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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.

What happens to a solar system when it snows?

01 Mar 10 | Solar Electric, Solar Hot Water, solar thermal

I have good customers, they ask good questions.  One such question asked of me lately has been “what happens to my solar system when it snows?”  Since I have both a solar thermal system and a photovoltaic system on my house, I can tell them.  Enough sunlight gets through the snow that the panels begin to heat up.  This, in turn, causes the snow to slide off.  Here is a picture of a ground mounted system after receiving over two feet of snow:

Ground mounted PV array after blizzard

Ground mounted PV array after blizzard

It helps that the panels are tilted to 40 degrees, roof mounted systems likely will not shed snow like this.  Still, on a roof mounted system, the snow will melt off, it might take a little longer.  The only system I would be careful of in this climate would be an evacuated tube collector.  Because the tubes have a vacuum, no heat is transfered to the glass envelope, which is really good for collecting heat, but not so good for melting accumulated snow off the collector.

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01 Mar 10 | Solar Electric, Solar Hot Water, solar thermal | Comments (0)

Solar Power: Save money, increase the value of your home

20 Dec 09 | Sales, Solar Electric, Solar Hot Water, solar thermal

I have been going over some of the bills from the last few years. My utility company, Central Hudson Gas and Electric has been increasing the cost of electricity by 9% annually.

central hudson electric rates

Nine percent per year seems like quite a bit, especially since inflation has been running around two to three percent. The increases of fuel costs and energy products in general has far outpaced inflation. Projected out 25 years, the cost per kWh is $1.53! I don’t expect it to get that bad, but one never knows.

Here are some solar facts:

Based on conditions here in NY state:

  • The average home owner chooses to install a 4 KW DC photovoltaic system. This generates 4500 to 5000 KWh per year.
  • With rebates and incentives, the final system cost is about $10-11K.
  • Over the course of the system life (25 years), the electricity generated will cost $0.09 per KWh. Currently, NY electricity averages $0.158 KWh (increasing at 9% per year).
  • Without inflation, that equals a savings of $29,000.00.

Also, based on conditions in NY state:

  • the average home owner chooses to install an 80 SF/80 Gallon solar hot water system. This will supply a family of four with 80% of their hot water annually.
  • With rebates and incentives, that system cost is around $3,800.
  • Over the course of the system life (25 years), the energy converted by this system will cost $0.03 per KWh. Currently, NY electricity averages $0.158 KWh (increases 9% per year)
  • Without inflation, that equals a savings of $16,500.00.

Of course, these are long term investments. In order to realize this type of savings, a homeowner will have to stay put for 25 years. That is a rarity these days.

Solar systems retain almost all of their pre-incentive/rebate value when added to a structure as a capital improvement. Here is a list of residential home improvements and the values added to a typical house:

  1. Two story addition: 94%
  2. Bathroom remodel: 93%
  3. Major Kitchen Remodel: 91%
  4. Solar System: 90%
  5. Basement finish/remodel: 89%
  6. Siding: 88%
  7. Roof Replacement: 85%
  8. Deck: 84%
  9. Hot tub: 84%
  10. Family room addition: 82%
  11. Sun room: 75%
  12. Garage addition: 70%
  13. Backup power generator: 58%

Of course, if the rebates and incentives are considered, then the installation of a solar system is cash positive from day one. What this means is the homeowner pays $11-12K but gets $32,000 of additional home value. I can’t think of a better deal than that.

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20 Dec 09 | Sales, Solar Electric, Solar Hot Water, solar thermal | Comments (0)

Solar Site Assessment Tool

07 Dec 09 | Solar Electric, Solar Hot Water, solar thermal

File under: Yeah, there’s an app for that.

Sun Tracker mashup

Sun Tracker mashup

I received an e-mail from Andrew about a Solar Site Assessment app for 3G iPhones.  I’ll let him tell the story:

I live in Vancouver, BC, when evaluating my own home for a solar installation I discovered a gap in the solar tools market. I have a lot of trees in my backyard and was interested in doing my own shade analysis assessment. So, I looked around and found expensive tools and manual sun plots, and nothing in between. At the same time my son happened to get an iPhone. I was intrigued with the built in compass and inclinometer capabilities, and putting two and two together I come up with an iPhone based solar assessment tool.

