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Sun Volt Solar

earth, the final frontier

Clean Energy, Clean Environment

We are at a cross roads in human history, we can choose to continue on as we have been, or we can make a change to improve our future and quite possibly the future for several generations to come. We are here to promote energy independence, a better environment, a secure future and a higher return on investment for your hard earned dollar. It is what I believe in, it is why I am in the solar business.

Prism Solar Technologies

28 Dec 09 | Solar Electric, Technology

Prism Solar Technologies is continuing to grow their manufacturing facility located in Highland, NY. They took over the PLASMACO plant last March, which coincidentally, had much of the equipment and clean rooms needed to manufacture their product. PLASMACO was a subsidiary of Panasonic corporation, they manufactured Plasma screens for TV’s and computers.

What Prism Solar makes is a proprietary holographic planar concentrator™ (HPC) film that, when used in conjunction with conventional silicon photovoltaic cells, increases the cell efficiency by about 40%. According to their website, the increased efficiency allows for use of 30-50% less silicon during the manufacture process, making the the cost around $1/watt.

Here are the advantages of HPC technology:

  • Less silicon reduces cost per watt
  • Passive tracking from holographic effect produces more energy from diffuse and reflected light.
  • Cooler operation than conventional PV module, most unusable light passes through module without being turned into heat.
  • Bifacial PV cells can increase module performance when mounted over a reflective surface.
  • Lower embodied energy, the energy required to manufacture the HPC film is much less than that required to mine and process silicon.

They have four prototype modules on line in Tucson, AZ connected to Enphase inverters. One can look at the module performance on the Enlighten website. There is also a specification sheet for a 160 watt module.

According to their latest press release, they are about to create 175 new jobs in the Hudson Valley (although there is nothing on the careers page yet). All of that is good news for the solar industry and I look foward to seeing their product out in the field. I must say, it certainly looks cool.

holographic optical photovoltaic panel

I previously wrote about them here.

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28 Dec 09 | Solar Electric, Technology | Comments (0)

System verification for Enphase Inverters

16 Dec 09 | Solar Electric, Technology

In New York State, there is something called the Standardized Interconnect Requirements (or SIR) that governs how utility companies handle grid connected renewable energy systems such as Photovoltaic and Wind energy systems.

Among the requirements, usually known as “Step 5,” a verification that the system meets UL 1741 is required. This means that after a power outage, the inverter stays off for five minutes before it begins exporting power to the grid. For most inverters, the verification procedure is simple, turn off the breaker feeding the inverter for a short period, then turn it back on. Watch the LED indicators on the inverter and time how long it takes to come on line and produce power. If it is 5 minutes or longer, the system passes.

enphase energy M210 inverters

enphase energy M210 inverters

The problem with the [e] Enphase inverters is there are many of them, they are located with the solar panels, and it would be difficult to watch the LED start flashing green especially if the inverters are under a PV panel bolted to the roof. Therefore, an alternative verification procedure must be effected. One suggestion by the utility company was to use a clamp on ammeter to measure the AC current in the branch circuit between the inverters and the panel. One small problem was that some “leakage current” had been detected in previous tests of this nature.

I sent an e-mail off the [e] Enphase Energy, Inc. They responded very quickly with the following suggested verification procedure:

  1. Turn off the breakers to the array.
  2. Turn on the breakers to the array and make a note of the time down to the second.
  3. Using a clamp on ammeter, verify that the array is not producing current until 5 minutes have passed. During the non-producing period, the ammeter will show a slight current draw of 0.056 Amps +/- 5% for each installed inverter. In this case, there are 10 inverters in each string, therefore the clamp on ammeter will show 0.56 Amps +/- 5%.
  4. After 5 minutes have passed, the ammeter will show the array producing power by indicating greater than the quiescent current noted in step 4.

The test should be run when the array is in full sunlight so the AC current meter will obviously indicate the array is exporting power to the grid since AC current meters do not indicate the direction of current flow.

The second method proscribed by Enphase involves using the utility meter. This can only be used in arrays that are large enough to get the meter spinning, and should only be performed in full sunlight.

  1. Observe service meter and note direction it is turning while consuming power.
  2. Turn off main service breaker and all other breakers feed the various household loads, simulating a power outage.
  3. Turn on main service breaker and breaker feeding the inverter(s) only and note the exact time.
  4. Observe service meter. A very slight movement forward direction indicates the inverters are consuming a small amount of power in their monitoring circuit.
  5. After five minutes have passed, the meter will begin to turn in the opposite direction, indicating the inverters are exporting power.
  6. Close the breakers to the rest of the household loads.

Finally, if the inverters are ground mounted and the LED indicators can be readily observed, this procedure can be followed if the first two do not satisfy the utility company.

