Adding many more active parts to a system seems like an invitation for failure.  Placing those inverters outside attached to a solar panel, sometimes on a hot roof, also seems like a problem.  Finally, investing in a brand new technology from an unknown company might not be wise.

But then I installed them.  Here is what I like:

1. Each panel now operates at its own Maximum Power Point.  Since I have worked in electronics for over 20 years, I realize that every transistor (thus every panel) has slightly different characteristics.  Having an inverter that is able to adjust for these differences increases efficiency.
2. Some array shading issues are mitigated.  In the Northeast there are a lot of trees.  Leave any plot of land alone for about 10 years and there will be trees growing on it.  Many home owners do not want to clear cut their property.  Using these inverters means that partial array shading will not be as devastating as it would be with a single large inverter.  Basically, each panel acts as its own mini solar array, thus if one panel is shaded, the other unshaded panels are working at full power.
3. The warranty is for 15 years, most inverters are warranted for 5 years.
4. The array wiring is extremely simple, it would be difficult to install these incorrectly.
5. The array is scalable.  If a homeowner Can’t afford 100% PV power right now, install what they can afford, then revisit the situation later.
6. May be a good solution for apartment dwellers and other renters using temporary mounting systems.
7. Can be used in an array with different size PV modules.
8. Monitoring service available.  Monitors and logs output of each solar module in the array, thus can track array performance and be notified of any problems.

Obviously it is better to have a shade free solar site than to compromise the efficiency of the PV panels installed.  However, this makes it a viable option for sites that have a mostly shade free solar window (9am- 3pm year round), and can live with some reduction in array output.

Regarding the issues raised in paragraph two, I think the Enphase record speaks for itself.  I would recommend these to any customer who was looking to do a scalable system, or a system using different sized or types of PV panels.  I would install these on my own house and recommend them to other people as well.  I would be very surprised if other manufactures do not come out with a miniverter product lines.

Unfortunately, the power companies around here are a little behind the curve when it comes to new or innovative technology.  One in particular has been difficult to deal with for establishing a net metering account.

Part III: Liquid Bio Fuels

Renewable: Yes
Environmental impact: Moderate
EROEI: Low
Cost: Low to High
Maintenance cost: Depends

Corn Field prior to harvest

Bio fuels and bio mass can be anything that was grown for the purpose of conversion to a fuel.  A wood lot use to provide fuel for a wood stove to heat a house can be considered bio fuel.  For our purposes, however, I will limit the discussion to liquid fuels mostly used to replace fossil fuels in the transportation sector.

Plants convert sunlight and CO2 into starches, complex sugars and O2 via photosynthesis.  The process of photosynthesis is not fully understood and has not been replicated in a non-living organism.  Some plants, such as corn, sugar beets, sugar cane are good feed stocks for ethanol production.  Other plants, such as soy, corn, palms are good feed stocks for vegetable oils, which can be burned in their raw state, or turned into bio diesel.

The advantages are mainly that these fuels can be used in existing cars and trucks with little or no modifications.  They are lower carbon emitters than conventional fossil fuels because the feed stocks remove CO2 from the atmosphere.  They also produce less non-carbon pollutants such as sulfuric acid, sulfuric oxides and nitric oxides.

The intrinsic value of liquid fuels is high for the transportation sector.  Liquid fuels are easily shipped, stored and transferred between storage and use facilities using existing infrastructure.  Liquid fuels are the densest form of conventional energy and are easily converted to both heat and mechanical motion.  For that reason, many are viable even with low EROEI numbers.  It would be extremely difficult to power a car or truck on solid bio mass such as wood or switch grass.

The down side, especially for corn based ethanol is it increases food costs for two reasons.  Corn used as feed grain is diverted to the energy sector, and farmers who might grow wheat or some other crop end up growing corn because the government subsides are better.

There is also some very serious questions about bio fuels being able to meet the demands for especially the transportation sector

Since this deals only with the Cooler Planet website and there are several other solar oriented “finder” sites out there, one can extrapolate the interest in PV for country. Cooler Planet states that they have about one inquiry per minute. I would multiply that by at least four because there are at least four other well known solar finder sites, making the total solar inquiries about 5700 or more per day.

The solar awareness is creeping in slowly among the general public. If asked, most people could describe a basic solar system. Fifty percent would know the difference between a solar hot water system and a PV system. The solar industry is making in roads, but there is a long way to go.

TACO (Thermal Appliance COmpany) is one of my perennial favorites.  I have used their circulator pumps for all of my solar hot water installations.  I like them because they are efficient units, well made, rugged, easy to service and are manufactured in Rhode Island, which, last time I checked, was a part of the United States.

