Posts regarding ‘Photovoltaics’

Building Fundamentals: Renewable Energy, a Discussion with Ole Sorensen

April 22nd, 2010 by Clarke

This article by Clarke Snell was originally printed in the New Life Journal.

When we meet with clients in our office for the first time to discuss their desires for a “green” house design, they seldom talk about pivotal but boring things like insulation levels or conscientious weatherization detailing. In fact they very often know very little about what might make the house itself “green”.  Invariably, though, they do discuss alternatives to conventional energy production. Solar electricity, hydronic in-floor heating, and solar hot water are almost always mentioned. That’s a good thing because our buildings are responsible for the lion’s share of our societal energy use and consequently play a huge role in our present pollution and environmental degradation problems. To help us all get a bead on our energy use options,  I sat down recently with Ole Sorensen of Solar Dynamics, a renewable energy system design and installation company based in Asheville.

Most of our clients say they want to take advantage of alternative energy technologies, but in my experience few know what that really means. What is “alternative energy”?

I try to stay away from the word “alternative”. To me “alternative energy” is coal and propane. In the final analysis, the only energy sources that make sense, the ones that need to be our primary sources, are those that can be part of a sustainable lifestyle. My ultimate goal is sustainability. A sustainable energy source is one that can be continually renewed. In other words, things that we don’t have to worry about running out of. As it turns out, almost all renewable energy on this planet comes from the sun. Every ½ hour enough energy from the sun hits the earth’s surface to power human civilization for a year. In other words, we don’t even need to be efficient, we just need to commit to tapping this basically infinite resource in it’s various forms.

The most basic solar energy is direct sunlight which can be used to heat buildings through passive solar design. Direct sunlight can also be used to heat water or some other liquid to create domestic hot water and energy for in-floor hydronic heating. We can also turn that same sunlight into electricity using photovoltaics. Wind-power and hydro-power are also forms of electricity whose power source is the sun. The sun heats air to, in combination with the rotation of the earth, create wind. The sun also evaporates water to create rain and other precipitation, the force that creates a constant cycle of falling water on the planet. We use both wind and falling water to turn turbines that create electricity. The energy held within ocean waves is another largely untapped source of solar energy that is starting to be commercialized for electricity production.

There is constant and exciting innovation in the world of renewable energy technology. However the tech stuff is only half of the equation to creating a sustainable approach to energy. The other part is lifestyle adjustment. Billy Jonas has an environmental song that my kids and I love that repeats the line, “It all comes from the groun-duh.” It’s a basic and profound point. All we have is this one earth. Duh. We simply have to find a balance between what we take and what we leave behind. I’ve seen statistics claiming that if everyone lived like we do in the US, we’d need five planets. Talk about unsustainable!

This is a point that really scares me. I know that we in the US are out of control in terms of our energy consumption and then it seems like the rest of the world is frantically trying to catch up with us. There just isn’t enough planet to go around. How do you see us getting out of this mess?

To illustrate let me tell you a story from my own life. I’m from Denmark and started out in a highly academic environment. I then decided to move into boat building. I couldn’t get my fellow classmates to approach the process academically. We had a hard time communicating. My teacher pointed out to me that my classmates and I were talking two different languages and asked me the question, “Who would have the easier time changing their language, you or them?” I realized that it was up to me to bridge the gap because my background gave me the skills.

I see our present energy and environmental problems in the same way. The rich industrialized countries are the ones using the most energy and creating the most pollution. We’re also the ones with the technology and resources to find sustainable solutions. It’s up to us to solve this problem, to change our language so to speak. Rather than having poorer countries struggling to catch up to us in our present consumption patterns, which is simply impossible, we can show the way for them to utilize renewable energy to prosper sustainably. The concept is not that hard to grasp. We are the ones who have the knowledge and are using the excess. It’s up to us to create enough for others. The wonderful thing is that we actually have the know-how to make this happen if we have the will.

As someone who has lived in this country almost all my life, that’s a little hard to imagine. Our whole paradigm is based on trying to get ahead, seemingly at any cost. How do we go about changing the paradigm. How do we go from being the problem to solving it?

We are already in the middle of the paradigm shift. It’s you and I and all our fellow citizens who create change and most people today want sustainable energy. There is a demand for it. The problem is that in many cases the solutions are not available to everyone because they are too expensive. Since I got into this business, PV (solar electric) panels have gone from 12 to 20% efficiency. In other words, panels now transform into electricity 20% of the solar energy that hits them. That’s an amazing technological improvement in a short time, but clearly there is a lot more energy there for us to capture. We simply need more research and development money to reap even greater improvements in efficiency that will allow prices to come down even further. If we really got behind renewables, put our money where our mouth is so to speak, we could be getting a lot more and paying a lot less.