You can check out more at their website:

www.imeasuresystems.com/

I know in New York State, NYSERDA requires a site assessment be submitted for each application.  In order for a site to qualify for the NYSERDA rebates, it has to be 80% unshaded or more.  The rebates themselves are performance based, e.g. the better the site, the more the rebate.  This app has the ability to print out a site assessment, which is key.

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07 Dec 09 | Solar Electric, Solar Hot Water, solar thermal | Comments (0)

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)

Solar pool heating

17 Jun 09 | solar thermal

Summer is here and the pools are open, if not a little bit chilly.  Many folks and municipalities with swimming pools extend the swimming season by heating their pools.   Most use some sort of propane or natural gas system to heat the pool water, I have even seen a few heat pumps.  That sounds expensive.  Solar pool heating has been around for a long time and it relatively easy and inexpensive and simple to implement.

I was driving down the road this morning on my way back from an appointment and I saw this:

Enersol unglazed swimming pool heating solar collectors

Enersol unglazed swimming pool heating solar collectors

Just out of the picture to the right is the swimming pool that these collectors service.

Enersol pool heating system

Enersol pool heating system

I had to stop and take a few pictures. According to the sign, this pool is owned and maintained by the Home Owner’s Association (HOA) for the housing development just down the street.

These look like Enersol S-1000 collectors.  They are made of plastic and come in a roll.  To increase the side of the collector system, simply add more collector rolls on the end of the string.  The existing pool pump circulates pool water through them by use of a temperature controlled diverter valve.  I lifted this diagram from their site.  Looks pretty efficient and likely gathers a lot of heat on a sunny day.

The wood frame mounting rack that this installation uses looks first rate, my only comment on it is I think I would put a little more tilt to the south to gather more heat during the spring and fall seasons.  Then again, this is in the middle of the Catskill Mountains, altitude around 2,000 feet AMSL.  When it is raining almost everywhere else, it snows here.  Perhaps there is no spring or fall swimming season, only summer.

In any case, they are likely saving a good deal of money heating the pool this way.  The only other comment I have is there are no state or federal subsides for solar pool or jacuzzi heating.

Here are a few more pictures of this installation:

Enersol pool heating collectors on a wood framed rack

Enersol pool heating collectors on a wood framed rack

Solar heated pool

Solar heated pool

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17 Jun 09 | solar thermal | Comments (0)

Can plastic piping be used in a solar hot water system?

12 May 09 | Solar Hot Water, Training, solar thermal

Short answer: Don’t do it.

Plastic piping such as PEX, PEX AL PEX, PVC, ABS, etc. can be safely used with hot water systems, radiant floor heating and so forth.  It is much cheaper and usually easier to work with than copper or stainless steel.  That being said, it is not appropriate for use in any solar thermal application.

Solar thermal systems have much less control over high temperatures than conventional fossil fuel based systems.  Summer time collector stagnation temperatures can easily reach 300° F.  At these temperatures any plastic piping will melt.  This will cause the Heat Transfer Fluid (HTF) to leak creating a big mess and likely an insurance claim.  The only type if piping that should be used in a collector loop is copper or stainless steel.

Even copper fittings with rubber gaskets (AKA Pro-Press or Viega fittings) are only rated for 250° F.  They should not be used in a solar loop either.

It is worth the extra time, effort and expense to solder copper piping and or purchase stainless steel tubing for use in the solar loop.  This will ensure that the system works well for years to come with no leaks and no call backs.

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12 May 09 | Solar Hot Water, Training, solar thermal | Comments (0)

Calculating energy needed to heat water

05 May 09 | Solar Hot Water, solar thermal

In order to properly size a Solar Domestic Hot Water (SDHW) system, a few pieces of information are needed:

  1. Current and future occupants of the house or average hot water use.
  2. Water supply temperature
  3. Desired hot water temperature
  4. Stand by loss of heating unit

We know that in this area (Mid Hudson Valley) ground water temperature averages 53 degrees.  I know this because I have personally measured the well water temperature at all of our SDHW installations.  This is a good starting point.

Most people desire their hot water temperature to be between 110 to 120 degrees.  There are some applications where hotter water (laundry, dish washers, etc) is desired.  For general purposes 115 degrees is a good ending point.

We also can base average hot water useage on the number of occupants of any house.  The rule of thumb is 20 gallons per person for the first two people, 15 gallons per person for any additional people.  This means that the average family of four uses 70 gallons of hot water per day (20+20+15+15 = 70).