What has me intrigued today is their 00-VT variable speed control product line for solar hot water applications.  They appear to have integrated a Differential Temperature Controller (DTC) into a variable speed motor drive and attached it to a circulator pump.

From the TACO website:

The (00VT) circulator continually adjusts its speed, maximizing the output of the collector, increasing the usable higher temperature water throughout the day, eliminating short cycling and increasing system performance by 20%.

Features:

• All-in-One Pump and Variable Speed Solar Control
• Available in Several Sizes, 006, 008, 009 and 0011
• User Definable Line Voltage Output,
• Supports Drain Back Applications
• Freeze Protection for Open Systems
• Holiday Function, Minimizes Collector Stagnation
• Adjustable Storage Tank Maximum Setting

Makes a lot of sense to reduce the pump speed based on the Δt of the heat exchanger. This reduces electrical use of the circulator pump, increases the heat transfer efficiency of the heat exchanger and eliminates short cycling.  From the literature, I cannot tell if the pump has an full featured differential temperature controller which would eliminate the need to install a separate one.

I called the factory to ask that question, but did not receive a good reply, so the question remain unanswered.  I believe next spring I will purchase one of these units to experiment with.

The variable speed motor controller is one of two designs, either a variable frequency drive (VFD) which will work on some permanent split capacitor motors such as the 00 circulator pumps use, or a TRIAC device.  One issue with variable speed motor drives is they can often cause RFI (radio frequency interference) if they are not properly shielded and grounded.  It would be interesting to learn which type controller this pump uses and whether or not it produces RF noise.

To that end, there are several advanced PV training courses available from providers like SEI, local community colleges, etc.  In order for a installer to maintain proficiency and keep abreast of changes,  reviewing the code changes as they occur is important.  Taking refresher or advanced courses is a good way to accomplish this goal as well.

In addition to this, NABCEP certification requirements have a minimum formal course requirements.

Solar energy, especially photovoltaics, is an evolving field.  The industry knows a lot more about safe solar installations than even a few years ago.  In order to maintain top notch installations, continued education is a must

They have been not making as much money as in previous years.  Meanwhile, Xcel Energy has come right out and said it:  Customers who have PV panels installed are getting a free ride.  They would like to charge those customers for energy that they might use, which in the face of things sounds a little off to me.

So what is the role of a utility company for those customers who choose to install renewable energy systems?  Are they a giant battery, ready to give and receive power at the whim of a customer?  Can they charge for goods and services that might or might not be used?

This leads to several questions about the way we distribute electrical power in this country.  The customer who invests thousands of dollars to generate a portion of his own power should not be penalized because he doesn’t use utility company power.  On the other hand, utility companies incur significant expenses maintaining the distribution grid.

Then there are the power generators supplying the grid.  Those companies have to anticipate load demand and start or stop entire generating facilities to meet that demand.  Power plants cannot be simply switched on and off, it takes a good deal of effort to get some of these facilities on line.

Clearly some type of working arrangement needs to be implimented between small renewable energy generators and traditional utility companies.  Most of the PV systems being installed today, at least in my area, are grid interactive.  Take the grid away and the system shuts down.  Perhaps some small fee for storing the renewable enery system’s excess kWh until they are used would be fair.  After all, if not grid interactive, the other option is to install a battery storage system, which is expensive and maintenance intensive.   The utility grid is not free for the utility company, they should get something for providing a storage service.

Part II: Hydro Energy

Renewable: Yes
Environmental impact: Moderate to high
EIER: High
Cost: Moderate
Maintenance cost: Low

Hydro energy occurs when the sun heats the earth’s surface causing water to vaporize.  The water vapor is lighter than air so it rises.  Water consists of H₂O, which has a standard atomic weight of  18 versus air which is about 80% nitrogen (N₂) and 20% oxygen (O₂) and have a standard atomic weights of 28 and 32 respectively.

When water vapor rises in the atmosphere, it begins to cool and condense into water droplets.  These droplets form clouds which then become saturated and precipitate.  The water vapor can travel hundreds or thousands of miles from its evaporation point to its precipitation point.  Water falling on higher elevation flows down to sea level (or below) releasing potential energy along the way.

Water wheels and other water powered mechanical devices have been used for over 6,000 years to grind grains, make paper, pump water, etc.  World production of hydro-electric power totaled 2341.1 TWh in 2008.

This is a picture of a small hydro generating station owned by Central Hudson Gas and Electric company located on the Rondout Creek in High Falls, NY.  It was constructed in 1986 and generates approximately 3.2 MW of electricity.  This is enough power to supply about 1400 homes in the Hudson Valley Region.

High Falls hydro generating house

The generating house is to the right, the penstock starts at the weir gate (upper middle of picture between the trees) and goes underground to the generating house where it spins the generating equipment.

