But this mode of access needs to negotiate with the grid company related to power sales agreement, taking into account the interests of both sides. By the grid company to install two-way smart meters, respectively measuring the power generation of photovoltaic power plants and users of electricity, and according to the policy and negotiation of electricity prices to pay or collect electricity.
The biggest drawback of this operation model is that its revenue model cannot be fixed, the proportion of self-generation and surplus power online is always changing, the assessed value of the power station when financing and selling may be discounted compared to the actual output, and even the capitalist cannot get a reasonable asset value because he is worried about the user’s future operation.
Self-generated and offline surplus power
The notable feature of the grid-connected mode for self-use and self-use is “grid-connected but not connected to the grid”. The access point of this model is at the lower end of the power grid company’s meter, which is the private side of the complete demarcation point of property rights. Theoretically, the power grid company will not interfere with the access of the system, but this mode requires that photovoltaic power generation cannot be sent out (to the grid), so a set of anti-backflow devices must be installed.
When the power generated by the photovoltaic power station exceeds the load consumption, the anti-backflow device must feed back the signal to the inverter, and the inverter will reduce the capacity according to the load to generate electricity to meet the load demand and not transmit power to the grid. To achieve the anti-backflow function of the photovoltaic system.The role of the inverter is very important here.If you want to know more about inverters, you can find the answer in top 10 PV inverter suppliers in the world.
This photovoltaic system mode is generally applied to the user side of the electricity load is large, and the electricity load continues, there are few shutdowns or semi-shutdowns occur during the year, or even during the holiday period, the user’s electricity consumption to maintain the load size is sufficient to consume most of the electricity issued by the photovoltaic system, as far as possible to use up the power generated by the photovoltaic, will not cause waste.
This grid-connected mode is to connect the AC output of the PV system directly to the low-voltage side or high-voltage side of the grid, that is, the grid side of the property rights demarcation. In this way, the electricity generated by the system is sold directly to the grid company, and the sales tariff usually adopts the local average feed-in tariff, while the customer’s electricity tariff remains unchanged, so called “two lines of income and two lines of expenditure, each accounting for the other”.
This model is also the mainstream of PV applications; because of its simple financial model and relative reliability, it is happy to be favored by investors.
This off-grid mode is also called independent photovoltaic power station, which is a power generation system that does not depend on the grid and operates independently; this power generation system is widely used because it is not restricted by geography, and can be installed and used wherever there is sunlight, so it is ideal for remote areas without grid, isolated islands, fishing boats, outdoor breeding bases, etc. It can also be used as emergency power generation equipment in areas with frequent power outages.
This power generation system must be equipped with batteries. Battery is the heart of this power generation system. As the technology of lithium batteries continues to advance, later maintenance and battery replacement will be more convenient and the cost of use will be further reduced. It is expected that this will be widely promoted.
For areas without grid or frequent power outages, it has strong practicality. Especially for the purpose of solving the problem of lighting during power outages. Therefore, off-grid power generation systems are specifically designed for use in areas without a grid or in places with frequent power outages.
Photovoltaic street lights, lawn lights and other photovoltaic products also belong to the PV off-grid system.
This grid-connected mode of application scenario for frequent power outages, or self-consumption electricity prices are much more expensive than feed-in tariffs, peak electricity prices are much more expensive than valley electricity prices.
This one is to use PV to supply power to the load, which can be set to output at the peak of the electricity price to reduce electricity expenses. Secondly, it can charge at the valley of the electricity price and discharge at the peak, making money by using the difference between peak and valley prices.Thirdly, when the grid is normally supplied, the system operates as a normal grid-connected system, with the electricity generated by PV giving priority to the load, and the excess electricity is given to the battery for storage or sold to the grid.
When the grid is blacked out, PV can still continue to generate electricity. The inverter can be switched to off-grid mode, and the system continues to work as a backup power source, and the PV and the battery can supply power to important loads through the inverter without causing waste.
Both grid-connected mode and off-grid mode require batteries, and there are certain requirements for batteries. You can check out our top 10 photovoltaic cell manufacturers in China to learn more about photovoltaic battery. This mode of access needs to negotiate the relevant power sales agreement with the grid company to take into account the interests of both parties.