Solar Power

[glutomoto]

Hi Stevehw33,<br /><br />Re: <i>...it will drop by more than $1-2/mo., depending upon the power usage. In the summers about 60 sq. m. of panels can produce enough to run an entire household and more...</i><br /><br />I have no doubt that the setup you propose will porduce more power than nexium's guerrilla setup. Payback is the issue with your setup too, and it will take much longer, like 25 or 30 years. Payback for me the consumer is the issue with all alternative energy setups.<br /><br />I still say the 60sq.m. array is way to big for the average home, or perhaps i should say the average for my neighborhood. That 60sq.m. will cover almost half of my roof, this time I measured. Then there is the weight factor, can my 1950's house support more than 2000 pounds, on one side, before it snows?<br /><br /><img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[glutomoto]

Hi Nexium,<br /><br />Re: <i>...you can be a pirate co-generator.</i><br /><br />I still don't understand why I would want to.<br /><br />i found this Home power magazine article about guerrilla pv installations. for one panel with inverter and no battery, they paid over 1100 dollars. They say the savings was 5 dollars per month. At that rate it will take over 16 years to payback.<br /><br />The group in the article claim they aren't interested in payback. They just like pulling on over on the utility company, and feel good by contributing to the decentralization of power distribution.<br /><br />In my dreams about pulling one over on the utility company, I want to save way more than 60 dollars a year. I'll bet a lot of consumers could save 60 dollars a year just by following all that advice about how to save on your power bill.<br /><br />:| <div class="Discussion_UserSignature"> </div>

 

[yurkin]

Photovoltaic cells will never be as efficient as solar thermal power plants, especially for large scale generation. Like the one being built in Australia. Granted the company is getting a huge subsidy to build it, but that’s still a lot closer to commercialization then PV cells are.<br /><br />Btw check out all the cool movies on their website.<br />http://www.enviromission.com.au/<br />

 

[nexium]

Nearly every one who wants to sell something uses half truths and worse, so the solar thermal power plant likely is about 20% effeciency and has little or no net advantage over PV = photovoltac other than bigger subsidies.<br /> If this is the same system I looked at about a year ago, The best arrangement would be to build the kilometer tall chimney at the top of a steep cliff that faces north or north west (in Austraila) South or south west in the north temperate zone. A rather flimsey green house would cover about 2 square kilometers of the cliff face. The air in the green house would be heated by about 500 megawatts of solar energy which would produce a strong wind up the face of the cliff, inside the green house. Perhaps ten wind turbines (five ~not 50~ megawatt each) would be mounted in ten holes about five meters above where the chimney touches the ground. Several meters is needed unless costly methods are used to minimise the amount of dust picked up from the floor of the green house. The green house needs to be about 7 meters tall surrounding the base of the chimney, but three meters tall at the base of the cliff is likely optimun, with two meters ok. The system would produce little or no electricity between midnight and about 9 am, but might produce almost 50 megawatts average the rest of the day in December and January, provided cloud cover was miminal. Output would rarely reach 50 megawatts in the fall and winter months even briefly. The green house would store considerable hot air (and hot stones) to allow power output for an hour or more after sunset. This is a big plus over PV. Neil

 

[bushuser]

Another key element is the price of electricity, which is sure to rise with the increasing cost of oil and natural gas.<br /><br />It is a shame the US energy tax credit was repealed. That kind of subsidy could make solar electric generation financially attractive for many people. The savings in natural resources and coal emissions would benefit everyone.

 

[nexium]

