Solar panel inverter directly to PSU & system?

Hello, one of my future goals is to have a small house with a solar panel setup, and I did a bit of research into modern solar panel setups. Many are still really expensive though I expect them to become more affordable and carry more capacity for continuous power through them. Here is one I found:

"New Lithium battery 2000 watt model:
- 600 watts PV input
- Will run 800 to 1000 watts all day, and 400 watts all night
....
Uses: Run production command posts, gate posts, remote posts, vendor booths, art installations and fountains, pumps, LED lights , etc. Charge all production radios, laptops, cameras, video equipment, tools, etc."

http://www.sol-solutions.com/index.php/products-services/solman-portable-solar-solutions.html

When I saw 400 watts all night, I got thought of this fun, extreme idea to be able to game overnight even in a snowstorm and a power outage. But of course, that power would be best reserved first for heating and other necessities. But, just to entertain this thought, has any one been able to connect a solar setup as convenient as this one to a desktop with a 300 or 400watt PSU? I have a 330w. The link includes a picture of a Macbook running on it, which is probably around 60 watts. Ideally I'd use a desktop when it'd be charged above 2kwhs, so there'd always be at least an hour remaining. Also, while this solar setup has an inverter, my guess is that there could also be some solar setups that supply directly to a PSU that doesn't need the AC->DC conversion and only relies on the transformer, since solar could provide DC directly from the lithium batteries. I'm also curious how the system would turn off if it ran out of juice.

Edit: I also think it can run up to 25amps, which might be enough for some PSUs.

the psu your after is a wide-range-Dc power supply. like one of these two..
http://www.mini-box.com/PicoPSU-120-WI-25-12-25V-DC-DC-ATX-power-supply
http://www.mini-box.com/M4-ATX?sc=8&category=981
though that would limit the video card you can run.. it would allow you to run either 12v=16+v nom dc panel or 24v=26+ nom dc panel. i would suggest some kind of power smoother in line before the psu, like a small bank of SLA/AGM batteries or a small bank of super caps.

Evilsizer said:

the psu your after is a wide-range-Dc power supply. like one of these two..
http://www.mini-box.com/PicoPSU-120-WI-25-12-25V-DC-DC-ATX-power-supply
http://www.mini-box.com/M4-ATX?sc=8&category=981
though that would limit the video card you can run.. it would allow you to run either 12v=16+v nom dc panel or 24v=26+ nom dc panel. i would suggest some kind of power smoother in line before the psu, like a small bank of SLA/AGM batteries or a small bank of super caps.

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Thanks, that's awesome. I'll look into that more and see what kind of setup I might use. I read some MiniITX motherboards on Wikipedia have some DC-DC inputs, which might simplify a future build. I don't know the exact terminology (DC, etc), as I'm new to this. I also plan to keep my current build and see what I can do with that. 250 watts might even be enough for the light gaming that I do.

___________________________________________
"In Solar Russia, the sun works for YOU."

Regardless of whether you choose direct DC or an inverter, keep in mind that the specified available amp hours contemplate a full day of sun. In most locations, especially those in the north, there will be times (occasionally extended) when very little sun hits your panels, so you must have an alternative means (generator, grid) to charge your batteries/power your system.

FWIW, our system. Be sure to check phase 2.

hafa said:

Regardless of whether you choose direct DC or an inverter, keep in mind that the specified available amp hours contemplate a full day of sun. In most locations, especially those in the north, there will be times (occasionally extended) when very little sun hits your panels, so you must have an alternative means (generator, grid) to charge your batteries/power your system.

FWIW, our system. Be sure to check phase 2.

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Thanks. I don't plan on using it near Alaska or where there's no sun for 3 months, but I have been trying to figure out exactly how much solar I could live off if I devise a very modest list of material needs. But in the short term, I definitely see backups as more practical. I'm really curious of setups that do get enough amps with more than 10 panels or so with even the seasonal low of just a couple hours of unoptimal cloudy light to charge the batteries for the whole day. And of course batteries that are built for frequent recharging would be ideal.

