Tag Archives: Photovoltaics

PV Panel Energy Conversion Efficiency Rankings

Posted on by
Reply

The purpose of this brief is to investigate into the types of solar panel systems with a look at their theoretical maximum Energy Conversion Efficiency both in research and the top 20 manufactured commercial PV panels. 

PVeff(rev160420)

Figure 1:  Reported timeline of solar cell energy conversion efficiencies since 1976 (National Renewable Energy Laboratory) (1)

Solar panel efficiency refers to the capacity of the panel to convert sunlight into electricity.   “Energy conversion efficiency is measured by dividing the electrical output by the incident light power.” (1)  There is a theoretical limit to the efficiency of a solar cell of “86.8% of the amount of in-coming radiation. When the in-coming radiation comes only from an area of the sky the size of the sun, the efficiency limit drops to 68.7%.”

Figure 1 shows that there has been considerable laboratory research and data available on the various configurations of photo-voltaic solar cells and their energy conversion efficiency from 1976 to date.  One major advantage is that as PV module efficiency increases the amount of material  or area required (system size) to maintain a specific nominal output of electricity will generally decrease.

Of course, not all types of systems and technologies are economically feasible at this time for mainstream production.  The top 20 PV solar cells are listed in Figure 2 below with their accompanying measured energy efficiency.

top-20-most-efficient-solar-panels-chart

Figure 2:  Table of the top 20 most efficient solar panels on the North American Market (2)

Why Monocrystalline Si Panels are more Efficient:

Current technology has the most efficient solar PV modules composed of monocrystalline silicon.  Lower efficiency panels are composed of polycrystalline silicon and are generally about 13 to 16% efficient.  This lower efficiency is attributed to higher occurrences of defects in the crystal lattice which affects movement of electrons.  These defects can be imperfections and impurities, as well as a result of the number of grain boundaries present in the lattice.  A monocrystal by definition has only grain boundaries at the edge of the lattice.  However a polycrystalline PV module is full of grain boundaries which present additional discontinuities in the crystalline lattice; impeding electron flow thus reducing conversion efficiency. (3) (4)

Other Factors that can affect Solar Panel Conversion Efficiency in Installations (5):

Direction and angle of your roof 
Your roof will usually need to be South, East or West facing and angled between 10 and 60 degrees to work at its peak efficiency.

Shade
The less shade the better. Your solar panels will have a lower efficiency if they are in the shade for significant periods during the day.

Temperature
Solar panel systems need to be installed a few inches above the roof in order to allow enough airflow to cool them down.  Cooler northern climates also improve efficiency to partially compensate for lower intensity.

Time of year
Solar panels work well all year round but will produce more energy during summer months when the sun is out for longer.  In the far northern regions the sun can be out during the summer for most of the day, conversely during the winter the sun may only be out for a few hours each day.

Size of system
Typical residential solar panel systems range from 2kW to 4kW. The bigger the system the more power you will be able to produce.  For commercial and larger systems refer to a qualified consultant.

 

References:

  1. https://en.wikipedia.org/wiki/Solar_cell_efficiency
  2. http://sroeco.com/solar/top-20-efficient-solar-panels-on-the-market/
  3. http://energyinformative.org/best-solar-panel-monocrystalline-polycrystalline-thin-film/
  4. http://www.nrel.gov/docs/fy11osti/50650.pdf
  5. http://www.theecoexperts.co.uk/which-solar-panels-are-most-efficient
Advertisement

Is Utility-Scale Solar Power the Economic Choice to Residential Solar Power?

Posted on by
Reply

Originally published on Solar Love. A new study has concluded that utility-scale solar PV systems across the US are “significantly” more cost effective than rooftop solar PV systems. Sp…

Sourced through Scoop.it from: cleantechnica.com

“[…] the study, conducted by economists at global consulting firm The Brattle Group, found that utility-scale solar PV systems were more cost effective at achieving the economic and policy benefits of PV solar than rooftop or residential-scale solar was.

The study, Comparative Generation Costs of Utility-Scale and Residential-Scale PV in Xcel Energy Colorado’s Service Area, published Monday, is the first of its kind to study a “solar on solar” comparison.

“Over the last decade, solar energy costs for both rooftop and bulk-power applications have come down dramatically,” said Dr. Peter Fox-Penner, Brattle principal and co-author of the study. “But utility-scale solar will remain substantially less expensive per kWh generated than rooftop PV. In addition, utility-scale PV allows everyone access to solar power. From the standpoint of cost, equity, and environmental benefits, large-scale solar is a crucial resource.”

