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lutful
... of ideas
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join:2005-06-16
Ottawa, ON

lutful to gaforces

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to gaforces

Re: [Electrical] Small solar system

said by gaforces:

If the system can put out 20 amp in the sun then it is worth it to be able to use my tools at remote jobs or anywhere there is no power and without having to start my motor.

Can you elaborate on how much power you actually need and for how long?

voltage=120V
current=20A ???
total hours per day=
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

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gaforces (banned) to lutful

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to lutful
I am sorry your posts have not been useful in this thread.
You made a vague suggestion about a 435w sunpower for $419.

(Removed suspected scammer advertising on ebay that I quoted for clarification)

You say Im pushing renogy panels which is false. I don't care what you use, they just happen to be what I am using. You seem to dislike renogy panels, can I ask why? I haven't heard anything bad but shipping damage.
said by lutful:

That is ludicrous, or foolish, unreasonable, or out of place as to be amusing, ... and I highlighted a perfect example above.

I have posted lots of useful information about solar panel and battery sizing, charging, MPPT controllers, inverters, etc. in the past 10 years. I have also seen lots of useful posts from cowboyro See Profile in home improvement and electronics forum.

Search result using only "solar" keyword after you click my username: »/nsear ··· t6369309

Many of those threads deal with "small solar system" design. If you really came for suggestions, please have a look at such threads.

But if you came to push panels from Renogy Amazon store, I have to let others know that they are CERTAINLY NOT "re-badged" SunPower. Genuine SunPower panels use Maxeon back-contact cells which have no electrical connections on the top face.


snappypoo
@69.118.94.x

snappypoo to gaforces

Anon

to gaforces
said by gaforces:

If the system can put out 20 amp in the sun then it is worth it to be able to use my tools at remote jobs or anywhere there is no power and without having to start my motor.

I left out the part where you got snappy talking about hand tools... okay you want to output 20 amps, now you left out the voltage you want the 20 amps at...

I can only guess 120v...

So you need 2400 watts worth of solar, not accounting for lose, and that fact you will pretty much never be at 100% So say 3000watts of panels to get your 20 amps to be "worth it"

Okay great I can't wait to see your reply now.
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

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gaforces (banned) to lutful

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to lutful
2 1/2 hours till break time of 10 min, 2 and 1/2 hours till lunch of 1/2 hour so on for 8 hours or so. I hardly ever work more than 2 1/2 hours without resting eating and drinking anymore.
I had time to read your posts for a while, you mention high end stuff that is expensive.
Is the reason you don't like those panels is they are too cheap?

BTW those 435w panels your pushing are crap. 6.5 amp for a 7 foot panel? What a joke. It's pretty slick how you so nonchalantly enter the thread, and mock me for not buying a panel that is obviously obsolete. I don't want to buy your Snake Oil.
gaforces

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gaforces (banned) to snappypoo

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to snappypoo
Yes I get snappy when people basically calling me stupid and wasting money. And then I don't talk to them any longer, life is too short.
Reminds me of a good story!
This manager of a local surfshop sells 500-1200 dollar surfboards, 200 dollar watches, 600 dollar wetsuits etc etc all day long.
Welp some years back a guy made a deal to sell surfboards to Costco, they sold a lot for cheap, undercut everyone on price by quite a margin.
That manager, he shit talked those Costco boards to everyone, after a while with peer pressure he got most locals hating those boards, you would be ridiculed if you were seen with one.
HAH THE IRONY, that guy who did the costco deal got a contract with the surfshop that manager works at, so now he has to sell them.
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

lutful to gaforces

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to gaforces
said by gaforces:

BTW those 435w panels your pushing are crap. 6.5 amp for a 7 foot panel? What a joke. It's pretty slick how you so nonchalantly enter the thread, and mock me for not buying a panel that is obviously obsolete. I don't want to buy your Snake Oil.

At some point you will figure out that Watts=Amps x Volts. FYI exact same size panel that produces 20A at 18V is producing only 18VX20A=360W in full sun, a whopping 75W less than 435W panel.