Also, I am also considering seeking a desktop that uses an ultra-low voltage CPU, like the Athlon II X2 270u, which runs on 25 watts. I might not use it for heavy gaming, but I like the option of having a system where I can install it rather than buy a nettop or laptop that doesn't have the ability to upgrade or have an open case, and it would be one of the lowest "system-buildable" x86 TDPs, though the DX11 Zacates will also be out soon that use 18W (single) and 25W (for dual core). My estimate is that an entire MiniITX system could run on 60 watts with a low-power PCI-e cards+10 for the LCD, or like the Zacate, it'd be an APU.

the cpu or apu TDP is not a function of power draw, while lower TDP cpus = lower power. the TDP does not give a clear indication of how much power the system will use at a load state.

when sizing your panels you need to assume worst cases. as in the least amount of sun hours you will have on a given day, then factor in how long it might last. would do this based on past weather patterns for the day/week/month. if you were to only power your pc from solar with battery backup power. solar system should be at least 50% larger then the pc's WH figure. if it draws 50WH then get a panel that is 75WH or larger, depending on how big your battery backup will be.

as for batteries that can take recharging, optima yellow top or look for AGM batteries. if you got a bit more to spend and want a smaller battery with the same size AH rating, look at Lifepro4 batteries.

Xenohitsu said:

Thanks. I don't plan on using it near Alaska or where there's no sun for 3 months, but I have been trying to figure out exactly how much solar I could live off if I devise a very modest list of material needs. But in the short term, I definitely see backups as more practical. I'm really curious of setups that do get enough amps with more than 10 panels or so with even the seasonal low of just a couple hours of unoptimal cloudy light to charge the batteries for the whole day. And of course batteries that are built for frequent recharging would be ideal.

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Insolation is not only a function of latitude, but also the prevailing meteorological conditions. Check the chart for your region here. Solar calculators such as this one can give you a good rough estimate of your KWH/Year.

Take a look at our system as linked in my previous post; a full sunny day (~ 7-8 hours year round @ 15 degrees lat.) produces 12-13 KWH; a full day of very heavy overcast produces <2KWH. String 4-5 days like that together and you're firing up the generator.

In terms of batteries, the Surrette/Rolls have excellent service life and are currently an outstanding value.

Evilsizer said:

the cpu or apu TDP is not a function of power draw, while lower TDP cpus = lower power. the TDP does not give a clear indication of how much power the system will use at a load state.

when sizing your panels you need to assume worst cases. as in the least amount of sun hours you will have on a given day, then factor in how long it might last. would do this based on past weather patterns for the day/week/month. if you were to only power your pc from solar with battery backup power. solar system should be at least 50% larger then the pc's WH figure. if it draws 50WH then get a panel that is 75WH or larger, depending on how big your battery backup will be.

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I forgot that TDP is not exact. Oops. What I'm also interested in is the "surge" at first power on- so it's under surge capacity of the solar, peak loads, and perhaps Turbo Boost in i7 and Thubans that may use close to the TDP or more than it, just to account for any variable so it's always under the peak/surge capacity of the panel.
Also, if using your example and assuming with a full sunny day and optimum insolation with a 75WH panel, while not having the PC on, does that mean if the solar charges the batteries for two hours I would have 150WH for 3 hours of 50WH draw from the PC? These are some things I'm thinking about in terms of stored Kwh. (Edit 1: also, accounting for efficiency, I'm also taking into account that an 80 Plus efficient power supply would draw 62.5 watts for a 50watt system, and it'd be less than 3 hours. Edit 2: Oh wait, I'm not sure how DC PSUs computes that. I'm also considering a pure sine wave inverter if out of simplicity, I plan to run many other appliances too, and the batteries end up being further away from the PC in the house. Or I could wire the walls for DC?)

hafa said:

Insolation is not only a function of latitude, but also the prevailing meteorological conditions. Check the chart for your region here. Solar calculators such as this one can give you a good rough estimate of your KWH/Year.

Take a look at our system as linked in my previous post; a full sunny day (~ 7-8 hours year round @ 15 degrees lat.) produces 12-13 KWH; a full day of very heavy overcast produces <2KWH. String 4-5 days like that together and you're firing up the generator.

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I was figuring that I would probably get less than 2Kwh on really heavy overcast days. Not to add to my complications and slightly ambitious goals, I am interested in an electric heater, which I'd assume would be the most taxing on the panels. Extreme designs such as the Tumbleweed Tiny houses, which are built professionally and have square feet of 89-130, are conceptually simple, at least for me as a starting model. Looking up small space heaters, some (for bathrooms, lol) can heat that amount of area for under 500watts, at least for 20 minutes every couple hours or until thermodynamics does its thing-dissipating (or even continuous?). So that's my project- to see how many necessary appliances (water pump, LED lights, hot plate) I can power with solar using perhaps 5-10 panels and maybe on 2-3Kwh. I would still use a backup generator, but the idea that solar can do it all is interesting, if not an attainable goal.