The study yielded two key findings:

  1. The generation cost of energy from 300 MW of utility-scale PV solar is roughly 50% the cost per kWh of the output from an equivalent 300 MW of 5kW residential-scale systems when deployed on the Xcel Energy Colorado system, and utility-scale solar remains more cost effective in all scenarios considered in the study.
  2. In that same setting, 300 MW of PV solar deployed in a utility-scale configuration also avoids approximately 50% more carbon emissions than an equivalent amount of residential-scale PV solar. […]

The report itself was commissioned by American thin-film photovoltaic manufacturer and utility scale developer First Solar with support from Edison Electric Institute, while Xcel Energy Colorado provided data and technical support. Specifically, the report examined the comparative customer-paid costs of generating power from equal amounts of utility-scale and residential/rooftop-scale solar PV panels in the Xcel Energy Colorado system.

A reference case and five separate scenarios with varying degrees of investment tax credit, PV cost, inflation, and financing parameters were used to yield the report’s results.

The specifics of the study’s findings, which imagined a 2019 Xcel Energy Colorado system, are as follows:

  • utility-scale PV power costs ranged from $66/MWh to $117/MWh (6.6¢/kWh to 11.7¢/kWh) across the five scenarios
  • residential-scale PV power costs were well up, ranging from $123/MWh to $193/MWh (12.3¢/kWh to 19.3¢/kWh) for a typical residential-scale system owned by the customer
  • the costs for leased residential-scale systems were even larger and between $140/MWh and $237/MWh (14.0¢/kWh to 23.7¢/kWh)
  • the generation cost difference between the utility- and residential-scale systems owned by the customer ranged from 6.7¢/kWh to 9.2¢/kWh solar across the scenarios

The authors of the report put these figures into perspective, including the national average for retail all-in residential electric rates in 2014, which were 12.5¢/kWh.  […]”

See on Scoop.it – Green Energy Technologies & Development

Solar Energy and Battery Storage Coupled Provide Demand Response & Utility Peak Shaving

Posted on by
2

Borrego Solar, a developer, and Stem, an energy storage firm, discuss when PV, storage or both will benefit commercial customers the most.

Sourced through Scoop.it from: www.greentechmedia.com

>” […] Thanks to advancements in technology, there are more energy solutions available to consumers. As a result, the confusion about which option to choose — solar, storage or solar-plus-storage — is growing.

Utility energy costs

To understand the benefits of energy storage and solar at a customer facility, it’s essential to first understand the elements of most organizations’ utility energy costs: energy charges and demand charges. This is the bread and butter for energy managers, but many leaders in finance and/or operations aren’t as aware of the energy cost mix — despite it being one of their largest budgetary line items. It should be noted that this billing structure isn’t in place in every market.

Energy charges, the price paid for the amount of energy used over the course of the billing cycle, are how most people think of paying for electricity. A price is paid for every kilowatt-hour used. Demand charges are additional charges incurred by most commercial customers and are determined by the highest amount of energy, in kilowatts, used at any instant or over some designated timeframe — typically a 15-minute interval — in that billing cycle.

Demand charges are a bit more complex. They come from a need for the grid infrastructure to be large enough to accommodate the highest amount of energy, or demand, needed at any moment in order to avoid a blackout. Every region is different, but demand charges typically make up somewhere between 20 percent and 40 percent of an electricity bill for commercial customers.

Why storage?

Intelligent storage can help organizations specifically tackle their demand charges. By combining predictive software and battery-based storage, these systems know when to deploy energy during usage peaks and offset those costly demand charges. Most storage systems run completely independently from solar, so they can be added to a building whether or not solar is present.

Storage can reduce demand charges by dispensing power during brief periods of high demand, which in essence shaves down the peaks, or spikes, in energy usage. Deploying storage is economical under current market conditions for load profiles that have brief spikes in demand, because a relatively small battery can eliminate the short-lived peaks.

For peak demand periods of longer duration, a larger, and considerably more expensive, battery would be needed, and with the higher material costs, the economics may not be cost-effective. As system costs continue to decline, however, a broader range of load profiles will be able to save with energy storage.

Why solar?

For the commercial, industrial or institutional energy user, solar’s value proposition is pretty simple. For most facilities in states with high energy costs and a net metering regime in place, onsite solar can reduce energy charges and provide a hedge against rising electricity costs. The savings come primarily from producing/buying energy from the solar system, which reduces the amount of energy purchased from the utility, and — when the installation produces more than is used — the credit from selling the excess energy to the grid at retail rates.

