Inauguration Of Niger''s Largest Solar Power Plant

Are wall-mounted solar panels a success?

Our first-ever wall-mounted solar panel installation was a great success. This was also the first ever experience I had with installing solar panels. The system comprised four panels mounted in landscape mode. We used unistrut rails to mount the panels. The mounting rail and stages of progress of installing wall panels.

Can solar panels be mounted on a wall?

Roof-mounted solar panels are usually titled at a 20-50 degree angle, which allows them to capture sunlight when the sun is high in the sky. But most wall-mounted panels are parallel to the wall, or only slightly tilted. It's also harder to fit as many solar panels on a wall as you would on a roof.

How to install wall-mounted solar panels?

To maximise energy absorption, you need to make sure to install the wall-mounted systems strategically. You can do this by placing the solar panels directly parallel to the wall, tilting them away from the wall or overhanging them. The natural slope of wall-mounted solar panels requires special mounting hardware to ensure security.

Are wall-mounted solar panels a good option in winter?

The winter sun is relatively low in the UK, and energy usage typically increases during winter. Therefore, wall-mounted panels can be particularly beneficial here. Without projecting a panel beyond 200mm from the wall, from the wall, you can mount a typical panel with dimensions 170cm by 110cm at around 80°.

How far from the wall can a solar panel be mounted?

Without projecting a panel beyond 200mm from the wall, from the wall, you can mount a typical panel with dimensions 170cm by 110cm at around 80°. A wall-mounted panel gives much better consistency and peaks in spring and autumn compared to the summer. Yearly production ~290kWh. There are multiple options for mounting panels on a wall.

Are wall-mounted solar panels better than roof-mounted panels?

While wall-mounted panels are generally less efficient than roof-mounted ones, they can be viable in certain scenarios. South-facing walls offer the best sunlight exposure. The tilt and direction of panels are crucial for optimising efficiency, with a 60-degree angle ideal for capturing low winter sun.

How big is China's photovoltaic capacity in 2020?

In 2020, China's newly installed grid-connected photovoltaic capacity reached 48.2GW, a year-on-year increase of 60.1%, of which the installed capacity of centralized photovoltaic power plants was 32.7GW, a year-on-year increase of 82.68%; the installed capacity of distributed photovoltaic power plants was 15.5GW, a year-on-year increase of 27.04%.

How big is China's grid-connected photovoltaic capacity in 2021?

In 2021, China's newly installed grid-connected photovoltaic capacity reached 54.88GW, a year-on-year increase of 13.9%, of which the installed capacity of distributed photovoltaic power plants was 29.28GW, a year-on-year increase of 88.7%, and accounting for 53.4% of the total new installed capacity, and breaking 50% for the first time in history.

How many rooftop solar photovoltaic projects are there in China?

It has entered a rapid development stage (Li and Huang, 2020, Anon, 2022a). There are 676 rooftop solar photovoltaic (RTSPV) pilot projects in 31 provinces in China in 2021 (Anon, 2021a). Rooftop solar photovoltaics use building roof resources to design distributed photovoltaic power stations (Tripathy et al., 2016).

How big is photovoltaic power generation in China?

According to data released by the National Energy Administration, the cumulative total installed capacity of photovoltaic power generation in China in 2020 was 253GW, a year-on-year increase of 23.8%. As photovoltaics gradually enter the era of parity and 14-five-year plan, the installed capacity will show a more rapid growth trend.

How much photovoltaic is installed in China in 2021?

In 2021, the new installed photovoltaic in China reached 54.88GW, with a year-on-year growth of 13.9%. The cumulative grid connected installed capacity reached 306GW, ranking first in the world in terms of new and cumulative installed capacity. Among them, 25.6GW and 29.28GW of centralized and distributed photovoltaic were added respectively.

How to assess PV power generation potential of rooftop in China?

In this paper, we present an assessment method for the PV power generation potential of rooftop in China. Using machine learning model processes the big data that consists of the gross domestic product, building footprint, road length and population, at a high geographic resolution of 10 km by 10 km.

Why is Elisa Europe's largest virtual power plant project?

This enables Elisa to target 150MWh storage capacity which makes it Europe's largest distributed virtual power plant project. The capacity is among the largest European battery storage systems even when compared to centralised grid-scale battery installations.

How does a virtual power plant work?

