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Dorothy Cepcz0d3cls Gast. Читать далее far, I have spentabsolutely nothing on maintenance, and здесь a lot on fuel cost. One of the benefits ofAC modules includes even-quicker installation, since theinverter is preinstalled—there is no DC field wiring, and noDC arc-fault protection necessary. The program uses severalsheets within an Excel workbook to perform its analysis.❿
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Windows 10 1703 download iso itasca mantrap door – windows 10 1703 download iso itasca mantrap door
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Any solar energy system capable of meeting this intermittent loadwould be so large that its size and cost would be prohibitive. Theonly solution is storage. In the case of a SWH system similar to theone described in HP, a larger storage tank and more collectorsurface area would be required. In Hawaii, an SWH system would require about three 4- by 8-footcollectors and a gallon tank to keep up with the load.
To keep up with theheat loss, a pump of about 10 to 15 gpm a medium-head pump would be needed to transfer the heat from the storage tank to the tub. In Hawaii, a batteryless grid-tied PV system that could supply the The SWH system would cost about half that.
This would change depending on applicable tax incentives and doesnot address the significantly reduced energy required to maintain thehot tub temperature with its cover on. Please keep in mind this is a hypothetical scenario.
Changes in heatloss, usage per day, installation location, and time of the year will allaffect system size and performance. Due to mailvolume, we regret that unpublished letters may not receive a reply. It usesadvanced power electronics to efficiently match up to Voc PV to 48 or Vdcbattery systems. Solar EquipmentInnovationsAlong with a growing dem and for PV systems comes pressure for lowercost and higher-efficiency equipment, safer operation, and faster installations.
Manufacturers of PV equipment—inverters, modules, racks, and other balance-ofsystemcomponents—respond with innovative devices, drawing upon feedbackfrom installers and designers.
CommentDiscussthis article home power. First,manufacturers make incremental improvements thatresult in efficiency— and power —gains. Second, majordesign changes happen, like increases in the size ornumber of cells in a module, different frames or mountingmethods, and different materials used for the front and back protection.
Higher PowerThe PV industry experiences a seemingly inevitable marchtoward more power ful, larger modules: In , wattmodules were commonplace; in , W modules wereplentiful; in , W modules were becoming the norm. Today, there are more than 1, different models of W orgreater modules on the market and manufacturers continueto exp and the selection in this size range. Larger modules mean more power installed morequickly—15 years ago, a 3,watt array would havemeant racking and wiring 40 modules.
Today, that can beaccomplished with 10 modules. Fewer wired connectionsmean savings for both the system owner and the manufacturer. For framed modules, the ratio of aluminum frame material tothe module footprint decreases with wattage increases, whichlowers costs for manufacturers and reduces mount costs.
Most higher-wattage modules, in the range of to W, are designed with 72 or 96 cells in series, rather than60 cells, which was the st and ard for many years. Because all those cells are wired in series, higher voltage isproduced as well. The open-circuit voltage on cell modulescan exceed 45 volts 60 V on cell modules.
Connecting fewermodules in series a PV source circuit means fewer conductors and connections, reduced voltage drop, fewer fuses orbreakers, and fewer or smaller combiner boxes.
Higher voltagealso means lower current for the same amount of power , whichallows using smaller-gauge wire that costs less. This is especially true forclimates that experience wide temperature swings. Higher-wattage modules can sometimes limit the overallarray size. For example, if a string inverter has a voltageinput window of to VDC, in many locations whentemperatures are hot at least 10 of the cell watt modules need to be in series to keep the inverter humming. This translates to a minimum 3, W array—with onlyone string.
This results in a very narrow range of systemsize options: 3. This could allow as few as six or seven modules inseries. AC modules or microinverters see below are anotheroption for high-wattage modules.
Higher-wattage modules also have a larger footprint. Forexample, while cell modules are generally about the samewidth about 39 inches as cell modules in the W to W range six cells wide , they are 12 cells high instead of 10—about 12 inches taller and 8 pounds heavier. This increasesthe load on the rack attachment points, with the same amountof rail holding more module weight. Also, more caution isneeded when moving larger modules—typically it requiresthat two people carry each module.
Kelly DavidsonSome glass-on-glass modules allow light to pass through orbetween cells, creating a pleasant ambience beneath and thepossibility of collecting more light reflecting up from below. Class A roofing materialsor assemblies have a greater ability to resist fire spreading and to resist burning embers. While residential roofs have notgenerally been required to be Class A, some areas with highfire hazards are moving in that direction for new constructionor significant reroofing projects.
PV innovationsagency ordinance requirements for residential Class A roofs. Some roofing materials are considered Class A, like slate, clay,concrete roof tiles, and steel, although they must be installedcorrectly for example, eliminating gaps between the roofcovering and decking where birds could build nests to earnthis rating.
Class A fiberglass-reinforced asphalt compositionshingles are also available, while other types of asphalt orwood shingles will typically have a lower Class B or C rating. Most glass-front, plastic-backed modules have a Class Cfire rating, but modules with glass on both sides may meethigher Class A rating requirements. Besides their improved fire resistance rating, some glasson-glassmodules have the benefit of allowing dappled lightto pass through for structurally integrated arrays like patioor walkway covers.