The demand savings are a relatively small part of the benefit of solar because the timing of solar production and peak demand need to line up in order to cut down demand charges. Solar production is greatest from 9 a.m. to 3 p.m., but the peak period (when demand for energy across the grid is highest) is typically from 12 p.m. to 6 p.m. If demand-charge rates are determined by the highest peak incurred, customers with solar will still fall into higher demand classes from their energy usage later in the day, when solar has less of an impact.

That being said, solar can reduce a significant portion of demand charges if the customer is located within a utility area where solar grants access to new, solar-friendly rate schedules. These rate schedules typically reduce demand charges and increase energy charges, so the portion of the utility bill that solar can impact is larger.  […]”<

See on Scoop.it – Green Energy Technologies & Development

Virtual Power Plants Aggregate Renewable Energy Battery Storage Systems

Posted on by
3

Aggregating connected energy storage systems to create ‘virtual power plants’ is likely to become a big part of the next phase of storage, according to the executive director of the US-based Energy Storage Association.

Sourced through Scoop.it from: storage.pv-tech.org

>” […] Part of the beauty is that this kind of storage-based ‘multi-tasking’ could be secondary to the main aims of the storage being installed, such as integrating solar.

“You don’t have to do it every day, but on an infrequent basis you can jump into the marketplace to help make money and subsidise all your projects. And, you can do big things for the grid. You will look like a power plant as far as the grid can tell. You can replace the need for a new peaking plant or something like that. [There are] a lot of great things you can do with distributed storage; the sum of [its] parts is greater than the individual pieces.”

Companies are already trialling the concept in various configurations around the world, analyst Omar Saadeh, senior grid analyst at GTM Research, told PV Tech Storage recently. Saadeh said VPPs are one way utilities could use storage to meet “a higher demand for rapidly deployable grid flexibility”.

One example Saadeh cited was a project called PowerShift Atalantic in Canada, which was “designed to manage and mitigate intermittent power from large-scale wind generation, currently totalling 822MW”.

“Through the multiple flexible curtailment service providers, aggregated loads have the ability to balance wind intermittency by responding to virtual power plant dispatch signals in near-real time, providing the equivalent of a 10-minute spinning reserve ancillary service typically executed by pollution-heavy peaker plants,” Saadeh said.

“Since March 2014, the project included 1,270 customer-connected devices with 18 MW of load flexibility, approximately 90% residential.”

Saadeh said Europe has been especially active on the concept, calling France one of the “leading supporters” of such developments.

“They’ve looked at many promising applications including partial islanding, or microgrids, DER-oriented marketplace development, and renewable balancing services.”

German utility Lichtblick, which claims to generate its power 100% from renewables, is another entity which has already got started on VPPs, which it calls a “swarm” of devices. Its battery system providers in VPP programmes include Tesla Energy and Germany’s Sonnenbatterie. Meanwhile another big Tesla partner, SolarCity, also intends to aggregate storage using the EV maker turned energy industry disruptor’s Powerwall for homes. […]”<

See on Scoop.it – Green Energy Technologies & Development

Transparent Solar Cells Could Turn Office Tower Windows and Mobile Devices Into Power Sources

Posted on by
3

“It’s a whole new way of thinking about solar energy,” says startup CEO about using transparent solar cells on buildings and electronics.

Sourced through Scoop.it from: news.nationalgeographic.com

>” […] With the help of organic chemistry, transparent solar pioneers have set out to tackle one of solar energy’s greatest frustrations. Although the sun has by far the largest potential of any energy resource available to civilization, our ability to harness that power is limited. Photovoltaic panels mounted on rooftops are at best 20 percent efficient at turning sunlight to electricity.

Research has boosted solar panel efficiency over time. But some scientists argue that to truly take advantage of the sun’s power, we also need to expand the amount of real estate that can be outfitted with solar, by making cells that are nearly or entirely see-through.

“It’s a whole new way of thinking about solar energy, because now you have a lot of potential surface area,” says Miles Barr, chief executive and co-founder of Silicon Valley startup Ubiquitous Energy, a company spun off by researchers at Massachusetts Institute of Technology and  Michigan State University. “You can let your imagination run wild. We see this eventually going virtually everywhere.”

Invisible Spectrum Power

Transparent solar is based on a fact about light that is taught in elementary school: The sun transmits energy in the form of invisible ultraviolet and infrared light, as well as visible light. A solar cell that is engineered only to capture light from the invisible ends of the spectrum will allow all other light to pass through; in other words, it will appear transparent.

