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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.

How will Solar change the electrical contractor business

16 Feb 10 | Solar Electric

I read an interesting article yesterday regarding how the solar industry will change the job of electricians.  My experience is thus:  Electricians get asked a lot of questions about solar (photovoltaics mostly) by their customers.  Some attempt to give good answers, some may even look into doing solar installations a little, but most are not interested.  At least right now.

In the future, perhaps solar installation training will become part of electrical apprenticeship programs.  The main skill sets that a solar installer has, which an electrician does not, is the site analysis, system design and intimate knowledge of available incentives and grants.  System design is getting easier with the advent of microverters.  In new construction, at least some of the system design aspect should be up to the architect, e.g. a roof facing true south tilted at latitude.  In retrofitting existing buildings, however, compromise is often the case.  With performance based incentives, such as what is available in New York state, that can increase the system’s cost.

In general, green construction requires an integrated approach.  All of the various systems need to work together to reduce or eliminate traditional energy inputs.  Electrical contracting is but one part of that equation.  There are many other green technologies available to electricians, such as reduced power lighting, variable speed motor controllers, energy efficient appliances, smart building systems, etc.

The article is an interesting read and brings out many good points.

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16 Feb 10 | Solar Electric | Comments (0)

More Solar jobs in the Hudson Valley

14 Apr 09 | Solar Electric

In the good news department, another PV company has chosen the Hudson Valley to set up manufacturing facility.

SpectraWatt, Inc., a manufacturer and supplier of advanced silicon photovoltaic cells, announced it would move its headquarters from Oregon to the Hudson Valley Research Park in East Fishkill, initially creating over 100 jobs within the first year of operation. That will go up to 150 by the time phase one is up and running in two years.The company expects to be in production early in 2010. Its first factory line will have an initial manufacturing capacity of 60 megawatts; additional lines are being planned with site capacity exceeding 120 mw within the first two years of operation.

This is a good use of excess manufacturing space at the IBM East Fishkill’s Hudson Valley Research Park. Building 334 is currently a 300 mm and 200 mm chip fab for NXP (Formerly Philips Semiconductor). The press release goes on to cite an abundance of skilled labor plus many economic incentives offered by Dutchess County and the State of New York.

All of this is good news of course, for the local community and for the solar industry. I would like to see some type of solar thermal panel manufacturer in this area. Solar heating is still 4-5 times more efficient that photovoltaics. As proven by my own solar thermal installation plus many many more in the area, it works well in this climate and can make a significant reduction in residential energy use.

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14 Apr 09 | Solar Electric | Comments (0)

Research&Development of Solar Selective Coatings Pays Off

07 Nov 08 | General, Solar Electric

From just up the road a short distance, researchers at RPI (Rensselaer Polytechnic Institute) have discovered a process that greatly increases the absorption of sunlight by photovoltaic panels and allows those panels to use the entire solar spectrum from nearly any incident angle.

“To get maximum efficiency when converting solar power into electricity, you want a solar panel that can absorb nearly every single photon of light, regardless of the sun’s position in the sky,” said Shawn-Yu Lin, professor of physics at Rensselaer and a member of the university’s Future Chips Constellation, who led the research project. “Our new antireflective coating makes this possible.”

It is possible by using nano technology to create seven layers nano rods.  Each layer is designed to transmit a specific wave length (color) of light.  The result is an absorption efficiency of greater than 96%.  This is indeed great news for PV cell producers, as the current light absorption efficiency is about 67 percent for the typical PV panel.

The seven layers, each with a height of 50 nanometers to 100 nanometers, are made up of silicon dioxide and titanium dioxide nanorods positioned at an oblique angle – each layer looks and functions similar to a dense forest where sunlight is ‘captured’ between the trees.

The major implication for solar manufactures is smaller more powerful PV cells can be produced with less raw material.  Is this the breakthrough the solar industry has been waiting for?  Maybe.  In any case, it certainly seems like a step in the right direction.

The one problem I see with all of this is the efficiency of the photovoltaic cell itself.  A PV cell is essentially a large exposed transistor.  When a photon strikes a P-N junction, one of four things happens; it bounces off, it passes through to the other side, it gets converted to heat, or it knocks an electron free.  Of course the first situation is mostly cured by the selective coating.  The last situation is the desired outcome.  Conversion to heat remains a problem.