Looking up at the back of a module thatis letting light into an atrium and seeing the PV cells insteadof an opaque plastic backsheet is considered by many peoplean aesthetic improvement and architecturally interesting. Another advantage of glass-on-glass modules is superiorprotection for the back of the module as compared to plastic, and enhanced resistance to sheer stresses. Frameless versions of glass-on-glass modules are available including many thin-film modules that have no metal framesto ground, so the labor and material costs of groundingmodule frames to racking are eliminated.
Note that the railsstill have to be grounded. Unlike with a string inverter, one module or inverter failuredoes not affect the whole system. In addition, module-leveldata monitoring capabilities allow easy troubleshooting of anunderperforming array or module, and arrays are more easilyscalable, as modules can be added without dealing with theconstraints of series strings.
Both system types are extremely safe to install and operate,compared to systems with string inverters, because DCvoltages are kept to a one-module maximum; all equipmentconnectors are touch-safe; and DC voltages will generally staybelow the 50 V limit associated with shock hazards. Shuttingoff the main service AC disconnect or PV system disconnectalso immediately deenergizes all the PV system conductorsexcept module leads, as the inverters shut off immediatelywithout the presence of grid voltage.
One of the benefits ofAC modules includes even-quicker installation, since theinverter is preinstalled—there is no DC field wiring, and noDC arc-fault protection necessary.
Metal module frames and any other metal equipment like junction boxes or racks stillneed equipment grounding. PV innovationsCourtesy SunPowerAC modules have microinverters preattached,providing the same benefits asmicroinverter installations, but reducinginstallation time and complexity. NEC and an installation perspective.
Microinverters arefield-installed, one inverter per module, while AC moduleshave factory-integrated inverters and have one warranty forthe complete assembly.
AC modules generally have a st and ard year performancewarranty, like PV modules, while microinverter warrantiesvary from 10 to 25 years. There are only a few microinverters currently availablein the United States.
Inverter InnovationsHigher-Efficiency InvertersGrid-tied string inverters are more efficient than ever. Inverters operate more or less efficiently atdifferent power output levels, so weighted efficiency is an average across a range of power , with estimated percentage of time spent in a given power range factored intothe equation. One technological development that helps increase efficiencies is the move totransformerless inverters also called nonisolated inverters.
Instead of relying onan iron-core or high-efficiency transformer, transformerless inverters convert DC toAC through rapid electronic switching, with no isolation between the DC and ACconductors. These inverters are not only more efficient, but weigh less and featuresuperior ground-fault protection that detects faults more reliably and at lower currentlevels.
Some can be enabled to check the insulation resistance of DC conductorseach day before beginning operation—helping reduce the potential of fires due toundetected ground faults. The fourthgenerationEnphase M is an ungrounded microinverter and does not require aDC-grounding electrode conductor. In the past, capturing power from autility-interactive array during a power outage was only possible ifthe system had a battery bank and inverter with st and -alone capabilities.
When the sunis shining at a high-enough irradiancelevel, the inverter can provide up to1, watts through the outlet. The power supply can be used for smallappliances or to charge cellphonesor computers, but there is no energystorage for use at night or duringcloudy weather.
Charge Controller InnovationsModern modules come in a wide range of voltages that rarelymatch nominal battery bank voltages, so higher-voltagecharge controllers make designing battery-based systemsmuch simpler. These MPPT controllers include a voltagestepdown capability to convert higher array voltage intolower battery-bank voltage. The controller input is at a highervoltage and lower current; the output is at a lower voltagewith a higher current.
For example, a W module mayhave a maximum power voltage of 30 V and a maximum power current of 8 amps. With the module operating atmaximum power and charging a 12 V nominal battery, astep-down charge controller would output around Schneider Electric— and , expected in late ,Morningstar—makes controllers to h and le PV arrays up to V maximum.
The output is current-limited, so ahigher-voltage battery bank allows more array watts to passthrough the controller. MidNite Solar offers controllers thatcan h and le maximum voltages of , , or up to voltsfrom the array, depending on the model. High-voltage chargecontrollers enablethe use of smallerdiameterwire fromthe array to thecontroller, and theability to use a widerrange of highervoltagemodules inthe system.
One of the biggestrack innovations is making it easier to ground the metalmodule frames to the equipment-grounding conductor orrail. Manufacturers including PanelClaw, S-5!
This means thatmodules are bonded to the metal rack as part of the mechanicalinstallation and do not need any other grounding device. Railless MountingSeveral rack manufacturers offer pitched-roof mountsdesigned to reduce installation time by eliminating thetraditional module support rails. Courtesy Zep SolarRailless mountingdecreases the time,materials, and costof mounting PVarrays, as do autogroundsolutionslike the dimpleddisk at right ,which scratchesthrough theanodization on thealuminum moduleframe to electricallybond it to theadjacent modulevia the disk.
Courtesy S-5! Arc-faults can quickly burn throughconductor insulation, plastic connectors, module back sheets, and even metalconduit and electrical boxes.
They can also lead to ground-faults. For example, whena current-carrying conductor behind a module burns through, one energized endmay fall onto the metal rack, allowing fault current to flow through the groundedmetal until detected by the ground-fault protection device. The arc-fault protection requirement only applies to DC circuits on or entering abuilding, with a maximum system voltage at or above 80 V.