Organic chemistry is the secret to creating such material. Using just the simple building blocks of carbon, hydrogen, oxygen, and a few other elements found in all life on Earth, scientists since at least the early 1990s have been working on designing arrays of molecules that are able to transport electrons—in other words, to transmit electric current.  […]

Harvesting only the sun’s invisible rays, however, means sacrificing efficiency. That’s why Kopidakis says his team mainly focuses on creating opaque organic solar cells that also capture visible light, though they have worked on transparent solar with a small private company in Maryland called Solar Window Technologies that hopes to market the idea for buildings.

Ubiquitous Energy’s team believes it has hit on an optimal formulation that builds on U.S. government-supported research published by the MIT scientists in 2011.

“There is generally a direct tradeoff  between transparency and efficiency levels,” says Barr. “With the approach we’re taking, you can still get a significant amount of energy at high transparency levels.”

Barr says that Ubiquitous is on track to achieve efficiency of more than 10 percent—less than silicon, but able to be installed more widely. “There are millions and millions of square meters of glass surfaces around us,” says Barr. […]”<

See on Scoop.it – Green Building Design – Architecture & Engineering

Comfort is key in a passive house

Posted on by
1
0620 home green Rendering of the home Chris Weissflog, who operates the renewable energy firm Ecogen Energy, is building for his family. Among other green features, its solar panels will meet most of the 3,000-square-foot home’s heating and cooling needs as well as powering a greenhouse with an extended growing season. With story by Patrick Langston.

0620 home green Rendering of the home Chris Weissflog, who operates the renewable energy firm Ecogen Energy, is building for his family. Among other green features, its solar panels will meet most of the 3,000-square-foot home’s heating and cooling needs as well as powering a greenhouse with an extended growing season. With story by Patrick Langston.

>” […] The falling price of technology may still help us out of the quandary. The CHBA is currently developing a net zero and net zero-ready labelling program for home builders and renovators. A net zero home typically uses photovoltaic panels to produce as much energy as it consumes, generally selling excess electricity to the grid. A net zero-ready home is set up for, but does not include, the photovoltaic system.

The CHBA’s Foster says that a net zero home including photovoltaic panels now costs $50,000 to $70,000 more than a conventional home. That’s 50 per cent of the cost of just five years ago, and the price of PV panels continues to drop.

With rising energy prices, the CHBA says the extra monthly mortgage costs associated with a net zero home are now comparable to the savings in energy costs, making it net zero in more ways than one. […]”<

New California Housing Community Goes Zero Net Energy

Posted on by
2

California has set a goal for all new residential construction in the state to be ZNE by 2020 and all new commercial construction to be zero net energy by 2030. Spring Lake uses no natural gas and receives most of its power from photovoltaics.

Source: www.calenergycommission.blogspot.ca

>”The $13 million Spring Lake project in Woodland has 62 affordable apartments and townhomes for agricultural workers and their families.  […]

“The community will generate at least as much energy as it consumes,” says Vanessa Guerra, a project manager with Mutual Housing California, a Sacramento-based non-profit that develops sustainable affordable housing communities.

The California Energy Commission adopted zero net energy goals in its 2007 Integrated Energy Policy Report (IEPR). It further defined what ZNE buildings are and laid out the necessary steps and renewables options for achieving the ZNE 2020 goals in the 2013 IEPR.

The project was financed by the U.S. Department of Agriculture, Citibank, Wells Fargo Bank, the California Department of Housing and Community Development and the City of Woodland.”<

See on Scoop.it – Green Energy Technologies & Development

Renewable Energy Provides Half of New US Generating Capacity in 2014

Posted on by
2

According to the latest “Energy Infrastructure Update” report from the Federal Energy Regulatory Commission’s (FERC) Office of Energy Projects, renewable energy sources (i.e., biomass, geothermal, hydroelectric, solar, wind) provided nearly half (49.81 percent – 7,663 MW) of new electrical generation brought into service during 2014 while natural gas accounted for 48.65 percent (7,485 MW).

 

Image source:  http://usncre.org/

Source: www.renewableenergyworld.com

>” […] By comparison, in 2013, natural gas accounted for 46.44 percent (7,378 MW) of new electrical generating capacity while renewables accounted for 43.03 percent (6,837 MW). New renewable energy capacity in 2014 is 12.08 percent more than that added in 2013.

New wind energy facilities accounted for over a quarter (26.52 percent) of added capacity (4,080 MW) in 2014 while solar power provided 20.40% (3,139 MW). Other renewables — biomass (254 MW), hydropower (158 MW), and geothermal (32 MW) — accounted for an additional 2.89 percent.

For the year, just a single coal facility (106 MW) came on-line; nuclear power expanded by a mere 71MW due to a plant upgrade; and only 15 small “units” of oil, totaling 47 MW, were added.