Currently manufactured PV cell technology has roughly a 15% efficiency from insolation rate to electricity production.  As we learned above, some of this efficiency loss is due to reflection of light from the surface of the PV cell.  A comparison of the total light reaching the PN junction (67% of the available sunlight) compared to the output of the PV cell, shows that the actual conversion efficiency of the PN junction is about 22%.  The remainder either passes through the PV cell substrate or generates heat.  The selective coating applied to a PV cell will increase the heat in the PN juction by 25-30%.

Heat is a major problem to semiconductors.  Heat reduces efficiency and lifespan of a traditional silicone based PV cell.  The computer industry has gone to great lengths to improve the heat tolerances of the semiconductors used in computer chips, therefore, this is not an insurmountable problem.  It does, however, need to be addressed in cells that will use the selective coating developed at RPI.

It will likely take several years for this technology to make it onto the general market.  In the mean time, every watt of installed PV is one less watt generated by fossil fuels.

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07 Nov 08 | General, Solar Electric | Comments (0)

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)

Sizing a grid tied PV system

01 Sep 08 | Solar Electric

photovoltiac module

I get several calls per week from potential customers wondering how much or how little of a PV system they will need to off set their electrical use.  Grid tied PV sizing is pretty straight forward.  A Basic due south facing system should be tilted at latitude (~42 degrees in the Hudson Valley).  This is the bench mark for system sizing.  Unfortunately, most systems are not tilted at latitude and/or facing due south.  The benchmark system looks something like this:

  1. Annual kWh ÷ 365 days = kWh per day
  2. Percentage of electricity to offset (decimal)
  3. kWh per day ÷ sun hours (about 5 hours in the Hudson Valley)
  4. Figure in losses (temperature loss 88%, system derate 84%, inverter 94%)

For example, my house uses about 8,000 kWh (obtained from utility bills) per year.  Therefore:

8000 kWh ÷ 365 days = 21.9 kWh per day.

I want to offset 100 percent, so 21.9 kWh × 1.0 = 21.9 kWh

I have an average of 5 sun hours per day, so 21.9 kWh ÷ 5 hours = 4.38 kW

Calculate system temperature loss, 4.38 kW ÷ 0.88 = 4.98 kW

Calculate system derate, 4.98 kW ÷ 0.84 = 5.93 kW

Calculate inverter loss, 5.93 kW ÷ 0.94 = 6.3 kW

Therefore, I would need a 6.3 kW system facing due south, tilted at 42 degrees to off set 100% of my electrical use.  That is the simple answer.  It gets more complicated (and larger) as the azimuth and elevation of a typical installation are not usually ideal.  A site visit and investigation with a solar path finder will usually nail down the specifics.

Installed, with all federal and state credits and rebates, that system would cost about $4.50 per watt, or about $28,350.00.

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01 Sep 08 | Solar Electric | 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)

Central Hudson is requesting a rate hike

29 Jul 08 | Solar Electric

In one of the stranger press releases I have read in a while, Central Hudson Energy Group (NYSE:CHG) states:

Higher energy costs induced our customers to use less energy… the weakening economy has further induced our customers to use less energy… As a result, we believe it is necessary and prudent to take two actions. First, we are reducing our earnings guidance for 2008, and second, we are filing a utility rate case to bring our revenues into line with the costs to serve our customers. (emphasis mine)

Which is interesting in a way. The stock holders of a publicly traded company expect a certain payout over time, the utility company does everything in it’s power to provide that payout, including reducing line men and support staff, ect. However, when the economy really hits the floor and people begin conserving electricity so they can still pay for it, it is time to ask for a rate increase. Nice. By the way, I am already paying ¢16.8/kWh. How much higher can it go?

This is the problem with a publicly traded utility company. The most important thing is not the customer or the quality of service, its the bottom line on a P&L. It is more important to the CEO and the board of directors to keep the stock value high so they can get their yearly bonus and retire to Martha’s Vineyard than to provide good, reasonably priced electrical service to the community.

So, what is a homeowner to do? If you have read this blog, you already know the answer to that. Take control of the situation and be your own power company. Photovoltaics are looking more and more competitive these days especially with the state incentives available. As energy prices continue to rise and PV prices either stay relatively the same or drop, the utility companies will find themselves competing head to head with renewable energy products. They may find that they are pricing themselves out of a customer.

Update: It looks like they are filing for 3.5% increase on electricity and 10% on natural gas.

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29 Jul 08 | Solar Electric | Comments (0)

How long do Solar Systems last?