The system must be ableto detect and interrupt series arc faults as described above a failure in conductorcontinuity and disconnect inverters or charge controllers connected to the fault or system components within the arcing circuit.
In addition, the equipment mustnot automatically restart after a fault and have a visual indicator that a fault hasoccurred. Opening the circuit stops the arc immediately, so this technology decreasesfire potential. Courtesy Fronius PV innovationsWhile there are still very few choices of equipment availableto meet these requirements, more are appearing. In the spring of, SMA America was the first inverter manufacturer to providearc-fault detection in its inverters.
Fronius now offers its IG PlusAdvanced inverters with built-in arc-fault detection. Microinverter and AC module systems less than 80 VDC are exempt from thisrequirement, as are ground- and pole-mounted systems thathave no DC circuits inside a building. Arc-fault protection that isintegrated into charge controllers is available, as well as breaker-likeunits that can be integrated into a combiner box. Courtesy SnapNrackKeeping Out CrittersWhether battling squirrels that chew on module wiring, or birds and rats that build nests under arrays, keeping critters away isan ongoing battle that, if lost, can result in electrical faults and decreased electric production.
Clips from Heyco Sunscreen and Spiffy Solar hold screening against the frames of modules,preventing animal access under the array. Future buildingor electrical codes may require this; in the meantime, installerscan save themselves a lot of headaches, callbacks, and liabilityby keeping the vermin at bay. Heyco also offers a vinyljacketedstainless-steel cable tie—the Sunbundler—for PVwire management. Rack manufacturers SnapNrack, Schletter, and Legr and , and module manufacturers Lumos Solar and Silicon Energy, make racks with integrated wire management.
On larger systems, cable tray, or similar products frommanufacturers like SnakeTray, are making quality wiremanagement easier than ever. Proper wire managementis key to professionallookinginstallations, and helps ensure that wiringstays safe and secure. AccessRebekah Hren rebekah. She works as a project engineer for groundmountedsolar farm developer O2 Energies in North Carolina, and asan instructor and curriculum developer for Solar Energy International.
The newlook ofquality. Buy withconfidence. Department ofEnergy, so it makes perfect sense to choose the mostenergy-efficient heating system possible. Ductless minisplitheat pumps, wood and pellet appliances, electric thermalstorage devices, ground- and air-source heat pumps, and gasburningfurnaces and boilers are potential choices. But thereis no single solution that covers all situations.
Climate, utilitycosts, labor rates, and the fuel all should figure into a decisionon which heating appliance to buy. Start with A Tight EnvelopeHouses with minimal air leaks, lots of insulation, and multipane windows require less energy to remain comfortablein cold weather than older houses or those built to codeminimums. In high-performance houses like these, heatingequipment can be of lower capacity, and therefore lessexpensive to install and operate.
Passive solar design is another way of lowering heatingbills. Orienting the house with its long axis east to west—so windows on the south face can capture the sun— and choosing windows with low U-values and the correct solarheat gain coefficients for the climate are among the steps thatcan reduce the need for fuel-fired space heating. Keeping heating loads at a minimum pays big dividends, notjust when buying a heating system initially but also in keepingoperating costs down.
It sets tough benchmarks for airtightness, total energyuse, and energy use for heating and cooling, and houses builtBefore you invest in a new space-heating system, be sure toweatherize your home. Ben Rootto these st and ards far exceed the performance of conventionallybuilt houses in the United States.
Finally, whether the house is old or new, make sure yourheating contractor calculates heat loss so the equipmentcan be sized correctly. Buying oversized equipment, whichcontractors sometimes recommend just to be safe, is a wasteof energy and money. No central ductworkrequired. Makes zoning simple.
Interior wall-mounted fan unit. Equipment more expensivethan air-source heat pumps. Modulating gas furnaceFans todistribute heatNatural gascheaper thanmost otherfuelsNoNoVery efficient. Forced-air systems are noisierthan some options.
Ductsdifficult to install in retrofit. High-efficiency boilersCirculationpumpsNatural gas isbest choice ifavailableYesNoQuiet, especially with hydronic. Good source of DHW whenpaired with indirect tank heater. More expensive than forcedairsystems. Ground-sourceheat pumpCirculationpumps,compressorNo on-sitecombustionYesYes, withforced-airdistributionForced-air or hydronic heatdistribution. Very quiet withhydronic. Can be operated byon-site renewable energy. High initial cost.
Requiresdeep wells or significant openl and. Pellet biomass Circulationpumps ordistributionfans, pelletaugerLimitedavailability ofbulk pelletsYes, forboilersNoSome clean automatically. Low fuel cost. From arenewable source. No fossilfuels. Load by h and where bulk pellet distributionnot available.
Electric thermal storageHigh currentdraw forresistanceheatersNo on-sitefossil fuelconsumptionYes, but notall modelsNoAir or hydronic distribution. Best for low off-peak electricrates.
Can store RE. No heatercore maintenance. Higher operating costs thannatural gas or biomass. Mayrequire wiring upgrades. Just like conventional air-source heat pumps,minisplits have inside and outside components. As many as eightindoor fan units can be connected to a single outdoor compressor,although most systems have fewer than that. Airtight houses can beheated with just a few wall-mounted heads, and because the indoorfan units are operated individually, these systems make it easy tozone a house for heating and cooling.
