Solar PV Rooftop Power Generation and Grid Connection Implementation Program

As solar photovoltaic tends to be popular, more and more factories, commercial and public facilities are gradually starting to use solar photovoltaic power generation and grid-connected, on how to implement power generation and grid-connected in these places in detail, we combined with the technical specifications, implementation strategies, policy support and typical scenarios to comprehensively analyze the use of solar photovoltaic power generation on rooftops with grid-connected implementation plan:

I. PV system types and applicable scenarios

1. Grid-connected system

Grid-connected solar PV power generation requires PV modules, bi-directional meters (provided by the grid company), grid-connected inverters, and racking systems, and is applicable to roofs with stable grid access conditions.

When the PV is grid-connected, the revenue can be realized through full Internet access or residual power sales (self-consumption + residual power Internet access), and the payback period for common types of industrial and commercial projects is about 5-7 years.

As electricity is a special resource in some countries, it is necessary to apply for a grid connection license from the local power bureau, and the grid enterprise guarantees full consumption and priority access to the distribution grid.

2. Off-grid systems

Off-grid PV system requires PV modules, off-grid inverter, controller, battery pack (we usually provide Li-ion battery pack), which is suitable for areas without grid coverage or unstable power supply.

The battery used for PV energy storage has a lifespan of about 3-5 years and needs to be replaced regularly according to the specific environment, and the cost of the system is 30%-50% higher than that of a grid-connected system.

II. Roof Structure and Installation Solution Adaptation

Installation of solar photovoltaic panels on flat roofs

Roof types	Solutions	Technical Advantages
‌Flat roof	Adoption of tilt-adjustable mounts, in which the optimal angle of the solar panels needs to be calculated according to the latitude, and the PV array spacing is designed according to the shadow length of the winter solstice.	Power generation efficiency increased by 10%-15%, easy to operate and maintain clean.
‌Pitched Roof	Directly fit the roof tilt mounting, in the northern hemisphere, for example, the installation direction can be due south/southeast/southwest direction, the integrated design of modules and tiles to reduce the wind load.	No need for additional brackets, high aesthetics and strong wind resistance.
Steel Structure Plant	Use fixture type installation, so as to avoid damaging the waterproof layer, PV modules and color steel tiles are laid parallel to each other, reserving access for maintenance.	Load capacity of single tile≤3kg/m², suitable for lightweight roofs of industrial plants.

Ⅲ. System Configuration and Optimization Strategy

1. Photovoltaic power generation equipment selection

Two types of modules are available: double-sided double-glass modules and PERC/HJT modules.

Double-sided double-glazed modules: Suitable for high reflectivity floors, such as white roofs, with power generation 5%-12% higher than that of single-sided modules.

PERC/HJT modules: conversion efficiency of 23%-26%, better power generation performance under low light conditions.

Inverter Configuration: String inverters are recommended for roofs of factories and commercial yards, which are suitable for multi-directional installation, and micro-inverters can be selected for household roofs, which are more secure.

2. Energy storage system integration

Higee 280Ah Liquid Cooled / Air Cooled Container Energy Storage System

According to the optical storage synergistic approach, the need to configure lithium battery storage, most of the current manufacturers use lithium iron phosphate batteries, in the price of electricity during the low valley storage, peak discharge, internal rate of return increased to 8% -12%.

Calculated by capacity, it is 30% -50% of the average daily power consumption to design the energy storage capacity, to avoid excessive investment.

3. Intelligent operation and maintenance upgrade

A monitoring system needs to be installed, for example, when deploying platforms such as NiOS™ to monitor real-time data such as power generation, module temperature, etc., with a fault response time of ≤30 minutes.

Cleaning strategy can also be selected, with at least 1 manual or robotic cleaning per month, and the average annual power generation loss can be reduced by 3%-5%.

IV. Policy Support and Economic Analysis

1. Subsidies and tax incentives

Subsidies vary from place to place, for example, Jiangsu Province in China gives 15%-25% construction subsidy to industrial and commercial PV projects, superimposed on the national “three exemptions and three halves” income tax policy.

It can also be discounted according to the carbon trading revenue, for example, each MW of PV annual emission reduction of about 1,000 tons of CO₂, can be traded through the carbon market to obtain additional revenue.

2. Market-oriented operation

If the local government has a green power trading policy, it can sign a long-term power purchase agreement (PPA) with high energy-consuming enterprises, with a 10%-20% tariff increase over the benchmark.

Demand response according to the policy is also possible, such as participating in grid peaking services and obtaining the corresponding compensation for auxiliary services given per kWh of electricity.

V. Implementation Process and Risk Control

1. Feasibility Assessment

According to the house where PV panels are to be installed, the effective area of the roof should be calculated, under normal circumstances, about 6-8 square meters per kW, the load-bearing capacity (≥20kg/m²), as well as the need to check the surrounding shading situation.

It is also possible to simulate 25 years of power generation through the PVsyst software, with the error rate controlled within ±3%.

2. Construction Management

For the roof, anti-seepage treatment is also needed, which can be done by using non-penetrating brackets or special waterproof adhesive mats to avoid damaging the roof structure.

The DC side voltage of solar photovoltaic power generation is generally not more than 1000V, in order to ensure electrical safety, it is necessary to configure an anti-reverse current protection device on the AC side.

3. Grid connection acceptance

When the installation and testing of the solar PV system is completed, you can submit the “PV Project Access System Program” to the power grid company, and obtain the “Grid Acceptance Opinion” and then officially put into operation.

Ⅵ. Typical Case Reference

1.Rural household roof:

Grid-connected rooftop photovoltaic system for farmers in Shandong, China

Installation of a 20kW grid-connected system in an ordinary farmer's house in Shandong, China, generating 26,000 kWh of electricity annually, with an annual income of US$1,600 from the sale of the remaining electricity, and a payback period of about 6 years.

2.Industrial Park Optical Storage Project:

Installation of 5MW rooftop PV + 2MWh energy storage on the roof of an automobile plant in Jiangsu, China, can save 576,000 USD per year on electricity bill, and carbon emission reduction benefit reaches 66,000 USD/year.

The above programs need to be customized with local light resources, electricity price policy and building characteristics, and it is recommended to entrust qualified design institutes or EPC companies to implement.