Over zealous non technical swimming in too many options!

bornin1775bornin1775 Posts: 4Registered Users
Wow... This is crazy.  It all started when i realized that I pay more per KWH from Dominion Power in the summer - and that I use more electric during that very time (I heat the house with wood supplemented by propane heat in the winter).  So, with 2 1050 Watt AC units making up a lot of my electric costs, I figured - what the heck - I'll see of I can partially mitigate one of  them and give the kids a science lesson (we live in a 150 year old house and window ACs are our only comfort in the summer).  So.... what could go wrong?  LOL.

2 Weeks into research I've over spent my budget.  Not that I'm upset with that - I feel like it's been a good investment that will pay off, but now I'm at a point where I have to purchase a solar panel ever 2 weeks to match the battery back I stumbled on.  

First off, I bought a 400W Off Grid System (4) 100W Solar Panels w/ 1500W Inverter from Eco systems for $798.  Some of the particulars:
100W 18V poly solar panel, charge 12V battery (I got 4 of those)
Related power100W
Maximum/Peak Voltage(Vmp)
18V
Open Circuit Voltage(Voc)21.6V
Maximum/Peak Current(Imp)5.55A
Short circuit current (Isc)6.11A
Output Tolerance±3%
Temperate coefficient of Isc(010+/- 0.01 )%/ ℃
Temperate coefficient of Voc- (0.38 +/-0.01 )%/ ℃
Temperate coefficient of power Voc-0.47%/℃
Temperature range-40℃to +80℃
FrameHeavy duty aluminum
Guarantee of power90% with in 10 years 80% with in 25 years
Kind of glass and its thicknessLow Iron, high transparency tempered glass of 3.2mm
SLA Battery Voltage12V
Size665x1000x35mm(26.2"x39.4"x1.4")

15A Solar Charge Controller Regulator with timer and light sensor

 sc15-1_Copy


Features 

● Timer control for saving energy

● 12/24V system automatic detectable

● PWM charging available  

● With small self consumption, 2mA at 12V system

● 3-stage charging algorithm: impulse, bulk and float

● Wrong battery pole connection protection

● Light sensor adjustable

● Adjust the timer and light sensor

● Lightning protection

45A Solar Charge Controller

Features

 
● 12/24V system automatic detectable
● PWM charging available
● With small self consumption, 2mA at 12V system
● 3-stage charging algorithm: impulse, bulk and float
● Wrong battery pole connection protection
● Lightning protection



My thoughts?  I could probably run one window AC every 3 days if I got the right set of batteries. AND, I could expand to 800W really really easily.  So, I really just started looking for about 400AH of battery power, not really knowing what I needed.  Well, I was about to buy some brand new BMW deep cell batteries (knowing full well they weren't the perfect solution - but they were $500 for 5 of them), but a few hours before I was to go, I ran across a crazy good deal.  I ended up with 6 of these for $550:

GNB Marathon M12V155FT General Specifications:
Voltage: 12 V
8 hr To 1.75 VPC @ 25ºC: 155 Ah
10 hr To 1.80 VPC @ 20ºC: 150 Ah
Length: 559 mm, 22.00 in
Width: 124 mm, 4.90 in
Height: 283 mm, 11.15 in
Nominal Weight: 53.8 kg, 119 lbs
Short Circuit Current: 3,883 A
Internal Resistance: 3.0 mΩ

Now, I have too much battery and I haven't even set the system up yet (It'll give me something to do between Good Friday and Easter!.

I'm essentially way over my battery need, right?  I plan to add a 100W panel every 2 weeks until I max out my current system.  I may add a wind turbine for the kids afterwards, but honestly - I'm in a fringe wind area and its just for fun for the kids (guessing of the 300W advertised I'd only pull in 75 - 100.  Honestly - I'm getting a battery bank monitor because my balance is so out of wack, I feel like I lose complete situation awareness.

So, My plan is to set up with system using 6 gage wire (is that enough?), and run all 6 batteries in parallel (unless you all suggest I shouldn't!).  I've watched more youtube in the last 3 weeks - I know what it's like to be my 13 year old son now!  Anyhow, I've read a bunch of posts over here (this forum helped me decide to partially bury my battery bank against the house), and I thought "What could it hurt to post".  I'm an ol' jarhead that couldn't spell solar a few weeks ago, and am looking forward to making a few mistakes, but ultimately getting my AC costs down.

