What is the percentage increase in Grid revenue in the third quarter of fiscal year 2021 compared to the year-ago period, and what percentage of AMSC's total revenue did Grid revenue account for in the third quarter of fiscal year 2021
rld gears up for decarbonization to slow down climate change and create a path for a more sustainable world, so does the increased demand for renewable energy, semiconductors, and key materials for the new green economy, such as metals, mining, and chemicals. Our acquisition of Neeltran and NEPSI have allowed us to expand our business into the materials market. The materials market is fundamental to a sustainable energy shift.
If you're interested in reading some more about how materials are center stage to the energy transition, there was a 2022 McKinsey publication titled, the raw-materials challenge, how the metals and mining sector will be at the core of enabling the energy transition. If we look at this calendar year 2022, approximately 90 gigawatts of Wind capacity is projected to be added globally. The solar photovoltaic sector is projecting an annual global capacity, addition of over 175 gigawatts, and the worldwide semiconductor market is expected to grow and exceed $600 billion in annual sales, annual capital investments has trended at over $100 billion for the past few years. This transition to a low carbon economy raises demand for critical materials, semiconductors as well as spending on plant and equipment in the metals, mining, and chemical industries.
We are executing on our growth through Grid strategy, our Grid segment revenue for the third quarter of fiscal year 2021 broke a company record for the fourth consecutive quarter, we are growing. Grid revenue grew by nearly 50% versus the year-ago period and accounted for over 90% of AMSC's total revenue. This is a testament to our team's execution, particularly during these challenging times. Since the start of this fiscal year, our bookings momentum in the Grid business have been very strong, extending our Grid visibility into fiscal 2022.
In the third quarter of fiscal 2021, our Grid business was primarily driven by strong new energy power system shipments. We've already integrated NEPSI nicely into the business, and we're working to do the same with Neeltran. We are getting leverage across the product line, selling into a number of industrial markets, including mining and metals as well as chemicals. Our core markets for the new energy systems have expanded from two main ones, renewables and semiconductor to now three key markets: renewable semiconductor and materials, such as metals, mining, and chemicals.
Our largest customer for the third quarter of fiscal 2021 was in the semiconductor industry. We see the emergence of additional demand in new energy power systems for the semiconductor and materials markets coming in the subsequent quarters. As you can see from our revenue guidance for the fourth quarter of fiscal 2021, we are anticipating continued strength in our business. We see increasing demand in semiconductors for the fourth quarter of fiscal 2021.
During our fourth-quarter revenue guidance -- pardon me, driving our fourth-quarter revenue guidance, as expected, new energy power system shipments to be very robust. In fiscal 2021, we continue to expect year-over-year revenue growth again in our Grid and our overall business. In the longer term, we continue to see a significant rise in quotations for new energy power systems for renewable semiconductors as well as materials and general industrial markets. Let's talk about the drivers of Grid.
Grid is driving revenue growth for the company. Renewable semiconductors and materials are driving our new energy power system solutions. Our new energy power systems include our dynamic power correction platforms as well as our static power correction line of capacitor banks, our monic filter systems, rectifiers, and transformers. We're growing and diversifying revenues by geography and by market.
We are presenting more content to customers as we leverage the strong combination of our new energy power system solutions. This quarter, we supported renewable projects, both for wind developers and utility solar in the United States, Canada, Northern Ireland, and Spain. Over the last few years, we've seen the eco
rld gears up for decarbonization to slow down climate change and create a path for a more sustainable world, so does the increased demand for renewable energy, semiconductors, and key materials for the new green economy, such as metals, mining, and chemicals. Our acquisition of Neeltran and NEPSI have allowed us to expand our business into the materials market. The materials market is fundamental to a sustainable energy shift.
If you're interested in reading some more about how materials are center stage to the energy transition, there was a 2022 McKinsey publication titled, the raw-materials challenge, how the metals and mining sector will be at the core of enabling the energy transition. If we look at this calendar year 2022, approximately 90 gigawatts of Wind capacity is projected to be added globally. The solar photovoltaic sector is projecting an annual global capacity, addition of over 175 gigawatts, and the worldwide semiconductor market is expected to grow and exceed $600 billion in annual sales, annual capital investments has trended at over $100 billion for the past few years. This transition to a low carbon economy raises demand for critical materials, semiconductors as well as spending on plant and equipment in the metals, mining, and chemical industries.
We are executing on our growth through Grid strategy, our Grid segment revenue for the third quarter of fiscal year 2021 broke a company record for the fourth consecutive quarter, we are growing. Grid revenue grew by nearly 50% versus the year-ago period and accounted for over 90% of AMSC's total revenue. This is a testament to our team's execution, particularly during these challenging times. Since the start of this fiscal year, our bookings momentum in the Grid business have been very strong, extending our Grid visibility into fiscal 2022.
In the third quarter of fiscal 2021, our Grid business was primarily driven by strong new energy power system shipments. We've already integrated NEPSI nicely into the business, and we're working to do the same with Neeltran. We are getting leverage across the product line, selling into a number of industrial markets, including mining and metals as well as chemicals. Our core markets for the new energy systems have expanded from two main ones, renewables and semiconductor to now three key markets: renewable semiconductor and materials, such as metals, mining, and chemicals.
 Our largest customer for the third quarter of fiscal 2021 was in the semiconductor industry. We see the emergence of additional demand in new energy power systems for the semiconductor and materials markets coming in the subsequent quarters. As you can see from our revenue guidance for the fourth quarter of fiscal 2021, we are anticipating continued strength in our business. We see increasing demand in semiconductors for the fourth quarter of fiscal 2021.
During our fourth-quarter revenue guidance -- pardon me, driving our fourth-quarter revenue guidance, as expected, new energy power system shipments to be very robust. In fiscal 2021, we continue to expect year-over-year revenue growth again in our Grid and our overall business. In the longer term, we continue to see a significant rise in quotations for new energy power systems for renewable semiconductors as well as materials and general industrial markets. Let's talk about the drivers of Grid.
Grid is driving revenue growth for the company. Renewable semiconductors and materials are driving our new energy power system solutions. Our new energy power systems include our dynamic power correction platforms as well as our static power correction line of capacitor banks, our monic filter systems, rectifiers, and transformers. We're growing and diversifying revenues by geography and by market.
We are presenting more content to customers as we leverage the strong combination of our new energy power system solutions. This quarter, we supported renewable projects, both for wind developers and utility solar in the United States, Canada, Northern Ireland, and Spain. Over the last few years, we've seen the eco