Picture of the trash grate over weir gate at entrance of penstock.  The trash grate keeps junk from getting into the penstock and turbines causing damage.  Penstock is a fancy name for pipe.

Trash grate High Falls, NY hydro power plant

The water then outflows from the base of the generating house and returns to the creek.

High Falls NY hydro plant outflow

The energy converted by a hydro-electric plant depends on the height of the water above the generator, commonly called head, and the rate of flow.  Higher head means more pressure and higher generator speeds which translates to voltage.  Higher flow means stronger more reliable mechanical energy which translates to current.

High Falls, NY hydro dam

This site has been generating power of one form or another for nearly three hundred years.  Prior to this hydro electric plant, it was the sight of several mills.

5 KW DC Photovoltaic array mounted on a standing seam roof.

It is a 5 KW PV system attached to a standing seam roof. This system takes up about 420 square feet of roof area and consists of 24 Sharp ND-224UF1 PV panels.  We use Sunwize pre-packaged systems because it eliminates a lot of the minutiae involved in installing grid connected PV systems.  They produce well thought out systems complete with engineering drawings.  This speeds the permit process along nicely.  That being said, even Sunwize grid tied systems occasionally need some different parts than what is supplied.

First, all grid connected PV systems installed in New York state must have a lockable disconnect switch that is accessible to the utility company for safety reasons.  Because this is a pretty large house, the wire runs between the utility room and the disconnect switch are quite long.  I had to up size the wiring to stay below 2% voltage drop.  The larger wire would not work with the NEMA 3R switch provided with the pre-packaged system, so I needed to install a larger switch.

Second, this house has a backup generator with an automatic transfer switch for emergency power.  With that configuration, there could conceivably be a time when the generator is running that the inverter tries to come on line.  If the house was using less than 5,000 watts of power, the excess power from the PV array would be fed to the generator windings causing the field coils to melt.  This is a long shot because in all likely hood, the generator frequency would change dramatically when the inverter came on line causing the inverter to drop out again.  Never the less, in order to avoid any possibility of this happening, a generator running relay is installed between the inverter and the power panel.  This way if the generator is running, the inverter is forced off.

Third, because this is a standing seam roof, the traditional Unirack PV mounting racks that come with the Sunwize grid connected systems could not be used.  Instead, we used S5! standing seam mounts (S5! U mini) with PV clamps (PV anchor kit, 41-60 MM).  These worked out very well.  I used to of the S5! mini clamps to mount the combiner box at the top of the array.

S5! PV mount holding down two Sharp ND-224UF1 panels

We are waiting for the roofer to make an ingress port at the top of the array to make the final connection between the PV array and the inverter.  Once this is done, the system can be inspected and turned on.

To that end I purchased a book called Oil 101.  It is, indeed, a fascinating book that details the complexity of our current energy structure.  The book is an excellent primer on the oil industry, it is well written and easy to understand.  Anyone who drives a car, uses oil to heat their house, uses plastics or any other petroleum product should read this book.  That is to say, everybody should read this book.

What strikes me is how much effort is put into exploration, extraction, refining and shipping.  We take all of this for granted in this country, but any failure in any one of those steps would create a disaster of epic proportions.  Think Hurricane Katrina for the whole county.  The fact that so much of this energy depends on technology, specialized methods, and huge capital outlays should be at least slightly alarming.  That, and our entire economy is build on the availability of cheap energy.  As we have just seen, economic down turns can really put a damper on large cumbersome corporate operations.

It may seem natural to be angry at the oil companies when gas is $4.25 a gallon and electricity is $.20 a kWh.  However, when I read about all of the work and investment these companies have to make, all of the variables from bad weather to bad governments they have to deal with, it also makes me respect the oil companies for all that they do.

Part I: Wind Energy

Wind Energy is derived from the sun due to uneven heating of the earth’s surface.  This creates pressure gradients.  Because nature abhors a vacuum, air from high pressure areas moves toward areas of lower pressure.  From Wikipedia:

It is estimated that the total amount of economically extractable power available from the wind is more than present human power use from all sources.^[12] An estimated 72 TW of wind power on the Earth potentially can be commercially viable,^[13] compared to about 15 TW average global power consumption from all sources in 2005

Renewable: Yes
Environmental impact: Moderate
EIER: Moderate to high
Cost: Moderate
Maintenance cost: Moderate

Here are two videos of wind turbines in Portsmouth, RI.  These units are located about 2 miles apart, one was installed in 2005, the other in 2009.  The wind at ground level was low, but you would not know it watching these things turn:

Portsmouth Abbey, Vestas V-47 660 KW

Portsmouth High School, AAER A-1000S 1 MW:

The Vestas unit turns faster and is a little louder. They both look really cool, however, and both schools are saving a lot of money.