SunPower has been setting efficiency records since they started production. This is their latest model and getting 435W from a single 7x4 ft panel is the current world record!

You can easily swear to NEVER EVER buy SunPower panels! But others may want to know about it in a public forum. So please stop the insults.
said by gaforces:

2 1/2 hours till break time of 10 min, 2 and 1/2 hours till lunch of 1/2 hour so on for 8 hours or so. I hardly ever work more than 2 1/2 hours without resting eating and drinking anymore.

So you are looking to power your tools for at least 5 hours per day?

Multiply the average AC amps of your tools by 120V and 5 hours to get an idea of how many Watt-Hours do your solar panels need to provide each day?

If you do those calculations right, you may realize that your idea is hopeless on our planet.
Expand your moderator at work
lutful

lutful to gaforces

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to gaforces

Re: [Electrical] Small solar system

For anyone who need to estimate how many "watt-hours" you can get from panels:
»solar/wind powered nodes: worst-case calculations

PS. The numbers in that map are for each square meter of panel.
Divide by 10 for watt-hours per day per square feet.
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

gaforces (banned)

Member

You have been thread crapping and pushing sunpower panels. I think you have done them a disservice but I applaud you for your determination.
gaforces

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gaforces (banned) to snappypoo

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Click for full size
I've found the fuse placements and formulae and it looks like the battery's shipped early and will arrive around end of the week. This pic is for PWM controller but I don't think that's an issue.
gaforces

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gaforces (banned) to snappypoo

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I knew it would controversial to post about solar, but dammm, so many solar denyers.
The solar snobs are the worst, they will hold back the world for years with their greed.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

said by gaforces:

I knew it would controversial to post about solar, but dammm, so many solar denyers.
The solar snobs are the worst, they will hold back the world for years with their greed.

So anyone who doesn't agree with you elicits a label solar snob?

cowboyro
Premium Member
join:2000-10-11
CT

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said by gaforces:

I knew it would controversial to post about solar, but dammm, so many solar denyers.
The solar snobs are the worst, they will hold back the world for years with their greed.

Solar works, but it doesn't pay off everywhere. It only pays off where there is good exposure throughout the year, the utility rates are high, and any excess production can be sold to the utility co. using net metering rates. And even then the break-even period is 10-15 years if nothing breaks.
lutful
... of ideas
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join:2005-06-16
Ottawa, ON

lutful to Jack_in_VA

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Click for full size
Click for full size
said by Jack_in_VA:

said by gaforces:

I knew it would controversial to post about solar, but dammm, so many solar denyers.
The solar snobs are the worst, they will hold back the world for years with their greed.

So anyone who doesn't agree with you elicits a label solar snob?

The irony is that he was taking a shot at a person who has been bringing solar power to some really amazing projects including these mobile community centres and schools in my home country.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

1 recommendation

Jack_in_VA

Premium Member

You didn't agree with him. The positive things you have done is not in consideration.

mackey
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join:2007-08-20

mackey to gaforces

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to gaforces
said by gaforces:

I knew it would controversial to post about solar, but dammm, so many solar denyers.
The solar snobs are the worst, they will hold back the world for years with their greed.

Or perhaps they've had years of experience dealing with solar and know that what a real world panel actually puts out isn't close to what an ideal panel can theoretically put out. If you're basing everything on the numbers marketing slapped on the panels then you're going to be seriously disappointed with their output esp. with them laying flat on your vans' roof.
ke4pym
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join:2004-07-24
Charlotte, NC

ke4pym to lutful

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said by lutful:

At some point you will figure out that Watts=Amps x Volts. FYI exact same size panel that produces 20A at 18V is producing only 18VX20A=360W in full sun, a whopping 75W less than 435W panel.

And only when the panel is brand new. Output decreases as the panel ages. Some more than others, some less than others.
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

gaforces (banned) to Jack_in_VA

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Never said that and don't believe that, but whatever.
gaforces

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gaforces (banned) to lutful

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to lutful
said by lutful:

The irony is that he was taking a shot at a person who has been bringing solar power to some really amazing projects including these mobile community centres and schools in my home country.