Inside and outside components are connected by a smallrefrigerant line, a power supply, and a condensate drain. In newconstruction, these lines can be hidden in an exterior wall; in aretrofit, installers bore a hole 3 inches or less through an exteriorwall to connect the equipment.
A cover on the outside of thehouse hides the supply lines. Below that, electricalresistance heat or some other supplemental heat source has tokick in, lowering overall efficiency.
They allow fans and compressorsto run by variable speed motors—a more efficient option than theon—off cycling of conventional heat pumps. Ductless minisplits do not have supplemental sources ofheat. Heat pump efficiency is described by the coefficient of performance COP , which is the ratio of energy consumed to heat delivered. Ifa heat pump has a COP of 5 it means it produces five units of heatfor every unit of energy it uses.
Ductless minisplits also eliminate the heat losses of a ducted system,which, according to the U. Heatlosses are especially high when ducts pass through uninsulatedcrawl spaces or attics. Manufacturers say minisplits are often less expensive to install thanconventional ducted systems.
Minisplit indoor distribution units below can be installed on exteriorwalls anywhere that can be reachedby electrical source circuits and theplumbing from the outdoor unit right. The system includesa compressor, a closed loop of refrigerant, and an air orwater distribution system—just like an air-source appliance. Water-to-air systems also have a heat exchanger and aforced-air distribution system. Instead of capturing latentheat in the air, a ground-source heat pump uses a groundloop that runs in horizontal trenches or deep vertical wells.
An add-on component called a desuperheater can alsoproduce domestic hot water. Ground-source systems c and istribute heat via water or air. Most are forced-air systems,using ducts. Courtesy Water Furnace 2 Ground-source heat pumps run on electricity.
When combinedwith a renewable electricity system, they can make anextremely attractive heating and cooling package. Manufacturers claim COPs as high as 5, making these systemsvery efficient. But there is a catch: Published COPs do notinclude the electricity needed to run the pumps that circulatewater through the ground loops, so actual COPs are less—probably closer to 3.
Typical forced-air, ground-source heat pump equipment. In thiscase, the system includes a desuperheater to provide domestichot water, which is stored in the tank on the right.
In a conventional furnace, the burner and blower kick on when thethermostat calls for heat. When the room reaches the set temperature,the furnace shuts off. First, a modulating gas valve varies the amount of fuel the furnaceburns depending on how much heat is required. Second, modelswith variable-speed fans can run faster or slower to regulate theamount of heat delivered to the house much more precisely.
In old-stylefurnaces, this energy goes right out the flue. Because flue gasesare cooled as energy is extracted from them, a masonry chimney ordouble-walled stovepipe is not needed to vent a mod-con. Plastic PVC pipe will suffice, which reduces installation costs comparedto a conventional furnace.
An additional benefit to mod-cons is theirsize—some models are small enough to be hung on the wall of amechanical room. These furnaces are sealed-combustion units, which means theydraw in outside air for combustion rather than using air from insidethe house. This eliminates the potential for backdrafting, a dangerouscondition in which lowered indoor air pressure, from a bathroomfan, for example, draws combustion gases into the house.
It alsodecreases the infiltration of unconditioned outside air needed toreplace combusted air. Variable-speed motors for fans use less energy than single-speedunits. The American Council for an Energy-Efficient Economy warnsthat some furnaces can use more than 1, kWh of electricity peryear. The most efficient Energy Star models use roughly kWhper year. A typical modulating-condensing furnace.
Prices can differsharply in different areas and with different manufacturers. Courtesy RheemSite vs. As definedby the U. Because of the inefficiencies of generating electricity byburning coal or gas, along with some transmission losses, it takesabout 3 units of source energy to produce 1 unit of site energy.
Whenfossil fuels are burned on-site, conversion losses are much lower. The site-to-source conversion factor for natural gas is 1. The ratiois 1. When the site—sourceratio of 1. Comparing site and source energy gives a better pictureof heating efficiency, and a more accurate measure of theenvironmental impact of using different types of fuel. Pellet boilers are more common in Europe than the United States,but in parts of the country where pellets can be delivered in bulk,these heating systems are no more trouble to use than a gas- or oilfiredboiler and can offer substantial fuel savings.
Advanced pellet boilers, like those offered by Maine Energy Systemsor Greenwood Clean Energy, feature automatic pellet loading and automatic ash removal. Pellet boilers can also provide domestic hotwater and can distribute heat via air ducts or hydronically, such aswith a radiant-floor system. In the Northeast, where bulk pellets areavailable, a delivery truck offloads into a storage bin, much like fueloil or propane would be delivered.
The home owner never touches thefuel. Ash is collected and compressed in a container that needs to beemptied only four times a year, according to Maine Energy Systems. In other parts of the country, home owners have to resupply a pelletbin manually. Some biomass heaters, like those from MagnuM, alsocan burn corn. Depending on what type of conventional fuel they replace, pelletscan lower heating costs significantly. For an estimate, check theU. The calculator allows adjustments in appliance efficiencyas well as fuel costs to better reflect local prices for more accuratecomparison.
Compared to wood heaters, pellet heaters and , especially, pelletboilers require much less work on the part of the home owner. Courtesy Maine Energy Systems 2 This automatic pellet boiler manufactured by Maine Energy Systems includes an augerthat moves pellets from a nearby storage bin to a self-cleaning combustion chamber.