I did this separate calculation. If I used an electric heater that needed to be on 20 minutes every hour (40 minutes off), in the winter where heat would be needed around the clock, then if a solar setup produces 2Kwh, and I need 500/3 Wh per hour, that means I would have enough 20 minute intervals of heat each hour for 12 hours, still not enough for 24 hours, so casting out all other appliances, I'm assuming I'd need at least 4kwh (10-15 panels, or less heat loss per hour, so it could be activated maybe 2 hours.) Again these are estimates and I'm sure I could be way off. Maybe a space heater could run on half that (250w), and I could improve efficiencies all around. I'm basically thinking of an integrated system, where the whole system is optimized for the standardized building, since something like a Tumbleweed has already some standardized known variables, which makes it interesting for this academic/real-world exercise.

Something like the Solar Decathalon?
http://www.solardecathlon.gov/past/2009/team_illinois.cfm
"It has 100-year-old barn wood and high-efficiency solar panels on the outside and features a familiar gable roof profile. Inside, the newest structural bamboo and optimized windows, insulation, and appliances mean it can be heated with a single hair dryer."
Not sure about the hair dryer part...

Electric is really inefficient at producing heat. you would be much better off with a LPG or Natural Gas burner or even a wood burning stove.

Rizo-uk said:

Electric is really inefficient at producing heat. you would be much better off with a LPG or Natural Gas burner or even a wood burning stove.

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I know....it's just that if I had a rooftop full of panels it might be enough if I overcompensated. Not the most efficient, of course, but still convenient in a snow storm if wood (trees) or petrol supplies (in the unlikely event someone decided to forget to buy more propane/natural gas) were out of reach and roads were blocked from heavy snow. It's more of a proof-of-concept rather than something I'd expect other people to adopt.

Ans assuming I would be able to brush off the blanket of snow that covers the panels with some windshield wiper or by myself.

Edit: this kind of reminds me of another apparatus that acknowledges that something is inefficient, and there are better ways to do it, but it's done for another reason. In the following case, coffee is more flavored when the boiling is less efficient:
http://www.sciencemag.org/cgi/content/summary/315/5809/167c
"Comparing the work done pushing the water into the upper chamber to the heat energy absorbed by the boiler, the group found that the pot turned heat into work with an efficiency of 0.02%--compared to about 20% for a typical steam engine. Gianino, who reports the work in the January American Journal of Physics, notes in the moka's defense that its job is not to move water efficiently but to flavor it."
So the analogy I see this is that solar is more convenient(flavorful) when the heating does not require transportable fuel (via pipeline or loading up onto car), thus the "wireless" concept (from the sun), gives it a desired advantage, which to me outweighs the cons of inefficiency.

The two main obstacles I think are: How much heat and modest electric consumption can one get by on, and two, how affordable can it be made so it's not entirely a cost-prohibitive solution? If the batteries like one of the above links last 20 years, then the system would require no extra energy costs if none of the heaters or photovoltaics broke down.

Edit: Sorry for veering this convo towards energy in general.

if using a dc to ac inverter most if not all i have seen are at most 80% efficient. now take into account your computer psu is only 80% efficient at converting ac to dc. thats not real efficient looking at the bigger picture. i would go with a dc to dc power supply as they are more efficient at down converting dc.

my advice if you go with solar, get any appliances you can that are made to run on DC. i have seen some washers/dryers that will run off of 24v and some off of 48v. same thing for fridges and freezers. this way you minimize losses from having to convert DC to AC ect..

another thing when sizing a battery bank add 20% to what ever figure you come up with. as no battery likes to be fully discharged not even lifepro4 or SLA/AGM. about the only i can think of that might be ok would be the optima yellow top gel cells. still if you follow the 20%min charge state of the battery you should see 4+yrs of use. i was reading on site claiming longer life on a rolls battery that hafa posted a link to. they put the battery bank into service back in 1988 and it is still in use without replacing any of the cells.

