Now Solar's #1 Customers Report

 

    Jim Shirts Residents


Jim Shirts was our first customer in the city of Richland Washington. Jim had a quick understanding of solar and did some very extensive research. It was refreshing working with him as he had a great grasp not only on the economics but also the science and applications of solar. Jim agreed to keep a record of his system as I have found over my years in the industry that even with the great satellite information we can utilize, equipment operates differently in different environments. For example we can have some very cold but sunny days that cause panels voltage to raise.

 

Jim's Report

Hi Eugene,

 

On my last utility bill, I received a credit of $86.88 (including tax) for power fed back to the grid…yeah!!!  I’m attaching an update of production info.  I tried to calculate theoretical production based info in “Solar Electricity Handbook”, using orientation, tilt and temperature.  The numbers are close to what you estimated, but I couldn’t get exact insolation data for my orientation and tilt.  Also, I didn’t finish the shading experiment, based on the first test.  Any suggestions on what to do about that?  Hope all is well with you.  Take care.

 

Jim   

 

System Design/Installation/Production Details

Front Panels:

Twelve 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 50 degrees East of true South, and tilted 72 degrees from vertical (18 degrees from flat).

Back Panels:

Twenty-one 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 130 degrees WNW from true south, and tilted 72 degrees from vertical (18 degrees from flat).  Three of the panels are affected significantly by shading from a chimney, one is affected slightly by the chimney and two panels are affected slightly by shading early in the year by a large shrub.

(For comparison, the optimum fixed, roof-mounted position would be facing true south and tilted 43.7 degrees from vertical.)

The system was installed in March, 2015 and started producing power in the afternoon of April 2, 2015, with the installation of the city meters.

The actual PV panel average power production, thus far is as follows:

Month	April	May	June
12 Front Panels	42.1 kWh	50.0 kWh	51.6 kWh
15 Back Panels	31.8 kWh	41.7 kWh	44.0 kWh
3 Back Panels w/Major Chimney Affect	23.7 kWh	31.7 kWh	32.1 kWh
1 Back Panel w/Minor Chimney Affect	30.9 kWh	39.5 kWh	40.0 kWh
2 Back Panels w/Minor  Shrub Affect	27.4 kWh	41.4 kWh	44.6 kWh

 

For comparison, the theoretical calculated PV panel power production is:

Month	April	May	June
Front Panels	45 kWh	49 kWh	50 kWh
Back Panels	38 kWh	41 kWh	42 kWh

 

The actual total PV system power production compared to projected, thus far, is as follows:

Month	April	May	June
System Actual Power Production	1140 kWh	1440 kWh	1503 kWh
System Estimated Power Prod.*	1254 kWh	1357 kWh	1395 kWh

 

* Production estimate from Now! Solar.

As can be seem from the above, the actual system production compares favorably with the estimated production from the proposal.

 

Shading Test:

A test was devised to try to quantify the effects of shading on PV panel power production.  The plan was to cover one 6 in. x 6 in. cell in one corner of one panel with a square of white cardboard for one day then compare the production of that panel to an adjacent panel.  Next, two cells would be covered, the test repeated, and then 3 cells covered.   The plan was to start the test before the panels started producing power and then monitor it for the day.

By ~ 8:45 a.m. of the first day of the test, with one cell covered (less than 2% of the panel shaded), the test panel was producing only ~ 50% of the panel next to it (114W vs. 227W).  This was much more significant than expected and due to this result the test was discontinued.  This clearly shows that any amount of shading has a significant effect on power production.    





 

Hi Eugene & Lisa,

 

Was good seeing you at the BF Fair last week, Lisa.  I told you I would provide an update on my system, so here it is:

 

My July credit from the city was $61.01, bringing the total to $286.16, thus far, not counting saved power.  From going hot until the end of June, the state credit due is $1448.64 (4024 kWh generated).  The paperwork was filed but I have not received the check from the city yet.

 

August power production was off as expected, due to the smoke from the wildfires.  Attached is my summary to date:

 

Jim

 

System Design/Installation/Production Details

Front Panels:

Twelve 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 50 degrees East of true South, and tilted 72 degrees from vertical (18 degrees from flat).

Back Panels:

Twenty-one 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 130 degrees WNW from true south, and tilted 72 degrees from vertical (18 degrees from flat).  Three of the panels are affected significantly by shading from a chimney, one is affected slightly by the chimney and two panels are affected slightly by shading early in the year by a large juniper shrub.

(For comparison, the optimum fixed, roof-mounted position would be facing true south and tilted 43.7 degrees from vertical.)

The system was installed in March, 2015 and started producing power in the afternoon of April 2, 2015, with the installation of the city meters.

