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Golden Sandwich

Golden Sandwich Converts 85% of Visible Light into Electricity

Scientists have developed a photoelectrode that can harvest 85 percent of visible light in a 30 nanometers-thin semiconductor layer between gold layers, converting light energy 11 times more efficiently than previous methods.

In the pursuit of realizing a sustainable society, there is an ever-increasing demand to develop revolutionary solar cells or artificial photosynthesis systems that utilize visible light energy from the sun while using as few materials as possible.

The research team, led by Professor Hiroaki Misawa of the Research Institute for Electronic Science at Hokkaido University, has been aiming to develop a photoelectrode that can harvest visible light across a wide spectral range by using gold nanoparticles loaded on a semiconductor. But merely applying a layer of gold nanoparticles did not lead to a sufficient amount of light absorption, because they took in light with only a narrow spectral range.

In the study published in Nature Nanotechnology, the research team sandwiched a semiconductor, a 30-nanometer titanium dioxide thin-film, between a 100-nanometer gold film and gold nanoparticles to enhance light absorption. When the system is irradiated by light from the gold nanoparticle side, the gold film worked as a mirror, trapping the light in a cavity between two gold layers and helping the nanoparticles absorb more light.

Left: The newly developed photoelectrode, a sandwich of semiconductor layer (TiO2) between gold film (Au film) and gold nanoparticles (Au NPs). The gold nanoparticles were partially inlaid onto the surface of the titanium dioxide thin-film to enhance light absorption. Right: The photoelectrode (Au-NP/TiO2/Au-film) with 7nm of inlaid depth traps light making it nontransparent (top). An Au-NP/TiO2 structure without the Au film are shown for comparison (bottom). (Misawa H. et al., Nature Nanotechnology, July 30, 2018) (click on image to enlarge)

To their surprise, more than 85 percent of all visible light was harvested by the photoelectrode, which was far more efficient than previous methods. Gold nanoparticles are known to exhibit a phenomenon called localized plasmon resonance which absorbs a certain wavelength of light.

“Our photoelectrode successfully created a new condition in which plasmon and visible light trapped in the titanium oxide layer strongly interact, allowing light with a broad range of wavelengths to be absorbed by gold nanoparticles,” says Hiroaki Misawa.

From the left: Quan Sun, Hiroaki Misawa, Xu Shi, Kosei Ueno, Tomoya Oshikiri of the research team at Hokkaido University.

When gold nanoparticles absorb light, the additional energy triggers electron excitation in the gold, which transfers electrons to the semiconductor.

“The light energy conversion efficiency is 11-times higher than those without light-trapping functions,” Misawa explained.

The boosted efficiency also led to an enhanced water splitting: the electrons reduced hydrogen ions to hydrogen, while the remaining electron holes oxidized water to produce oxygen­­ — a promising process to yield clean energy.

“Using very small amounts of material, this photoelectrode enables an efficient conversion of sunlight into renewable energy, further contributing to the realization of a sustainable society,” the researchers concluded.

Hokkaido University

Home batteries: What are they, and is it worth it for you to get one?

Rooftop solar panels are common in Arizona thanks to abundant sunshine, but to get even more use from the technology, homeowners are beginning to pair them with large home batteries.

Batteries allow homeowners to store their surplus electricity, rather than send it to the grid in exchange for credit from their electric company.

Read more:

https://www.azcentral.com/story/money/business/energy/2018/07/18/everything-you-need-know-home-batteries-rooftop-solar-panels/772014002/

Should you install solar on your home? 10 key considerations

Arizona's endless sunshine continues to make rooftop solar panels an enticing proposal for homeowners. Already, tens of thousands of Arizonans have installed panels to make electricity for them, and falling prices and new financing options continue to draw consumer interest.

But homeowners should consider several questions before deciding to install rooftop panels. Here are 10 primary considerations you should think about before signing a contract:

Worth a read:

https://www.azcentral.com/story/money/business/energy/2018/07/04/solar-panels-worth-10-things-consider-before-installing/733033002/

Summary of Residential Rate Plans for APS Customers with an On-Site Distributed Generation System

Summary of Residential Rate Plans for APS Customers with an On-Site Distributed Generation System

(Interconnect applications submitted after August 31, 2017)

This is not an official APS document, it is a summary of residential rate plans for APS customers with an on-site distributed generation system put together by the Arizona Solar Center from the August 19, 2017 rate schedules posted at https://www.aps.com/en/Residential/Service-Plans/Compare-Service-Plans. See the actual rates by following the links at the above APS web page link. These are the charges for energy purchased from APS, see below for backfeed credits (exports of power to the grid).

