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  • magic8192
    replied
    New member here
    So new I can't figure out how to post a new topic.
    Looking forward to designing and installing a new solar power system.

    Leave a comment:


  • Matrix
    replied
    To the OP, do you have an inverter in mind? I did not see that in the opening list, and between a good inverter and batteries would seem you would be very close to your 1k budget long before you got to the panels and Charge controller. I also second the comments above to go 24v (if not 48v) right out of the gate.

    Leave a comment:


  • Mike90250
    replied
    If you even think you may need to grow into 24V system, just do it now, and not wait till you have to sell off the old 12V inverter to buy a new 24v inverter.
    Wire is cheaper (half the size), and thinner wire pulls easier too. Plan your solar rack and combiner box for future growth, you don't have to stuff them full now, but again,
    to pull the 3 ch Combiner Box, to install a 6ch Box, is a pain. If your loads this year are really light, a pair of 12V 100ah deep cycle batteries from a big box store will only set you back $200 for flooded lead acid batteries that are good for at least 2, maybe 4 years (if you did your sizing math right)
    I'd say get a decent controller that can grow with your system. Most of the better ones, allow you to set a amps limit in software, so you can overpanel a bit for cloudy weather harvesting.

    Leave a comment:


  • J.P.M.
    replied
    Originally posted by SupraLance View Post
    Any plans to eventually hook to the grid will be due to growing electrical requirements. Right now I live alone and don't require much electricity. If down the road I have a larger house, pool, and entertain there, then hooking to the grid to use as a battery may make more sense. There seems to be a point below which off-grid solar is actually cheaper and above which grid-tie is cheaper. But at no point will the solar panels be unused.

    I don't want to spend more than $1000 on solar equipment right now, and another $1000 when I upgrade to 24v. I think it can be done with a controller under $200 and about $500 in panels from SEP that I will pickup and install myself, but I won't be surprised if I go a little over budget. I'll run better numbers once I determine if I have to stick with a 30a controller to limit current to the battery and how much pv I can most efficiently run through a single controller.... Any thoughts on the over-dimensioning or whether a 40a controller will be ok when I don't want to charge the battery at more than 30a?
    Before I did any of that, and before I started ordering equipment, I'd get a realistic load size and use profile and PV generation potential, and see/estimate how much of the est. load can be met with an expenditure of $1K (including batteries ?). Not trying to rain on your parade, but consider that you may be underestimating costs, and maybe a bit light on design and understanding solar potential.

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  • SupraLance
    replied
    Any plans to eventually hook to the grid will be due to growing electrical requirements. Right now I live alone and don't require much electricity. If down the road I have a larger house, pool, and entertain there, then hooking to the grid to use as a battery may make more sense. There seems to be a point below which off-grid solar is actually cheaper and above which grid-tie is cheaper. But at no point will the solar panels be unused.

    I don't want to spend more than $1000 on solar equipment right now, and another $1000 when I upgrade to 24v. I think it can be done with a controller under $200 and about $500 in panels from SEP that I will pickup and install myself, but I won't be surprised if I go a little over budget. I'll run better numbers once I determine if I have to stick with a 30a controller to limit current to the battery and how much pv I can most efficiently run through a single controller.... Any thoughts on the over-dimensioning or whether a 40a controller will be ok when I don't want to charge the battery at more than 30a?

    Leave a comment:


  • J.P.M.
    replied
    I wonder if the OP knows what the cost in toil and treasure of off grid electricity. If it was me, I'd take my best shot at electrical service requirements at buildout, add 20-30% to it for goofs/giggles/feel good and run power now. Might make the build easier as well.

    Leave a comment:


  • Mike90250
    replied
    How much do you want to spend, before you hook to the grid ? Why build a large comfortable system, and then connect to the grid making it obsolete ?

    Leave a comment:


  • 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?
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