The actual PV panel average power production in kWh, thus far is as follows:

Month	Apr	May	Jun	Jul	Aug*	Sep	Oct	Nov	Dec
12 Front Panels	42.1	50.0	51.6	52.5	41.7	37.0
15 Back Panels	31.8	41.7	44.0	44.0	33.2	24.4
3 Back Panels w/Major Chimney Shade	23.7	31.7	32.1	31.8	25.1	18.5
1 Back Panel w/Minor Chimney Shade	30.9	39.5	40.0	40.9	32.5	16.7
2 Back Panels w/Minor  Shrub Shade	27.4	41.4	44.6	43.7	28.5	24.9

 

For comparison, the theoretical calculated PV panel power production in kWh is:

Month	April	May	June	July	Aug*	Sept	Oct	Nov	Dec
Front Panels	45	49	50	52	50	42	32	19	15
Back Panels	38	41	42	44	42	35	27	16	12

 

The actual total PV system power production in kWh compared to projected, thus far, is as follows:

Month	Apr	May	Jun	Jul	Aug*	Sep	Oct	Nov	Dec
System Actual Power Production	1140	1440	1503	1514	1163	924
System Estimated Power Prod.**	1254	1357	1395	1487	1405	1257	942	499	362

* August energy production was low due to extensive wildfire smoke in area for part of the month.

** Production estimate from Now! Solar.

 

The actual system production compares favorably with the estimated production in the proposal from Now! Solar.

 



New refrigerator cools food without electricity

The WindChill is designed to preserve food in places where money and electricity are scarce, taking cues from nature to help fight food waste and malnutrition in developing countries.

By: Russell McLendon

October 30, 2015, 4:24 p.m.

VIA http://www.mnn.com
 

The WindChill is inspired by animals ranging from bees and termites to elephants, kangaroos and meerkats. (Photo: University of Calgary)

 

More than 1 billion people around the world still don't have access to electricity, representing about 15 percent of humanity. That poses several problems, including not just heating, cooling and lighting, but also food preservation.
Universal access to electricity is still years away, with the World Bank having set 2030 as a target date. But in the meantime, a team of students from the University of Calgary has come up with a way to keep food cool without relying on electricity.
Named WindChill, the new refrigerator prototype instead turns to the animal kingdom for inspiration, using biomimicry to imitate animals including bees, termites, coral, elephants, kangaroos and meerkats. And not only is the Windchill designed to preserve food without electricity, but it's also cheap and relatively portable, making it a potential windfall for people living in remote, rural areas.
We thought it would be good to decrease the amount of food waste in the world," team member Michelle Zhou tells CBC News, "and we came up with this design because it's easy to build and the materials are relatively cheap."
The invention recently won first place in the student category of the Biomimicry Global Design Challenge (BGDC), an annual competition focused on "addressing critical sustainability issues with nature-inspired solutions."
"The cooling mechanism is inspired by temperature regulation approaches seen in mammals and insects and is a new way of approaching issues in the food system," the students write in their project overview. The device involves three main steps, each drawing inspiration from a different type of animal.
The process begins with an intake pipe that brings in ambient air using a method inspired by the way some marine animals accelerate water into their pores. Part of the pipe is buried underground, cooling the incoming air with a tactic borrowed from termite mounds. In the second step, the air flows into a copper pipe inside a transparent evaporation chamber, which also contains fluid. As sunlight evaporates this fluid, it cools the pipe — and the air inside — in a strategy the students say was gleaned from elephants and kangaroos, among other animals.
"[Elephants] get their ears wet and when the water evaporates it cools their skin," team member Jorge Zapote says in a statement from the university. "Kangaroos lick their forearms and when it evaporates off their skin, it cools their blood and they also dig and put their bellies in exposed ground and that cools them down."
In the final step, a pipe briefly carries the air back underground, cooling it further before it finally flows into the food-storage chamber.
 

 

The WindChill prototype includes a solar-powered fan in the evaporation chamber, so it technically does use a small amount of (self-generated) electricity in its current form. But the final version will be completely electricity-free, team member Jorge Zapote tells CBC News, which could be a game-changer for many parts of the world.
"Anywhere from a quarter to half of the world's food goes to waste every year, and in rural populations — about 70 percent of the people in rural Africa don't have access to electricity," Zapote says. "So this at the moment uses a tiny bit of electricity from a solar panel, but the end design is to use zero electricity. So this could really help people in those areas."
Although the team already won the BGDC student category, they're still honing their invention. In addition to phasing out the solar panel, they're reportedly still adjusting the design to consistently reach a temperature of 4.5 degrees Celsius (40.1 Fahrenheit) inside the food-storage chamber.
If this idea becomes a practical tool for rural food preservation, it could benefit not only people living in those areas, but also add to the growing popularity of biomimicry in general. People have a long history of borrowing design ideas from nature — like the way birds informed our invention of airplanes — but biomimicry has become especially important in recent years, as population growth and limited resources fuel the need for more efficient, lower-energy innovations.
"Biomimicry helps develop more sustainable solutions," says Marjan Eggermont, an associate dean at the University of Calgary who worked with the students on their design. "Because nature doesn't tend to foul its own backyard, you come up with solutions that can work locally and are benign to the environment."

Lithium-Air battery research shows potential paths to next-gen batteries

But a commercially viable Li-air battery is still “at least a decade away."
by Megan Geuss - Oct 29, 2015 11:23am PDT
VIA http://arstechnica.com

Scanning electron microscopy images of the electrode in its pristine state, after the battery is discharged, and after the battery is charged again.