 

 

APS Rate Plan - Customers with an on-site distributed generation system

Bundled rates

SAVER CHOICE

SAVER CHOICE PLUS

SAVER CHOICE MAX

SAVER CHOICE TECH

(Note 2)

Basic Daily Service

$0.427

$0.427

$0.427

$0.427

Energy Charges- per kWh

       

On-Peak Energy Charge-Summer

$0.24314

$0.13160

$0.08683

$0.05750

Winter

$0.23068

$0.11017

$0.06376

$0.04750

Off-Peak Energy Charge-Summer

$0.10873

$0.07798

$0.05230

$0.04750

Winter

$0.10873

$0.07798

$0.05230

$0.04750

Super Off-Peak Energy Charge

(November through April)

$0.03200

n/a

n/a

n/a

         

Demand Charges per kW (Note 1)

       

On-Peak Demand Charge:-Summer

none

$8.40

$17.438

$20.25

Winter

none

$8.40

$12.239

$14.25

Off-Peak Demand Charge:-Summer

none

none

none

$6.50

All above 5 kW

Winter

none

none

none

$6.50

All above 5 kW

         

Grid Access Charge per kW-dc of generation (Monthly fee)

$0.93

$0.93

$0.93

$0.93

         

APS Purchase Rates- per kWh

       

September 1, 2018 through

September 30, 2019

(Future rates to be determined)

$0.1161

 

after October 1, 2019 the Tranche 3 RCP export rate will be $0.1045 per KWh

$0.1161

$0.1161

$0.1161

         

 

Rate Periods for the above:

The On-Peak time period for residential rate schedules is 3 p.m. to 8 p.m. Monday through

Friday year round. Off-Peak time period is the rest of the day and holidays.

The Super Off-Peak period is 10 a.m. to 3 p.m. and applies to those plans with a rate shown above.

 

Holidays for Off-Peak:

  • New Year’s Day - January 1*
  • Martin Luther King Day - Third Monday in January
  • Presidents Day - Third Monday in February
  • Cesar Chavez Day - March 31*
  • Memorial Day - Last Monday in May
  • Independence Day - July 4*
  • Labor Day - First Monday in September
  • Veterans Day - November 11*
  • Thanksgiving - Fourth Thursday in November
  • Christmas Day - December 25*

*If these holidays fall on a Saturday, the preceding Friday will be Off-peak. If they fall on a

Sunday, the following Monday will be Off-Peak.

 

APS Residential bills will include the following adjustments:

  1. The Renewable Energy Adjustment Charge, Adjustment Schedule REAC-1. (
  2. The Power Supply Adjustment charge, Adjustment Schedule PSA-1.
  3. The Transmission Cost Adjustment charge, Adjustment Schedule TCA-1.
  4. The Environmental Improvement Surcharge, Adjustment Schedule EIS.
  5. The Demand Side Management Adjustment charge, Adjustment Schedule DSMAC-1.
  6. The Lost Fixed Cost Recovery Adjustment charge, Adjustment Schedule LFCR.
  7. The Tax Expense Adjustor Mechanism charge, Adjustment Schedule TEAM.
  8. Direct Access customers returning to Standard Offer service may be subject to a Returning Customer Direct Access Charge, Adjustment Schedule RCDAC-1.
  9. Any applicable taxes and governmental fees that are assessed on APS’s revenues, prices, sales volume, or generation volume.

And these Rate riders:

  • CPP -(RES) Critical Peak Pricing (Residential)
  • EPR-2 - Partial Requirements
  • EPR-6 - Partial Requirements – Net Metering (Residential Non-Solar)
  • RCP - Resource Comparison Proxy (This is for solar generation exports of power to the grid)
  • E-3 - Limited income discount
  • E-4 - Limited income medical discount
  • GPS-1, GPS-2, GPS-3 Â Green Power

 

Notes:

  1. The kW used to determine the demand charge above will be the Customer's highest amount of demand (kW) averaged in a one-hour On-Peak period for the billing month.
  2. The SAVER CHOICE TECH rate schedule is available to residential Customers with the following:
    1. 1. Two or more qualifying primary on-site technologies purchased within 90 days of the customer enrolling in the rate; or
    2. 2. One qualifying primary on-site technology purchased within 90 days of the customer enrolling in the rate and two or more qualifying secondary on-site technologies.