A hybrid power plant in simple terms is a plant which generates power by using two or more sources of energy. These sources could be either conventional or non-conventional or both. Such power plants are preliminarily useful as they reduce dependency on a single source while also enabling the power plant to produce more power output. Now with the world’s focus on non-conventional power sources (solar and wind energy predominantly) it is important that such sources are utilized to their maximum potential. While individually, these sources have been performing quiet fair, there are still few concerns which needs to be addressed in order to utilize these sources efficiently. A simple yet innovative solution is hybridization of this technology or a hybrid solar wind plant (shown in Figure 1). Similar to the other hybrid plants, here both solar PV panels and wind turbines could generate electricity and feed it into the grid. With the target of 10GW by 2022 from such hybrid plants and with both the central & various state governments supporting this idea, hybrid plants are poised to increase. This blog thus aims to educate its readers on the basic technical details along with the advantages of such hybrid plants.

Before understanding the technicalities of hybrid plant, it is important to understand why such plants are necessary at the first place. Its advantages are mentioned as below:

  1. Complementary power generation: The first and foremost advantage of such hybrid plant in the complementary power generation. The solar power plant produce energy during the daytime whereas wind plants are generally known to produce (more) energy during evening and night (compared to daytime). The individual generation curves of solar and wind plant as evident from figure 2 below are intermittent in nature and could not adequately match the overall energy demand. This is where the hybrid power plants could be of utmost importance. Superimposing both these generation curves they could manage the overall demand to some extent (as shown in figure 3). Additionally with the central/state regulators pressing against providing schedule and forecasting of renewable power plants such hybridization (along with storage) could help power generators to closely match the given schedule while helping the SLDC/RLDC/POSOCO in getting power generation values (with certain tolerances) and balancing the against the power demands.
  2. Increased capacity utilization factor (CUF): A capacity utilization factor in simple terms is the ratio of actual energy generation of the power plant to the maximum possible generation in such period (24 hours, 365 days in a year) under operation. A solar power plant (due to the limitation on availability of sun) has a CUF varying from 16-21%. A wind power plant (location wise variation of wind at different heights) may have CUF varying from 20% to 26%. This means that for about 74 to 84% of the time, the plant remains idle without any generation. Studies however suggest that CUF ranging from 35% to as high as 50% (in few cases) have been obtained for hybrid power plants. This means that a higher energy per watt could be obtained which primarily improves the plant statistics while holistically reducing the LCOE of the power plant (compared to LCOE of individual power plant).
  3. Increased utilization of transmission capacity: Utility scale renewable energy plants are usually located quiet far from load centers. This means that adequate transmission infrastructure is required to transmit such power to load centers. Individual power generation curve of solar and wind plants clearly suggest that such transmission infrastructure remains un-utilized. With tens of lakhs required to erect a HV transmission substation, it is important to utilize it to maximum. This is where a solar wind hybrid plant comes into play. The hybrid plant due to its complementary nature of generation (as we explained above) could utilize such infrastructure more efficiently when compared to individual plant.
  4. Efficient usage of land: The next advantage is that the hybrid power plants efficiently utilize the available land space. The land requirement of a utility scale power plant is in between 4-6 acre/MW. A wind turbine may vary in sizes and power output, however most commonly it would occupy an area ranging from 10 to 50 acre/MW (Source: NREL) (the wind turbine only occupies 5% of the area). The land savings per MW in hybrid plant could be as much from 10-30%. Additionally with same transmission infrastructure used to evacuate power, such costs could be reduced too.

Easier renewable energy purchase obligation (RPO) achievements: A RPO as the name suggest is an obligation for an entity (i.e. state distribution companies, open access customers and captive generators) to source a part of their energy need from renewable energy sources. It is divided into 2 components i.e. solar and non-solar RPO. While an enforcement of RPO is in place, (baring mere a few) as almost every obligator has been a defaulter. A hybrid power plant would help where both solar and non-solar RPO of an obligatory entity could be fulfilled.