Those same batteries either power the network or feed electricity back into the grid when electricity consumption is high. By doing this, the virtual power plant balances peaks in electricity consumption and high prices. Lower electricity prices benefit everyone who uses electric power.

What is distributed energy storage (des)?

The Distributed Energy Storage (DES) solution powered by AI/ML uses the flexibility of backup power batteries to control electricity supply in thousands of base stations in the radio access network throughout the day. The DES system optimises the timing of electricity purchases by scheduling charging and discharging periods for the batteries.

What is Elisa des virtual power plant?

Elisa's DES virtual power plant provides a critical source of supply for the Finnish power grid that can be used when there are disturbances in production or during peaks in demand, thereby improving the resilience of the grid in crisis situations.

What is a photovoltaic power station?

A photovoltaic power station, also known as a solar park, solar farm, or solar power plant, is a large-scale grid-connected photovoltaic power system (PV system) designed for the supply of merchant power.

Where do large-scale solar PV power plants locate?

Large-scale solar PV power plants mostly tend to locate on the areas with rich vegetation cover and close to grid lines. Spatial predictions of solar photovoltaics installations probability using three ML models presented a consistent distribution pattern.

What is global photovoltaic power potential by country?

The World Bank has published the study Global Photovoltaic Power Potential by Country, which provides an aggregated and harmonized view on solar resource and the potential for development of utility-scale photovoltaic (PV) power plants from the perspective of countries and regions.

How to choose a suitable location for a large-scale solar PV power plant?

To maximize the development of commercial resources and to minimize the impact of various issues, a number of evaluation criteria (such as availability of resources, climatic, ecological, and socio-economic factors) must be considered for determining suitable location for a large-scale solar PV power plant installation .

Do solar PV power plants have a good location?

It is assumed that the installed PV power station has a relatively ideal geographical location, which is jointly determined by investment decision makers and experts . The modeling procedures of evidence-based location choices of solar PV power plants with machine learning methods are shown in Fig. 1.

Where should a solar photovoltaic plant be located?

The new methodological proposal that includes the procedures for choosing and weighting the criteria that allow the optimal location of a solar photovoltaic plant can be extrapolated and therefore applied to any country, territory, or area of interest anywhere in the world.

How much does solar energy cost vs wind energy?

However, there are other reports that detail the potential cost of solar energy vs wind energy specifically. Those reports indicate that (some information is paraphrased): From group.met.com ' it about $2.19 per watt to install solar energy, while wind power costs only $1.50 per watt'

How do wind power and solar energy compare?

Let's explore how wind power and solar energy compare in this regard. Wind power has a relatively low environmental impact. The process of generating electricity from wind turbines produces no greenhouse gas emissions or air pollutants.

Why is wind power cheaper than solar?

For large scale systems, wind power breaks even and produces power cheaper than an equivalent solar system. Big wind farms make cheaper power than large solar installations. Wind farms generate more power in less space and need less maintenance for each megawatt they produce. Wind turbine upkeep costs $3,000 to $5,000 [$2,500 to £4,200] yearly.

Is solar energy better than wind?

Wind power currently outpaces that of solar when it comes to overall share of electricity generated. For homeowners, solar energy is a far more practical option. What it really comes down to, however, is location. In the world of energy, there is no one-size-fits-all solution.

How much does solar energy cost?

Those reports indicate that (some information is paraphrased): From group.met.com ' it about $2.19 per watt to install solar energy, while wind power costs only $1.50 per watt' Data provided by regenpower.com might indicate that (paraphrased) wind energy costs about 20.3 cents per kWh, and solar energy costs 4.6 cents per kWh

Should you choose wind or solar energy?

Consumers and energy providers look at cost when deciding between wind and solar. That includes the cost of initial setup, maintenance, and ongoing operation. The cost of wind power has decreased significantly over the years. It is often considered more cost-effective than solar energy, particularly in regions with strong and consistent winds.

How many kWh can a solar panel produce a day?

To contextualise the potential of solar panels: A household that installed enough solar panels to produce an average of 10kWh a day would generate around 3,650kWh annually. That would be enough power to cover the average household's yearly electricity consumption.

How much electricity does a solar system produce?