  1. Turn off the breaker feeding the branch circuit, if it is not already off, then turn back on.
  2. Observe the inverter(s) status LED, is should begin to flash red when AC power is applied then flash green when the inverter(s) begin to produce power. Time the period of the flashing red LED with a stop watch, it should be 5 minutes or greater.

This can be done for each individual inverter, or for each inverter string as the (utility company) representative present desires.

According to the manufacture, the system complies with the requirements of UL1741, which states that if the inverter detects that the grid has gone out of specification or has completely shut off, then the inverter will “cease exportation” of power. The inverter is allowed to draw current but cannot produce power. Therefore the small amounts of current indicated on an AC ammeter is not leakage current, rather it is the inverter consuming a small amount of power prior to in beginning operation.

Update: From Scott at Enphase Energy:

I had a brief, follow-up comment about one portion of the article. During the 5-minute wait time specified by UL-1741, the Microinverter is not consuming power. It is circulating reactive current in the A/C-filter section of the device.

I just wanted to make sure that the statement of “the inverter consuming a small amount of power prior to in beginning operation” was not potentially misinterpreted as tare-loss, with an Enphase customer thinking that he was losing some of that hard-earned energy during the 5-minute period.

No, we wouldn’t want them to think that, especially after I preached about unshaded locations and voltage drop during the sales presentation.

I have noted that these inverters come on line in 5 minutes and 20 seconds or so after a power outage.

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16 Dec 09 | Solar Electric, Technology | Comments (0)

Capture and store the energy from Lightning?

21 Mar 09 | Technology

A few years ago, I was having a conversation with my brother in law about wind mills and solar panels and he stated “Why can’t we just use the electricity in lightning?”  To which my answer was of course, there is no way to safely do that.  Then I thought about it.  Lightning has a large EMP (ElectroMagnetic Pulse) component that travels some distance away from the actual lightning strike.  In fact, most equipment damage cause by lightning is due to induced currents on power and telephone transmission lines, not direct strikes.

What if say, around tall metal structures like radio and TV transmitting towers, arrays of EMP capturing devices connected to banks of large capacitors were employed.  During a lightning strike the capacitors would become charged, then they could slowly discharge there stored energy to the electrical grid using grid tied inverters.  Of course, this would work best in an area where there is a lot of lightning to begin with, like Florida, for example.

The average lightning strike disipates about 1 Terawatt of power in about 20-40 microseconds.  The magnetic field generated from this event travels out uniformly from the strike point disipating exponentially as a function of distance.  Therefore, the closer to the stike point, the higher the field and the greater yield potential.  To store any meaningful amount of power, a massive capacitor bank, or capacitor bank and battery bank connected in parallel would be needed.

Perhaps some further research is in order.

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21 Mar 09 | Technology | Comments (0)

Solar Green Houses

06 Dec 08 | Solar Electric, Technology, solar thermal

So what you say, all green houses use solar energy.  True enough, but where I live, in the Northeastern US, the growing season is about 6-7 months.  The rest of the year, produce is trucked in from down the Southern US or South America.

What if we could extend the growing season to 10 months?  This would really help out the farmers, who can make more money.  It would help simulate the local economy.  It would reduce the embodied energy in our food.  In all likely hood, the local fresh produce would taste better.  Remember taste?  When was the last time you had a really good hot house tomato grown 1,000 miles away.  How about that fresh local corn?  Why have we settled for bland mass produced vegetables?

There are two main problems with this scenario:

  1. In the Northeast, the cold arrives toward the end of September and does not depart until around May or so.
  2. Coincidental with the cold weather, the amount of sunlight decreases shortening the available energy for plants to convert to the produce we want.

For the first part, the greenhouses can be heated.  Conventional heating systems would waste an inordinate amount of fossil fuel, thus contributing to the problem.  Using an array of solar collectors connected to an insulated underground drainback/storage tank would work nicely.  If the system where designed correctly, it could conceivably extend the growing season into the middle to end of November.  There should be enough solar resource to start the growing season around the middle of February.   Additionally, cold weather/frost tolerant crops, such as broccoli, spinach, lettuce, cauliflower, brussel sprouts, carrots, onions, turnips, beets, et. al. could likely be grown over the winter time, as long as the soil and roots do not freeze.

Then there is the issue of light.  All plants rely on Photosynthesis to convert the sun’s energy into vegetable matter.  Through a process called “Carbon Fixation” plants take in CO2 and H2O (water), using photons (light energy from the sun), create complex sugars which are used as energy for the plants to grow.  By this process, they also release O2 (Oxygen) into the atmosphere, which we need to live and breath.   According to this chart, Plants need specific wavelengths of light to thrive:

Plants required light wavelengths

Plants required light wavelengths

Plants need specific wavelengths of light. If you shine a green light on a plant, it will shrivel up and die. They thrive, however, in the deep blue (430-460 nm) and deep red (630-665nm) regions.  To that end, LED grow lights are becoming all the rage among hydroponics growers.

