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High voltage input question?

How do I get a certain Voltage and a certain Amperage out of so many watts from solar power?

  • I want to make a solar panel that is 12V D/C. I want all the amps i can get because my end goal is to power my house, or at least tie the power into the house. Here are the details as to what I (think I) know: A house runs off of 120V A/C and about 200 Amps. I know you can invert D/C to A/C, but i dont know what that does to effect total power. I know I could plug a 1000W inverter to a car battery and run a stereo or whatever. I have little knowledge on basic electronics, such as Amps X Volts=Watts, and watts = power. But when it comes down to series and parallel wiring, the only thing I think I know is that when you wire something in series, it doubles the voltage at each junction, and if you wire something in parallel, it doubles amperage. But maybe im wrong, maybe they dont double, but they increase, and depending on the resistance amount, will be the amount they increase. Anyway, I dont want to get into everything I know and dont know, I just want to try to find out how to get my goal voltage and aperage (120V A/C @ 200 Amps) from solar panels. Here is the data that i DO have: Each solar cell has a wattage rating of about 1.75W. This is with an output .5V @ about 3.5 amps through a multimeter. I was thinking of making a full panel consisting of 120 cells in rows of 10, columns of 12. Each vertical column (12 cells), when wired in series would output 6V D/C @ 3.5 amps, with a total of 10 columns. If every 2 columns were wired in series, it should be an output of 12V D/C @ 3.5 amps per 2 columns. Now I have 5 modules that are at a good voltage rating to input to an inverter, so i dont want to increase the voltage anymore, just the amps. So each of these 5 modules would then need to be wired in a parallel circuit which technically should add 3.5 amps for each module, totalling 17.5 amps and leaving the voltage at 12V. This should be the final output of the solar panel. 12V D/C @ 17.5 amps. Now, this is where i get lost (unless I have already, then someone needs to help me with my electricity knowledge)... I am also under the impression that amps are amps, no matter D/C or A/C. So i would guess that my next step would be to make enough 12V panels @ 17.5 amps each, to wire them parallel to equal 200 amps (household amperage). So this would be a little under 11.5 panels. Here in-lies another question, can I have more than 200 amps? Such as making it an even 12 panels to equal 210 amps? or does it have to be exactly 200? Alright, moving on, then I would have a total of 11.5 (or 12) panels equalling 12V D/C @ 200+/- Amps. This would be a total of 2.4kW or 2400 watts if I multiply voltage times amps, which would mean I would need at least a 2400W power inverter (grid tie inverter) for the system. But what confuses me is if I convert all that D/C power to A/C, what does that do to my voltage and amperage? I know it increases (or inverts I SHOULD say) the 12V D/C to 115-120V A/C, but do the amps honestly stay the same? They couldnt possibly, or it would make the wattage about 24,000W. Or is A/C amperage truly different than D/C and would it reduce it to 20Amps to keep the 120V x 20 Amps = 2400W equation correct? You can hopefully see where I am lacking knowledge and help me out, because I really just want to know how to convert all the DC power I can come up with (and I can make as many panels as I need), to an end result of 120V A/C @ 200 amps. Thanks for your time, I know this was a lengthy and somewhat drawn out question.

  • Answer:

    You want 120V at 200amps? What are you expecting to run? That's 24,000W! I'd suggest the maximum you sould allow for is far less than that! Solar cells are meant to charge batteries, not drive anything direct. The idea is you charge batteries, which then supply current to run to inverters etc. for household use. Especially at night! 120V at 20A would be 2400W., enough to run a typical electric heater. No, the amps don't "stay the same". To get 120V at 20A (2400W), the power requires at 12V is the same, 2400W. That is not allowing for inverter losses. So, the supply would need to be (2400/12) = 12V at 200A., and then some. Watts = volts x amps, volts = watts/amps, amps = watts/volts. You can reduce current from 200A to 50A if you increase battery voltage to 48. That is kinder on storage batteries. That is still 2400W, if you do the math. (48 x 50). AC or DC, measurements are the same.