According to our calculator, a 4.5 kilowatt (kW) system with 12 panels would produce on average 4,100 kilowatt hours (kWh) in a year, enough for a 3 bedroom house. However, there are a range of factors that can affect how much electricity your solar panels produce, from the efficiency of your system to the angle of your roof.

How much electricity does a solar panel produce per m2?

Though of course, if you have a solar battery, you can simply store the extra electricity and use it later. The average solar panel output per m² is 186kWh per year. Solar panels are usually around 2m², which means the typical 430-watt model will produce 372kWh across a year.

How much power do solar panels provide?

Nearly 30% told us that their solar panels provided between a quarter and a half of the total electricity they needed over a year. There's a huge seasonal variation in how much of your power solar panels can provide. Read our buying advice for solar panels to see how much of your power solar panels could generate in summer.

What is solar power & efficiency?

When it comes to solar panels, 'power' refers to the maximum amount of electricity a panel can generate (in watts). The panel's ' efficiency ' is all about how effectively it can convert daylight into electricity. Higher power and efficiency mean greater electricity production.

How much electricity can a 430 watt solar panel produce?

Solar panels are usually around 2m², which means the typical 430-watt model will produce 372kWh across a year. A solar panel system will need space on either side, so finding out your roof's area is only one part of working out how much solar electricity you can generate, but it's a great first step.

What are the negative effects of solar energy?

Negative: Solar energy has intermittency issues on cloudy days and at night, impacting efficiency. Negative: High energy storage costs hinder nighttime use of solar energy. Negative: Land use challenges exist due to space requirements for solar panel installation.

What are the positive effects of solar energy?

When you consider the positive effects of solar energy, you'll appreciate its ability to reduce electricity bills, provide sustainable power, and allow you to sell excess energy back to the grid for additional savings. What Is Positive and Negative in Solar?

How does solar power affect the environment?

Solar power helps in reducing greenhouse gas emissions by displacing fossil fuel energy sources, contributing positively to the environment. Additionally, while solar panels consume water during production, their operational phase has minimal environmental impact, making them a cleaner alternative for energy generation.

What challenges does solar energy face?

Solar energy faces various challenges that can impact its efficiency and widespread adoption. Some of the key challenges include: Intermittency: Solar energy can be inconsistent, with reduced efficiency on cloudy days and no energy production at night.

What are the advantages and disadvantages of solar energy?

Energy advantages. Solar energy offers numerous advantages, such as reducing energy bills, financial gains through schemes like the Smart Export Guarantee (SEG), and the potential to double or triple electrical input efficiency. Technological advances.

What is the economic impact of solar energy?

The economic impact of solar energy encompasses both positive and negative effects. On one hand, the shift towards solar energy creates job opportunities and drives economic growth. On the other hand, the initial investment in solar technology can be costly, impacting businesses and consumers.

Who are the top 10 Chinese solar battery manufacturers?

With the application of cutting-edge technology in the solar battery industry, China has made great progress in the field of energy storage around the world. This article lists the top 10 Chinese Lithium solar battery manufacturers. 1. Huawei 2. Pylontech 3. BYD 4. Sofar Solar 5. GoodWe 6. Dyness 7. AlphaESS 8. NPP Power 9. SolarX Power 10. Growatt

Do solar batteries have backup power for grid outages?

Backup power for grid outages is traditionally one of the most desired features of a solar battery. While most batteries have this feature, a few stand above the rest in 2024. Quick facts: What we like:

Who is the best battery manufacturer in China?

NPP Power CO., LTD. Before knowing the Top companies list, here is a special introduction to NPP POWER, NPP is not only the Top 10 VRLA battery manufacturer in China but also a World-class Lithium Solar Battery manufacturer.

Which solar power system should I Choose?

If you're looking to back up everything during a grid outage (including central air conditioning), the Franklin Home Power system is clearly the preferred choice among Solar.com's network of battery installers.

What is solar home storage system?

From a technical point of view, solar home storage system adopts the design concept of integrated micro-grid, which can operate in on-grid/off-grid dual modes, and can realize seamless switching of operating modes, which greatly improves the reliability of power supply.

Should you buy a sunvault Strage Solar System?

What we like: SunPower is a well-known and trusted solar brand and its 10-year/unlimited cycles warranty is on-par with Tesla's. If you're not a Tesla fan and a robust battery warranty is high on your list, the SunVault Strage system offers a great alternative.

What are the largest public listed companies in solar industry from China?

