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  • SupraLance
    started a topic In search of Best BAng for the Buck...

    In search of Best BAng for the Buck...

    Hi, I'm Lance from the Ozark Hills of Southwest Missouri, where we average 4.73 hours of solar insolation a day...

    I'm going to slowly build a home and live on-site in a mobile for the next several years, and can't/don't want to hook to the grid just yet. Right now I have a 2000w generator & two(2) GLC115 230ah 6v in service @12v. I don't yet have appliances other than LED TV, Blu-Ray, & laptop; and plan to use a propane stove, propane hot water, and wood heat. Refrigeration is undecided but probably a converted chest-type freezer. I'm going to have to start small on the solar system and upgrade along the way, so my goal is to get as much solar electricity as I can for my money. Rather than build to a certain watts/day goal, my thought is that I can add more creature comforts as the electricity to run them become available. I also think it's probably more economical to just fire up the generator during periods of lots of electrical use, like power tools, etc, rather than buying a large enough solar system to run them.

    Because it's a bad idea to mix new and old batteries and I already have 2 in service at 12v, I'm going to stick with 12v until these need replaced and then upgrade to 24v. If I understand correctly, it's best to charge batteries at 10-13% current, so my 230ah batt should be charged with 23-30a, which means I need 331-432w to charge these batteries with enough current to keep them mixed and not require charging off the generator (23ax14.4v=331w, 30ax14.4v=432w). I'm not entirely clear if this means I need a 30a charge controller to avoid sending too many amps to the battery, or if it means I need at least a 40a charge controller to handle the watts required before losses and have some overhead for usage while charging? If the 40a, do I need to limit amperage to the battery somehow, or will the battery simply not pull more than 30a?

    The best values in charge controllers seems to be at the 40a point, costing only $20 more than 30a controllers and hundreds less than 60a controllers (looking at EPever/EPsolar, which seems to be a decent brand of genuine mppt at a value price). Now I want to get the most out of every piece of equipment I buy, but this is a balance between maximum output and long life. The EPever Tracer4210 is rated 520w@12v, 1040w@24v and claims to be able to handle 300% more PV than that, but will clip production to no more than the rated watts. This means it can handle over-dimensioning, but only charges the battery at mpp if the panels are producing less than 520w. If the panels actually produce more than that, the excess is clipped to maintain the rated watts. And because STC rarely if ever occur in the real world, this means I need more than the rated watts of pv to full utilize the capabilities of the controller. But how much more? I see 75% thrown around as a downrating for real world conditions, so perhaps 690w STC generates about an actual 520w? If so, that would be the max pv to avoid any clipping, but when designing for maximum value it seems like some clipping would be desireable. But how can I determine how much? Perhaps I can maximize my power produced per dollar spent by going with 800 or 900w (rated STC) of panels into this controller? Anybody know where I can find more info on over-dimensioning calculations?

    Sanity check. If I produce an actual 520w with about 4hrs solar insolation/day, that is 2080wh/day actual production. That might work for most days, but seems likely I will need more with refrigeration. So my longer term plan would be to double this by eventually going 24v on the same controller and doubling the number of panels, if my actual usage on the 12v system indicates I need to. Thoughts?

  • JakeTrilla
    replied
    Originally posted by solar pete View Post
    Hi Jake, it can take anywhere from hours to days, its a manual process and I have to sleep sometimes
    hahahaha I understand THAT! thanks for the add, I look forward to being a part of the community from time to time!

    Leave a comment:


  • solar pete
    replied
    Hi Jake, it can take anywhere from hours to days, its a manual process and I have to sleep sometimes

    Leave a comment:


  • JakeTrilla
    replied
    Originally posted by carolinaken View Post
    What is the normal time frame to be approved ?
    I'm curious about the same...

    haha I thought I was a big dummy because I couldn't find the "post something new" button!

    Leave a comment:


  • carolinaken
    replied
    Thank you for the update

    Leave a comment:


  • carolinaken
    replied
    What is the normal time frame to be approved ?

    Leave a comment:


  • SupraLance
    replied
    How about splitting that convo off into a thread titled "Hijack me" (or "Where to post if you can't start a new thread rather than hijack somebody else). Giving people in that position a post to comment on may cut down the number of hijacked threads all across the board...
    Last edited by SupraLance; 02-18-2018, 07:52 PM.