26 Jul 08 | Solar Electric, Solar Hot Water

That is a very common question. The answer is, it depends. Solar systems, like all other mechanical systems require some maintenance. Last week, I came across a solar hot water drain back system that was 28 years old. The great thing is, it was still working just like the day it was installed. The only problem the home owner had encountered was a bad circulator pump, which the plumber replaced.

Properly installed drain back solar hot water systems using distilled water could, in theory, last almost indefinitely. Solar Hot water systems that use antifreeze will likely last only 30 years or so. Still, that is a great payback. For either system, over the course of its operational life, it should easily pay for it self 4 to 5 times over.

Photovoltaics are said to last 25 years however, their output slowly declines over time. After 25 years, most current photovoltaic panels will be producing about 80% of their rated power. Still, that is not bad, and a well designed photovoltaic system should pay for itself at least two to three times over its operational life (with current incentives).

The advantages of renewable energy systems, for those that are in it for the long haul, are:

  1. Stabilizes energy prices at or below their current levels, gives the property owner more control over expenses.
  2. Increases the property value of the residence or building they are installed on.
  3. Reduces emissions and environmental pollutants from nearby electrical plants.
  4. Reduces overall electrical load on grid, thus reducing the need for more power plants and high tension distribution lines.
  5. Spreads out electrical generation capacity, thus making it more difficult for any one catastrophic event to cause a regional blackout (distributed generation).
  6. Reduces the use of fossil fuels and thus dependence on other countries to provide energy for us.

As you can see, there are many advantages to a solar thermal, photovoltaic, wind, or microhydro system

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26 Jul 08 | Solar Electric, Solar Hot Water | Comments (0)

PV panels on Hybrid Cars

08 Jul 08 | Solar Electric

I always wondered why hybrid cars did not have some sort of PV panel on the roof or trunk area. It seems that a PV panel could help charge the batteries or keep them at optimum charge, thus reducing the use of the gas motor. This is especially true of plug in hybrids, which rely more on the electric motor and batteries than there non-plug in cousins.

It seems that Toyota has been thinking the same thing:

Toyota Motor Corp plans to install solar panels on some Prius hybrids in its next remodeling, responding to growing demand for “green” cars amid record-high oil prices…

The panels, supplied by Kyocera Corp would be able to power part of the air-conditioning on high-end versions of the gasoline-electric Prius, the source said.

“It’s more of a symbolic gesture,” said the source, who asked not to be identified. “It’s very difficult to power much more than that with solar energy.”

That is interesting that it is seen as a “symbolic gesture.” Of course, it would be impossible to power a moving car with a solar panel, but I would think that storage would not be an issue with the hybrid’s battery bank available. Plus, think of all those cars in the mall parking lot… If each one was charging a battery while it’s owner was in shopping, how much energy would that be saving when the happy shoppers returned home?

PV and all solar energy systems work rather like a marathon versus a sprint. Over long periods of time, large amounts of energy can be collected and used. High energy short term needs are still best met by hydrocarbon energy systems.

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08 Jul 08 | Solar Electric | Comments (0)

Solar power backup for Critical Household Systems

06 Apr 08 | Solar Electric, wind power

Almost everyone has experienced a black out. Thankfully, they are often for short periods and the line men work hard to get the power back on to everyone as quickly as possible. However, if major damage is inflicted upon the power grid, it can take quite a while to repair. Are you prepared to live without electricity for days, weeks or even months?

Many people have installed gas or diesel generators to power their houses. These units can run reliably for days or even weeks at a time, but they also require refueling. After Hurricanes Ivan in Pensacola and Katrina in New Orleans, it was discovered that motor fuel can often be in short supply after major disasters as the electric transfer pumps required to move the fuel from storage to use are inoperative. It can also be difficult to deliver fuel due to blocked or flooded road ways.

Additionally, generators require maintenance, the engine oil needs to be changed, they need to be  exercised periodically.  Solar panels need almost no maintenance, perhaps in a prolonged dry spell, the dust could be washed off once in a while.  Even that is optional.

As solar powered backup system requires no fuel and if properly sized can run your critical household electric load indefinitely. These systems can be individually sized according to the load calculations. Additionally, they can be configured as a normally solar powered system that is backed up by the electrical grid. If a location has a good wind resource, a small wind turbine and be used to augment the solar system during inclement weather.

Instead of using the PV panels to merely to keep a battery bank charged, the PV panels and battery bank can be the primary source of power. The electrical grid can be used as a standby in case the batteries get too low. A reserve charge can be built in to the battery bank to run the critical loads in absence of both sun and grid power.