This is the list of the largest public listed companies in the Solar industry from China by market capitalization with links to their reference stock. $10,000 in September 2023 would now be $32,767 by following this algorithm daily at market close. Use AI to boost your investing & swing trading, now! 1. Trina Solar Co. Ltd 2.

Where is solar power generated in China?

Most of China's solar power is generated within its western provinces and is transferred to other regions of the country. In 2011, China owned the largest solar power plant in the world at the time, the Huanghe Hydropower Golmud Solar Park, which had a photovoltaic capacity of 200 MW.

Who are the top solar panel manufacturers in China?

The following are the top solar panel manufacturers in China as of 2024. Jinko Solar Co., Ltd., now officially known as Jinko Solar Holdings Co., Ltd., was established in 2006 and is headquartered in Shangrao, Jiangxi Province, covering an area of over 500 acres.

Why is China the world's leading producer of solar panels?

China is the global powerhouse in solar panel manufacturing, driving the industry with unparalleled production capabilities and cutting-edge technological advancements. As the world's leading producer, China commands over 95% of the global market for key components such as polysilicon, ingots, and wafers, essential for solar panel production.

When did China start making solar panels?

China's photovoltaic industry began by making panels for satellites, and transitioned to the manufacture of domestic panels in the late 1990s. After substantial government incentives were introduced in 2011, China's solar power market grew dramatically: the country became the world's leading installer of photovoltaics in 2013.

Does China have a solar industry?

And despite all the turmoil, the Chinese solar industry has the manufacturing capacity to meet the demand. Discover all statistics and data on Solar energy in China now on statista.com!

What is an off-grid inverter?

Its primary job is to supply pure sine wave AC power, and it must be able to meet the power requirements of the appliances under all conditions. Off-grid (multi-mode) inverters are the central energy management system and can be either AC-coupled with solar inverters or DC-coupled with MPPT solar charge controllers.

What is an off-grid Solar System?

Modern off-grid solar systems use advanced inverters to manage batteries, solar, and backup AC power sources such as generators. The off-grid inverter, often called an inverter-charger, is the heart and brain of an off-grid system.

What solar systems are available off-grid?

Off-grid 3-phase Victron system using three Multiplus 2 5000VA inverters AC-coupled with a Fronius Symo solar inverter. System by Harpoon Electrics and Transfer Solar 24V DC coupled off-grid solar system with 2 x Victron Bluesolar charge controllers, 2.4kW solar array and Victron Phoenix 2.4kW battery inverter. 3. Outback Power Radian A-Series

Who makes Delta Solar inverters?

Delta Electronics is a well-established global manufacturer of solar inverters, offering reliable and efficient solutions for solar energy systems of all sizes. Based in Taiwan, Delta has a reputation for innovation in power electronics and energy management.

Who makes ginlong solar inverters?

Ginlong Technologies, the company behind the Solis brand of inverters, is a prominent solar inverter manufacturer focused on advanced, affordable technology. Based in China, Ginlong provides high-quality inverters known for their reliability, ease of installation, and efficient power management.

What does a solar inverter do?

Solar inverters play a crucial role in converting energy in solar power systems. They transform direct current (DC) electricity generated by solar panels into alternating current (AC) electricity, which can be used in homes, industries, and public utilities. These innovative inverters act as the brains of the solar power system.

What is cadmium telluride PV?

Cadmium telluride PV is the only thin film technology with lower costs than conventional solar cells made of crystalline silicon in multi-kilowatt systems.

What is cadmium telluride (CdTe) solar panels?

PV array made of cadmium telluride (CdTe) solar panels Cadmium telluride (CdTe) photovoltaics is a photovoltaic (PV) technology based on the use of cadmium telluride in a thin semiconductor layer designed to absorb and convert sunlight into electricity.

What are cadmium telluride solar cells?

Cadmium telluride (CdTe) solar cells contain thin-film layers of cadmium telluride materials as a semiconductor to convert absorbed sunlight and hence generate electricity. In these types of solar cells, the one electrode is prepared from copper-doped carbon paste while the other electrode is made up of tin oxide or cadmium-based stannous oxide.

What are the advantages of cadmium telluride (CdTe) thin film solar cells?

