How to Choose the Right Solar Inverter for Your Solar Power System (Part 1)

Photo by Alex Csiki from Pixabay

The solar inverter converts direct current (DC) electricity generated by your solar panels into usable alternating current (AC) electricity used by household appliances. If you have decided to go solar and install solar power system for your home, you have to do some research and have an initial knowledge about the solar inverter. 

The solar inverter consists of complex power electronics and software and it is crucial to the performance of your solar power system. When you choose your solar panels for your home it is important also to consider buying the right solar inverter for your solar power system. In this post, I’ll give you some basic information about solar inverters, their types, how they work, the best brands, and how to size an inverter to be right for your solar power system.

There are three groups of solar inverters: grid-tie, off-grid, and hybrid. There are three main types for grid-tied solar power systems: string inverter, microinverter, and string inverter + power optimizer. 

String inverters are central inverters and they are the most commonly used inverters for home solar power systems. When few solar panels of the same output voltage and power are wired together in series we have what is known as a "string”. All of the energy the panels produce is sent to a single inverter that is typically located on the side of your house, garage or utility room. String inverters are easy to install and maintain, and they also have the lowest price. 

This type of inverter is suitable when your panels are not facing multiple angles and have no shading issues. The disadvantage here is that if one panel is in shade and suffers reduced output, every panel in the string drops to that reduced output. 

Microinverters are small devices also known as module-level power electronics (MLPEs) that are attached directly to each solar panel, usually on the back. Thus they need to be designed to be resistant to humidity and heat. Microinverters convert DC power to AC right at the panel, providing a better performance of the solar array thus better performance of the whole solar power system. Just make sure the microinverter capacity matches that of the solar panel.

Microinverters allow you to monitor individual panel performance, giving you a more clear view of efficiency. Also, if something goes wrong with a particular solar panel, you can fix it easily. Because of all of this, and the need for multiple inverters, microinverters are the higher cost option. Besides that, another disadvantage is that they are located on the roof, so their maintenance is complicated. 

Power optimizers are small devices as well that is located on the roof alongside or integrated with each solar panel, allowing for more accurate performance monitoring. But unlike microinverters, they don’t convert power from DC to AC directly. Instead, they simply “optimize” the DC electricity before it is sent to a string inverter for conversion into AC. 

Power optimizers, similar to microinverters, make the solar energy system more efficient, but you can buy them at a more affordable price. And like microinverters, maintenance and repair cost power optimizers are high with power optimizers given their rooftop location. Microinverters and power optimizers typically come with a 20 to 25-year warranty while standard inverters typically have 12 to 15-year warranties.

Microinverters and power optimizers (together referred to as module-level power) are gaining popularity in residential solar markets. It’s always nice to have options, and string inverters and MLPEs each have pros and cons. 

The three best string solar inverters for 2020 are: Fronius (Primo and Galvo), SolarEdge (SE and HD wave), SMA (Sunny boy series). Enphase is a leading manufacturer of microinverters.

The inverter sizing refers to choosing the right size of solar inverter for your solar power system. As a general rule of thumb, you’ll need an inverter that matches the watts of your solar panel installation, For example, if you have a 3kW solar panel system, then you would install a 3kW inverter. In the case of microinverters, the size of the inverters should correspond to the energy output of each solar panel they’re connected to versus the entire system. 

If you plan to go off-grid, to choose the right inverter for your solar power system you must calculate the load your inverter can handle. You should know that inverters are rated in continuous/running watts and surge/peak watts. It’s important to consider both the continuous load and surge load when it comes to inverters (inverters have two capacity values printed on the manufacturer’s label: continuous watts and surge watts).

Surge watts are the amount of power the inverter can support for a very short time, usually no longer than a second when the appliance starts up. Appliances with motors require about 1.5 to 2 times the running wattage before the motor will start. Appliances and tools with induction motors such as refrigerators, freezers, air conditioners, microwave ovens, and pumps, need a much higher power level at startup. They may require a start up surge of 3 to 7 times the continuous rating.

Find out the appliance’s description and read the specific wattage requirements. If the wattage of the appliance is not listed on the specification, you may calculate the standard watts each of your appliances requires using the formula:

Amps x Volts = Required Watts

For example, if you have a microwave 7.5 amps x 120 (using a 120-volt ac) = 900 watts. It means that the inverter has to handle both the 900 running watts and the 2,700 watts surge requirements of your microwave. 