Another problem is one of scale. As with most things, the smaller the system, the more you pay per unit. PV is just too expensive for most people to put on their houses right now, that’s why most PV installations are commercial. It’s the same with wind power. Commercial wind companies won’t even consider a project unless it’s in the 10 to 20 million dollar range. Smaller and the economics just don’t add up. I think we need more options than simply residential and large commercial. We need community and neighborhood renewable power plants, large enough so that they are affordable but not so large that we necessarily have to wait for the large power companies to get on board.

Countries with high percentages of renewable energy, Denmark for example produces about 20% of its electricity demand from wind, are doing things like this. They have some residential and apartment buildings, but also a lot of larger commercial projects. Germany has a single PV array covering the equivalent of 11 soccer fields. Another array stretches more than ½ mile along the highway to the Munich airport. Germany made a very conscious decision in the 1990’s to go solar. To put it simply, people there were willing to pay more to move toward sustainability and that created the political will to get the government involved. That’s what we need in this county. We need to step up to the plate in support of renewables and then hold our government accountable to make a meaningful transition to renewable energy.

Okay, so far you’ve been talking about the big picture which is of course very important, but it can also be a formula for inaction because we tend to feel overwhelmed with the scale of the problem. It seems that thinking globally and acting locally really fits in this context. You started your business to be part of the solution and your solution is making renewable energy available to residential customers. How does someone go about making renewable energy a part of their daily life, in other words a part of their present or planned house?

When someone comes to me, the first thing we do is discuss their dream. Every situation is unique and depends on a client’s energy consumption, square footage, sun or wind exposure, budget, and current tax credits. Honestly, people almost always begin with dreams of a lot of technology, then we start talking price and many people back off. We then look in their budget for the thing that will make the biggest difference. I like to look at it in terms of a “sustainability budget”. You budget for other things, why not sustainability. Let’s say you have $15,000 in your sustainability budget. In other words, you want to invest $15,000 now in moving toward energy sustainability. You’ll get this money back in utility bill savings over time, but it’s an upfront expenditure. What’s the best way to spend that money?

Well, energy production isn’t the first thing to consider. That’s my dilemma as a renewable energy installer. I need to keep in business, but I also have a responsibility to the planet and society. So when someone comes to me with limited funds, I tell them first to reduce their energy needs by building smaller and by creating an efficient building envelope, in other words installing more insulation and paying attention to weatherization. Next, I tell them to choose construction methods that will create a long-lasting durable building that won’t require a lot  of maintenance. Then we talk about reducing energy usage because the less energy you use, the more affordable your renewable energy system will be.

At this point we’re ready to talk about energy. Let’s go back to the original example of a modest $15,000 sustainability budget. My suggestion would be to spend $8,000 for additional insulation and $7,000 for a quality solar hot water system. You’ll get more bang for your buck this way than spending the $15,000 on a solar electric system. Don’t get me wrong. I applaud and support clients who make a commitment to PV. I’m just realistic that for the majority of people right now there are more cost effective ways to get the same positive environmental effects. If a client can’t afford PV, then my “best of both worlds” solution here is to install solar hot water and plan for an eventual PV system by putting in conduit and other inexpensive infrastructure as part of the initial construction process. If the budget just really can’t support even solar hot water, we can also install transmission lines in the wall and take other steps to make the eventual installation easy, efficient, and more cost effective. In my opinion, a solar hot water rough-in should be as important as a front door in new construction.

What about hydronic in-floor heating. Why do you install these systems?

Hydronic heating can use either radiators or can be set in a slab or under a floor. These systems, especially the in-floor variety, are sustainable because they are incredibly efficient. The boilers I use are 97% efficient and don’t require energy hog fans as with air source systems. In addition, hydronics can easily utilize direct solar radiation as a heat input. The same solar hot water heating system we’ve been discussing can do double duty as a heat source for your radiant heating system. In my opinion, hydronic heating has the lowest environmental impact of any heating system available, including burning wood. Of course, a big selling point for hydronics is comfort. In-floor hydronic heat creates a wonderful, mellow heat that doesn’t dry the air or make noise while it’s running.