1. Introduction Cadmium Telluride (CdTe) thin film solar cells have many advantages, including a low-temperature coefficient (−0.25 %/°C), excellent performance under weak light conditions, high absorption coefficient (10 5 cm⁻ 1), and stability in high-temperature environments.

Are cadmium telluride photovoltaic cells toxic?

Cadmium telluride photovoltaic cells have negative impacts on both workers and the ecosystem. When inhaled or ingested the materials of CdTe cells are considered to be both toxic and carcinogenic by the US Occupational Safety and Health Administration.

Why is CdTe thin film solar cell suitable for building integrated photovoltaics?

Cadmium Telluride thin film solar cell is very suitable for building integrated photovoltaics due to its high efficiency and excellent stability. To further reduce the production costs, relieve the scarcity of Tellurium, and apply in building integrated photovoltaics, ultra-thin CdTe photovoltaic technology has been developed.

How do you replace a solar light battery?

To replace a solar light battery, first remove the cover and take out the old batteries. Then, input new batteries. It is important to know the type of battery required for optimal performance when replacing solar light batteries.

How to disassemble a battery?

When it comes to disassembling a battery, the first important step is removing the battery cover or casing. This outer layer provides protection to the internal components of the battery and prevents any damage from external factors. By following a few simple steps, you can safely remove the cover or casing without causing harm.

How to replace a depleted solar light battery?

You must replace your depleted solar light batteries with the same voltage and similar capacity. For instance, if you take AA NiCad or NiMH 1.2V 600mAh batteries out of the solar lights, be sure to replace them with AA 1.2V NiMH 600mAH solar light batteries. The mAh rating indicates the capacity and is usually printed out on the battery.

How do I remove the battery from my solar light?

You simply twist the light housing's top section anti-clockwise, and it pops out. To be extra safe, make sure to turn off the lights before opening the housing or touching the battery. After opening the battery cover, take a moment to examine the battery type your solar light has.

How do I remove a battery cover & casing?

By following a few simple steps, you can safely remove the cover or casing without causing harm. Begin by ensuring that the battery is turned off and disconnected from any power source.

What should I bring to a battery disassembly?

Before you start the process, gather the following items: 1. Safety glasses: Protect your eyes from any potential sparks or debris that may fly off during disassembly. 2. Gloves: Wear gloves to safeguard your hands from accidental cuts or exposure to harmful chemicals present in some batteries.

How does solar metering work?

When you install solar, the original meter gets replaced with a bi-directional (or 'Buy/Sell') meter. This bi-directional meter is what makes net metering possible by measuring solar energy production as well as any electricity that you are also buying from the utility company .

What does a solar meter tell you?

They can tell you how much power your system produces, how much energy you use, and how much energy you still have to buy from the utility. A solar meter is basically a device that measures solar power or sunshine in W/m2 and may be used to check the effectiveness of windows or to install solar power equipment.

What is a solar panel meter?

Solar panel metres, also known as net metering devices, play a vital role in monitoring energy production from solar panels. They help homeowners and businesses keep track of their electricity generation from the sun and make informed decisions to maximise their savings.

How do smart meters work?

Current Power Output: By monitoring the real-time power output of your solar energy system in kilowatts (kW) using smart metres, you can identify any sudden drops or fluctuations in solar radiation that may indicate a fault or maintenance requirement for your solar metres.

Can a solar meter measure electricity?

Traditional electricity meters can only measure the electricity that flows one way. That is, from the grid into the house. Solar meters, however, are bi-directional, which means they can also measure the electricity that the home exports to the grid.

How does a solar PV system work?

Solar PV panels – convert sunlight into electricity. Inverter – this might be fitted in the loft and converts the electricity from the panels into the form of electricity which is used in the home. Generation meter – records the amount of electricity generated by the solar PV system.

How do solar panels generate electricity?

Electricity is generated from energy from the Sun by solar panels. These are made up from individual solar cells (also called photovoltaic cells). Light from the sun passes through the glass cover of a solar cell. The sunlight hits layers of semiconductors, giving extra energy to electrons in the semiconductors.

How the sun can be used to generate electricity?

Find out how the sun can be used to generate electricity. Electricity is generated from energy from the Sun by solar panels. These are made up from individual solar cells (also called photovoltaic cells). Light from the sun passes through the glass cover of a solar cell.

How does solar power work?