Electric thermal storage ETS heaters are one way ofgetting around that problem. They draw energy during off-peak hourswhen supply is plentiful and rates are relatively low. An ETS systemcontains electric heating elements within dense ceramic bricks,which store heat. They can be incorporated into an existing heating systemas a backup for an electric furnace or to supplement a heat pump,but also work as a principal source of heat. HeatExchangerLocal electricity rates and rate structures are a key consideration inpurchasing an ETS heater, since these units use a lot of electricity.
Room-size heaters draw 1. The smallest Steffes central-air heater draws 14 kW. An ETS heater may require wiring upgrades to h and le the current. The run-time for the units depends on the size of the heater, the sizeof the heated space, the heating load, and how much stored energywas used during the previous heating cycle.
Take, for example, the residential ratestructure offered by Portl and Oregon General Electric. Thebiggest advantage for the utility is the avoided cost of not having tobuild new power plants to meet spikes in dem and during peak hours. Note that the side insulationhas been rolled back to reveal the ceramic bricks inside theunit. The ability of these appliances tobalance the load on the grid by storing energy is a key advantage,says Paul Steffes, CEO of Steffes Corp.
Manual J for Heat LossOversized heating equipment costs more initially and willnot operate as efficiently as a correctly sized appliance. Contractors once filled out the worksheets by h and , butthere are now a number of computer programs that do thework. A variety of factors are plugged in, including type and amount of insulation, window type, lighting, what applianceswill be in the house, and how much air leakage there is.
A Manual J calculation or an approved equivalent is now required in new construction by the InternationalResidential Code. Homeowners investing in new heating equipment shouldinsist the calculations be performed.
Alternately,boilers can supply a forced-air distribution system if it has a hot-water heat exchanger. Natural gas is the most common fuel, buthigh-efficiency models that burn No.
Courtesy LennoxCondensing boilers use the same technology as condensing furnaces to capture wasteheat. Combustion gases are routed through a stainless steel heat exchanger wherewater vapor condenses and releases more heat. A typical high-efficiency boiler. AccessScott Gibson writes about green building design and energy efficiencyfor a number of publications and blogs, including Fine Homebuildingmagazine and GreenBuildingAdvisor.
He and his wife live insouthern Maine. Toll Freewww. I wanted some l and where I could hunt and practice with my firearms, since Iam an avid hunter and enjoy competing in local shootingmatches. Teresa was interested in raising farm animals and keeping honeybees— and not having a neighbor right nextdoor. We used the Internet to search for properties and contacted a real estate agent to assist us. After months of searching, a couple of things became apparent. The first was that locals here in the southern tier of New York,near the Pennsylvania border, believe there is natural gas undertheir l and and wanted top dollar—or would not give up theirmineral rights.
The second thing was that it was going to take abit of luck to find a property where everything we wanted wouldmeet what we could afford. Prime Property? When our home came up on the radar, we knew it had what wewere looking for and it was a great deal, but it was a little fartheraway from work than we wanted.
An additional acres were also available. The description in the realestate listing was a little vague and seemed too good to be true. The house belonged to and was built by an Amish family—there was no electricity inthe house and no indoor plumbing. We made arrangementsto see the place, located in rural Steuben County, southernNew York, during one of the only snowstorms in the winterof Perched atop a hill, the house and property sit in awindy area, near several wind farms.
Away From the Rat RaceWe met the family and toured the house and some of theproperty. The home was beautiful and the l and was exactly whatwe were looking for, but there were no modern conveniences. Instead, there was a h and pump for water, an outhouse, and no central heat. There was a Hitzer gravity-fed coal heater and a wood-burning cookstove. Teresa and Iwere no better, with a lot of our free time being wasted infront of the computer or TV.
So we talked to the kids and ,surprisingly, they were all for it. I could write another article about the hurdles weencountered getting financing and insurance on a home with no electricity, no plumbing, and no central heat, but theimportant part is that we decided to buy this home and l and. We put in a purchase offer with a couple of contingencies incase we ran into problems and needed an out. The seed forliving off-grid was planted.
Mark McDermott 2 New meets old: A high-tech off-gridsystem now provides electricity forthis twentieth-century farmhouse. Originally built by an Amish family,it was formerly electricity- and plumbing-free. But our experience with the utility was notencouraging, and the cost and red tape were beyond our means and patience.
The grid ended 0. On the southern side, we would need to obtainpermission from one neighbor and we would need to remove or have removed all of the trees that were within 30 feet ofthe road. Coming in from thenorth, there were two neighbors who we would need to getpermission from, but most of the l and coming from that sidewas open field. We actuallyconsidered this option but unfortunately or fortunately neither of the neighbors was willing to grant us permission.
And both cost estimates were minimums and we were warnedthat it could be much more. So I was relieved when we finallymade the decision to keep the home off-grid. System DesignBefore we designed the off-grid system, we set a rough budgetfor the house, with two major considerations: We needed towire the house so that we could use whatever electricity oursystem would make and we needed a septic system so that wecould have indoor plumbing.
Early in the process, I decided on a solar-only system. Once I focused on a solar-only system, I beganthe critical process of sizing it. We used about 1, kWh per month at our grid-tied home.