On Thursday, a group of researchers from Cambridge University released a paper showing that they had developed a laboratory model of a lithium-air battery that solved several of the problems associated with batteries of similar chemistry. Their lithium-air battery had a high energy density, and it was capable of being recharged “more than 2,000 times.” The battery was theoretically more than 90 percent efficient in its energy use, as well.
It is the great hope of scientists that lithium-air batteries will one day replace the class of lithium-ion bricks we currently use. “The lithium-ion rechargeable battery is approaching its 25th anniversary,” Professor Clare P. Grey of the University of Cambridge’s chemistry department told a handful of journalists in a phone call on Wednesday. A quarter of a century ago, that new battery composition helped pave the way for the host of portable electronics that we carry with us today—relatively light and compact, Lithium-ion batteries are better-suited for consumer tech than their predecessors were.
But no chemist or engineer would claim that the lithium-ion battery is perfect. As electric vehicles become more popular, researchers are especially excited about lithium-air batteries because they would ideally be much lighter than anything we have powering cars today, and lighter cars mean a longer driving range before the battery runs out. That’s not to mention that the lithium-air batteries would ideally have a higher energy density.
In a press release (PDF), the University of Cambridge scientists admitted that a commercially viable lithium-air battery was still “at least a decade away,” but their research showed that some of the big roadblocks to developing such batteries can be tackled.
So far, previous research has been able to create lithium-air batteries that can hold a charge but can not be cycled frequently enough for commercial use (think of how many times you can recharge your smartphone before the battery kicks the bucket). Or, their laboratory batteries are too unstable for the real world because the oxygen will create unwanted chemical reactions inside the battery.
Whereas several earlier experiments on Li-O₂ batteries have cycled by creating a chemical reaction that results in lithium peroxide (Li₂O₂), the Cambridge researchers built their battery to produce lithium hydroxide (LiOH) as a discharge product. The battery was composed of a lithium metal anode, a graphene oxide electrode, and a lithium iodide (LiI) additive, which acts as a mediator of redox reactions, as well as a dimethoxyethane solvent. The result was that the researchers were able to form and then remove lithium hydroxide during charge and discharge. (They also found that adding a little bit of water(!) to the battery helped.)
The researchers noted that "The cells tolerate high concentrations of water, water being the dominant proton source for the LiOH.” However, the battery can only cycle in pure oxygen, which is less than ideal for a true lithium-air battery (because air, of course, contains more than just oxygen).
As the battery discharged, lithium hydroxide built up in the graphene oxide electrode. That material was chosen among other possible materials because graphene electrodes are "light, conductive, and have a large pore volume that can potentially lead to large capacities,” the researchers write.
In many lithium-air battery prototypes, scientists have struggled to figure out how to most effectively fill and then flush the receiving electrode of the batteries’ discharge products. How well an electrode accepts discharge products and then flushes them when the battery is being recharged affects how many cycles the battery can be used for, as well as its overall efficiency.
Because of graphene oxide’s porousness and because of the way the lithium hydroxide particle built up in the graphene oxide, the researchers estimate that this battery can be cycled more than 2,000 times. They write that the lithium hydroxide discharge products can be quite large compared to the lithium peroxide that's found in other Li-air batteries, but despite their size, they fit into the porous graphene oxide much better than the doughnut-shaped lithium peroxide molecules (sort of how you'll have more room in your suitcase if you fold your clothes rather than just ball them up and throw them in there). "The large LiOH agglomerates efficiently fill up the pore volume available in the [...] electrode, leading to much larger capacities," the researchers write.
The researchers were also able to reduce the “voltage gap” in their Li-air battery, a measure of efficiency that has been difficult for earlier experiments to achieve. With this new chemistry, researchers were able to reduce the voltage gap to 0.2V, a number closer to what is seen in a Li-ion battery.
In their press conference, the researchers noted that their new battery had a theoretical energy density 3,350Wh/kg of electrode. That’s quite impressive, given that current Li-ion batteries can run between 140-250Wh/kg. (But maybe not as impressive as research from 2012 that predicted a Li-air battery with a 13,500Wh/kg capacity.)
This is all well and good, but naturally there are still some issues. The voltage gap decrease and the graphene oxide electrode’s large capacity only hold true for very specific rates of charge and discharge, and the researchers noted in a press conference that the lithium metal anode in their battery can sometimes form dendrites that hinder the battery’s performance. As we noted before, other compounds in air besides O₂ could also potentially cause negative chemical byproducts.
All these problems mean you won’t be able to buy a Li-air battery for your phone any time soon. It’s easy to think of new battery technology as vaporware, but instead it’s just painstaking, diligent science. “If we can really understand the nature as to how lithium hydroxide is formed [in the battery], that can give us some clues,” Grey said on Wednesday. Other teams will be able to build off the Cambridge research in the future, and maybe soon scientists will be able to “get at some of the fundamental mechanisms of what’s going on,” the professor added.