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Sun Volt

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.

Variable Speed pumps

10 Oct 09 | Solar Hot Water, solar thermal
TACO 00 VT solar circulator pump

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.

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10 Oct 09 | Solar Hot Water, solar thermal | Comments (0)

Do solar panels increase global warming?

01 Aug 08 | Environment

I have had several people tell me that solar panels, both photovoltaic and thermal, increase climate change, aka global warming due to the local “Heat Islanding” effect.

Others have said the cost (in CO2) of manufacturing and shipping solar panels is more than there subsequent use would eliminate.

Solar panel Heat Islanding

There is some validity to the first concern. If you take an area that was normally light reflective and put a solar panel in it, less light is being reflected and thus more heat is being generated. However, in the case of a solar thermal panel, most of that heat is then conducted away by Heat Transfer Fluid (HTF) for use or storage. A typical solar thermal panel is 65-70% efficient at converting and removing the energy striking it. The remaining 30-35% of the energy is either reflected off of the glazing or the absorber plate or it is lost due to heat transfer inefficiencies, insulation losses, etc. In short, a solar thermal panel is very efficient at collecting energy and removing it. Having a solar thermal panel on the roof of your house would reduce the solar gain because most of the heat energy is being removed to another location and the panel shades the roof it is attached to.

Photovoltaics however, are not as efficient as solar thermal. The average PV panel in use today is around 15% efficient. Some of the energy passes through the panel and some of it is reflected. Therefore, about 80% the energy striking the panel is converted to heat. The average insolation on earth at mean sea level is 1,000 watts per square meter per hour.

A 4.3 KW grid tied solar system has 24 Sanyo HIP190BA3 PV modules. Each Module is 1.16 M2. The total area is 26.78 M2. Therefore the total energy striking this array is 26.78 KW/hr. The total heat being generated by this array on a sunny day is about 22 KW/hr or about 75,000 BTU/hr. In the mean time, it is producing 4.3 KW of electricity. The average peak sun hours in the Hudson Valley is 4.5 per day so this system can be expected to produce an average of 19.35 kWh per day or 7063 kWh per year. Electricity production in the United States is about 32% efficient. Therefore, that 19.35 kWh if purchased from the power company, would have produced 60.41 KW of waste heat and 32.9 pounds of CO2 vs 99 KW of waste heat and zero pounds of CO2. This system will save 12,000 pounds of CO2 per year or 150 tons of CO2 over a 25 year life.

This should trigger two questions; How much of the sun’s energy would have been absorbed by the surface of the earth and turned into heat regardless of the solar panel and what importance does CO2 have on climate change. To answer the first question is rather complicated. It depends on the color of the surface, the angle of the sun striking the surface and the atmospheric insulative effect. The second question is a little easier to answer

CO2 in the production of solar panels

It takes about 3.6 years (in average insolation) for a PV cell to make the energy used in its production. Therefore, over a PV cell’s 25 year life, it will produce electricity and contribute 86% less CO2 than electricity generated by fossil fuels. This reducing in CO2, a known Green House Gas (GHG) which is thought to be significantly contributing to the global rising in temperatures more than off sets the local heat island effect that PV panels have.

Solar thermal panels take much less time to payback because they are made mainly from copper (absorber plate and piping), aluminum (frame and mounting), insulation and glass. These materials are readily recyclable which greatly reduced the energy required for extraction and refining.  Additionally, a solar thermal panel is much more efficient at collecting energy, so the energy payback comes in about 1.5 years.  Most solar HW systems have some type of AC pump.  Taking that into consideration, the Energy Returned on Energy Invested (EROEI) while the system is operational is about 15, or for every 1 watt of electricity used, 15 watts of energy are gained.  In the Hudson Valley, a two panel SDHW system can expect to save about 3,350 kWh per year. That equals about 5,690 pounds of CO2 per year or 71 tons of CO2 over a 25 year life span.

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01 Aug 08 | Environment | Comments (0)

National Grid petitions to Raise Electrical Rates by 21.7 percent

04 Jul 08 | Conservation, Solar Electric, Solar Hot Water, wind power

Here it comes; the high price of fossil fuels are driving up electrical rates just like everything else.  I read that headline in Rhode Island over the holiday weekend.  How soon until Central Hudson and NYSEG follow suit? How will this impact your family’s budget? 

Current fuel prices in the Hudson Valley (via NYSERDA) are as follows:

  • Electricity: ¢17.1/kWh
  • Natural Gas: $1.68/CCF
  • Propane: $3.149/gallon
  • Home Heating Oil: $4.809/gallon
  • Kerosene: $5.077/gallon

I am very concerned about home heating this coming year.  Many families may need to choose between heating and eating.  Not a pleasant thought.

There are some things that can be done to reduce heating and electrical costs.  I strongly recommend that people start now by

  1. Adding insulation to the attics, walls and floors.
  2. Seal up any outside air infiltration with calks and foam fillers.
  3. Replace old single pane windows and doosr with new energy efficient units.
  4. Have you furnace or boiler serviced.
  5. Replace old inefficient boilers or furnaces with newer more efficient models.
  6. Replace old inefficient appliances such as refrigerators, air conditioners and dishwashers with newer energy star rated models.
  7. Employ energy saving devices like programable thermostats.

Many of these items will pay for themselves with the money you save in a year or two.

If you have done all those things and still want to reduce you energy usage, look into renewable energy systems such as Solar Thermal, Photovoltaics and Wind Power to generate home energy.

Installing such systems can save you lots of money and free you from worrying about rate hikes and fuel costs in the future.  At current equipment and energy prices, a solar domestic hot water system (SDHW) will pay for itself in 4-5 years.  A photovoltaic system will pay for itself in about 8-9 years.