That works out to be about 33 kWh of electricity a day used or,mostly, wasted. I had never examined our electricity usagebefore.
All I saw and complained about was the monthly bill. Defining the LoadThe first step in system design is to figure out how manykWh a day are needed. That seems simple enough, but it isvery difficult to arrive at an accurate number.
I bought a KillA Watt meter and measured the energy use of the toaster,computer, TV, dryer, washing machine, and everything elsein our existing house that plugged into a VAC outlet. Irecorded all of the watts and watt-hours used for everythingin the house on a spreadsheet. Some of our appliances were very energy-efficient and other older ones were energy hogs.
But knowing how muchenergy everything used was crucial. Next, I needed toestimate how many kWh we would need per day in our newhouse. That sounds easy, but it is also quite difficult. Howmany lights would we use during the evenings and how longwould they be on?
The same question applied to everythingMark McDermottEnergy-efficient appliances play a critical role in reducing theelectrical loads in an off-grid system. Going off-grid forces you to be veryaware of how you use your energy. The trick to off-grid living is conservation and efficiency.
After looking at many different scenarios, I came up withan estimated minimum of 6 kWh per day. After getting realdata from our appliances and deciding that we would be ableto change some of our electrical usage habits, I targeted a 3 to 4kW system.
Once your average daily electricity use is estimated, thesize of the battery bank can be calculated, based on a specificdepth of discharge and the number of days of autonomy nosun you expect. Battery SizingSince the solar energy is stored in a battery bank, its capacityhas to be enough to provide the energy you need withoutoverdischarging your batteries.
The battery bank feeds theinverter that converts the DC to AC electricity used byst and ard household appliances. Our grid-tied houseused natural gas for space heating, water heating, and clothesdrying. Everything was plugged in and power ed most all times. Every night, there were fans and other electronics running. I made some drastic assumptions toreduce our electricity usage. That worried me.
What if I hadmade a wrong calculation? And what if I could not install thesystem in time for our first winter? With those fears, I decidedto hire a professional to help design and install our system. I had a good idea of what the complete system would looklike and what equipment was available, so this was kind of atest for the two I sought bids from. After Roy did a site survey, wetook his proposal and tweaked it a little bit to arrive at oursystem design: a 4 kW PV system with a Ah batterybank and a 6 kW backup generator.
Determining the size of your array and battery bank is a bit of a balancingact. I gathered all my data,calculations, and best guesses and cameup with a target system: a volt, to amp-hour battery bank and a 3kW solar-electric array.
We knew that heating anythingsignificant with electricity was going tobe too big a burden on our PV system. We kept the two Hitzer gravity-fed coalstoves, and decided to use propane forbackup space heating, water heating,cooking, drying clothes, and to run thebackup generator. I was also responsible forselecting and installing the generator and its fuel supply—apropane Generac 6 kW EcoGen, which is the only generatordesigned and warranted for off-grid use with a renewableenergy system.
We started the installation the first week of September. Setting the two 6-inch, foot-long steel poles for thepole-mounted system was a critical step. They had to belifted into place with the backhoe and set in inch, 6-footlongconcrete form tubes.
Since the arrays presented a largesurface area for wind loads, plenty of ballast was needed tokeep them in place. While the concrete was curing around the poles, weinstalled the BOS equipment. The inverter, charge controllers,battery box, and batteries were all wired, connections torqued, and parts labeled. Some sensors, surge protection, and equipmentgrounding omitted or simplified for clarity. Mark McDermott 2 Strong, Silent EnergyA couple of days later, the first array was installed and was charging the batteries.
Our new system sounded likenothing—it was dead silent. No generator noise, just adull hum from the battery box fan. A day or two later,the second array was online. The backup generator wasdelivered, and we installed that and wired it into thesystem for those stretches of little to no sun, and for enoughenergy to occasionally equalize the batteries an intentionalovercharging of the battery bank to remove imbalancesbetween individual batteries.
The first thing we did was plug in our refrigerator. Iremember my wife saying that if all we could ever supplyelectricity to was the refrigerator, it would be OK with her. By the last week in September, our new systemwas complete. There was still much to learn and do—underst and ing the technical and practical details of a wholenew electrical supply system, tweaking the charge parametersto properly charge the batteries, and reminding the kids toturn off the lights!
I pay special attention to the batteries, sincethey are the heart of the system and its most vulnerable part. To date, there have not been any major issues or problems. The array tilt was adjusted to an optimum angle for thewinter and left there. I adjusted the array for the summerangle on April 1, and will readjust it again this fall. Embracing Off-Grid LivingOur system is well-balanced, and our family is well-matchedto it.
On the weekdays, we typically use between 2 and 3 kWh. On weekend days, our use climbs to 4 or 5 kWh. However, since last winter was our first winter with thesystem, we were very conservative with our usage. But noneof us feel like we have had to make huge sacrifices to keep ourusage low. We currently have a spring-fed cistern that we usefor our water supply.
We may need to drill a well, which willrequire a different pump and more electricity. We are and willbe using more energy as our comfort level with living off-gridincreases.