Thus, new capacity from renewable energy sources in 2014 is 34 times that from coal, nuclear and oil combined — or 72 times that from coal, 108 times that from nuclear, and 163 times that from oil.

Renewable energy sources now account for 16.63 percent of total installed operating generating capacity in the U.S.: water – 8.42 percent, wind – 5.54 percent, biomass – 1.38 percent, solar – 0.96 percent, and geothermal steam – 0.33 percent.  Renewable energy capacity is now greater than that of nuclear (9.14 percent) and oil (3.94 percent) combined.

Note that generating capacity is not the same as actual generation. Generation per MW of capacity (i.e., capacity factor) for renewables is often lower than that for fossil fuels and nuclear power. According to the most recent data (i.e., as of November 2014) provided by the U.S. Energy Information Administration, actual net electrical generation from renewable energy sources now totals a bit more than 13.1 percent of total U.S. electrical production; however, this figure almost certainly understates renewables’ actual contribution significantly because EIA does not fully account for all electricity generated by distributed renewable energy sources (e.g., rooftop solar).

Can there any longer be doubt about the emerging trends in new U.S. electrical capacity? Coal, oil, and nuclear have become historical relics and it is now a race between renewable sources and natural gas with renewables taking the lead.”<

See on Scoop.it – Green & Sustainable News

Concentrated Solar Power Projects in 2014

Posted on by
Reply

“It was a good year for solar power in the USA, with over six gigawatts of photovoltaic (PV) capacity and more than one gigawatt of concentrated solar power (CSP) being added in 2014, bringing the nation’s total solar power capacity to more than 17 gigawatts. That’s a 41% increase in solar power capacity in just one year…”  Source: www.engineering.com

>” Photovoltaic vs Concentrated Solar Power

Photovoltaic technology converts light directly into electricity. PV panels produce DC, which needs to be converted to AC before being placed on the grid. PV panels work best in direct sunlight when they’re pointed perpendicular to the sun’s rays, but they also work reasonably well in diffuse light, even when not pointed directly at the sun. This makes them inexpensive and suitable for rooftops, since solar tracking isn’t required. PV also works in climates that aren’t particularly sunny; Germany gets less sunlight than the northern US, and yet it has a large portion of its power generated by PV.

Concentrated solar power, on the other hand, requires direct sunlight and solar tracking. CSP focuses the sun’s energy and uses the resulting heat to create steam that drives a traditional turbine generator. Even better, the heat can be stored – usually in the form of molten salts – so the CSP plant can generate electricity even when the sun isn’t shining. Because CSP relies on direct sunlight, it’s most suitable for very sunny locations like the American southwest.  […]

US Concentrated Solar Power in 2014

These five major CSP plants went online in 2014 (give or take a few months – one went live in late 2013):

Gila Bend, AZ is the home of the Solana parabolic trough power plant, which provides 250 MW of power to residents of Arizona. The turbine It went live in October of 2013. Spanning 1920 acres, the solar farm includes over two million square meters of reflective troughs and two tanks of molten salts, which provide up to six hours of thermal energy storage. If the stored energy is depleted and the sun isn’t shining, the turbine can be powered by natural gas as a backup.

The Genesis power plant in Blythe CA generates 250 MW of power using a parabolic trough array consisting of more than half a million mirrors. Unlike the Solana plant, Genesis includes no storage or backup fuel. Brought online in April of 2014, designers expect it to generate about 600 GWh of energy each year.

Probably the most famous CSP plant in the US, and the largest of its kind in the world, is the Ivanpah Solar Electric Generating System in Ivanpah Dry Lake CA, about 50 miles south of Las Vegas NV. Its three power towers fired up in February 2014, and the facility now produces 377 MW of power. Its annual production is expected to exceed one terawatt-hour. Ivanpah includes natural gas as its backup, but has no on-site storage.

About 270 miles northwest of Ivanpah is the Crescent Dunes Solar Energy Project in Tonopah, NV. Originally planned to go online in late 2014, the start date has been pushed back to January of 2015. When operational, this 110 MW power tower should produce nearly 500 GWh per year. Crescent Dunes uses molten salt to store heat, allowing it to generate power for ten hours without sunlight.

The Mojave Solar One facility came online in late 2014 and now generates 250 MW of electricity. Located about 100 miles northeast of Los Angeles CA, this parabolic trough array feeds a pair of 125 MW steam turbine generators. The plant should produce about 600 GWh per year. […]”<

 

 

See on Scoop.it – Green Energy Technologies & Development