This is your rational for trying to sell overpriced crap with no warranty, even after I told you 3 times I wasn't interested?
You omitted the truth and ignored a potential customer, shame on you, since you actually do know better.

ampsmore
@50.138.50.x

ampsmore to gaforces

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to gaforces
please,

note the general rule, that solar power typically costs double the price of power company nuclear, mostly cause of the expensive batteries, which typically last only 5 years, then need to be replaced. though that is changing, as cheaper Chinese panels become available in the USA

note the general practice, that the diagram you show relies ENTIRELY on solar, so if you have a couple days with no sun, you have no charge in the batteries. adding a circuit to also charge from the alternator, when you are already driving, works well. as does a circuit to connect a standard 120 volt ac battery charger.

note the general practice, for any extreme battery mobile system, is NOT to use the primary alternator and battery for heavy accessories, since you don't want to take a chance of flat starting battery leaving you stuck.

use a second battery, either with a 2nd alternator, or with the existing one alternator, and a diode blocking arrangement, to prevent a flat accessory battery from running down the primary starting battery. look for a diode set that uses two schottky diodes, more expensive, but a bit less voltage loss.
here's a generic link term, you can make your own brand decisions.

"schottky diode battery isolator"

note the practical rule, as others have mentioned, that due to the difference between specifications and practice, you will normally only be getting half the watts from the panels' specifications. the specs are for midday full sun time, just a few hours, with the panels pointed directly at the sun, with NO clouds or shadows.
in other words, a 400 watt panel will only be giving you 200 watts or less, average, for your installation.
ampsmore

ampsmore to gaforces

Anon

to gaforces
just one more tedious calculation, based on your diagram and added specifications.

your source is four 100 watt panels, at nominal 12 volts dc.

the panels in midday perpendicular sun will give you 400 watts, for say 4 hours, less for nonmidday, so say 200 watts for the other 4 hours. that's a total of 400x4, plus 200x4, total 1600 + 800, or 2400 watthours, per sunny day.

you want 20 amps max, at 120 volts ac.
that's 2400 watts (20 x 120),

for say 4 hours a day, actually using the power?,
that's 9600 watthours.
so you will be pulling out FOUR TIMES the power that you are putting in with the panels.

your results will differ, probably in your favor.
likely you are using the power even less than the 4 hours a day,
and likely you are NOT using the whole 20 amps the whole time that you are using it.

keep us posted with what actually works.

use the 10:1 general rule to convert that to 200 amps out of the battery.
lutful
... of ideas
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join:2005-06-16
Ottawa, ON

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lutful to gaforces

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to gaforces
This is a public forum and many different suggestions are provided to help the original poster and also others who may come across this thread with a similar problem.

I will summarize my suggestions for both you and future readers:

Because you are working with limited space on roof of a van, first I pointed out that a single SunPower 435W panel exists which is smaller than your 4x100W panels and is also cheaper.

You later explained it would not "fit" because a vent in the middle of roof. So I pointed out that perhaps 6 of the SunPower semi-flex panels - same ones on the Ford car - can be stuck around the vent on the van's roof. Obviously that would give you even more power - almost double of the 4x100W panels.

Then I pointed out that (MeanWell TN-1500 or TN-3000) has everything else you need: the MPPT charger, the inverter, and even the transfer switch inside same compact box. I linked to a relevant thread.

*** SunPower, a very successful US company, with significant presence in Canada makes the most efficient commercial solar panels and also introduced the longest warranty in the industry.

warranty: »global.sunpower.com/prod ··· arranty/
efficiency: »cleantechnica.com/2014/0 ··· ficient/

SunPower solar modules hold the commercial solar module efficiency record. ... other SunPower solar modules come in #2 and #3 in those tests.

If you are limited in total area, you should consider SunPower and if you are concerned about total weight AND total area, you should consider SunPower semi-flex panels. If your budget allows them, please buy from a dealer in USA or Canada.
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

1 recommendation

gaforces (banned)

Member

I was pretty clear I had already purchased panels, and everything else but battery's and a cabinet on my first post.