As we mentioned above, the solar wind hybrid plant would be of importance given their advantages compared to the individual plant. With such understanding in place, let us understand the technical scheme in practice for a hybrid power plant. There are two categories by which there hybrid plant could be erected. They are:

  1. AC coupled hybrid plant: An AC coupled power plant as the name suggest is the one where the individual power plant are interconnected at AC side. A single line diagram (SLD) for an AC integrated hybrid power plant is shown in Figure 4 below. The configuration of both solar and wind power plant here remains almost comparable to the individual standard plant with their output most likely integrated at HT panel of AC yard after individual meter. This ensures that the utility company knows the exact generation from each plant and financial settlements could be done accordingly (if PPA for the solar and wind plants were signed individually at different rates). Such integration may be perfect for plants existing solar/wind power plant are hybridized with new wind/solar power plant. This type of system would be more perfect for fixed speed wind turbine given the fact that they are directly integrated to the grid (using intermediate induction generator).
  2. DC coupled hybrid plant: A DC coupled hybrid power plant (as shown in Figure 5) on the contrary is the one where the DC power output of individual is connected to a common DC bus. This entire power output is then converted to AC power by using a common inverter which is further connected to the grid. Such plants are termed in the market as “true hybrid” because they use the evacuation infrastructure to the maximum. This configuration is more often suitable for new power plants and/or for specifically with plants having variable speed wind turbine. This is because the capacity of common bus, inverter and the protection on both DC & AC side would require adequate planning which is not possible in existing plant. If optimally erected, such hybrid plant could offer a potential savings from INR 5-10/Wp.

While the technology is in place, it was necessary that a policy specific to this technology was passed. This was also to ensure that in addition to erecting new plants, the existing solar/wind plants were given fair chance to upgrade their power plant by adding appropriate capacity of wind/solar power plant. The MNRE has released the solar wind hybrid policy where both AC & DC coupling is allowed, however to be termed as hybrid plant, the power capacity of one resource should be at least 25% of the rated power capacity of other resource. The hybrid plants are encouraged to sell the generated energy with all the available business models i.e. captive consumption, sale via open access, sale to Distribution Company via bidding or at APPC. It also allows power plants to install battery storage given its various benefits. Few states (Gujarat, Andhra Pradesh) have realized potential of hybrid plants and have released draft policies (hybrid policy of Gujarat is finalized and notified). With more states realizing its potential, such plants would increase in years to come.

We at Waaree Energies could help you set up solar power plant at ideal locations. With an experience of executing more than 500+ MW EPC projects, the customer could be ensured that their plants would be up and running for more than 25 years.

Let us all pledge to make solar energy the primary source of energy in the near future.

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Figure 2: Power output generation curve; solar power (left) & wind power plant (right)

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Figure 3: Super imposed generation curve of solar and wind energy in comparison to energy demand

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Author -Mr. Sunil Rathi, Director- Sales and Marketing, Waaree Energies ltd

Bifacial PV modules are the upcoming product & future of solar Industry. They offer several advantages over traditional solar PV Modules. Power can be produced from front and back side of a bifacial module thus increasing total energy generation within same area. Since both sides of these modules are UV resistant, they are more durable and have reduced potential-induced degradation (PID) concerns especially when the module is frameless, however it increases the chances of breakage.

Read more: Key Parameters Contributing Gain in Bifacial PV...

Solar trackers have become important components of solar photovoltaic installations. Their ability to track the changing position of the sun in the sky can dramatically boost the energy gains of PV systems, by as much as 25 to 35 percent in some cases according to EnergySage.

Read more: The Importance Of Solar Tracker Flexibility For...

The Internet of Things represents the biggest expansion of network connectivity in history. By connecting home appliances, embedded sensors and many other systems not conventionally regarded as "computers" to IP networks, the IoT could unlock many new interactions between devices and applications.

For example, Amazon announced in late 2018 a microwave that could be connected to an Alexa-powered speaker for voice controls, and which also featured an integrated dash button for easy reordering of popcorn. This appliance is pretty simple as IoT inventions go, but it illustrates the potential of connecting devices other than traditional PCs, servers, phones and tablets, in the delivery of innovative services.

Solar power solutions have an important role to play in the growth of the IoT. Providers of integrated solar platforms, like Trina Solar with TrinaPro, are particularly well-positioned to ensure that the IoT infrastructure of tomorrow can harness solar energy for enhanced reliable and resiliency.
 
