does this work

System
System Posts: 2,511 admin
Concorde PVX-2580L (8D) Deep Cycle AGM Battery 12 Volt, 255 AH
Sharp 235 Watt Solar Module NU-U235F1 (White)
and a inverter ?
and battery charger?
what kind of power would i get
saying 30 percent of the sun aday in winter
for backup purposes only
sometimes i lose power for a week

Comments

  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    Re: does this work

    First, we need to know what things you expect to power during that week while the grid is down. You will be asked this question by those that follow me.

    Your solar panel is too small to recharge your battery (can you even lift it by yourself? Just wondering.) And your PV (solar panel) is too small to recharge your battery.

    These comments are given just "off the cuff," and should be regarded as such. But, not knowing what you are trying to do, it's as good as I can give.

    K

    BTW, I have a glass of JBeaM nearby.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: does this work

    If you need back-up power for a week, buy a generator. Solar power is a very expensive investment for emergency power.
    Your 255 Amp/hrs will get you about 1.5 kW/hrs per day at most (50% DOD).
    Your 235 Watt panel will yield 752 Watt hours per day and would barely be enough to charge the battery on a good day.

    Really; for occasional black-outs the generator option is a better investment. Get some good measurements on your 'critical' power needs (like the 'frige/freezer) and base your generator size on that. The inverter type like the Honda EU2000I are quiet, dependable, and economical.

    I sound like a Honda commercial! :p
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: does this work

    the genny will do well for long term stuff, but you may need quiet at night so you still would want a battery and inverter that will cover you nighttime needs. the pv will help in charging the battery and will be near the minimal charge rate of 5% that we recommend and that would mean a 20hr rate and hence about 20hrs for recharging a dead battery, at least in theory. point there is that you may get about 5hrs of sun on a good day. the range we normally state for charging is between 5% and 13%, but that battery can take 100% with ease if you can supply that much for it.
    anyway, the battery should not be allowed to discharge beyond 50% dod so half of the ahs are really usable and you can get even longer life with not going to 50% too, but then it may become less useful for the big $ invested. some may argue that point, but 50% i'll stick with here. if your loads are larger than what the battery can deliver then you may need more batteries. this would up the charging requirement as well. the pv will need regulated so a controller should be gotten and for pvs that are in ranges suitable for 24v batteries then the controller will need to be an mppt downconverting type. there are many to chose from and remember in sizing them that as the controller reduces the voltage that it will up the current making the wattage key. watts = volts x amps.
    now some inverters do have built-in chargers and some do not. in any case the generator will need to be able to deliver all of the power the charger would need in delivering its charge to the battery.
    also, in general large copper wiring is going to be needed for the battery to inverter minimally and depending on the distance and current flowing it may need large wires for the pvs to controller to battery as well. to help you find out what may be good there you can figure this out from the voltage drop calculator in the facts, links, and info area of the forum. do keep the wire large and as short as possible between the controller and the batteries as a voltage drop there could influence if your batteries reach a full charge or not. there is much more to all of this and i suggest more reading on your part to get better acquainted with the subject matter that can help you make a better decision for yourself. i hope i didn't forget anything and of course we will still be here for questions.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: does this work

    Although I have frequently recommended what Niel has suggested, I have to point out that it is not strictly necessary. I have run through extended grid outages without any inverter back-up, using only a small generator which was shut off at night. Most refrigerators will stay cold enough (if kept shut) for ten hours. Freezers will last without power for a day or two, if no one opens them. It takes a bit of judicious care and planning of power usage, but it can be done.

    Quiet power can be had at night with suitable inverter and battery pack which can be recharged from the generator during the day. The solar panel is an expensive option, in my opinion. Also, there is always a tendency to use more power than is necessary if power is available. That's a sort of hard-and-fast rule to off-grid! :p
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: does this work

    i agree with you marc. but as to this,
    "Quiet power can be had at night with suitable inverter and battery pack which can be recharged from the generator during the day.",
    he will have to upsize the generator to power both the charging of the batteries and his current ac loads at the same time and is something that can easily be overlooked so i thought i better mention this.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: does this work
    niel wrote: »
    i agree with you marc. but as to this,
    "Quiet power can be had at night with suitable inverter and battery pack which can be recharged from the generator during the day.",
    he will have to upsize the generator to power both the charging of the batteries and his current ac loads at the same time and is something that can easily be overlooked so i thought i better mention this.

    Right you are, Niel! You have to consider the total loads that could be drawing from the gen at any given time. :D

    But it's amazing what you can do with a 2kW Honda and a little forethought!
    Oops! There goes the Honda commercial again! :p
  • System2
    System2 Posts: 6,290 admin
    Re: does this work

    thanks. you guys think there might be cheaper solar power in th near future 1 or 2 years?
    for the below average income people
    or is everybody trying to keep BP happy
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: does this work

    Who knows about pricing... Raw material pricing is probably going up, US dollar is probably going down, labor costs in China are probably going up, state and federal tax breaks/rebates are probably going down.

    At the moment, the price of solar panels has probably hit near bottom for now while the rest of the prices are stable or going up (inverter, copper wire, etc.).

    About the only thing that may continue to drop is labor--but that will probably be offset by higher employment/income taxes.

    So, overall, the best time to install solar is probably "now".

    However, (in my humble opinion) I would make sure you have 6-12 months of savings in cash before spending on solar (solar is expensive up front, and takes quite a while before you 'break even").

    Conservation is usually a better investment before solar. Double pane windows, lots of attic insulation, energy star appliances, laptop instead of desktop computers, more efficient A/C / Heat-pump / Central Heating / heat pump based hot water if no gas/propane, CFL/Florescent lighting, turning off unused appliances, etc.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: does this work

    thanks for all the info
    if i didn`t ask then i wouldnt know because there`s alot of info out there
    but i dont want to learn it all, heads not big enough
    again thanks people
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: does this work

    I am surprised that so many think the battery bank and single panel array are so out of line, I lived several years with @220 watt array (in a relativly poor location) and 2 golf cart batteries, of course I wasn't running much, a couple 13 watt CF lights, a laptop, small TV and VCR, radio, cd player, and couple fans(@10 watt O2cool fans) figured I could run 400 watthours a day unless I hit a very long cloudy period.

    Now it's not going to run a normal house hold, but others here have lived on tiny systems. Conserve first!...

    ...Then again, now I pay homage to the great air conditioner...lol
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.