Did we give up any modern conveniences? Yes and no,according to how you define modern conveniences. We gave up having multiple cable boxes, DVRs, and a largesurround-sound system. We gave up having a huge chestfreezer filled with who knows what and a large side-by-siderefrigerator. We gave up having every light in the house onall the time. We gave up having all of our electrical devicesplugged in and ready to go. Right: Teresa inspects herbeehives and checks for honey. Noticethe solar- power ed electric fence usedto keep out pesky black bears.
TVs, gaming console, computer, and printers—are pluggedinto power strips that are turned off when not in use. We letthe kids have limited use of the gaming console and TV mostof the time they limit themselves. We have family TV time inthe evenings—when we decide to watch TV.
We brought ina fiber-optic phone line to the house, since there was no cellor Internet service. The modem is power ed all the time. Allof our lights are energy-efficient and only one or two are onat a time most nights. Overcoming our bad energy practiceshas actually been a little easier than I thought it would be.
We all work together to conserve electricity, which is reallyastonishing to me, since conservation was not even in ourvocabulary a year ago. Going off-grid has taught me many things.
First wasthe importance of tracking the energy usage of all of yourelectrical appliances—clocks, chargers, everything—it all addsup.
Do not depend on the sticker that gives the amperageon the back of an appliance—they are not accurate enough. Second, every dollar spent on conservation will save youmore than that on the cost of your PV system.
Energyefficiency in your lifestyle and appliances is a must. If youhire an installer, check references and go see at least one oftheir installations.
Ask questions. If you look at changing to off-grid living strictly as afinancial problem, it may or may not pencil out, since thecost of electricity from the grid is usually cheaper than froman off-grid system. In our case, the costs of bringing in thegrid and installing an off-grid system were about the same ifconsidered over 10 years.
It may even have been cheaper if wehad gone the grid route. But being on our own and telling theelectric utility to take a hike…well, that is priceless! As we moved into our first spring off-grid, the system wasreally coming into its own. We have embraced living off thegrid. I think our family and friends thought we were crazy tobuy a home with no electricity or plumbing.
But now all wehear is how lucky we are and how beautiful it is out here. Welove it and would definitely do it all again. He currently serves as adevelopment engineer there, working on optical fiber and photoniccomponents. Call us forfree help designing your system. Premium Article Content Contractors Directory Help is on the way. See for yourself. Modern, high-quality solar hot water SHW systemsare reliable and long-lasting if designed and installedproperly.
Many systems installed more than 30 yearsago are still going strong. However, most systems this old and older have needed repairs and component replacement fromnormal wear and tear. Whole-System ChecksSHW systems are fairly simple appliances—not asstraightforward as a tank-style water heater but nowherenear the complexity of a car. Seeing, hearing, smelling, and touching components carefully can assist in diagnosingproblems before any troubleshooting equipment and tools areused.
Experienced technicians use their senses to determinethe status of a solar water heater. Unusual, high-pitched noises and burning odors are associated with bearing wear from thepumps. Burning smells can also indicate electrical problems,such as burned motor windings, loose connections, or damagefrom excessive voltage or current.
Visual inspection can revealcontroller malfunction, leaks, and fluid levels. If pipe temperaturesallow it, feel the two pipes, with one h and on each pipe. A noticeable differencein temperature between the two pipesindicates that the collectors are addingheat—the system is working.
Cold supply and return pipes area symptom of no flow—check thepump s or controller first. Both pipesbeing hot and at the same temperatureis likely only to occur in a systemwith an external heat exchanger. Moredetailed symptoms are componentspecific. What goes wrong and why dependson the SHW system, the climate, and the water conditions. The survey indicatedthat most problems resulted fromcomponent failures.
Failures due toinstallation and maintenance were inthe minority. The fact that valves accounted forthe highest percentage of reportedproblems can perhaps be attributedto hard water and open-loopthermosyphon and direct forcedcirculation DFC systems.
Therelatively high problem rates of valvesalso include a significant number offreeze-protection valves, which areused only in very mild climates, inlieu of true freeze protection, whichis accomplished by drainback and antifreeze-based systems. They experience lifetimesexceeding three decades and can probably last 60 years ormore if not abused.
That said, these are some problems thatcan be encountered with collectors. Flat-Plate CollectorsBroken glass.
Glass breakage is the problem that most oftenarises with flat-plate and evacuated-tube collectors. Whilethe glass can be replaced by removing the collector trim,finding a source of low-iron tempered LIT glass can bedifficult. Because of this, most people opt for commontempered glass. Any metro area will usually have at least onetempering plant that supplies local dealers with temperedglass for commercial windows, and patio and shower doors.
Carefully measure the glass before ordering, sincetempered glass cannot be re-cut. Broken glass should bereplaced quickly or additional damage to the collector canresult from wind and rain.
The gasketaround the glass can most often be reused. If it is defective,fill in with a contractor-grade silicone sealant. Heavycondensationbuildup usuallyindicates a leakor st and ingwater within thecollector. Condensate buildup. All collectors will exhibit somecondensate on the glass intermittently, but if it is present allthe time, st and ing water may be accumulating in the bottomof the collector.
The holes mustbe placed in the back of the collector and away from theglass front, since a drill will fracture tempered glass, and careshould be taken to avoid drilling into any tubes. Right: Once the glass face is broken,other elements within the collectorcorrode and degrade rapidly. Below: A damaged frame allows moistureto infiltrate, increasing the componentbreakdown within the collector. Absorber coating deterioration.