If the running wattage of your fridge is indicated as 600 watts, the surge wattage will be about 1,800 watts, but this surge is needed for only a fraction of a second. To run this refrigerator, you will need an inverter that can handle 600 running wattage and a surge of about 1,800 watts for a split second. At discount stores or home centers, you can find a typical inverter that provides 1,500 watts of continuous power and 3,000 watts of surge power. https://homeguides.sfgate.com/run-refrigerator-inverter-49672.html

For your inverter to be right for your system, its surge watts rating must be approximately equal to (or greater than) the potential surge watts of each appliance. You can find this out by looking at the label on the back of all of the appliances.

If you want to use multiple house appliances at the same time use the appliances running and surge wattage to determine which devices you can run simultaneously. Just add up all the continuous watt ratings of all the appliances that may be running simultaneously. The sum of continuous watts you get will determine if you're inverter can handle it. Always keep the running load under the maximum limit of your inverter.

With an inverter, with a continuous rating of approximately 1500 watts and with a surge rating of approximately 3000 watts, you can run a wide range of household appliances simultaneously by managing the running load. You can run LED lights, TV, stereo, laptop, fans, fridge, and a microwave (depending on the wattage) at the same time. Just put a current display meter to check the running load before you switch on a new appliance.

It is also recommended to provide a safety room of 10% - 20% watts (more than your largest load) when sizing up an inverter.

Remember: always seek professional help for the installation of your solar power system because of the specific power needs and circumstances of every home.

Next post: How to Choose the Right Solar Inverter for Your Solar Power System (Part 2)

Sources: unboundsolar.com, altenergy.org, homeguides.sfgate.com, batteryspace.com 

Why Now is the Right Time to Switch to the Solar Powered Lifestyle

(Guest post by Rich Feola)

Have you found yourself intrigued by the thought of switching your home’s energy power to solar? It is sure to have crossed every homeowner’s mind as solar energy growth exploded during the past decade. In the United States, it remains one of the top two renewable energy sources with no sign of slowing down. 

The exponential growth in the solar industry is proof that millions of homeowners have discovered the benefits of solar energy. Yet others are in the same boat as you and hesitant to make that switch. 

However, when you realize the shift away from traditional power sources means you are not only bringing down your electric costs but also decreasing your effect on nature’s domain, the decision to go solar becomes an easy one. Let’s review just a few benefits you will see when you invest in solar solutions for your home.

Lower those soaring utility costs.

I am from Las Vegas where the sun is always shining and air conditioning is a must. You wouldn’t believe the astonishing advantages of solar energy. Unfortunately, many homeowners are oblivious to just how beneficial solar power could be to their life. 

One of the most clear-cut benefits of solar panels is the ability to hedge utility prices. According to the Energy Information Administration, the average United States resident used roughly 10,649 kilowatt hours in 2019 at a cost of around $1,950 dollars for the year. 

You will begin experiencing savings on those high utility costs the minute your solar panels are installed. Holding off any longer means you are stuck paying those extreme electric costs each month. If you pull the plug now, that is an extra $1,950 you could have in your pocket this time next year.

But the most important factor is how electricity rates rise each year by an average of 6%. This means that your energy bill will cost you double in ten years’ time! If you had invested in solar ten years ago, your own personal power plant would have saved you tens of thousands and you wouldn’t have to worry about the rising cost of electricity on the grid. In fact, many states and local utilities even pay you a credit for the extra energy you produce and transfer to the grid through solar energy.

It should be noted there are a number of variables that will determine the total financial returns you can expect from solar during its lifetime, but with a high quality photovoltaic solar system in place, whatever those costs are will be lowered significantly as your home uses an environmentally friendly way to power itself each day. 

If utility prices continue to rise as expected, those savings will do nothing but surge as time goes on. Going solar is the only way to help protect against these unpredictable increases.

Take advantage of incentives.

Today’s market is experiencing a progressive government attitude towards solar energy, which has resulted in attractive solar power tax rebates at both the federal and state levels. 

In addition to significant tax credits and rebates in place to encourage homeowners to go solar, the installation cost of panels has significantly dropped. As the government continues to incentivize the continued growth of the solar industry, it is important to take advantage while you still can. 

In other good news for today’s shoppers, it costs roughly 70 percent less than it did a decade ago to install a residential solar energy system. Combined with the rebates, your total costs could be potentially cut in half making it the perfect time to use photovoltaic technology. 