You alluded to a cheap panel on ebay, well I wasted my time looking at that panel.
That company magma solar usa is non-existent except for ebay.
The warranty is illegal in California.
They removed the sunpower branding, and sunpower does not warrant them.
That person Marc at ebay supposedly doing business as magma solar usa will not give shipping price unless you call him long distance.
He will not say what brand or model controller he says he has for $275, except if you call him. There are none on his other auctions.

And lastly, I challenge you to build that system from Marc with that panel with your sodium lithium ion battery's and his imaginary controller for a price close to the US $2400.00 that is equal or greater output of Amperage. That includes the battery bank.

I am confidant this system I am building will put out more amperage than that pos system you specced.
I am going to dedicate my do it yerself with basic electronics small solar system writeup to you and the others on this thread, and maybe my Amazon review as well!
I will clean up the schematic with the final product specs and if anyone wants the parts list I will make one and send by IM if requested.
said by lutful:

...

lutful
... of ideas
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join:2005-06-16
Ottawa, ON

lutful to gaforces

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My final post in this thread is a simple explanation of "amperage" calculations which seems to confuse some people.

Solar panels are always rated in watts. You can use watts divided by area to compare panels.

The volt and amp specifications are secondary and must be considered together because volts multiplied by amps = watts.

It is usually better to have lower amps and higher volts to reduce the losses from cable resistance. Lower amps also allow thinner gauge and reduce cable cost.

Good quality MPPT controllers will handle the most efficient high voltage, low amps panels.
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

gaforces (banned) to mackey

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said by mackey:

with them laying flat on your vans' roof

You are correct, I did consider the tilt mounts, just the expense right now I need to recover from this one. I should be recovered by Christmas
gaforces

gaforces (banned) to ampsmore

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Thanks that's good info! I need to find a 300 amp 3 way switch that only lets one work at a time, otherwise I'm considering using the 300 amp battery disconnects which would be more tedious, I would have to manually make sure only one is on at a time. Cant find a 3 way atm.
Battery isolator will have to wait till I recover from expense of this system.

mackey
Premium Member
join:2007-08-20

mackey

Premium Member

said by gaforces:

Cant find a 3 way atm.

You may have better luck searching for "single pole double throw" or SPDT, the technical name for a "3-way." A DPDT would also work, you just wouldn't use the 2nd set of contacts.

/M
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

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gaforces (banned) to ampsmore

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I have the add-on meter for this controller, it will be able to tell me most everything. Looks like the inverter has an output display as well. And I will be using the kill a watt meter.
Right at this time of year we get 10 hours of sun a day when it's not foggy from the ocean. It is looking to be a non foggy summer this year, hotter than normal.

Thanks that's more good info!
Do you know how much switching to 24v battery bank would help?
I know I could put 10 panels total instead of 5 for 12v per controller. Assuming I could afford a 24v inverter, which I cannot atm.
gaforces

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gaforces (banned) to mackey

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Thanks!
There seem to be a lot of 2 way, it's on/off/on and I found a Generac 6333 60-Amp Single Load Double Pole Manual Transfer Switch for Portable Generators that looks pretty good for $100 and has a panel. There is a 100/60 amp reliance controls one as well.
I saw one they use for electric fences, I like it but its too small amperage.
It's like a timer dial 1-2-3.
ke4pym
Premium Member
join:2004-07-24
Charlotte, NC

ke4pym to gaforces

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to gaforces
said by gaforces:

Right at this time of year we get 10 hours of sun a day when it's not foggy from the ocean.

Don't count on those panels to have full output for 10 hours (you should have more than 10 hours - first light here is around 6am and dark is closer to 9pm). At most, you may have 2 to 2.5 hours of full output. May be closer to 1h45m.

I have a 23 panel - 5.62kw array on the roof of my house. I get the benefit of tilt. By 10am the array is around 3kw. Only for a short period between 11:30 and 1 do I have full output. Which this year seems to be around 5.1kw (last year was closer to 5.25). And super sunny days I'm producing 37kwh/day. That's rare. Most days it is closer to 30-32.

Fog, unlike clouds will absolutely kill your output (to be fair, clouds are bad. Fog - kills). And in the winter, output drops significantly.