The original coating may have been a selectivesurface like black chrome but that will be impossible toreplicate in the field. Semi-selective paints like Solkoat areavailable online but difficult to apply without experience. Use high-heat stove, barbecue, or engine paint to refurbishabsorber coatings. Roughing the absorber surface with s and cloth from a soldering kit can help the new paint adhere tothe metal.
High collector glass temperature may be due to failedsolder joints or a low flow rate through the collector, whichcould be caused by several things. Some collectors used alower-temperature solder to bond the copper tubes to theabsorber plate. After years of enduring repeated heating and cooling cycles, these joints can separate, reducing efficiencysignificantly. A collector with a debonded absorber will bevery hot, and the temperature difference between the supply and return lines will be small.
Much of the heat in a collectorwith a debonded absorber will be reradiated through theglass and can be detected with an infrared thermometer. Absorbers that have debonded need to be replaced if you canfind a manufacturer that will supply them—ask if they makecustom absorber plates. Unlike a debonded absorber, low flow rates will showas a high temperature difference between supply and returnpiping. Lower flow rates could be caused by installation designflaws, an undersized pump, a partial pump failure, or arestriction in the piping, heat exchanger, or collector tubes.
Partial pump failures can be due to hidden impeller damage. In hard water areas, reduced flow rates may be caused byscale buildup from dissolved minerals in open-loop, directforced-circulation, and thermosyphon systems. First look forinstallation design flaws like the tubing being too small or toomany collectors for the size of tubing. The pump problems in particular, impeller damage may require pump removal and inspection. Leaks in collectors are mostly due to freezing—usually theresult of gizmo freeze-protection like freeze valves.
Freezebreaks in the absorber tubing should be repaired by brazingor silver soldering. Softsoldering inside collectors is not suitable due to the lowermelting point of the solder. Automotive radiator additives, like Alum-A-Seal, a powderthat accumulates to plug leaks, can be used to stop pinholeleaks caused by slightly corrosive fluids like overheatedantifreeze, but this is a temporary repair. As it does in carradiators, the conditioner can give an old collector a fewextra years of life.
However, this strategy should only beused in systems with double-wall heat exchangers due tothe uncertainty of the chemical contents in additives. Although the tubes have been in the marketplace formore than three decades, due to higher costs than flat platesthey have been popular mostly in cold, cloudy climates likenorthern Europe and Canada.
The superior insulation of thevacuum in the tubes makes them most applicable in harsherclimates with reduced solar resources. Broken glass. Evacuated-tube manufactures use borosilicateglass or soda lime glass in the collectors.
The glass is nottempered, so breaks into shards that can be more dangerousthan the small pieces from tempered glass breakage.
Consequently, evacuated-tube collectors are more fragile thanflat plates, as glass strength is proportional to its thickness. The vacuum in twin-tube collectors is between the two piecesof glass much like a thermos bottle. The heat pipe in twin-tubemodels slips into the tube on installation and can be removed and reinserted into a new glass tube.
In single-glass collectors,the heat pipe is factory-installed. The tube on the right has lost its vacuum, and will feel veryhot to the touch. Its single-wall design means that the wholetube or entire collector will need to be replaced. Double-wallevacuated tubeshave replaceableglass. Vacuum loss. Evacuated tubes have life spans of about15 years but this varies depending on the type of tube and manufacturer. Vacuum loss, through glass breakage orthrough the connections, is the most common failure withtubes.
Once the vacuum is gone, there is little insulationleft to retain the collected heat. Thereis little evidence left as to how the vacuum was lost in mostcases unless glass breakage is evident. However, polypropylene is a high-temperatureplastic polymer to which normal sealants and glues will notadhere. The repair process requires cutting the leaking tube at bothends near the large header pipes and inserting the correct-sizerubber plugs into the tube. This repair isolates the leakingtube but is often a stopgap repair, since these types of leaksindicate that plastic tubes are deteriorating and the collectoris likely near the end of its useful life.
Pinholes in pool collectors usually indicate that the wholecollector is reaching the end of its life. SHW troubleshootingPotential Pump ProblemsSHW circulation pumps have no suction lift and must beprimed be below the source water at all times to function.
Alternating current AC solar pumps are lubricated onlyby the circulating fluid. The magnet is an interface between the motor and thespinning impeller. These also usually lack provisions forperiodic lubrication. Always replace pumps with ones made of the samematerials and close to the same head and flow specifications.
Pump stations are factory-assembled with most of thecomponents needed for an antifreeze system and saveinstallation time. A caution with the stations is that some havepumps with a check valve in the pump impeller housing. Pumps used in a drainback system cannot include a checkvalve, so be sure that you use the correct one for your system. Bearing failure. The most common problem with pumps isbearing failure, which becomes more likely to occur if thepump is installed incorrectly.
The shaft of the pump shouldbe oriented horizontally. A pump with the impeller housingon the top or bottom has the shaft in a vertical orientation,which can increase lateral pressure on the bearings.
A continuous screeching noise is a sign of bearings that areabout to fail. If the pump impeller is locked up not movableby h and , the bearings are frozen and the pump needs to beA vertically oriented pump shaft shown above will increasewear and tear on the bearings.
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