One of the common complaints I hear about renewable energy systems is that the exposed machinery is “ugly”. What’s your response to that criticism?

Personally, I can get ruthless when it comes to aesthetics. If the most efficient car in the world looked like a piece of cheese, I’d drive a piece of cheese. Of course, as a company we are sensitive to and try to accommodate the aesthetic needs of our clients. To give solar panels as an example, at our latitude and with most roof pitches, it is going to be more efficient to raise roof-mounted panels at an angle to the roof. However, sometimes customers want their panels to lie flat on the roof because they feel it looks better. If our analysis tells us that this will result in only an insignificant reduction in system efficiency, we’re happy to do it. If, on the other hand, that isn’t the case, then we feel the need to stand our ground and install the panels at an angle to the roof. In the end, this always results in a much happier customer. We have to hold on to the big picture: our goal of sustainability. If it means getting over a perception of what you consider to be ugly, then so be it.

Here’s another example. One of our wind power customers had a hard time convincing his neighbors and the press that the wind turbine he planned to install wouldn’t be an eye sore. It wasn’t until we finished the installation that they realized what a simple, eloquent machine this was and not as huge as they imagined in their minds. One journalist even apologized and wrote a second positive article about it. Education is the key. When people complain about how ridge-top wind-power systems will adversely effect their “view shed”, I tell them that there won’t be a view shed without wind-power. In the last few years, there has been a marked deterioration in air quality even in our rural area. That’s not haze, people, that’s smog.

I like to say that sustainability and denial are archenemies. They just can’t work together. We have to decide to let go of our denial and embrace sustainability. To contact Ole and for more information on Solar Dynamics:

Phone: 828-665-8507 or 828-231-9106

Email: ole@solardynamicsnc.com

Web: http://solardynamicsnc.com

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Micro-Inverters

October 30th, 2009 by Seldom

Since there are no moving parts, PV doesn’t require any maintenance except cleaning the glass.  The photovoltaic collector doesn’t fail.  If a panel fails it’s usually because a solder joint connecting the cells fails.  Most manufactures warranty their panels for 80% of rated output for 25 years.

Inverters have traditionally been the weak point in the system. Mean failure rate has been 5 years. 2 year warranties were the norm in the late 1990s. 5 year warranties are common now, and some manufacturers offer 10 year.

Central String Inverters

PV panels produce DC power which is either used directly by DC lighting and appliances or wired to a central inverter, typically located indoors. An NREL study (PDF page 41) found that inverters have needed to be replaced every 5-10 years while panels last 25 years or more.

Central inverter PV systems are wired in series like Christmas lights. Central inverters use a Maximum Power Point Tracking (MPPT) algorithm to determine the optimal output of the system. Therefore, the output of the whole system was only as good as the worst performing module. If there is one bad solder connection, one dirty cell, or one partially shaded cell the whole system is affected. Just like Christmas lights it is impossible to find a problem without testing every individual part.

http://www.ratechsolar.com/galery/watsonville_b/2.jpg

German and Austrian central inverters are the best quality because their government incentive programs require installers to warrant the system for 10 years which put pressure on manufacturers to improve their reliability to stay competitive. North American manufacturers have not kept up.

Micro-Inverters

That’s all changed with micro-inverters. They mount outside attached to each panel. With micro-inverters AC power leaves each panel. There’s less inefficiency due to DC voltage drop. The Christmas light problem is solved. Micro-inverters get as much energy out of each panel as it can produce, so partial shading is no longer a problem. If an inverter fails the rest of the system still functions, and it’s a relatively small replacement cost compared to a central inverter.

Enphase micro-inverter

Micro-inverters are also designed to be much more reliable. Enphase credits four things:

  1. Micro-inverters process relatively small amounts of power at low DC voltages which allows them to incorporate more components on the semiconductor chip rather than soldering together a bunch of analog electronics.
  2. Because of the small amount of power processing, the temperature rise is lower. In fact they use passive cooling rather than fan cooling like traditional inverters.
  3. NEMA 6 enclosure is air, water, dust, and insect tight. Traditional inverters are like computers with cooling fans actively flowing dust into the enclosure.
  4. Potted design. The enclosure is filled with “an encapsulating compound” which improves heat dissipation and provides component protection.

