GoodWe inverters help university campuses use green electricity

At present, GoodWe HT series models have been widely used in industrial and commercial power stations. The string solution based on GoodWe 120/100kW inverter has played a role in reducing costs and increasing efficiency, and has been recognized by investors or owners.

HT Project Case

At the request of the project party, GoodWe's technical personnel came to a campus photovoltaic power station project in Texas to inspect and debug the equipment before grid connection. At the same time, this article introduces the project in three stages: project preparation, construction and operation and maintenance.

1. Preliminary preparation of the project

The project site is a school in Dezhou, which was invested and constructed by Dezhou XX New Energy. After many consultations with school leaders and property companies, Dezhou XX adopted an energy contract management model. The project adopts a multi-point low-voltage access model of "self-generation for self-use, and surplus power to the grid". The photovoltaic power generation is sold to the school at a 25% discount (the school's normal electricity consumption is 0.8 yuan).

The total installed capacity of the project is 1.3MWp, which is connected to the low-voltage side of the school's original transformer at 9 grid connection points. The power station consists of 5,072 solar cells, with an annual parity utilization hour of more than 1,300 hours (optimal inclination angle of cement roof), an annual power generation of nearly 1.7 million electricity, and can generate nearly 1 million yuan in revenue per year. It is expected that the project can recover its costs within 5 years.

Through preliminary surveys, the installation capacity of each roof (including apartments, canteens, libraries, office buildings and laboratory buildings, etc.) was determined. Considering that the DC strings on a single roof are not cross-connected, it was decided to use two types of inverters, 100/50kW from GoodWe, and 22~24 components were connected to the inverter in a string.

Office building electrical diagram Office building string wiring diagram

II. Project Construction Period

The construction period of the entire project is 2 months. The work content includes early site preparation, support foundation, support installation, bridge installation, photovoltaic line laying and connection, inverter installation, AC cable laying, full-site lightning protection and grounding, distribution cabinet installation, grid-connected commissioning, component and electrical equipment testing, maintenance channel and water washing system testing, grid-connected startup, etc.

2.1 Foundation and scaffolding (10-14 days)

2.1.1 Cement foundation

The roof is a cement roof, the foundation is a cylindrical cement pier structure, with pre-embedded M12 U-bolts and a pre-embedded depth of 180mm.

Cement foundation

2.1.2 Bracket Installation

The entire site has three installation forms: single row 10 degree angle, double row 10 or 20 degree angle, and triple row 10 degree angle. By raising the inclination angle, the distance between the front and rear rows of the string is reduced, making it easier to install more modules. For roofs with slopes, brackets are also required for leveling.

Three rows of 10 degree angle installation

Double row 20 degree angle installation

2.2 Component installation (3~5 days)

The on-site components use 60-cell polycrystalline components, which are laid out in vertical rows. There is no obstruction from surrounding buildings, so there is no shadowing problem. In addition, sufficient space is reserved between components to facilitate later operation and maintenance. The components are very easy to accumulate dust and need to be cleaned regularly.

Component installation completed

2.3 Inverter installation (2~3 days)

The inverter adopts GoodWe GW100K-HT/GW50KS-MT model. According to the principle of economy, the inverter is installed close to the module array. On the cement concrete roof, it can be installed on the back of the module bracket, and the inverter reserves enough space for heat dissipation.

GoodWe's industrial and commercial products include models with multiple power ranges of 30/36/40/50/60/80/100/120kW, which can meet all the needs of industrial and commercial power stations. Among them, the HT 120/100kW has the most obvious cost reduction and efficiency improvement. The HT maximum efficiency can reach 98.6%, with multi-channel MPPT, 15A high current compatible with high-power & bifacial components, integrated PID repair function, intelligent air cooling, and higher power generation in summer; it supports a maximum of 300mm? aluminum wire/aluminum alloy cable and DC string two-in-one, saving AC and DC cable costs.

Inverter installation diagram (before wiring)

2.4 Cable and grounding (5~7 days)

The cable from the string to the inverter uses PV 1-F 1*4mm2 photovoltaic special cable, which is laid along the bracket beam; the inverter AC cable uses aluminum alloy cable YJLHV22-0.6/1kV-3*150+2*70mm2, which is laid in the bridge. The cable is covered with a leather tube when entering and leading out of the bridge to prevent the cable from wear and damage.

Xiao Gu reminds: When the AC side wiring of the inverter is completed, it is recommended to fill and seal the gap with fireproof mud.

Inverter AC cable

The array is reliably connected to the original roof grounding device through flat steel around it, the inverter casing is repeatedly grounded, and multiple lightning protection grounding measures are taken between the cable troughs.

2.5 Connect to the power distribution cabinet (2~3 days)

Install 9 custom-made distribution cabinets at different grid connection points, then connect the AC cables to the corresponding distribution cabinets, and wait for the power grid company to install the electricity meters.

Grid connection point 9-Comprehensive office building

3. Operation Period

After passing the acceptance of the power grid company and being connected to the grid, it was observed that there was no abnormality in the operation of the power station and the power generation of the power station exceeded expectations. The figure below shows the power generation curve of one of the GW100K-HT on October 21, with a cumulative power generation of more than 600 kWh.

Power generation data (single unit per day)

The stable operation of the power station is inseparable from high-quality equipment. In addition, the installation and operation and maintenance are also worthy of attention. The following is a list of some precautions in industrial and commercial projects:

· The component pressing block needs to be tightened to prevent the component from falling and being damaged;

· Ensure that the components are effectively grounded to prevent insulation or grounding faults in the system;

The inverter is installed securely and a certain amount of space is reserved to facilitate heat dissipation and ventilation;

Safe and efficient industrial and commercial photovoltaic power stations are inseparable from standardized installation, and long-term stable photovoltaic power stations are inseparable from professional operation and maintenance; relying on the GoodWe smart energy management platform, the power station can accurately locate each power station, equipment, and string, efficiently and quickly reflect fault information, and give reasonable suggestions.

Summarize

As a government educational institution, the school has stable operation, clear land ownership, good building structure, generally no major renovation, stable electricity consumption, and relatively high power station income. It is helpful to build an environmentally friendly and energy-saving campus, green electricity use, let students have a more direct understanding of new energy, and stimulate students' enthusiasm for research.

GoodWe provides integrated solutions for photovoltaics, energy storage, and smart energy, helping every building become a power station and using clean energy.