Why solar and the IoT are a perfect match

IoT assets are not like most networked devices:

  • They're more likely to have streamlined, space-optimized designs that exclude displays and other conventional components, and may even share power sources with the sensors connected to them. This is the case with some IoT weather stations.
  • They may be built in unusual (compared to the familiar form factors of PCs and similar devices) shapes and with rugged materials. so that they can function in specific outdoor locations. However, these design decisions can complicate how they receive power. 

With these requirements and restrictions in mind, solar power is often a good fit for IoT implementations. High-quality solar PV panels are rugged enough to withstand significant wind and snow loads, in addition to having certified waterproofing. The ongoing development of thin PV film may also boost solar's role in IoT, since lightweight panels could be installed in many possible locations.

Solar and IoT have a symbiotic relationship. Installing PV panels and batteries for solar energy storage can make certain types of IoT infrastructure more viable, while the wide-reaching connectivity of the IoT has benefits for solar power management. Indeed, the later has been proposed as a breakthrough IoT application – the use of smart sensors, software and algorithms could bring big changes to the monitoring of solar PV panels voltage, temperature, current and irradiance.

In other words, by connecting their solar infrastructures to the cloud, solar customers will be able to keep close tabs on performance degradations before they get out of hand. In a pre-IoT world, it's often necessary to send out technicians to address issues with causes that are difficult to pinpoint. With IoT solutions in place, issues within solar PV systems can be spotted in real-time and likely resolved with higher success rates.
 
Solar for utility-scale IoT projects

Moreover, integrated solar solutions, such as TrinaPro, can extend the possibilities for energy and utility projects in the IoT. Companies in these spaces have already tapped into the IoT's potential by monitoring critical infrastructure like pressure gauges, supporting preventative maintenance strategies and gathering data for business intelligence initiatives, but solar power opens new horizons.

With an all-in-one solar platform for utility projects, they gain convenient access to panels, inverters, batteries and trackers from a single provider. Modern trackers allow for higher-gain solar installations in a wider range of terrain than was available even a decade ago, when obstacles like pipelines and wetlands limited the feasibility of tracker implementation. The single-axis tracker in TrinaPro adjusts to the sun's east-west movement, providing significant energy gains that can channeled into IoT devices and applications.

Contributed by Trinasolar

TrinaPro is ideal for today's utility-scale projects and will continue to be a powerful platform as energy providers integrate more aspects of the IoT into their operations. Trina Solar combines high-quality components with attentive service to deliver the best possible experience for customers. Its scalability, reliability and overall are well-suited to unlocking the main advantages of the IoT, namely improved insight into operations and tighter integration between IT systems.

Micro inverter market is expected to garner $2.7 billion by 2022. In 2014, North America dominated the market and contributed about 45% share of the overall market revenue, followed by Europe. The presence of key market players in the U.S. and rising micro inverter installation activities, primarily in residential sector, have fueled the market growth.

Micro inverter market is expected to garner $2.7 billion by 2022. In 2014, North America dominated the market and contributed about 45% share of the overall market revenue, followed by Europe. The presence of key market players in the U.S. and rising micro inverter installation activities, primarily in residential sector, have fueled the market growth.Micro inverter is an emerging solar inverter technology used to convert direct current (DC) electricity generated by solar panels into alternating current (AC) electricity. The rise in micro inverters market share in the overall photovoltaic (PV) inverter market can be attributed to improved efficiency and higher power output. Micro inverter is a type of Module Level Power Electronic (MLPE) technology that has separate inverters for each solar cell. Presently, the world micro inverter market is driven by its various benefits for smaller (less than 6kW) size photovoltaic systems in addition to being more cost effective, which is further supported by the enhanced safety. Fast growing residential market and government subsidies and economic incentives have further supported the growth of micro inverter market. Micro inverters are highly efficient as compared to other inverters such as string and central inverters. However, high installation and tough maintenance techniques could limit the market growth. Technological advancements in the field of micro inverters to increase efficiency and rise in government spending on renewable energy projects are expected to provide greater opportunities in the market.

Segment Overview:Segment Overview:The world micro inverter market is segmented on the basis of type, connection, end user, and geography. The type segment is dominated by single-phase micro inverters due to its wider application in residential end-user segment as compared to three-phase micro inverters. Among various connection types, grid-connected micro inverters dominate the global market due to higher energy conversion rate and flexibility.