Solar power works by converting energy from the sun into power. There are two forms of energy generated from the sun for our use – electricity and heat. Both are generated through the use of solar panels, which range in size from residential rooftops to 'solar farms' stretching over acres of rural land. Is solar power a clean energy source?

How do solar cells convert light to electricity?

The conversion of light to electricity in a solar cell is a process underpinned by the photovoltaic effect. When sunlight, composed of photons, strikes the solar cell, these light particles transfer their energy to electrons in the cell's semiconductor material, typically silicon.

Where does solar energy come from?

Solar energy is derived from the sun, which emits an enormous amount of energy continuously. This energy travels through space and reaches the Earth, where it can be harnessed for various uses. Most commonly, solar energy is captured and converted into electricity using solar cells.

How is solar energy converted into electricity?

Most commonly, solar energy is captured and converted into electricity using solar cells. These cells are designed to absorb sunlight and convert it directly into electrical power without any moving parts, making them highly reliable and low-maintenance.

How to make solar panels in a solar plant?

Step-by-Step Guide on Solar Panel Manufacturing Process in a Solar Plant. Sand → Silicon → Wafer → Photovoltaic Cell → Solar Panel. Complete solar panel manufacturing process – from raw materials to a fully functional solar panel.

What is solar manufacturing?

Solar manufacturing refers to the fabrication and assembly of materials across the solar value chain, the most obvious being solar photovoltaic (PV) panels, which include many subcomponents like wafers, cells, encapsulant, glass, backsheets, junction boxes, connectors, and frames.

How are solar panels made?

Sand → Silicon → Wafer → Photovoltaic Cell → Solar Panel. Complete solar panel manufacturing process – from raw materials to a fully functional solar panel. Learn how solar panels are made in a solar manufacturing plant, including silicon wafer production, cell fabrication, and the assembly of panels into solar modules.

How are PV solar cells made?

The manufacturing process of PV solar cells necessitates specialized equipment, each contributing significantly to the final product's quality and efficiency: Silicon Ingot and Wafer Manufacturing Tools: These transform raw silicon into crystalline ingots and then slice them into thin wafers, forming the substrate of the solar cells.

What is a photovoltaic (PV) solar cell?

Central to this solar revolution are Photovoltaic (PV) solar cells, experiencing a meteoric rise in both demand and importance. For professionals in the field, a deep understanding of the manufacturing process of these cells is more than just theoretical knowledge.

What is solar-thermal manufacturing?

While some concentrating solar-thermal manufacturing exists, most solar manufacturing in the United States is related to photovoltaic (PV) systems. Those systems are comprised of PV modules, racking and wiring, power electronics, and system monitoring devices, all of which are manufactured. Learn how PV works.

What causes a solar panel to register no power?

These are actually common problems and there are ways you can fix them. A faulty inverter or charge controller are the most likely reasons for a solar panel to register no voltage. Other possible reasons for low to zero power are a damaged PV module, poor wiring, shading and temperature higher than the ideal operating range.

What are some common problems with zero voltage solar panels?

Common problems with zero voltage include a faulty inverter or charge controller, a solar panel that has failed, shading, increased temperature, hotspots in a solar panel, poor connection or faulty wiring, and delamination caused by water entering one of the solar panels. We will look at the most common scenarios where PV systems fail:

Do solar panels have no voltage?

No Voltage From Solar Panel (Solutions) - Solar Panel Installation, Mounting, Settings, and Repair. It can be frustrating to find you don't have voltage from your solar panels, but the potential problems are relatively straightforward to diagnose as there can only be a few issues that cause the lack of power.

Why isn't my solar panel generating volts?

If your solar panel is not generating volts, it's likely due to lack of sunlight. Environmental issues like shading, a dirty solar panel, high temperature, and bad weather can also prevent the panel from producing volts. In extreme cases, these factors can cause the voltage to drop to zero.

What causes a lack of voltage from solar panels?

Aside from the above, high temperatures, shading, panel damage, and faulty connections can cause a lack of voltage from solar panels. All electronic devices, including solar panels, operate far better at lower temperatures.

What should I do if my solar panel system is disconnected?

If you are considering disconnecting your solar panel system, seek guidance from a qualified solar installer or electrician. Additionally, install backup power solutions to ensure an interrupted power supply when your solar panels are disconnected and not generating electricity. This could include backup generators or UPS systems.