Have a great evening!
Bob

Comments

  • PhotowhitPhotowhit Posts: 4,702Solar Expert ✭✭✭✭
    Bob, STOP BUYING STUFF!

    First figure out your loads, 1 - 1020 watt air conditioner?

    Something that uses 1020 watts AC will require (at no loses, we'll discuss that later) 1020 watts an hour÷ 12 volts = 85 amps per hour (amp x volts = watts)

    So if you wanted to run this during the day time with direct sun you would need to produce 85 amps, your 400 watts of panels would produce about 20 amps with your PWM charge controller. You would need more in charge controllers to run a 12 volt system.

    Your 1500 watt modified sine wave inverter, will not likely run the 1020 watt A/C as the compressor startup might be 3-4 time the running wattage. And the modified sine wave will shorten the life of your A/C and use more electric doing it.

    a 1020 watt load would require a huge system to run all day, I don't know what your duty cycle looks like (how long the compressor runs) but in an old home with little help it will likely run a lot...

    I figure I use about 10-14 Kwh's during the summer (mostly in direct sun, I'm guessing you would be in that ball park, think 4kw array, 15Kwh of storage, and a 2500 watt inverter.

    What does electric cost per Kwh for you?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • PhotowhitPhotowhit Posts: 4,702Solar Expert ✭✭✭✭
    Sorry, I never went back to discuss losses, inverters are usually 85-90% efficient converting Dc to AC, batteries use about 20% more power to charge than you use. Solar panels will usually produce about 75% of their panel rating (a 100 watt panel will normally produce about 75 watts) much of this loss is in voltage with a PWM charge controller figure loss at about 10%.

    BTW- the above figures are for running the system while the sun is shining, stored energy will be very hard on your system.

    If you choose to continue, I would consider a higher system voltage, a charge controller than can handle 60 amps at 12 volts can handle roughly 1000 watts of panels, at 24 volts can handle 2000 watts at 48 volts 4000 watts. (These will vary with type and properties of the charge controller) 
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    +1 on what Photowhit said, especially the stop buying stuff part.

    We can work on what you need for your application, but a couple quick comments in the meantime.

    The batteries you have appear to be AGMs designed for telecom use. This means they're meant to spend nearly their entire life sitting in float on a charger, and only cycled a few times during a power outage. They may not last long in your application. I'd be inclined to try to sell them before using them while they might still be worth something. I wouldn't pay more than scrap value for cores on used AGM telecom batteries.

    If you do decide to use them, 6ga wire is way too small. At 12v, you'll be pulling upwards of 100a. I would use more like 4/0. Also, wired in parallel, each battery positive should be fused. Also, each panel in parallel should have a properly sized breaker or fuse.

    What you've bought would work for small loads like lights in an off-grid cabin. To run air conditioning you really should start over, but if you decide to keep what you have, we can help you work with it. Please don't just start hooking stuff up to see if it works.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • bsolarbsolar Posts: 103Solar Expert ✭✭✭
    you should have asked first .. im far from an expert but have experience with my own home built system i can throw in a few cents at you .. for starters, those batts you could have done much better on .. a typical golf cart batt is 210ah and runs about 90 bucks and will likely last through twice or more as many cycles down to 50% .... as far as panel goes your going to need enough to push your 1000w ac - think at least 12 100w panels, and you'll need them to support a bank of 8 or more large batts also, and you'll need at least 2 60amp chargers, and probably a 2500 watt sine inverter .. you cant run electronics at their max capacity for more than a few seconds, you need to have overhead .... but realistically running an ac like that on even the system i just described, which is about what my system is, just isnt realistic ... sure i could run your ac for a couple of hours, but i would be taxing several thousand dollars worth of equipment, and a 100w fan sounds alot more reasonable ... the system though is there for me personally when i need it such as in a long term power outage after a bad storm .. it runs my pumps and fridge, a few lights, i can mic something for a minute during the day ect ...
  • bornin1775bornin1775 Posts: 4Registered Users
    OK... It's definitely going to take me some more time to digest all of the good knowledge flowing!

    1.  Answer to one of the questions - our usage last year (family with 5 kids) was about 3000 kWh per month:  First 800 ES kWh @ 3.795¢ per kWh Over 800 ES kWh @ 5.773¢ per kWh.

