Building off-grid system

offgridoffgrid Registered Users Posts: 20
Hello,
I am fairly new to solar energy. I am in the process of building a 1.5 Kw expandable system 24 volt from the ground up, off-grid. I will be using this system here at home, will be moving it to my property in the mountains. I am on a budget but have been saving my money and buying what I can as I go. Recently I have purchased an Outback FM80 amp Charge controller [from NAWS...best price including shipping, thanks !], although not sure if the 80 will work on the flex 500... I have purchased and building 4x63 watt solar panels (using solar cells bought from EBay...I'm sure I will hear it from you on this). Each panel will be 18 volts @ 3.5 amps. I will be purchasing better/bigger panels in the future. I am considering the Outback flexware 500 with 1 inverter to start (pure sign to run TV and the like). Then off to the battery bank (any recommendations). What I would like from you is your thoughts and do any of you have similar systems with experience to share.

Thanks in advance,
Tom

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Building off-grid system

    Uh, you're going about it kind of "sideways".

    First thing you need to do is determine your intended loads - for real - with a Kill-A-Watt meter.
    From that info you can size your inverter and battery bank, and thus determine the Watts of panels needed to keep it going.

    When you go at it "sideways" you end up having to shut off power because you ran out of capacity or there isn't enough sun/panels to recharge the bank or something.

    There's only two things I'll say about the panels: 252 Watts probably won't be enough and home-made panels don't survive long-term.

    The FM 80 was probably more of an expense than you needed, but will allow for the inevitable future expansion.

    I suggest you get a more definite idea of what your intended power usage will be and plan from there before you spend any more money.
  • offgridoffgrid Registered Users Posts: 20
    Re: Building off-grid system

    Cariboocoot,
    Thanks for the reply. I am currently using more power than the system I am building however; I need to have a system in place to power my fridge and freezer when the grid goes down. Here in California we have power outages quite a bit. Power seems to go out as soon as I get back from the store with a couple hundred dollars worth of food. I have a kill-a watt meter, however I also have on-line access to the power company that provides a usage history. As the system grows I will add the computer, TV, lights and someday Heater-A/C. I want to be able to take the system with me when we go, which is why I asked about the Flexware, being compact and pre-wired. I am not able to do this all at once, so a little at a time is my approach. I am in the process of adding solar panels from NAWS as we speak. Question for anyone, with a twenty four volt system why is it better to use 6 volt batteries than 12 volt ? What do you think of AGM batteries ? For me, the less maintenance the better.

    Thanks
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Building off-grid system

    It's not necessarily better to use 6V than 12V batteries. It's just that as the Amp/hr capacity goes higher, the batteries get heavier. They simply become difficult to physically handle. A T105 is 6V @ 225 Amp/hrs and it weighs 62 lbs. An 8D AGM is 12V @ 230 Amp/hrs and weighs 167 lbs. That's a slightly unfair comparison, but the basic rationale is there.

    AGM's are less maintenance and safer, but are more exacting on their charge standards (they don't tolerate a lot of 'abuse') and are more expensive per Amp/hr. This is why most people at least start out with flooded cells, until they get the 'hang' of it and feel confident enough to invest in AGM's.

    If you're looking for back-up power with an eye toward future expansion, skip the panels to start with. Measure your 'critical' loads and get an inverter/charger and battery bank that will handle that. It will recharge from the gird (I assume that the power doesn't stay off for long?) You can add the solar panels and charge controller later. That would be my recommendation anyway.
  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: Building off-grid system
    If you're looking for back-up power with an eye toward future expansion, skip the panels to start with. Measure your 'critical' loads and get an inverter/charger and battery bank that will handle that. It will recharge from the gird (I assume that the power doesn't stay off for long?) You can add the solar panels and charge controller later. That would be my recommendation anyway.

    I'd suggest just barely enough solar panels be included to exploit any available rebates or tax incentives. Adding panels can help reduce battery requirements as well, if the desired period of autonomy is more than a day. Plus, it makes electricity, instead of just consuming it. Win-win, to me.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Building off-grid system
    tallgirl wrote: »
    I'd suggest just barely enough solar panels be included to exploit any available rebates or tax incentives. Adding panels can help reduce battery requirements as well, if the desired period of autonomy is more than a day. Plus, it makes electricity, instead of just consuming it. Win-win, to me.

    that is a good point because it'll go from just being a backups to being a renewable power source that has rebates and such that will cover percentage of the entire install. on reducing battery requirements, i don't think so as pv is only a charging source and not a storage medium.
    win win to you? ok, pat yourself on the back.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Building off-grid system

    Ah, rebates and tax incentives. I keep forgetting those because we haven't got any here! The one small PV advantage we do have, "no PST", is about to go away as they hike our taxes again.

    Welcome to "Green" British Columbia.
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