Evilsizer said:

if using a dc to ac inverter most if not all i have seen are at most 80% efficient. now take into account your computer psu is only 80% efficient at converting ac to dc. thats not real efficient looking at the bigger picture. i would go with a dc to dc power supply as they are more efficient at down converting dc.

my advice if you go with solar, get any appliances you can that are made to run on DC. i have seen some washers/dryers that will run off of 24v and some off of 48v. same thing for fridges and freezers. this way you minimize losses from having to convert DC to AC ect..

another thing when sizing a battery bank add 20% to what ever figure you come up with. as no battery likes to be fully discharged not even lifepro4 or SLA/AGM. about the only i can think of that might be ok would be the optima yellow top gel cells. still if you follow the 20%min charge state of the battery you should see 4+yrs of use. i was reading on site claiming longer life on a rolls battery that hafa posted a link to. they put the battery bank into service back in 1988 and it is still in use without replacing any of the cells.

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You're right, I'd definitely go with DC for pretty much everything, including the PC. I think it was http://www.compactappliance.com or this other site where I saw lots of DC things for mobiles. Will take that into consideration. Thanks.

Electric is really inefficient at producing heat. you would be much better off with a LPG or Natural Gas burner or even a wood burning stove.

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I would think it's very efficient. At very close to 100%. All electrical power input becomes heat.

I meant what I said about electric being in efficient by the fact the supply was coming from PV Array. Seems such a waste to use all the energy from the array to run a heater. Save the electric for things like fridges, lights, dc appliances

Rizo-uk said:

I meant what I said about electric being in efficient by the fact the supply was coming from PV Array. Seems such a waste to use all the energy from the array to run a heater. Save the electric for things like fridges, lights, dc appliances

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Hahaha. It's inefficient to use electricity to heat things up. But it's pretty efficient at doing it.

Rizo-uk said:

I meant what I said about electric being in efficient by the fact the supply was coming from PV Array. Seems such a waste to use all the energy from the array to run a heater. Save the electric for things like fridges, lights, dc appliances

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cyberfish said:

Hahaha. It's inefficient to use electricity to heat things up. But it's pretty efficient at doing it.

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you're both right. First I'll find out out how to run a DC fridge, LED light, DC washer/dryer/induction stove top, etc, then set aside another whole PV array just for heating, unless combining them helps. If it's only 89 square feet as an example: http://www.tumbleweedhouses.com/houses/epu/
,I'm curious if there's enough surface area on the roof for panels to provide that amount of electric (i.e 2-3 kw minimum in winter?) I definitely think 5-6 panels could fit on one side facing the sun, so I'm not sure if it's better to have them automatically rotated so they tilt to match the angle of the sun, or put 5 on each side and have the morning light charge one roof and the afternoon light charge the other roof.

i dont think your going to find a induction stove stop that runs off DC, that is one your going to need to run of AC. though it would be nice to see them in dc, if they are, they are prolly 48V or higher in DC.

Evilsizer said:

i dont think your going to find a induction stove stop that runs off DC, that is one your going to need to run of AC. though it would be nice to see them in dc, if they are, they are prolly 48V or higher in DC.

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Interesting, and seems true. It looks like Alternating Current is intrinsic to the mechanism of heating:
"Induction heating is a method whereby some ferromagnetic material (iron, steel, nickelicon, etc.) is subjected to an alternating magnetic flux which is generated by an AC voltage and induction coil (there is no such thing as DC induction heating)."

If it were inverted from DC though, it seems like it'd need a lot:
"In each of the electronics modules, the 240V, 60Hz domestic line power was converted to between 20V and 200V of continuously variable DC by a phase-controlled rectifier. That DC power was in turn converted to 27 kHz AC by two arrays of six paralleled Motorola automotive-ignition transistors in a half-bridge configuration driving a series-resonant LC oscillator, of which the inductor component was the induction-heating coil and its load, the cooking pan."

"For installation in facilities that are powered by DC batteries such as RV's or Solar, the inverter that creates the AC current to power the induction cooktop must be a true sine wave inverter and not a 'modified' or square wave inverter. The reason for this is devices with IC's like induction cookers need to measure the peaks of the sine wave to produce timing cycles for the proper functioning of the IC. Sine wave inverters are significantly more expensive than square wave inverters and less common. Many of the newer four stroke generators however, do produce a sine wave and are therefore suitable to run an induction cooktop, which typically requires a minimum of 1200 watts."

Wow. I will probably go for something else.

1200watts isnt that bad in terms of power used by everyday devices... consider you might only use the cook top for about 30mins maybe a 1hr, so if its 30mins your looking at 600WH vs 1200WH for using it for one hour. since induction heats up faster other electric style/type stoves. the only other i would consider using is a propane or natural gas stove...