    Leave a comment:


  • dstroot
    replied
    Thanks Solar Pete! I just thought I was missing something.

    Leave a comment:


  • solar pete
    replied
    Hi All

    We still have an issue that I have to manually approve new members, so when you first join you can only respond to a post you cant start anything until approved and sometimes that takes too long and frustrates everyone including the mods (sorry guys) but hey I have to sleep sometimes

    Leave a comment:


  • J.P.M.
    replied
    Originally posted by dstroot View Post

    Thanks Mike! So reading between the lines I am hearing that I can't create posts because I lack privileges and I need an upgrade?

    Cheers!
    Unless things have changed, you can post a new topic or start a thread.

    --->>>Solar Panel Talk --->>>Forums --->>> pick a forum that covers the area that seems to cover what you want to discuss click on it --->>> click on button that says "new topic" --->>> start typing.

    Not an immediately apparent path, and as a computer Luddite, I take the admin. to task for that. But on the user side, some user input and daring to try new stuff and root around is probably reasonable to expect.

    Leave a comment:


  • dstroot
    replied
    Originally posted by Mike90250 View Post

    I'm a low level mod, and cannot upgrade you, split a thread, but I can approve your posts
    Thanks Mike! So reading between the lines I am hearing that I can't create posts because I lack privileges and I need an upgrade?

    Cheers!

    Leave a comment:


  • Mike90250
    replied
    Originally posted by dstroot View Post
    Hey all - new here and I am embarrassed to hijack the thread but I cannot create a new post! I seem to be only able to reply to existing posts. Anyone know how to create a new post? (yes, I feel stupid but I can't figure this out!)

    Cheers,
    Dan
    I'm a low level mod, and cannot upgrade you, split a thread, but I can approve your posts

    Leave a comment:


  • dstroot
    replied
    Hey all - new here and I am embarrassed to hijack the thread but I cannot create a new post! I seem to be only able to reply to existing posts. Anyone know how to create a new post? (yes, I feel stupid but I can't figure this out!)

    Cheers,
    Dan

    Leave a comment:


  • SupraLance
    replied
    Matrix, just assume my load predictions are over the amount of solar I can afford right now, and I'm trying to run the generator less by charging the 230ah@12v battery bank I already have with solar, and won't have trouble using any extra but can only spend about $1000.

    As of right now, the following options are the best I've found and I would appreciate opinions and/or better options:

    620w (clipped at 520w at controller when pv actual production exceeds that):
    $140 ....EPever 4210a 40a mppt (can only run pv in parallel or exceed mpp range)
    $440 ....two(2) Trina 310w 72cell 61lb panels including $150 shipping from SEP batteries
    $110 ....Wagan Elite 2601 400w inverter
    $60 ......wiring/breakers
    =$750 plus mounting costs for 620w

    OR 690w (clipped at 520w at controller when pv actual production exceeds that):
    $190 ....EPever 4215bn 40a mppt
    $456 ....three(3) EcoSolargy 230w 60cell 42lb panels including $150 shipping from SEP batteries
    $110 ....Wagan Elite 2601 400w inverter
    $72 ......wiring/breakers
    =$828 plus mounting costs for 690w ($28 for 70w, $50 for more robust controller)

    The EcoSolargy panels are cheaper per watt, but I'm concerned that they are likely to be older stock, and perhaps not as good as Trina panels. Do pv warranties go from date of manufacture? For instance, if I buy panels that have sat in a warehouse unused for 8 years, with a 25 year warranty, do they only actually have 18 years left on warranty?
    Last edited by SupraLance; 02-16-2018, 02:11 PM.

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  • Matrix
    replied
    To be able really take a shot at your needs, we need to see projected load calculations in Watt Hours per day. That is how many Watts total from all devices you anticipate to need to power And also how many days of autonomy you plan to build into the system. You need either 1.) 2-3 days of autonomy (so that would be daily Watt Hours x the number of days = total need) Or a generator to off set those days when you have no sun or grid power or charging. Batteries do not like to sit around under charged for very long.

    Leave a comment:

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