The system, I suggested was only a few square meters. Sixty square meters might save you $200 per month. Not good, if the inital cost plus likely repairs is $30,000 over the next 150 months.<br /> I agree, 60 square meters is near the upper limit for most roofs. I have about that much South facing roof, but most of it is continuosly shaded December afternoons by trees in my neighbor's yard, I likely will not instal more than one square meter.<br /> My electric company has a specialist who will "help" you (for free) design your solar energy system, so that it is legal. Unfortunately the inverter is several times more costly than the same power from Walmart or Sam's club. The costly inverter has extra circuity that insures that you don't put power into your neighbor's houses while the power company is blacked out. This is very improbable for a small system, but likely for a 60 square meter system.<br /> Twelve years ago I got detailed information from a different power company. They insisted that you measure the amount of power you supplied to the grid and the time of day it was supplied. They payed close to nothing for power except during the peak demand period. The measuring meters added perhaps $1000 to the inital cost. Trivial for a $15,000 instalation, but ruinous for a tiny hobby type co-generator. <br /> The roof tilt is not critical. Your roof tilt in degrees the same as your latitude is close to optional. Most people settle for 10 to 20 degrees tilt as the inital cost of steeper rises rapidly. 50 to 60 degees would be good if your roof faces South-West (latitude about 35 degrees/North) but only A frame constuction gives a roof that steep, unless you know something I don't. You might consider putting the solar panels on a west facing outside wall = 90 degrees tilt. That would produce power afternoons until almost sunset. Neil

 

[ehs40]

i think solar power should be used in places like la because of the polution and stuff solar energy would help the problem

 

[nexium]

Perhaps the best reason for pv solar panels on your roof is you have some electricity when the power company fails temporarilly. In some projections, future power outages will be more frequent and/or last longer. Improvement has not occured in 60 years, so it is hard to be optimistic.<br />Multi family stuctures that are multistory, typically have less useful roof area per person for solar energy than single family one story which typically are more cost effective. Neil

 

[dan_casale]

>Put up the solar panels. More than 30 degrees tilt to the South is best, if you live North of Jacksonville, Florida. Connect a deepcyle battery to >each square meter of solar panel. Not critical, but the panel should produce 15 to 20 volts, at no load, in moderate sunlight. Connect a cheap 12 >volt inverter to each 12 volt battery. About $40 for 500 or 600 watts. More is better, but the price rose rapidly, the last time I checked. Build a >suicide cord = plug on both ends. Turn on the inverter, and a heater just before you plug it into any outlet in your house. You can then turn off >the heater, unless you want it for heat. <br /><br />If you do the above procedure with out a utility interactive inverter you are likely to increase your power bill...unless you kill yourself first. There is some very good information here and some very bad information. I have a 5KW solar pv array and I am out of time today, but tomorrow I will try to answer as many of the questions as possible.

 

[nexium]

Hi Dan;: First hand info is usually better, so we look forward to your next post. If the utility voltages is higher than the no load inverter voltage, I presume the inverter will be heated = increase your power bill. If the inverter fails to phase lock quickly with the utility phase, the inverter fuse will blow, the house circuit breaker will trip or most likely with a modern inverter the protective circuit will shut off the power output and a whistling sound will be produced until the inverter is turned off briefly or a reset button is pushed, if I understand correctly. Neil

 

[dan_casale]

I'm going to break this up into several posts. The first is important terminology.<br /><br />Cell – the part of a solar panel the produces electricity. A cell produces about 2 volts and 100 milliAmps.<br /><br />Panel – a collection of cells wired in a series-parallel arrangement. A typical panel will produce between 12 to 40 volts and up to 8 amps.<br /><br />Array – a collection of panels wired in a series-parallel arrangement. The maximum voltage and/or amperage will depend on the Inverter used.<br /><br />Inverter – converts DC voltage into AC voltage. There are two types. Utility interactive inverters require the AC sine wave to operate. A standalone inverter produces its own sine wave.<br /><br />Charge Controller – is used to control the charging of batteries by using Array power or grid power.<br /><br />Voc – Open circuit voltage. This is the maximum voltage. <br /><br />Vmp – Voltage at Maximum Power. This is the optimum voltage for this panel.<br /><br />Isc – Short circuit current. This is the maximum current the panel can produce.<br /><br />Imp – Current at maximum power. Imp * Vmp = STC wattage<br /><br />STC – Standard Test Conditions. 1000watts/meter squared and a cell temperature of 25C.<br /><br />PTC – California Energy Commission (CEC) Practical Test Conditions. – 1000 watts/meter squared, 40C cell temperature, and 1 meter/sec wind.<br /> <br /><br />Now about my system.<br />My system consists of 32 – Kyocera 187 watt panels, 2 – Xantrex GT 3.0 utility interactive inverters, and 11 adjustable racks from UNIRAC. The panels have a warranty of 25 years, and the inverters have a warranty of 5 years. <br /><br />The panels are designed to withstand up to 1” hail, and wind speeds between 80 - 100 MPH. For best results the panels must not be “bent” when installed or the glass will break with much lower wind speeds or<br />hail size.<br /><br />My racks are sitting on a concrete pad that is 10x54. The panels are arranged in a 10x51 rectangle. During the summer the pan