There also are an abundance of financing options available if you don’t have the funds for an upfront purchase. If you don’t have the money on-hand, there is most likely a financing option suited just for you, which means you don’t have to outlay any cash upfront for the switch to solar energy.

Reduce your carbon footprint.

Solar energy is clean energy, and I don’t think it is reaching to assume we all want that. Solar systems use pure energy from our sun, helping to combat gas emissions and reduce our collective dependence on fossil fuel. Solar panels absorb D/C current from the sun and convert it to A/C electricity through an inverter which is included in your installation.

Did you know solar can reduce your home’s carbon footprint by more than 3,000 pounds annually? That equals 15,000 pounds of CO2 each and every year. That’s pretty amazing.

Solar panels protect your home, too.

While solar panels are busy helping out the environment, they also protect your home. They start at the very top of your house by extending the life of your roof as it shields it from harmful elements like snow, ice, rain and debris. Likewise, it absorbs the sun and keeps it from beating down on the roof directly. 

Homebuyers also know they have struck gold when they come across a home for sale with solar panels, which increases your value. This provides you a large return on your investment if you ever decide to sell your home. Many local real estate markets see an increase of a home’s value by as much as $26,000 if a solar system is intalled.

As awareness has increased on the importance of reducing our carbon footprint on the environment and financing options have become more readily available, the solar market continues to increase, but is it the right choice for your family? 

Only you can answer that question, but doing research on how solar energy works and the science behind it will help you feel confident in your investment. There is an abundance of information on the long-term benefits of solar on platforms such as YouTube for homeowners ready to go solar. 

It also is important to find the right company. I know from helping solar companies in 39 states that finding the right one for you will pay off in great rewards both environmentally and financially.

Rich Feola is the Founder of the Solar Exclusive, an 8-figure advertising company that generates unique, qualified leads and appointments for solar companies. Solar Exclusive works with solar companies in over 39 states. Rich’s work has been featured in Digital Journal, Yahoo Finance, NBC and Fox among other publications. Want to skyrocket the success of your solar business with top-notch leads? Visit this link to find out more: https://solarexclusive.com/. 

Solar Power Stations in Space - Science Fiction or a Future Reality?

                  Image credit: solarspacetechnologies.com.au

Solar power stations in space or the so-called space-based solar power (SBSP) concept means capturing solar power in outer space and distributing it to Earth. In 1941, science fiction writer Isaac Asimov first wrote about space-based solar power stations in the short story “Reason”. Later, American aerospace engineer Peter Glaser wrote the first technical article on the concept – Power From The Sun: Its Future, and it was published in the journal “Science” (1968). 

Generating solar power in space has many advantages. As we know, the Earth’s atmosphere absorbs and reflects some of the Sun’s light. A considerable fraction of incoming solar energy (55–60%) is lost on its way through the Earth's atmosphere. So, solar cells above the atmosphere will receive more sunlight and produce more power as the Sun always shines in space. An orbital solar power station will be an inexhaustible source of clean energy.

One of the major challenges will be getting the power transmitted back to Earth. The idea is to convert electricity from the solar cells into microwaves or lasers and transfer them down to an antenna on the Earth’s surface. The antenna would then convert the waves back into electricity. 

Recently, the UK government reveals an ambitious new plan for a space-based solar power station that could collect solar energy and beam it down to the UK. According to it, giant solar power satellites in orbit could harvest solar power and transmitting it as high-frequency radio waves to ground-based receivers connected to the electrical power grid.

The big question is how to launch such large structures into space. One possible solution is to develop many smaller satellites that could easily connect in space to form a single solar power station. In 2017, researchers at the California Institute of Technology created a prototype for a modular power station, using thousands of ultralight solar cell tiles. 

Another related news is that researchers at the University of Liverpool are working on a project to design and manufacture low-cost, ‘origami’ deployable structures consisting of thin-film photovoltaic cells incorporated onto a sail. A swarm of photovoltaic solar sails could be configured in-space to provide large-scale and versatile Space Solar Power (SSP) energy generation. 