Traditional inverters use electrolytic capacitors which are notorious for their short life. Microinverters still use them, but they use a more durable design. From Enphase Reliability Study for Electrolytic Capacitors:

“For traditional power converters, an acceptable useful life of capacitors is as low as 2000h at 85°C. Out of desire to increase the reliability of its inverters, Enphase Micro-inverters use capacitors rated from 4000 to 10000h at 105°C. The capacitor lifetime is very sensitive to temperature as its useful life doubles for every 10°C temperature drop.”

Enphase also parallels their capacitors. When one fails the quality of the current wave degrades because it gets a little more ripple in it, but it’s not catastrophic to the inverter.

Since micro-inverters are a new development there’s no lifespan data. In an Enphase white paper they compare their Mean Time Between Failures (MTBF) determined from accelerated lifecycle testing to other electronics:

Sun Microsystems:

“The concept of MTBF is often confused with a component’s expected useful life. In fact, these concepts are not the same. For example, a battery may have a useful life of four hours and have an MTBF of 100,000 hours. These figures indicate that in a population of 100,000 batteries there will be approximately one battery failure every hour during its four hour lifespan.”

Enphase has a 600 year MTBF goal, which would make integrating micro-inverters with solar panels at the factory the default. At that point solar panels will be truly plug and play.

The one downside to micro-inverters seems to be for off-grid systems. Since each panel is putting out AC power, you have to have another central inverter to convert it to DC to store it in the batteries.

There are at least a dozen companies working on micro-inverters, but Enphase is the only company shipping a product that we’re aware of.

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Electrical Cost Trend

October 5th, 2009 by Seldom

This chart is from Mike and Chris at Solarnomics. Progress Energy is our local utility.

Historic Electrical Cost2

Combine that with the falling price of PV, and solar is looking pretty good.

Check out this graph too. Even though the cost of electricity is going up, earning power increases faster: US Labor for Electricity

:: Solarnomics.net

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Wind and Solar Resource Maps

September 4th, 2009 by Seldom

FirstLook has really pretty wind and solar resource maps.

Picture 4

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Solar Panel Price Drop

August 27th, 2009 by Seldom

From a New York Times article on solar pricing:

Panel prices have fallen about 40 percent since the middle of last year, driven down partly by an increase in the supply of a crucial ingredient for panels, according to analysts at the investment bank Piper Jaffray.

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Grid Parity

May 17th, 2009 by Seldom

I keep being surprised that people who should know this don’t.  This is from Wikipedia:

Photovoltaic production has been doubling every two years, increasing by an average of 48 percent each year since 2002, making it the world’s fastest-growing energy technology.[4]

For the last 40 years, every time the world production rate of PV doubles, the price falls by 18%.  See this earlier post for more information:  PV Price Declining Again

Grid parity, the point at which photovoltaic electricity is equal to or cheaper than grid power, is achieved first in areas with abundant sun and high costs for electricity such as in California and Japan.[77]

Grid parity has been reached in Hawaii and other islands that otherwise use fossil fuel (diesel fuel) to produce electricity, and most of the country is expected to reach grid parity by 2015.[78][79]

General Electric’s Chief Engineer predicts grid parity without subsidies in sunny parts of the United States by around 2015. Other companies predict an earlier date:[80] the cost of solar power will be below grid parity for more than half of residential customers and 10% of commercial customers in the OECD, as long as grid electricity prices do not decrease through 2010.[81]

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Buying PV is a Dumb Use of Money

March 16th, 2009 by Seldom

Brad Templeton explains that you have to look at the bigger picture.

If you’re the sort of person who would put up a solar system, you probably already switched to CFL or other efficient lighting. Good. But you can do more. If you took a few hours of your time, and just six of your dollars, you could walk down the street in some town giving out CFL bulbs to people who would let you take out their old bulb and install the new one, making sure the bulb will really be effective. If you manage to get just 13 bulbs replaced that are used for just 3 hours per night, you’ve taken as much power off the grid as a $7,800 1000 watt PV panel. All for $40 and an hour or two of your time…

The bulbs stick out, but there are other things you can do. A new fridge, as noted, will save a lot of power. It’s surprising how bad fridges from the 80s and 90s are compared to those of 2009. Buying one for yourself actually saves you money, but you could even go out and buy new fridges for any neighbours who have models that are 15 to 20 years old, and it would still be better than putting that solar panel on your roof.

You could also buy people new gas dryers. Because gas has gone up they don’t save as much money as they used to, and they need a gas plumber to install, but they still beat the panels. Not buying one for yourself. I mean simply going to your neighbour and saying, “would you like a brand new gas dryer and the free services of a plumber at my expense to hook it up and toss out your electric one?” It’s a real win if you single out people with large families and lots of laundry. You could do even better if you convinced them to use a clothesline more, but that’s a harder sell. A new dryer is much easier.

