Let's look a little bit closer at the U.S. energy market and see where that lies. Right now, the United States electricity use is over 4 million gigawatt hours of energy. The majority of that coming from coal and other fossil sources. If you look at just the renewable energy market however, we see something a little bit more interesting. Hydroelectric remains rather steady it hasn't grown very much because the United States is not adding hydroelectric power stations. But we do see large increases in wind up to 225,000 gigawatt hours of production and solar at near 50,000 gigawatt hours. You might wonder why solar appears to show up so late chronologically and so small. Well while broad-based solar has been around for over a decade, a majority of it has been in distributed residential and some commercial installations. Very little of it until now has been on the utility scale and that's the only place it can be measured accurately. Some estimates place the total US photovoltaic production closer to 60,000 gigawatt hours or 600 terawatt hours. Expect to see large-scale solar photovoltaic grow exponentially in the US in the beginning and we're now at the beginning of that growth curve but, why should we begin to grow solar at all? Well a recent report from the National Renewable Energy Lab shows that the U.S. can supply 80% of its electricity from renewables alone by 2050. As long as there are some improvements that are made to the grid, and what this means is that we have more than enough renewable resources to supply the U.S. electrical energy needs. Could the U.S. produce 100% of its electricity through renewables? Yes, but there's a limit of having enough electricity to meet peak load demand. Even when renewables might not be available we still need to be able to supply the demand. So this 80% number includes meeting that hourly electricity demand in every region of the country day and night all year long. We also need to increase the flexibility of the electrical system, a better balance of distribution and storage so electricity can be used from the most efficient stores or stored efficiently for later use. To meet this mix of demands, we can look at also balancing electrical devices like improved batteries and capacitors as well as improved energy efficiency and smart grids. Conventional sources like fossil are still need to provide the flexibility and generation and be responsive to those in renewable output. We know that there's a large potential for even more solar photovoltaic in the US. As an example, we currently use 4 million gigawatt hours of electrical energy and according to that enrol report, 80% of that which could be renewable comes out to be 3.2 million gigawatt hours. So that's how much renewable we could potentially have. Current total renewables add up to only 640,000 gigawatt hours of electrical energy leaving 2.56 million gigawatt hours available for renewable development. A large portion of that could come from solar photovoltaics. This will likely be developed at the utility scale and some smaller portions at the distributed scale for residential and commercial. So, where do renewables fit into the U.S. energy strategy? Well the US has both an abundance and diversity of renewables. One of the major players being photovoltaics. Capital investment costs can be a major limit to growth but growth can't happen without increased employment which is an economic gain. Solar has limited operation and maintenance costs with zero fuel costs. So there's a point at which the system can pay for itself and that doesn't happen with conventional power generation plants. Photovoltaics and all renewables need to work together with conventional fossil technologies to be effective. If we look at the historical, current and projected installations for electrical energy, we say that historically a large portion of that capacity has been in oil and gas with growing wind and then growing solar. Coal is slowly decreasing as the natural gas increases but nuclear is starting to decrease as you project forward as these plants begin to be decommissioned with no new plants being developed. Conventional plants also become decommissioned, but are projected to be built again rebuilt. We're adding more solar but growth in wind slows due to limits and usable land as well as expiring tax incentives for constructing, installing, operating those larger turbines. Solar becomes the largest addition as we go out towards 2040. So, where can we install these renewables in the United States? Well, large utility-scale solar farms can be used for centralized generation as one point but there's also the availability for commercial and industrial rooftop installations which can be used for decentralized production, mean that many installations that are a little bit smaller and may not be controlled by utility. Residential solar still has a place but it carries a higher balance of system cost. This means that all the system integration including wiring and inverters needs to be installed and each individual home whereas it only needs to be done once for a large rooftop commercial building. Most commercial rooftops are flat so installations can be oriented in any direction and tilt. Many residential homes however have limited solar gain due to roof angle and direction. Residential photovoltaics will still have its place for individual users and will certainly be the go-to for people living off grid and have their own energy storage technology. Let's look at electrical generation by sector. Utility-scale photovoltaic generation is now growing at a faster rate and as a higher generation than distributed electrical and it's projected to stay higher going forward. This means that powerplants are being operated by utility companies who are owning and managing the system. If we look at local generation, a study by the National Renewable Energy Lab looked at how each state's electricity need compares to its availability of rooftop solar. We see a few states jump out California, Maine and Vermont. These states have the highest potential for meeting electrical needs with rooftop solar based upon their current state's electricity use in this case above 55% of their needs. California makes sense since there's a lot of commercial buildings as well as a large amount of sunlight. Maine and Vermont on the other hand have relatively low amounts of sunlight, but there are enough buildings and low enough of populations and electrical needs that they can support up to or even a little bit more than 55% of their electrical needs with just commercial rooftop solar. Other states in United States have less available sunlight and their land use may vary from farmland to industrial and urban. There are many studies like this coming out these days that really show the available potential for solar not just whether or not you can afford it looking at a larger national or global scale. So by now you should be able to define the current market share of photovoltaics in the international and national marketplace. You should be able to identify which countries are installing photovoltaics and explain why they may or may not be doing that. You should also be able to define the current outlook for photovoltaic installation including sectors, and pricing and assess what types of photovoltaic investments are available referencing the United States as a model. In upcoming lessons, we'll look at different types of photovoltaic technology and how photovoltaics can be integrated into rooftop as well as small scale applications.