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Some basic calculations and configurations of solar cells can be found here: http://solar-panel-future.blogspot.com/2010/06/basics-to-building-solar-panel.html

bukko

You want 120V at 200amps? What are you expecting to run? That's 24,000W! I'd suggest the maximum you sould allow for is far less than that! Solar cells are meant to charge batteries, not drive anything direct. The idea is you charge batteries, which then supply current to run to inverters etc. for household use. Especially at night! 120V at 20A would be 2400W., enough to run a typical electric heater. No, the amps don't "stay the same". To get 120V at 20A (2400W), the power requires at 12V is the same, 2400W. That is not allowing for inverter losses. So, the supply would need to be (2400/12) = 12V at 200A., and then some. Watts = volts x amps, volts = watts/amps, amps = watts/volts. You can reduce current from 200A to 50A if you increase battery voltage to 48. That is kinder on storage batteries. That is still 2400W, if you do the math. (48 x 50). AC or DC, measurements are the same.

Technobu...

ok your basically correct except on the point of DC amps and AC amps are the same. they are not. nether is the voltage. the 120 VAC you read on your meter is in the form of RAMS. (root means square) the DC equivalent. but the AC will peak at 1.414 times higher than the RAMS reading. At 120 Volts RAMS would peak at 136.92 volts. the same RAMS and peak is true for current readings. you also have to consider that some things in your home require 3 phase AC to work correctly. and most important is the frequency of the ac as well. some inverters models will take care of the frequency problem for you. but not the 3 phase. you will need to have your electrical panel upgraded to a butterfly set up to tie into your home electrical system safely. this with and auto switching system is not inexpensive. but must be done by a qualified professional. yes each cell in series will increase voltage DC by addition. and in parallel will increase current by addition as well. so the series/ parallel will work. my advice is to calculate the correct total DC values to peak AC values. then multiply by 4 at least. you need to calculate for surge on. this occurs when a device is first turned on from the off state. anything with a electrical motor including a hair dryer or fan. talk with well known solar cell manufactures. you will need a power usage audit to determine the correct power levels needed. but a certifed and accreadeted electrican in solar pannel in solar panel installation. due to building codes. this can not be done safely any other way. if installed incorrectly electrical fires or worse can and will occur.

Charlie A.

ok your basically correct except on the point of DC amps and AC amps are the same. they are not. nether is the voltage. the 120 VAC you read on your meter is in the form of RAMS. (root means square) the DC equivalent. but the AC will peak at 1.414 times higher than the RAMS reading. At 120 Volts RAMS would peak at 136.92 volts. the same RAMS and peak is true for current readings. you also have to consider that some things in your home require 3 phase AC to work correctly. and most important is the frequency of the ac as well. some inverters models will take care of the frequency problem for you. but not the 3 phase. you will need to have your electrical panel upgraded to a butterfly set up to tie into your home electrical system safely. this with and auto switching system is not inexpensive. but must be done by a qualified professional. yes each cell in series will increase voltage DC by addition. and in parallel will increase current by addition as well. so the series/ parallel will work. my advice is to calculate the correct total DC values to peak AC values. then multiply by 4 at least. you need to calculate for surge on. this occurs when a device is first turned on from the off state. anything with a electrical motor including a hair dryer or fan. talk with well known solar cell manufactures. you will need a power usage audit to determine the correct power levels needed. but a certifed and accreadeted electrican in solar pannel in solar panel installation. due to building codes. this can not be done safely any other way. if installed incorrectly electrical fires or worse can and will occur.

Charlie A.

I think the music itself plays a very large part. I get frustrated with politics as much as the next person (probably more so), but quality speaks volumes. Your run of the mill Anarcho punk band can be grating with all the politics and reiterated political messages. Yet you put in Propagandhi, Anti-Flag, Bad Religion, Manner Farm, etc and you can't help but love it! Those bands all have a distinct sound that would work, political or not. And the lyrics, though a deterrent for wanting to listen to other bands, are outweighed by skill and originality. Good to see you to Rckts.

Jennifer

Some basic calculations and configurations of solar cells can be found here: http://solar-panel-future.blogspot.com/2010/06/basics-to-building-solar-panel.html

bukko

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