 

[dan_casale]

There are three basic types of cells. monocrystal, polycrystal (multicrystal), and amorphous (thin-film). Quantum dots are the newest type of cell and they are expected to be over 40% efficient, however they are still a being developed. Monocrystals are the most efficient with 20% being the current peak. The cells in my panels are 15% efficient. Amorphous cells are peak at about 10%. <br /><br />Cells can also have multiple layers that are sensitive to different wave lengths and they can be about 30% efficient. <br /><br />The panel (a collection of cells) is about 3% less efficient than the cell in the panel. Cells are connected in series until the panel voltage is reach and then strings of cells are connected in parallel until the panel amperage is reached. It is very important that cells are not shaded. Shading a single cell stops the entire string of cells from producing power. Typically, shading a single cell will drop a panels output by 1/2.<br /><br />Solar panels have two ratings STC is the manufacturers ratings, and PTC is considered the California testing standard. Panels perform about 10% worse on the PTC than on the STC. This is due to the higher cell temperature during the PCT test. A clear, cold, windy day is a perfect solar day.<br /><br />Temperature is very important when sizing an array because the voltage varies inversely to temperature. <br /><br />Speaking of voltage, Solar array voltages can be VERY high. At 50 degrees, my 16 panel array has a Voc of over 500 Vdc. I was measuring the amperage output from my panels when I was installing them, and I was able to draw an arc almost 6”. <br /> <br />Here are some panel links<br />http://www.kyocerasolar.com/pdf/specsheets/kc187g.pdf <br />http://www.xsunx.com/index.htm - building integrated solar panels<br />http://www.spheralsolar.com/

 

[dan_casale]

Another thing that will reduce the output of your array is the inverter. The inverter that I have is CEC rated at 94% and is a utility interactive inverter. That means that it will sync up with the utility and if the utility fails, I go offline. <br /><br />MPPT stands for Maximum Power Point Tracking. Most inverters will constantly vary the amount of current they draw trying to find the point where the panels are producing the maximum amount of power. If you look at the electrical characteristics chart at http://www.kyocerasolar.com/pdf/specsheets/kc187g.pdf you will see that the voltage will suddenly drop toward zero. Right where it begins to fall sharply is the maximum power.<br /><br />Utility interactive inverters are not allowed to operate without the sine wave from the utility company and must be within +- 2 cycles. This is so that a synchronous motor cannot fool the inverter by back-feeding onto the grid. Another requirement is the voltage must be within 10% of the rated voltage. My inverter is a 240v inverter. I have seen it raise the voltage as high as 252 volts to push 4.3 Kilowatts onto the grid. In the heat of the summer, the voltage only went up to 248v.<br /><br />Stand alone inverters use both the array power and battery power to meet the needs of the load. A stand alone inverter will not phase match with the utility grid. This will cause your power consumption to increase, damage electronic equipment, and burn your house down. <br /><br />If you want to do gorilla solar be sure your inverter is utility interactive. The smallest one that I know of is the Sunny Boy 700 produced by SMA-AMERICA. Another good candidate is the OutBack GVFX3648. The Sunny Boy is a high array voltage inverter (200v – 600v) and the OutBack inverter is a 48Vdc inverter.<br /><br />Most inverter manufactures have a sizing tool to help configure the array.<br />http</safety_wrapper

 

[dan_casale]