This is best of both worlds.

Critical loads

Indentifying critical loads is the first step. At my house we have a well pump to supply water, an oil fired boiler for heat, an electric refrigerator, two sump pumps to keep the basement dry, and two circulator pumps on the solar hot water system. I would also like to power the computer network and one or two outlets for lighting. All of these appliances have name plate information which give the power consumed. If the loads are given in watts, they need to be converted to amps. To do this, use Ohm’s law, which states:

P=I x E

where P is the power in watts, I is the current in Amps and E is the Voltage.

Thus if something if something draws 300 watts, you would divide that by 120 volts and get 2.5 amps.

Load Name
 Manufacture/Model
 Load Current @ 120 VAC (Amps)
 Load Power (Watts or VA)
 Duty Cycle (percent/hr)
 Amp/day (Amps x duty cycle x 24)
Well Pump
 Goulds 10GS10422
 7.9*
 948
 2
 3.8
Boiler, heating
 Dunkirk/Grundfos
 4.3
 516
 10
 10.32
Refrigerator
 Kenmore
 2.1
 252
 10
 5.1
Solar Hot Water Pumps
 Taco 009B and 006B
 1.8
 216
 20
 8.64
Computer Network
 Various
 0.3
 36
 100
 7.2
Water Filters
 Kenmore
 0.3
 36
 100
 7.2
Misc loads, lights, etc
3.0
 360
 40
 28.8

Total power required is 2364 watts, if all loads are one at the same time, which is unlikely. Additionally, the well pump requires a large starting load, something in the range of 5,000 watts. This will have to be figured into the sizing of the inverters.

Total storage is 71.06 Ah per day at 120 VAC. Some of these loads are seasonal, e.g. the boiler will not run in the summer, but the refrigerator will likely run more. Over all, I think this represents a good picture of my critical household loads.

I plan to have a 24 VDC battery bank running two inverters tied together to derive 240 VAC for the well pump. I estimate a 355.3 Ah battery bank will give me 24 hours, but there are other considerations:

I would like to run for several days without recharging because sometimes stormy weather lasts for quite a while. Therefore 355.3 x 3 = 1065 Ah.

A battery bank should never be discharged by more than 40 percent. Doing so leads to shorter battery life and increased operating expense. 1065 Ah x 1.4 = 1493 Ah.

Finally, the inverter has some losses. A good inverter usually operates at about 95 percent efficiency. 1493 Ah x 1.05 = 1567 Ah.

That is a pretty big battery bank

The inverter chosen is a Xantrex SW2524 Plus, which as an internal battery charger and an optional controller for starting a generator. I plan to use the generator starting contact to close a power contactor from our house panel, which will be used to recharge the batteries when they reach 55 percent discharge and grid power is available. If the grid is not available, we have a 15 percent reserve, which means I will load shed until the batteries can be recharged.

Next consideration is the size of the solar array charging this battery bank. The total daily storage from above is 71.06 Ah. All solar panels are sized in Watts, therefore, using Ohm’s law, we have P=71.06Ah x 120 Volts = 8,527.2 watts or 8.5 kW rounded total charging per day.  We have about 5 sun hours per day average, so 8.5 kW / 5 = 1.7 kW of charging power.

I will be using a MMPT charge controller to charge the battery bank, as well as tracking mounts for the panels, both of which will increase the efficiency of the system.

Finally, I will be using a 400 Watt Southwest Windpower wind generator to keep the batteries topped off during story conditions. Without the wind turbine, I would have to double the size of the Battery bank.

Here is a list of parts:

  • Batteries; Surrette 4-KS-21PS 4V 1557 Ah, 6 each
  • Inverters; Xantrex SW 2524 plus, 2 each
  • Inverters, Xantrex SWI stacking kit, connects two inverters to generate electric for 230 VAC loads
  • Inverters, Xantrex GSM generator starting module
  • Charge controller, Blue Sky Energy Solar Boost 3024i MMPT controller
  • Photovoltaic panels, Sharp NE-170U1 170 watt panel, 10 each
  • Tracking Mounts, Zomeworks URTF90, 2 each
  • WInd Turbine, Southwest Windpower Air X 24 VDC
  • Wind Turbine Tower Kit, Southwest Windpower 45 ft

Total cost, retail $26,000.00

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06 Apr 08 | Solar Electric, wind power | Comments (0)
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