Standby losses for water heaters generally range from 5-10% for electric and oil fired systems and 40% for natural gas or propane water tanks.

For the purposes of Solar Hot Water, an appropriate unit of energy would be the BTU.  If we were using SI units (metric) it would be the Mega Joule (MJ).  Since most HVAC contractors understand things in terms of BTUs, it is easiest to use this unit.

A BTU is defined as amount of heat required to raise the temperature of one pound of liquid water by one degree Fahrenheit.   That is close enough for our purposes.

Therefore, the formula to calculate energy use is:

BTUneeded= 8.34 x Gallons x (desired°F-supply°F) x Standby

Where:

  • BTUneeded = BTUs needed to heat the water for one day
  • 8.34 = Weight in pounds of one gallon of water
  • Gallons = Gallons of hot water used in one day
  • desired°F= Desired temperature of the hot water
  • supply°F= Cold water supply temperature
  • Standby= Standby loss of the heating appliance

A typical family of four heating their hot water with electric or oil would expect to use:

BTUneeded = 8.34 x 80 x (115°F-53°F) x 1.10 = 45,503 BTU/day

A typical family of four heating their hot water with gas or propane would expect to use

BTUneeded = 8.34 x 80 x (115°F-53°F) x 1.40 = 57,913 BTU/day

To get an idea of cost, BTUs need to be converted to energy units that are used for electricity, oil, and gas.

  • Electricity has 3412 BTU per kWh.  Therefore 45,503 ÷ 3412 = 13.3 kWh.  Going rate per kWh is about $0.16.  13.3 kWh x $0.16 = $2.13 per day or $778.83 per year
  • Heating oil has 138,700 BTU per gallon.  Therefore 45,403 ÷ 138,700 = 0.33 gallons.  Going rate per gallon $2.459.  0.33 gallons  x $2.459 = $0.81 per day or $269.19 per year.
  • Propane has 93,000 BTU per gallon.  Therefore 57,913 ÷ 93,000 = 0.62 gallons.  Going rate per gallon $2.428.  0.62 gallons  x $2.428 = $1.51 per day or $549.46 per year.
  • Natural gas has 102,000 BTU per CCF.  Therefore 57,913 ÷ 102,000 = 0.56 CCF.  Going rate per CCF is $1.633.  0.56 CCF x $1.633 = $0.93 per day or $338.42 per year.

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05 May 09 | Solar Hot Water, solar thermal | Comments (0)

Cheap oil=Less solar?

18 Dec 08 | Conservation, Solar Electric, Solar Hot Water, solar thermal

The price of a barrel of oil has dropped more than 70% since it’s all time high of $147.00/bbl in July.  Prices for home heating oil, gasoline, propane and kerosene have dropped accordingly.  All of this seems like welcome relief and great news for the ordinary homeowner especially as this winter looks to be a bad one weather wise.

OPEC meet yesterday and agreed to cut production by 2.2 Million Barrels per Day (MBD).  Non-OPEC oil producers have promised to follow suit.  Will this have an effect on the plummeting value of crude oil?  Apparently not, as oil prices fell below $40.00 per barrel today.  What really seems to be driving the price of oil down is the recession and the fact that people are driving less.  How much less?  About 5% or so.

It might be reasonable to extrapolate a few things from this:

  1. A 5% reduction in driving translates to a 70% reduction in the cost of a barrel of oil, then a relatively small conversion (about 10-15%) of the US fleet to Plug in Electric Vehicles (PEVs) powered by solar, wind or non-fossil fuels would have a significant effect on the price of gasoline.
  2. Use of hybrid technology for public service vehicles, taxi’s, government business, mail delivery, police, etc could reduce government fuel use, costs, and reduce pollution.
  3. Rail transport is the most efficient way to move bulk goods across land.  A typical freight train can transport 1 ton goods 450 miles on one gallon of diesel fuel.  A typical Tractor Trailer (18 wheel truck, 80,000 lbs GVW) moves 1 ton of freight about 250 miles on one gallon of fuel.  Reducing cross country truck transport, using rail instead, then using truck for the last mile deliveries would significantly reduce diesel fuel usage, thus prices.

That is, if the markets are not manipulated by traders to drive up energy prices.  I have a strong feeling that in the next year or two we will find out that the $147.00 barrel of oil was a farce, just like the ENRON induced electrical shortages in California a few years ago.