Also, the Australian-based company Solar Space Technologies, working in partnership with US-based Mankins Space Technologies, Inc. (MSTI), is planning to develop, manufacture, deploy and operate a solar power satellite (called SPS - ALPHA) into geostationary orbit to supply baseload energy to the Australian grid by 2027. SPS-ALPHA was first-examined under a NASA Innovative Advanced Concepts (NIAC) project (2011-2012). The newly proposed solar power satellite has been re-designed to be made up of many repeatable building blocks that can be assembled in space instead of manufacturing one, expensive, single large system. This approach makes the cost of building the platform much lower than if traditional satellite building approaches were. SPS- ALPHA platforms are sized to deliver 2.1 GW each at a levelized cost of electricity (LCOE) of 5¢ per kilowatt-hour ($, US) over a 30-year nominal lifetime. 

Researches in Japan led by the Japan Aerospace Exploration Agency have been working on a project to build a space solar power station for a long time. They have already developed designs and demonstrated solar power satellite of sandwich type.

In my post “Solar energy interesting facts” I have mentioned that China has designed a space solar power system, which they aim to have operational by 2050. This system should be capable of supplying 2GW of power into Earth’s grid at peak performance. 

It seems that scientists are already much closer to construct solar power stations in space. Currently, we are reliant on materials from Earth to build power stations but maybe one day we can use resources from space for manufacturing, such as materials found on the Moon.

The concept for constructing a space solar power station has fantastical origins but it is now being researched by several nations and many scientists around the world are working on it. Thanks to rapid advances in lightweight solar cell tiles and wireless power transmission technology it may become a future reality sooner than we could imagine.

Sources: wikipedia.org, bbc.com, imeche.org, solarspacetechnologies.com.au

Solar Panels for Your Home - How to Choose The Best

Solar panels are the most essential components of the solar power system. To choose the best solar panels (also called solar modules) is the most important thing for every homeowner who has decided to go solar. In this post, you will find some directions on how to choose the best solar panels for your home.

First of all, you have to choose the type and the brand of solar panels. There are four key technical specifications you have to consider: panel efficiency, temperature coefficient, the materials warranty, and the performance warranty. 

There are two main types to choose from when it comes to solar photovoltaic panels: monocrystalline solar panels and polycrystalline solar panels. Monocrystalline solar panels (black color) are more efficient because they are manufacture from the purest silicone. Each solar cell here is cut from a single, continuous piece of silicon crystal. Monocrystalline solar panels are also more expensive. They cost between $300-700 USD per panel. Monocrystalline solar panels produce the most waste when they're manufactured. 

Polycrystalline solar panels (dark blue color) are considered to be less efficient and this is due to the method of production. Manufacturers melt multiple silicon fragments together to produce the wafers for this type of solar panel. They are the most commonly purchased solar panels, simply because they are the most affordable option. Polycrystalline solar panels usually cost between $200-500 USD per panel. They are an environmentally-friendly option because they utilize all of the silicon material they are manufacture. 

There is also another type of solar panel - thin-film solar panels. Thin-film panels are cost-efficient and most sustainable to produce and they are least expensive. However, they are also the least efficient (commercially available generally have efficiency in the 10–13% range) and degrade faster. Thin-film panels need more space, even twice as much room as a mono- or polycrystalline solar panel with the same energy output. These types of solar panels usually cost between $175-300 USD per panel. It is rare to see thin-film panels on the roof. Thin-film photovoltaic cells are used for large and small PV application such as a calculator, solar-powered charger for smartphones, solar-powered purse, solar-powered backpack, curved surfaces on buildings and cars, even on clothing to charge small electronic devices. They are also used to power traffic and street lights, and for commercial and industrial projects (solar farms).

You may have heard about bifacial solar panels, which can absorb light on both the front and the back of the panel. They have higher rates of power output and higher efficiency than traditional solar panels. But these types of solar panels aren’t typically used for residential solar installations. They are more expensive and they are more suitable for large ground-mounted projects.

The second thing to consider is the brand. Some of the best quality and most reliable panel manufacturers are LG, SunPower, REC, Solaria, Panasonic, and QCells. You can see the list of the best manufacture at Top 10 Solar Panels - Latest Technology 2020 — Clean Energy Reviews. Another review of solar panels you can find at Best Solar Panels in 2020 [Complete List] | EnergySage. The best brands of solar panels have the best solar panel efficiency and temperature coefficient.