The best bang for the buck isn't solar PV...it's solar thermal, but that is an entirely different discussion.<br /><br />If you will only install a solar PV system because the power is cheaper that your utility, then the place to start is<br />http://www.dsireusa.org/<br /><br />Click on your state to find the incentives that are available in your area. When you are done the those review the federal incentives. 2006-2007 promises to be a good period for renewable energy installations.<br /><br />I developed a spread sheet that I have uploaded at http://groups.yahoo.com/group/alternatepower/ You will need to join the group to get to the files section. Download the solar10.xls spreadsheet. It will help you work through the calculations. It helps to remember that you are PRE-paying your power bill for the life of your system (25 - 50 years).<br /><br />Here's the ugly side of my system. I paid $41,073.98 in materials and contract labor. If I include my time @ $25/hr the cost is $52,698.98.<br />More math.<br />$52,699 / (25 year system life * 32 panels * 167.4 CEC panel rating * .94 inverter efficiency * 7 average hrs of sun per day) / 1000 = $0.1661/KWh <br /><br />My current utility rate is 12 cents per KWh, so it isn't a good deal yet.<br /><br />My utility had a rebate program where they would pay me $5/watt for my Renewable Energy Credits (RECs or green credits). This dropped my cost to $0,087/KWh. (looking better)<br /><br />If you have a little business that needs a solar system, the federal business tax credit of 10% applies, and the balance of the system can be depriciated. This drops the cost to $0.064/KWh. (Now were talking) Which is competitive with almost every utility in the U.S. In the 2006-2007 the tax credit will rise to 30%. So get ready to install your systems.<br /><br /><br />Economic Myth #1 - Solar panels never produce as much

 

[nexium]

Very informatve; Thank you. Does your Xantrex GT 3.0 utility interactive inverter restart each time the utility comes back up for a second or two, or do you need to press a reset button?<br />If I spend $666.67 on my PV system in 2006 will that produce a tax rebate of $200? My neighbors have too many tall trees for me to hope to match what I pay the utility, so I should think small. Apparently I need to buy a stand alone inverter and a battery which I switch to when the utility supplies no power. I need to open the main circuit breaker, so I don't power my neighbors and the utility technicians. Can I add the cost of the stand alone inverter and battery to my co-generator costs, for calculating my tax rebate? Alternately could I get the sine wave for the utility interactive inverter from a small gasoline powered generator or a small stand alone inverter, while the utility is down, if they produce between 59 and 61 hertz at 115 volts to 122 volts? <br />Do you know a simple way to make potable warm water with the hot exhust from the small gasoline generator that would possibly reduce the noise? Neil

 

[dan_casale]

>>Does your Xantrex GT 3.0 utility interactive inverter restart each time the utility comes back up for a second or two, or do you need to press a reset button?<<<br /><br />All utility U.S. interactive inverters must wait 5 minutes to connect.<br /><br /><br /> />>If I spend $666.67 on my PV system in 2006 will that produce a tax rebate of $200? <br /><br />The tax rebate is 30%, so yes you would get a $200 credit.<br /><br /><br /> />>Apparently I need to buy a stand alone inverter and a battery which I switch to when the utility supplies no power. I need to open the main circuit breaker, so I don't power my neighbors and the utility technicians. <<<br /><br />That would be the correct proceedure. I believe that automatic switches are available. Remember, that the inverter must be matched to the load and not the array size. In your example, the Charge controller (which maintains the battery state of charge) must be matched to the array. The Outback inverter I previously mentioned, is both an inverter and a charge controller.<br /><br /><br /> />>Can I add the cost of the stand alone inverter and battery to my co-generator costs, for calculating my tax rebate? <br /><br />I don't know that I completely understand the question but, as I understand the law, all expenses related to installation are eligible.<br /><br /><br /> />>Alternately could I get the sine wave for the utility interactive inverter from a small gasoline powered generator or a small stand alone inverter, while the utility is down, if they produce between 59 and 61 hertz at 115 volts to 122 volts?<<<br /><br />In theory, yes it will work if a large enough load is available to absorb the entire output of the solar array. Because a utility interactive inverter will attempt to output the entire amout of power available from the array. It will raise the voltage attempting to do this until the inverter trips off because it is over voltage. It will then wait for 5 minutes before t