Therefore, I have been working on a prototype design for a PV power LED grow light.  Something that can be used on grid with a power supply, or off grid with a Photovoltiac panel.  So far, my small panel works quite well, I am growing some spinach with it in my basement.  What is really cool, under the grow light, the plant’s leaves look black or dark gray.  That means that it is absorbing all of the light from the LED’s and not reflecting any of it back.

This light is a bunch of 5mm LEDs wired in series.  It is designed to work on a 12 volt system.  It covers about 1 square foot of growing area and uses 12 watts of power.  It cost $125.00 to prototype (or $1.15 per square inch), although production costs would come down considerably if it were mass produced.

I am currently working on a high powered design that will cover 5-6 square feet of growing area.  It will use 88 watts of power and cost $398.00 to prototype, or about $0.49 per square inch.   Again, costs would come down considerably on a production run.

Larger arrays of these lights would cost even less per square inch as economies of scale takes effect.

There are some advantages to LED’s over conventional grow lights:

  1. LED’s are much more efficient, producing less heat (thus less wasted energy) than conventional grow lights.
  2. Long life.  My prototype LED lights are rated for >90,000 hours.  Using a LED grow light for 12-16 hours per day, that translates to 17 years.  If they are used for supplemental growth (e.g. 8 hours per day for half the year) then the life span would be about 60 years.
  3. It is generally though that LED’s are about 4 times as efficient as High Pressure Sodium (HPS) lights, so a 90-100 watt LED light could replace a 400 watt HPS light.
  4. Light can be tailored to plants or desired outcomes.  Most experiments show adding more blue light (430-450nm) increases vegetative growth.  Adding more red light increase flowering. Other wavelengths can be added depending on the plants needs.

The question is this; will this technology become economical in the future for ordinary growers to use?  Growing food locally would certainly cut down on the transportation costs and the associated polution of long distance farming.

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06 Dec 08 | Solar Electric, Technology, solar thermal | Comments (3)

Is the Solar Energy field recession proof?

23 Jan 08 | General Business, Solar Electric, Technology

Starting a small business during a recession may seem like a recipe for failure. The basic premise is that people will not buy anything other than what is absolutely necessary. So the questions are; is electricity necessary today? How about hot water or heat, is that necessary? Would people be interested in saving money on those things if it involved an initial outlay of cash? How fed up are people with paying for oil, gas or electric? Here is a basic recap (prices for New York State, Hudson Valley region as of January 20, 2008 from NYSERDA):

  • Home heating oil $3.484/gallon
  • Propane $2.851/gallon
  • Electric $0.138 kWh
  • Natural Gas $1.926 therm
  • Solar $0.00
  • Wind $0.00

Will people get that? I know many are rushing off to trade in their SUV’s for fuel efficient cars, but will they consider the energy they use at home as well? Those are things that I want to find out.

Right now, the solar industry is dependent on government subsides, there are no two ways about it. Without generous help from the government (federal and state) neither solar thermal nor photovoltiacs would be viable except in situations where grid power was unavailable (i.e. remote cabins, telecommunications sites, etc). In fact, in the mid 1980’s the industry was brought down to almost nothing as the Reagan administration killed all the tax incentives that were then fueling the solar sector. Will congress restore the tax breaks? Only time will tell. Even if they do, it will take a huge effort to move them away from their corporate sponsors toward the less corporate renewables.

I was listening to an interesting report on the local NPR station on my way home from work today. Amid reports of troubled economic times and other bad omens, there was an upbeat report on the Solar economy right here in the Hudson Valley. You can listen to an .mp3 of the report here (opens media player window). Basically, the it speaks about TSEC (The Solar Energy Consortium) based in Kingston, NY. This is more along the lines of research and development, but that is what will fuel the green economy in the future. It is clear to me that the sustainable movement must be able to stand on it’s own, without government assistance, to succeed. This is a tall order, considering how unfavorably the deck is stacked against renewable energy due to the huge subsides given to coal and oil.

It is, however, possible.

For the short term, the solar energy sector may well be able to weather the up coming recession as more and more people are aware of it and are looking for ways to save money. As much as we would like to believe that the human race is altruistic and will alter it’s behavior of the benefit of the planet, economics trumps environment.

For the long term, the only way that solar, wind and other renewable energy sources will survive is if they become competitive with fossil fuels on their own. This means that fossil fuels have to become more expensive (than they already are) and renewable energy, particularly photovoltaics must become less expensive.