Higher output and cost-efficiency

Micro inverters are recognized to produce more energy as compared to other solar inverters such as central inverters and string inverters. Micro inverters operate individually as each panel is connected to a single micro inverter, so that each panel can performs to its fullest and any shaded or infected panel would not have effect on the rest of the system. Hence, the average conversion efficiency of an individual micro-inverter is in range of 93 to 98%, which is somewhat superior to conventional central and string inverters that offers average efficiency of 92%. Hence, in long run micro inverter brings in a lot savings for end-users.

High Installation cost

Micro inverter installation is more expensive than central and string inverter installation as it requires more components such as interconnecting cables, sealing caps and terminators. In addition, monitoring systems also add to the overall installation cost of the micro inverter technology. However, this cost can be accepted in some cases when installation challenges are present and partial or full shading can deteriorate the overall performance of solar system.

Japan Is Expected To Be The Most Lucrative Market For Micro Inverters

In Asia-Pacific, micro inverter market is expected to have the fastest growth in Japan during the forecast period. On a global scale, Japan is not the biggest market but it’s in the top three, with strong governmental support, and its huge solar energy industry. However, in spite of representing a major residential market potential, it has been facing limited micro inverter shipments. It is expected that the penetration rate of micro inverters into Japanese market would increase drastically to 7% of total installations by 2018. Another factor for catalyzing the market in Japan could be micro inverter suppliers obtaining Japan Electrical Safety & Environment Technology Laboratories (JET) certification.

Competitive Landscape

The report provides a comprehensive analysis of major market players such as Enphase Energy Inc., ABB Group, SunPower Corporation, SMA Solar Technology AG, Delta Energy Systems GmbH, SolarEdge Technologies, Inc., ReneSola, Siemens AG, P&P Energy Technology Co., Ltd. and Involar. Further, the prominent strategies adopted by the leading players are analyzed to highlight the top winning strategies.

Top Winning Strategies

Presently, growth strategies such as acquisition, product launch, partnership, agreement and expansion are adopted by key market players. Micro inverter market is largely driven by product launch and acquisition. Companies such as Enphase Energy Inc., and ABB Group have acquired local inverter manufacturer companies to enhance their global outreach and increase their market share.

Key Benefits of Micro Inverter Market:

  • The study provides an in-depth analysis of the world micro inverter market to elucidate the prominent investment pockets in the market.
  • Current and future trends are outlined to determine the overall market scenario and to single out profitable trends to gain a stronger foothold in the market.
  • The report provides information regarding key drivers, restraints, and opportunities with impact analysis
  • Geographically, the market is analyzed based on four regions namely, North America, Europe, Asia-Pacific, and LAMEA
  • Analysis of value chain is conducted for better understanding of the role of intermediaries

Micro Inverter Market Segmentation:

By Type

  • Single-phase
  • Three-phase

By Connection

  • Stand Alone
  • Grid Connected

By End-User

  • Residential
  • Commercial

By Geography

  • North America - U.S., Mexico, Canada
  • Europe- UK,Germany, France, Rest of Europe
  • Asia-Pacific- India, China, Japan, Australia, Rest of Asia Pacific
  • LAMEA- Latin America, Middle East, Africa

Credits: Micro Inverter Market- Global Opportunity Analysis and Industry Forecast, 2014 - 2022, Allied Market Research

Effective management of a solar PV plant could be divided into 3 distinctive steps i.e. Engineering Procurement & Construction, Commissioning and Operations & Management. EPC deals with the pre-construction and construction activities of the PV power plant. Commissioning is the process that starts along with the construction of plants and proceeds through PV system acceptance. It also deals with the necessary documentation processes required for system acceptance.

Read more: PV System Commissioning – Perfection Is The Key

You’re a developer or engineering firm who is working on a large solar project and you’re deciding which solar resource dataset to use. You know you need to use a high-quality resource dataset to get the project across the line. How do you make a good choice on the resource data, which will be the backbone of your project?

Three key questions will help you make a wise choice:

  • Are hourly data available, or only monthly means?
  • How old is the dataset?
  • What is the dataset’suncertainty?

If you can answer these questions about the resource data used in your projects, then you’re already on the path to making better choices then many. Based on these answers and how much risk you are willing to live with, you can make an informed tradeoff between schedule, accuracy, and cost. This article focuses on the first question.