Solar panel efficiency means the percentage of sunlight that hits the surface of solar panels converted into electricity for your home. Currently, most solar panels have an efficiency between 15% to 22%. The average efficiency of solar panels is between the 17% to 19% efficiency range. The higher the efficiency rating, the more sunlight your solar system can turn into electricity to power your home. SunPower’s A-Series Residential Solar Panels are 22.8% efficient at their maximum and they are the best solar panels available on the market today. Keep in mind, however, that efficiency also depends on factors like placement, orientation, shading, time of year, dust and dirt, weather conditions, etc. If you have enough roof space you may choose less efficient and not so expensive solar panels.

The temperature coefficient tells you how well your solar panels will work on hot summer days. Solar panels operate most efficiently when they are kept cool (ideally around 25° C or 77° F panel’s temperature). The temperature coefficient usually ranges between -0.3% and -0.5 %/°C. Solar panels are tested according to international technical standards at 25°C, and that is why this is used as the reference point. For every degree above that temperature, your solar panel’s electricity production will decrease by the temperature coefficient. If the temperature coefficient is -0,3% and your solar panel’s temperature increases by one degree Celsius (from 25° C to 26° C), its electricity production will fall by 0.3%. If the temperature increases ten degrees Celsius to 35° C (or 95° F), the panel will produce 3% less electricity. So, a lower temperature coefficient is better. The temperature of the panels depends on your location, roof material (some absorb more heat than others), and the installation of the panels (if they are angled or mounted flat on the roof). In many instances, a solar panel’s surface can get as hot as 50° - 65°C. If the installation is a typical rack-type, you will have a gap of greater than 150mm between the roof surface and the panels. It will allow airflow to have a cooling effect on the panels.

Thin-film solar panels have a lower temperature coefficient than traditional monocrystalline or polycrystalline panels. Their temperature coefficients are closer to -0.2% / °C.

Another important thing is a solar panel’s materials warranty which protects against failure due to manufacturing defects. Solar PV manufacturers provide a minimum 10 - 12 years product warranty but many solar panel manufacturers offer 15, 20, and even 25-year product warranties. This means the manufacturer must either replace or give you a refund for solar panels that fail within the product warranty period.

The performance warranty is different from the solar panel’s materials warranty. The performance warranty is called also the 'power output warranty' and it ensures that the solar panel still produces a minimum power output after a specific amount of time. The common industry standard is 80-83% power output after 25 years. Some top manufacturers such as SunPower and LG guarantee 88-92% power output on most modules after 25 years of use.

Besides the top solar panel brands, many manufacturers are offering a wide range of quality, affordable panels. The most well known of these manufacturers are Jinko Solar, Canadian Solar, and Trina Solar. See other brands at Choosing a quality Solar Panel - Reliability, warranty and efficiency — Clean Energy Reviews

And finally, to determine the number of solar panels you need to do some calculations regarding current energy consumption in your home, and how it will change in the future.

When you choose your solar panels it is important to know, that a solar power system is a complex system of several components and the overall performance depends not only on solar panels. All components should be compatible with each other (solar panels, solar inverter, battery storage, charge controller). Also, the homeowners should carefully consider their unique house and household circumstances and maybe even seek the advice of an expert before choosing the right solar panels for their home. 

Sources: wikihow.com, cleanenergyreviews.info, energysage.come & Internet

Read also: Basic Things to Consider Before Buying a Solar Electric System
                   Applications of Photovoltaic PV Power Today

Solar Energy Interesting Facts (30 Solar Facts)

Image by PublicDomainPictures from Pixabay                                         

In this post, I’m going to represent some interesting facts about solar energy and how it is being used.

1. Solar energy is created through nuclear fusion reaction at the Sun’s core. Hydrogen atoms fuse to create helium.

2. The distance between the Sun and the Earth is about 150 million km (93 million miles). The average time it takes for the Sun’s rays to reach the Earth is 8 minutes and 20 seconds.

3. About 29 percent of the solar energy that arrives at the top of the atmosphere is reflected back to space. About 23 percent of incoming solar energy is absorbed in the atmosphere, and 48 percent passes through the atmosphere and is absorbed by the Earth’s surface. 

4. On average, the total rate of energy from the sun that hits the earth is around 173,000 terawatts (trillions of watts) or 173,000,000,000,000,000 watts. 50 Facts About Solar Energy

5. Sunlight that strikes the Earth for one hour is enough to power the entire planet for one year. Sunlight Striking Earth’s Surface... - EcoWatch

6. Solar energy is the most abundant renewable source of energy in the world. About Solar Energy | SEIA

7. Solar energy is the most sustainable and cleanest resource available. There are no carbon emissions and noise pollution. 