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23 Jan 08 | General Business, Solar Electric, Technology | Comments (0)

Solar Energy Consortium, Kingston NY

21 Dec 07 | Solar Electric, Technology

I was reading the local on line news source this morning when this caught my eye:

Just under $1.5 million has been secured by Congress for the Solar Energy Consortium in Kingston.

Congressman Maurice Hinchey, who secured the funding, said it will be used to develop solar technology.

“These funds will be used to bring a new manufacturing partner into the field here of the solar consortium, and as a result, that consortium is going to grow as a whole and help strength the Hudson Valley’s identity as well,” he said.

Hinchey has already secured $3.2 million for C9 Corporation to conduct solar research and development in conjunction with TSEC.

Which leads me to the question who or what is C9 and TSEC? Here are some of the answers. About 2 years ago, C9 corporation opened a semiconductor manufacturing facility in Kingston. They have been working on research and development in several areas.

C9 Corp. plans to produce three advanced technologies. First, it will manufacture silicon carbide-based, wide band gap, superlattice wafers for high power electric switching devices and high temperature, high speed chips. Superlattice is an alloy of different elements used to form a highly-ordered, crystal lattice structure in semiconductor materials. Wide band gap semiconductors such as silicon carbide have about three times the band gap of silicon with corresponding increases in power density, temperature tolerance, speed and voltage.

For example, wide band gap silicon carbide would allow organizations like NASA to create 600 degree C Integrated Circuits to tolerate the harsh environments encountered by spacecraft, which it can only do in the lab today.

If you have a background in electronics or electrical engineering, you can appreciate the importance of what they are doing. Basically, the enemy of all semiconductors is high heat. Heat will kill a transistor or computer chip, and it makes photovoltaics run less efficiently. Developing a heat tolerant semiconductor will greatly improve the efficiency of photovoltaic cells.

…C9 is helping Nanodynamics-88 develop and manufacture large, high-voltage SiC Schottky diodes and other power devices for the power conversion market. The contract is for next-generation hybrid electric military vehicles.

Or their civilian counterparts… More interesting stuff:

For 40 years, researchers and the government have been trying to produce silicon carbide semiconductors, which have a Figure of Merit improvement of 136 over silicon. Figure of Merit is a number that represents a composite of all the positive features of semiconductor material.

What has held back the success of silicon carbide is the defects that occur from the extreme temperatures – 1,600 and 1,800 C—that must be used to produce it. The primary defects are micropipes, which show up as Swiss cheese-like holes in the wafer, and screw dislocations, which are crystal imperfections throughout the material.

“C9 has developed a technology that is free of both micropipes and screw dislocations,” said Donegan. “C9’s version of silicon carbide can extend the functions of silicon devices to include high temperature operation. Our form of silicon carbide will complement silicon by extending Moore’s Law of Exponential Advancement to several generations,” said Dr. Wang. Moore’s Law states that the transistors on a wafer will shrink in size by 50% every 18 to 24 months.
Dr. Babiak referred to the potential for C9 to manufacture advanced silicon carbide materials as a technology leap that would result from overcoming a number of technical problems, including the limitations of narrow band gap.

The band gap of semiconductor material determines its temperature and voltage characteristics. One of the original semiconductor materials predating silicon is germanium, which has a very narrow band gap and consequently unfavorable temperature and voltage characteristics. Silicon’s wider band gap vastly improved upon that, bringing temperature ranges up to 125 to 150 degree C operation and thereby making electronics available for everyday use in every aspect of life from automotive to home appliances, entertainment and office products.

Silicon carbide’s even wider band gap vastly extends the operating temperature range, speed and voltage characteristics of today’s semiconductors, allowing the creation of new devices that will be a major leap in semiconductor technology. This will affect everyday life in much the same way silicon did 20 years ago with the introduction of microelectronics.

That development would be highly beneficial to photovoltaic technology as well. One of the downsides to photovoltiacs is their low efficiency and high cost. Increasing the band gap width is huge step forward.

Photovoltaic cells produce electricity when they are struck by photons from the sun. When a photon hits the cell surface, one of three things happen; it either passes through the panel, bounces off of the panel (reflected) or is absorbed by the panel. When a photon is absorbed by the panel it excites the electrons in the semiconductor material, which is the desired effect.

However, if the electron is not excited enough to move through the band gap to the next (conduction) level, it generates heat, which is undesired. If the photon contains more energy than what is needed to move through the band gap, the excess energy also creates heat. Heat lowers the efficiency of the semi conductors in general.

By increasing the band gap, more energy will be converted to electricity. By increasing the efficiency of a photovoltiac cell, less raw materials and labor will be needed per manufactured watt, this will be key to lowering costs.

And this is really exciting, to me anyway.

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21 Dec 07 | Solar Electric, Technology | Comments (0)