::  Are Solar Panels a Wasteful Way to go Green?

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PV Price Declining Again

March 12th, 2009 by Seldom

For the last 40 years, every time the world production rate of PV doubles, the price falls by 18%.

However, the PV price drop stalled out in 2004 – mainly due to a shortage of silicon. Demand has been artificially inflated by government subsidies (mostly Germany), and the price of silicone went from $25/kg in 2003 to $400/kg in 2008.

Now prices are falling again. I’m sure it’s partially due to a recession induced drop in demand for computer chips and solar panels, but more silicon processing plants are also coming on line.

After hitting $4.20 a watt in the middle of 2008, solar panel prices have slid almost 30 percent to about $3 a watt, with research firm New Energy Finance predicting a further 20% drop this year.

PV prices are likely to continue dropping in months ahead. Renewable Energy World reported, “The cost of photovoltaic electricity is due to plummet in 2009, according to a new analysis by New Energy Finance. Its latest Silicon and Wafer Price Index shows average silicon contract prices falling by more than 30% in 2009 compared with 2008. . . . Furthermore, with thin-film PV module manufacturing costs approaching the $1/watt mark, crystalline silicon-based PV will come under severe competition for larger projects, resulting in margins shrinking throughout the silicon value chain, the company argues. . . . This may pressure crystalline silicon module manufacturers to reduce selling prices . . . $4/watt could drop to $2.60/watt by the end of 2009.

Keep in mind, this is for the PV panels themselves. For residential sized systems the costs break down roughly like this:

$4 PV modules
$1 Inverter
$1 Installation
$2 Balance of system (wiring, disconnects, etc.)
$8 per watt installed

:: Green Building Advisor

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R.I.P.V.

November 25th, 2008 by admin

Spain Solar Cemetery

MADRID, Spain—A new kind of silent hero has joined the fight against climate change.

Santa Coloma de Gramenet, a gritty, working-class town outside Barcelona, has placed a sea of solar panels atop mausoleums at its cemetery, transforming a place of perpetual rest into one buzzing with renewable energy.

Flat, open and sun-drenched land is so scarce in Santa Coloma that the graveyard was just about the only viable spot to move ahead with its solar energy program.

The power the 462 panels produces — equivalent to the yearly use by 60 homes — flows into the local energy grid for normal consumption and is one community’s odd nod to the fight against global warming.

“The best tribute we can pay to our ancestors, whatever your religion may be, is to generate clean energy for new generations. That is our leitmotif,” said Esteve Serret, director Conste-Live Energy, a Spanish company that runs the cemetery in Santa Coloma and also works in renewable energy.

In row after row of gleaming, blue-gray, the panels rest on mausoleums holding five layers of coffins, many of them marked with bouquets of fake flowers. The panels face almost due south, which is good for soaking up sunshine, and started working on Wednesday — the culmination of a project that began three years ago.

The concept emerged as a way to utilize an ideal stretch of land in a town that wants solar energy but is so densely built-up — Santa Coloma’s population of 124,000 is crammed into four square kilometers (1.5 square miles) — it had virtually no place to generate it.

At first, parking solar panels on coffins was a tough sell, said Antoni Fogue, a city council member who was a driving force behind the plan.

“Let’s say we heard things like, ‘they’re crazy. Who do they think they are? What a lack of respect!’ “Fogue said in a telephone interview.

But town hall and cemetery officials waged a public-awareness campaign to explain the worthiness of the project, and the painstaking care with which it would be carried out. Eventually it worked, Fogue said.

The panels were erected at a low angle so as to be as unobtrusive as possible.

“There has not been any problem whatsoever because people who go to the cemetery see that nothing has changed,” Fogue said. “This installation is compatible with respect for the deceased and for the families of the deceased.”

The cemetery hold the remains of about 57,000 people and the solar panels cover less than 5 percent of the total surface area. They cost 720,000 euros ($900,000) to install and each year will keep about 62 tons of carbon dioxide out of the atmosphere, Serret said.

The community’s leaders hope to erect more panels and triple the electricity output, Fogue said. Before this, the town had four other solar parks — atop buildings and such — but the cemetery is by far the biggest.

He said he has heard of cemeteries elsewhere in Spain with solar panels on the roofs of their office buildings, but not on above-ground graves.

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