To all those that say a 10 or 20% renewable energy target by 2015 will make not matter, I beg to differ.  Every little reduction matters.  Many many small reductions through improved efficiency, better technology, and renewable energy systems will add up to a large number.

If anything, the low price of oil shows that we are still vulnerable to unscrupulous operators that would seek to profiteer.  As energy prices drop, we should look at is as an opportunity to install renewable systems while prices are favorable.

For example, the cost of raw materials is coming down.  The price of copper (a significant part of solar thermal collectors are made from copper) has dropped from $9,000 per metric ton to a little under $3,000 per metric ton. Pure Silicon (major component in PV cells) is still high, but has dropped slightly over the last year.

One other possible bad effect of cheap oil.  The oil companies are not going to do any exporation and development of new fields as there is no profit in it for them.  Even if the regulations were relaxed and new leases signed, the whole “Drill baby, Drill” mantra may be met with “No thanks, we’ll just sell what we already have.”  In which case, we may indeed be driving ourselves over a cliff.

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18 Dec 08 | Conservation, Solar Electric, Solar Hot Water, solar thermal | 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)

Five Good Reasons to Install a Solar Energy System

02 Nov 08 | Conservation, Environment, Solar Electric, Solar Hot Water, solar thermal

A friend of mine has a blog called “Today’s Green Construction.“  Todd is a principle engineer for a large construction company and when it comes to construction, he knows what he is talking about.  Recently, he wrote an article called “OPEC is the Best Reason to go Green,” which I thoroughly agree with.  That got me thinking about other reasons to go green and more specifically, to install solar systems.

So here they are, Five (really) good reasons to install a solar energy system:

  1. Energy independence.  No two ways about it, solar systems save energy.  If you heat your hot water with oil, propane, natural gas or electricity, you are almost certainly using fossil fuels.  Some percentage of that is likely to come from imports originating in countries that don’t like us, except for our money.  These countries include Saudi Arabia, Iran, Venezuela, and Russia.  The less energy we use from those source, the less petro dollars that will have to use against us.  My last customer stated “Every dollar that I don’t send to the middle east makes me happy.”  Amen, brother.
  2. Cost savings.  Saving energy means saving money.  With fuel prices rising, all energy costs are going up, even domestically produced natural gas.  Solar systems will pay for themselves many times over during their operating lifetime.  By installing solar equipment, expenses are fixed at their current levels, so as inflation and other economic pressures cause prices to go up, a homeowner that has solar installed will be paying the same price as before.  Remember when gas was $1.00 per gallon?
  3. Environment.  Saving energy also means reducing emissions.  This varies from fuel to fuel, but almost all fossil produce sulfur dioxide and nitric oxides, additionally, carbon monoxide, carbon dioxide, volatile organic compounds VOC’s and toxic metals can also be released into the atmosphere.  Reducing energy also means reduction in energy used to extract energy being used.  The fuel oil delivery truck uses diesel to bring the fuel to a building, that is energy used to supply energy.
  4. Green Jobs.  The more demand for solar (and other green) equipment, the more jobs will be created right here in the United States.  As a solar contractor, I only purchase equipment that is manufactured here.  Last summer, when my normal supply of solar thermal panels dried up, I could have purchased panels made in Israel.  I opted to wait for the US panels, even though it meant loosing business.  Not that I don’t like Israel, I just thought that there was a lot of transportation overhead involved with shipping a panel from half way around the world, and I would rather support the company making products that I know here in the US.
  5. The future.  The earth has a finite amount of oil and other fossil fuels.  Some of those fuel, like natural gas (which is mostly methane) does regenerate, but in much smaller amounts through landfills and large manure digesters.  Others, like oil and coal, do not replenish themselves.  Most geologists agree that we are approaching or have passed the peak oil point, which is the point where oil extraction begins to drop off as resources are depleted.  In order to maintain the society that we and our forefathers have built, a replacement energy system needs to be implemented, else we will find ourselves in a new dark age.  Some predictions are dire, but that does not have to come to pass.

These reason also apply to wind power, geothermal, tidal, and all other renewable energy sources.  Renewable energy is no longer alternative energy, it must grow into our primary energy source.

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02 Nov 08 | Conservation, Environment, Solar Electric, Solar Hot Water, solar thermal | Comments (0)
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