    2.  I knew the system I was buying was less than my immediate needs.  We did want to do a couple of things:
    - Begin to put together a system knowing we'd have to upgrade piecemeal.   
    - Build a system that would give us the necessities (like power our water pump!) when the electric goes off (which happens every few months).
    - Teach the kids a few things about different power sources (and learn ourselves)
    - Ultimately build a system that support some of the functions around the house - ultimate was cut some utilities in the summer and some Christmas lights in the winter.

    3.  I took one of the AC units to the place where i was buying the batteries, and the Inverter, to make sure one battery would support it as a test.  I only ran it on 'Low / AC' as that is what I usually set the ACs on.  It ran, and when I did, I bought 6 of them.  I knew they weren't the perfect solution, but a guy they hired to do work on their shop had just bought 4 to support his 1150W on his truck.  

    4.  I bought the 400W with the plans to expand to 800 - hoping we could support every other day of the AC..  I know that isn't much, but honestly - it was enough for the 'experiment' as we learn.   I was hoping (admittedly, hope is not a plan) that I could use the current system to expand until I got where we wanted to.

    So... where do I go from here?  

    Most likely Course of action:

    1.  I'll probably stick with the batteries.  What techniques and procedures to I employ to give them the best chance at meeting my needs?  I assuming I don't throw good money over bad and buy a few more - but that is probably the only other COA given I'm kinda stuck with these.

    2.  4 Guage wire... roger!  For the entire system?  

    3.  Roger the fuse/breaker system.  I'm really busy w/ community stuff through Easter - I'll watch and get smart between now and then.

    So... given those parameters - where to I go on the controller / Inverter etc?  I could always shift fire and employ the system to handle what it could handle... vice what I want it to handle.  And expand to 800w as the system was designed to be expanded, unless for some reason you fine gentlemen recommend against such a thing?

    So... I've executed poorly.  I'd appreciate any guidance on what I need to do to deliver some level of limited capability via our great heat tab in the sky.

    Thanks,
    Bob
     
  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    Okay, so let's step back a bit. Even at your "high" rate of ~$0.06/kwh, solar isn't going to come anywhere remotely that cheap. When you do the arithmetic, it will almost certainly end up north of $1/kwh for battery based solar. The sun is free, but batteries, panels, and electronics aren't. Realistic life expectancy for panels is 20-25 years, 10 for electronics, and 3-10 for well maintained designed for purpose batteries. You might do better, but you might do worse.

    So doing this as a cost saving exercise is unlikely. That leaves a couple of possible goals.

    One is to be able to run your a/c and pump in a power outage (certainly not at the same time, and the pump maybe not at all - would need to know more about the pump). This may be the most realistic goal given what you currently have in purely practical terms.

    The other would be to use the system to power some smaller loads more regularly with the objective being to get practical experience with operating a battery based solar system, just because. Not as practical as the first option, but maybe better in terms of knowledge.

    It would help if you could noodle on it a bit and let us know.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Posts: 4,702Solar Expert ✭✭✭✭
    edited April 2017 #8
    Lot's of stuff and I hate requoting, so I can make the references easy, so if I lose you, ask what the heck I'm talking about.

    1. WOW very cheap electric! is that in the US!

    2. You have a good sample system to teach the kids. You might want to get spec's on your water pump.

    3. I'm surprised it cranked up the A/C, did you let it run long enough for the compressor to kick in? A/C's usually run their fan to circulate air by their thermostat before the compressor starts, so may take a pretty good bit of time, and depending on your settings and the room temps, it might not have kicked on. I am going to go against my original suggestion and say you should buy a Kill-A-Watt Meter.

    https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_1?ie=UTF8&qid=1491951844&sr=8-1&keywords=kill-a-watt+meter

    This will measure the actual electrical use on 120 volt <1500 watt items. Wish it would measure your well pump, but that is most likely a 240 volt item.

    4. I doubt it's in the cards unless you want a seriously larger system. Just imaging if you had it running, during the day when the compressor was running almost continuously, you have 800 watts of panels that will be producing about 600 watts of energy, that must be run through an inverter that is 85% efficient. The 1020 watt load now becomes a 1200 watt load so half of the current must come from the batteries. So no charging just discharging.

    where from here;

    1. Well this is a quandary, These are the first batteries I have ever seen that have a lower capacity at C10 than at C8! I had to hunt up the spec sheet when I read it!

    http://www.jantechups.com/userfiles/files/Battery/GNB Exide/VRLA/Marathon M FT/M12V155FT data sheet.pdf

    I have no clue as to the nature of these batteries, since they don't even give a C20 rating I suspect they are designed for short outages. ..but really I have no clue!