Long-term monthly mean meteorological data is sometimes used as a basis for predicting the yield of photovoltaic systems, since such data is widely available at little or no cost. Also, software tools like PVsyst and Plant Predict allow users to input monthly mean data, and then generate from this a year of synthetic hourly data that can be used as an input to photovoltaic yield modeling.

At very early stages of project design, this can be a quick way to get indicative numbers. The problem with this approach isthat – depending on the location and type of project - it can add too much resource risk, even in the early prospecting stages of project development. This is especially true for tracking PV plants and locations - such as India - with high resource variability.

Study Conditions

In a recent Vaisala study, PVsyst was used to compare the P50 energy results derived from using multiple years of Vaisala’s 3TIER Services hourly meteorological data (Vaisala, 2017) to those derived using two types of synthetic years based on the same data: a PVsyst synthetic year (hereafter: PVsyst-SYN) and a Typical Meteorological Year (TMY). The same underlying resource dataset was used, and the only difference in the projects was the temporal resolution.

Modeling was performed for ten Megawatt-scale photovoltaic projects in six different countries including India. For each project, simulations were run for two configurations: an equator-facing fixed tilt orientation and one with horizontal single-axis East-West trackers with backtracking.

PVsyst was used to run all simulations, with only the meteorological data varying between the three approaches.

  • Full timeseries approach: The hourly timeseries for the ten project locations covered roughly 20 years of individual simulations run separately in PVsyst to derive the corresponding annual yield. The full timeseries yield estimate (P50) was then taken to be the median of the individual annual yields.
  • PVsyst-SYN approach: In this approach, the long-term monthly means of global horizontal irradiance (GHI) are first used to stochastically derive synthetic hourly GHI data as described by Meteotest in 2017.
  • TMY approach: Vaisala creates TMY datasets using an empirical approach that selects four-day samples from the full timeseries to create a “typical year” of data with 8760 hours, while conserving the monthly and annual mean of GHI. The process is iterated until the annual means of all solar variables in the TMY dataset match the means of the full timeseries to within 1% or less.

Finally, the simulated yields from the PVsyst-SYN and TMY approaches were compared to the P50 yields from the full timeseries approach for each of the ten PV systems, for fixed and tracking configurations.

Study Results
For all project types and locations, we saw significantly more deviation from the PVsyst-SYN approach. Notably, it was difficult to predict whether the bias was high or low – this means it cannot be treated as a consistent known bias.

The deviation between the energy yields from the long-term hourly timeseries and the TMY files relates to how well the TMY averages match the long-term dataset. If the TMY was not well matched for GHI we would expect these energy yield biases to be larger. Vaisala’s TMY creation process is designed to minimize these deviations for that very reason.

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For tracking plants, the average difference in the hourly vs monthly average approach was about 2%, but the maximum difference was over 7%!For tracking plants, the monthly averagePVsyst-SYN approach has too much uncertainty to use even in the early prospecting stages of project development. A 7% difference in energy from predicted to actual production is more than enough to make or a break a project; thus, we recommend hourly data at all project phases if you’re developing tracking plants.

The news is better for fixed PV. The energy differences between the models was less than 1%, and the maximum difference was around 2%. That is a deviation that’s generally acceptable at early project stages. In later development stages, you should incorporating hourly timeseries data to reduce the uncertainty, especially if you are in a competitive financing situation.

A Proactive Approach

So as a proactive project developer or engineer how can you make sure you are making the best resource choices for your projects? Vaisala and other providers cover most geographies with satellite-based datasets at and hourly or even sub-hourly resolution at a reasonable cost.

If you have received a report from an engineering firm and are wondering what resource methodology they have used in order to understand the accuracy of the estimates, you should look past the name of the data provider. Many prominent engineering firms use the low-cost monthly means but not the hourly time series. Any time the words “synthetic” or “generated” are used in regards to the resource data, that is an indication that hourly values are derived and not native to the resource timeseries.

Given the increase in availability and the decrease in costs for hourly timeseries we would encourage others in the industry to drop the synthetic data creation practice so we can all build projects we will be proud of.

Authors: Gwendalyn Bender, Sophie Pelland Ph.D,Louise Leahy Ph.D. and Rajni Umakanthan
Vaisala, Seattle (U.S.A.) and Bangalore (India)

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