Interest rates are very low.  If you choose to finance you system, you loan payment will likely be lower than potential savings, meaning you will see a an immediate decrease in expenses.  You may also be able to write off the interest on a home equity loan as these systems are capital improvements.  Of course every situation is different and tax matters are best discussed with an accountant or tax preparer.

If you have any questions, contact us, I’d be glad to discuss your options over the phone.
 

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04 Jul 08 | Conservation, Solar Electric, Solar Hot Water, wind power | Comments (0)

Books for the Solar Professional

27 Mar 08 | Solar Electric, Solar Hot Water

There are several reference books about solar energy and wind energy on my book shelf that I refer to from time to time. I find it helpful, especially when I am dealing with a complicated design issue, to do a little research. These books offer guidance and theoretical information which can greatly improve design considerations.

  1. de Winter, Francis, Et Al. Solar Collectors, Energy Storage and Materials, Cambridge, MA: MIT Press, 1990. This book is a great resource for theoretical problems. Very technical with lots of Calculus and Physics base equations for heat transfer, storage, black body radiation, etc. I like to pick it up and peruse through it once in a while just to keep on my toes. More for engineers than for the run of the mill solar installer.
  2. Lane, Thomas. Solar Hot Water Systems, lessons learned 1977 to today Gainesville, FL: Energy Conservation Services of North Florida, 2004. This is the bible on Solar Domestic Hot Water systems. There are a few pages devoted to space heating, but most of the book is for SDHW. Includes information on sizing, mounting of collectors, storage, pumps etc. If you are going to install a SDHW system, this book is a must
  3. Solar Energy International. Photovoltaics Design and Installation Manual. Gabriola Island, BC Canada: New Society Publishers, 2004. Excellent PV installation manual, covers both grid connected and independent PV systems. Has chapters on system sizing, battery sizing, mounting, wiring, etc. Great resource for anyone getting into the PV end of the solar business.
  4. Siegenthaler, John, PE. Modern Hydronic Heating for Residential and Light Commercial Buildings, 2nd edition. Clifton Park, NY: Thomson Learning, Inc, 2004. Great reference book on any type of Hydronic Space heating. Good design resource for heat load sizing, heat loss calculations, radiant systems, etc. I bought this because I am getting more and more inquiries about space heating. I have yet to read this one cover to cover, but I am working on it.
  5. NFPA. National Electrical code, 2008 edition. Quincy, MA: NFPA, 2008. I like to keep the latest edition of the NEC on hand and available. Section 680 deals with PV installations.
  6. Small, Lloyd L. Analytic Geometry and Calculus. New York, NY: Appleton Century Crofts, Inc, 1953. This is an old college Calculus text book that I picked up at a used book store. It helps me remember some of the math if I have any questions or problems working on a calculus equation. Fortunately, almost everything can be plugged into an excel spread sheet and quickly calculated that way, but every once in a while I find myself scratching my head over something.

There are numerous other online sources that are also available. These are huge files and if you click on the link it will start downloading automatically, only use these links if you have high speed internet. They are well worth the trouble to download and read.

  1. Photovoltaic Power Systems and The National Electrical Code: Suggested Practices
  2. A Guide to Photovoltaic System Design and Installation, California Energy Commission Consultant Report 500-01-020, June 2001
  3. Stand-Alone Photovoltaic Systems: A Handbook of Recommended Design Practices

Of course, there are many, many other sources of reference material and I could probably write a book about solar books. However, these are the ones that I find most useful.

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27 Mar 08 | Solar Electric, Solar Hot Water | Comments (0)

The Greater Concern

06 Jul 07 | Commentary, Conservation, Environment

I was thinking about climate change, the human race and other things last night as I drove home. I often use the drive home to contemplate things that happened during the day, things I have heard or read, concerns, plans, etc.

Driving in my car with the air conditioner on it occurred to me that humans may not be able to grasp the big picture, at least not most of them. I say this because I am fairly environmentally conscious, however, because it was a little bit warm out, I saw the need to run the AC. It may seem like such a small thing, turning on the AC in your car, but I’ll bet that act alone uses hundreds of thousands, if not millions of gallons of gas every day. Why? So our hair doesn’t get blown around?

Think about a typical house. How much energy is used or wasted by us every day on things like not turning off the lights, wasting hot water, inefficient appliances, air conditioning set too low, heat set too high. I was reading one of those store catalogs once where it was describing a small blanket. The description stated “Perfect for taking the chill off an air conditioned room.” How about turning off the AC and opening a window if you are chilly?

We are all the center of our own universe. It seems, in spite of the fact that our current communications technologies are unprecedented, that universe is getting smaller. There is so much information available, important stuff, yet most people remain fixated on Paris Hilton, or themselves.

Changing our habits to prevent environmental disaster will require sacrifice. I don’t think it is in us to voluntarily take that on. Sure, there are some who will, but most will continue on as before, oblivious, until some misfortune befalls them and then woe is me.

In this country, there is a culture of consumerism and greed. If we cannot get around that mindset, than we will go no further than this. We are constantly bombarded with advertising for items that we don’t really need. The latest greatest video games, cell phones, toys, clothes, shoes, fast food, cars, etc. How much stuff do we really need?

We need to invest the energy that we have available today in developing and manufacturing renewable energy systems for tomorrow. The current abundance of high energy fossil fuels should be used cautiously and conserved rigorously, not only because it is good for the environment, our existence as a society depends on it. Otherwise we will be like the people of Easter Island, who cut down the last tree on the island in the early 1600’s, after which a great portion of the population starved to death.

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06 Jul 07 | Commentary, Conservation, Environment | Comments (0)