    2. No not 4 gauge, he's talking 4/0. I think a smaller gauge between batteries and breaker would be okay, I wouldn't expect each to handle as much load as the total bank. But 4/0 minimum from where they connect to the inverter. On of those reasons for a higher system voltage, wires are rated for their ability to handle amperage, each time the voltage doubles the amperage is halved.



    3; Yes if you are teaching your kids, you will want to do it right. each panel when more than 2 would need a fuse of breaker, a breaker between the combiner box (where the panel fuses or breakers hang out) and the charge controller is good and even necessary if you want to turn off inexpensive charge controllers. A breaker between the charge controller and the batteries, a large breaker to handle the current to your inverter. Likely want battery post type breakers on individual batteries.

    I would NOT add to your system. I am guessing, but think the batteries are designed to stay in float and think your lower than normal charging amperage will work out so long as you control your loads.

    I think if you check out your loads with the Kill-A-Watt meter you will find you can run and charge the kids laptops, cell phones and other loads. See if you can get them in the habit of putting them on charge when they get home, by saying everything off the solar at dusk! It could also run the entertainment center, depending on the size and type of TV/stereo.

    You really have cheap electric, in general it's hard to do solar electric cheaper than 35-40 cents a Kilowatt other will use numbers up to $1 a Kilowatt!

    Here's the story of my new system, trying to be less than 26 cents a watt! (so far so good)
    http://forum.solar-electric.com/discussion/comment/199655#Comment_199655




    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • bornin1775bornin1775 Posts: 4Registered Users
    Thanks for all the info!  And yes... I'm in Northern Virginia.  I'll definitely check out the forum.

    Hey.. check this out.  I was searching all over because i wanted to find the difference between 20 and 25 Celsius and I found the battery for sale on a solar energy site.  I admit, I am concerned about the delta between 8 and 10 hours.  http://www.windsolarenergy.net/marathon-m12v155ft-front-terminal-flame-retardant-sieries-12v-battery-nom-155-ah 
  • bornin1775bornin1775 Posts: 4Registered Users
    All - I also forgot!!  I only posted the Electrical Supply serviced charge.  There is also a Distribution charge:

    First 800 kWh @ 2.244¢ per kWh
    Over 800 kWh @ 1.271¢ per kWh

    And a transmission fee @ 0.970¢ per kWh
  • PhotowhitPhotowhit Posts: 4,702Solar Expert ✭✭✭✭
    All - I also forgot!!  I only posted the Electrical Supply serviced charge.  There is also a Distribution charge:

    First 800 kWh @ 2.244¢ per kWh
    Over 800 kWh @ 1.271¢ per kWh

    And a transmission fee @ 0.970¢ per kWh

    Do they have net metering for solar? It might be that they only do net metering on the energy cost.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    @Photowhit

    I don't think the c/8 and c/10 capacities are directly comparable in the way we normally compare them. The specs have different terminal voltages and temps, both of which affect apparent capacity. The c/8 capacity is higher temp (25°c) and lower voltage cut-off (1.75v per cell) than the c/10 (20°c - 1.8vpc).

    I guess the idea is the battery will recover to the same resting voltage and temp after the load is removed after either rate of discharge, which may be more relevant in a telecom application.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    @bornin1775

    Not sure of the °f conversion, but 20c is comfortable room temp (low 70s?). 25c would be a warm but not hot summer day (mid 80s?).

    Those batteries are definitely not designed for deep cycle use.

    Even with the extra charges you're under $0.10/kwh. That's probably a bit under what grid power costs in Ontario (time of use pricing complicates comparison), and a bit higher than grid in Manitoba. At my cabin in Ontario, I'm over a mile from nearest neighbour with grid. Even assuming I could hook in there, it would be mid five figures to bring it to my site, plus ~$100/mo fixed charge, plus actual power used.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Posts: 4,702Solar Expert ✭✭✭✭
    Estragon said:
    I don't think the c/8 and c/10 capacities are directly comparable in the way we normally compare them. The specs have different terminal voltages and temps...
    Haha, it's not even in fine print, it wasn't mentioned in the 1st place I checked, I was just found the spec sheet to check the bottom line and ignored the print! Oddly enough I might have read a footnote, but ignored what was right in my face.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
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