8. Solar energy has been used by ancient people. For example, the Greeks and Romans used magnifying glasses to concentrate the light of the sun and burn the sails of enemy ships. The ancient people also used passive solar energy designs to warm their homes.

9. In 1447, Leonardo Da Vinci predicted there would be industrial solar use. He designed a solar power system to heat water for Florence. 

10. The photovoltaic effect, which converts sunlight into electricity, was first observed by physicist Alexandre-Edmond Becquerel in1839. 

11. Albert Einstein published his paper on the photoelectric effect In 1904. In 1921 Einstein received the Nobel Prize for his theories explaining the photoelectric effect. Photovoltaic History - Key Milestones in the 1900s (Timeline) | Solar Energy - Green Lifestyle for You

12. The space industry was the first market for photovoltaics. In the 1950s, the space industry began to use solar technology to provide power aboard spacecraft. Vanguard 1 is the first artificial earth satellite powered by solar cells. The International Space Station is entirely solar-powered.

13. The first solar-powered automobile was demonstrated in Chicago in 1955. It was a 15-inch Sunmobile built by William G. Cobb of the General Motors Corporation.

14. The first solar-powered calculators were invented in 1978. 50 Facts About Solar Energy

15. Solar energy and solar power are not interchangeably terms. Solar energy includes solar power and solar power means electricity created from the sunlight. It is generated in two ways: using solar (photovoltaic) panels or using concentrating solar power systems.

16. Solar panels work even on cloudy days. They just produce less energy than on sunny days (around 10-25%). Also, solar panels function better at cooler temperatures than the very hot climate.

17. China is the world’s leader in the field of solar energy. By early 2020, China was the leading country for solar power with 208 GW, accounting for one-third of global installed solar capacity. Solar power by country - Wikipedia

18. The United States, Japan, Germany, India are countries that follow China in solar electricity generation. Top 10 Countries in the Solar Electricity Generation All over the World in 2019 | Solar Edition

19. China has a plan to build an orbital power station that would capture solar energy in space and beam it back to Earth. According to an article in the Sydney Morning Herald, they are already testing the technology and they intend to build the station by 2050.

20. Many US states allow solar owners to sell back excess power generated by the sun to the grid, which is called solar net metering.

21. Since 2008, the price of the solar system has dropped by 80%, and it is expected to keep falling. 50 Facts About Solar Energy

22. By 2024, the world’s solar capacity will grow by 600 GW, almost double the installed total electricity capacity of Japan. Another prediction state that the US will double its solar installations to four million by 2023. The Growth of Renewable Energy: What Does the Future Hold? | Earth.Org - Past | Present | Future

23. Australia has the highest average solar radiation than any other continent in the world. 50 Facts About Solar Energy

24. India's Cochin International Airport, the seventh busiest in the country, is the first airport in the world powered entirely by solar energy. In 2015 the airport built a 12-megawatt solar plant that has more than 46,000 solar panels. The solar plant provides all the power the airport needs, and even generates surplus for the state electrical grid, according to the BBC.

25. The world's largest solar power park is the Pavagada Solar Park in Karnataka, India. The solar park becomes entirely operational in January 2020. World's largest solar park in Karnataka is now fully operational

26. The world’s first 100% solar-powered five-star resort Finolhu Villas is situated in the Maldives. Designed by New York-based architects Yuji Yamazaki Architecture, the resort was opened in 2016. Tour the World's First Completely Solar-Powered 5-Star Resort | The Weather Channel - Articles from The Weather Channel | weather.com

27. The Walt Disney Company built a 50-megawatt solar facility shaped like Mickey Mouse’s head. The solar park has more than a half-million solar panels and produces enough solar energy to fully power two of its four parks at the Walt Disney World Resort in central Florida. 

28. An 80-story, 1,273-foot rotating skyscraper powered by wind and sun is being built in Dubai, in the United Arab Emirates. When it is completed, It will be the first rotating skyscraper the world has ever seen.

29. Wind energy is a form of solar energy. It is created by the movement of air relative to Earth’s surface. This form of energy is generated by the uneven heating of the atmosphere by the sun and modified by Earth's rotation and surface topography. Wind energy | form of solar energy | Britannica

30. An interesting fact is that in 1979 the American President Jimmy Carter installed solar heating panels on the roof of the White House West Wing. It was more as an effort to set an example for the nation during the second US oil crisis.