Small PV For Convenience. What Can Be Improved Upon?

Soulearner
Soulearner Registered Users Posts: 18
Greetings,
We will be putting together a small PV system just for a lightbulb, a ceiling fan, charge a laptop or phone, in a very small weekend cabin in West Virginia, where, power is purely a convenience. We have a Honda eu2000 for backup battery charging and, (gotta have it!) a coffee maker. If it is cloudy for a week and all we have is a lantern and no extra PV - that's fine too.

Please tell us if the following is sized correctly and, if I could make it better/cheaper, etc.
Thanks!

2 Renogy 100 watt panels (200W total) 18.9V 5.2A
A Morningstar SS-MPPT 15L charge controller
2 GC230 6v FLA batteries
A Cotek S1500 12 volt pure sine inverter

We will keep the batteries above 80% DOD and get about 4 hours/day direct sun
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Welcome to the forum.

    Other than the coffee pot your needs are fairly minimal. That one item, however, should be kept on the generator. Even though it isn't used for very long (low Watt hours) it is probably near or at the limit of a 1500 Watt inverter's output and on 12 Volts would draw over 100 Amps which a couple of 200-ish Amp hour batteries would have a hard time supplying without going 'flat' fairly quickly.

    The 15 Amp MPPT charge controller is probably not needed and affords little advantage for a system this size. Mostly it would be money better spent on more panel as 200 Watts putting out about 10 Amps is bare minimum for 200 Amp hours of battery.

    I'd suggest you increase the amount of PV to 300 or even 400 Watts and use a less expensive PWM type controller of around 30 Amps to handle it.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?

    For making coffee, Coleman makes various forms of "camp stove/propane" coffee makers:

    www.amazon.com/s/ref=nb_sb_noss/177-3232182-4768900?url=search-alias%3Daps&field-keywords=propane mr coffee

    Measuring your loads and conservation are your friends here... Get a Kill-a-Watt type Watt*Hour meter and measure each of the loads you want to power (measure "1 day of usage").

    And, anything that generates lots of heat (coffee maker, cooking, etc.) or moves air/water will use a surprising amount of power. If you have specific needs for electric coffee maker (propane not available, fuel fired stove not practical), there are "other options" (such as AGM or LiFePO4 batteries)--But they do tend to be more expensive (at least the initial out of pocket costs)--That may not be something you want to leave at a remote cabin with less than ideal security.

    A pair of 6 volt @ 200 AH batteries (for a 12 volt @ 200 AH battery bank) would handle all of your basic needs (excluding cooking). Assuming 2 days of storage (bad weather) and 50% maximum discharge:
    • 12 volts * 200 AH * 1/2 days * 0.50 maximum discharge * 0.85 AC inverter eff = 510 Watt*Hours per day (2 days)
    • 200 AH * 1/2 days * 0.50 maximum discharge = 50 AH per day @ 12 VDC loads
    Get a smallish AC inverter (the MorningStar 300 Watt TSW 12 volt inverter is pretty nice, has a remote on/off and "search" mode for low(er) power standby).

    Assuming 10% rate of charge:
    • 14.5 volts charging * 200 AH * 1/0.77 panel+charger derating * 0.10 rate of charge = 377 Watt array (plus or minus)
    You can run 5% to 13% rate of charge--And 10% makes for a pretty reliable/robust system (usually pretty cost effective performance, longer battery life, etc.).

    And if this is a cabin used ~9 months of the year and the solar panels are in full sun, you will probably see a minimum of 4 hours of sun per day:

    377 Watt array * 4 hours of "noon time equivalent sun" * 0.52 end to end AC system eff = 784 Watts of available solar power per "average" sunny day minimum

    You can get a 20 to 45 Amp 12 @ vdc Iota battery charger to run off the Honda eu2000i genset. If this is Off Grid (no utility power), you do not need the IQ4 module.

    The choice between ~140 Watt Vmp~17.5 volt panels and >200 Watt Vmp~30 volt panels--Your choice. Smaller panels tend to be more expensive per Watt but cheaper to ship and easier for a single person to move around.

    And panels with Vmp>>18.6 volts or so, really need a MPPT charge controller (vs PWM)--Which are nicer controller, but much more expensive. You will probably have to do several paper designs to see what works out best for your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?

    To charge a phone roughly uses 88watts, charging laptops that use between 200 and 400 watts typically require 550 watts per day, ceiling (NOT BOX fan) usually around 400watts a day.
    Light bulb wattage varies anywhere from 30 watts to 180watts depending on bulb/lumen/wattage type, per day. I actually pulled this information from enphase energy's My Enlighten pages.

    So roughly 1.06kWh daily usage that is if you are using everything simultaneously all day, if not de rate 50% for .503kWh.

    I would throw in a couple more of those 100 watt panels.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?

    I think I am clarifying here:
    To charge a phone roughly uses 88Watt*Hours (88 Watt*Hours per day, would be my guess, a Smart Phone used very heavily all day long/as a Internet Access point. Otherwise 10-20WH per day may be a closer guess), charging laptops that use between 200 and 400 Watt*Hours typically require 550 Watt*Hours per day, ceiling (NOT BOX fan) usually around 400 Watt*Hours a day. (fans may use a lot more, a Kill-a-Watt type meter will be a big help)

    Note, that a typical ~15" laptop may use 20-30 Watts average power when the battery is charged... May use 60-100 Watts when running+battery charging. My old laptop would use ~500 WH (0.5 kWH) per day of AC power when used much of the day (moderating forum, reading, etc.). The heavier loads you place on a laptop, the higher the draw may be.
    Light bulb wattage varies anywhere from 30 watts to 180watts depending on bulb/lumen/wattage type, per day. I actually pulled this information from enphase energy's My Enlighten pages.

    I think SolarPowered also intended Watt*Hours per day above--But this is highly variable. The new 120 VAC LED lights can run from something like 5 watts to 20 Watts or so--* hours of day you need lights.

    15 watts * 6 hours of lighting at night = 90 Watt*Hours of energy. That is probably around a 70-100 Watt equivalent to Filament Lamp.

    If you had filament lamps--An old nightlight may use 4-7 watts, and 40-100 Watts are (where typical) * Hours per day of usage, per lamp.
    So roughly 1.06kWh daily usage that is if you are using everything simultaneously all day, if not de rate 50% for .503kWh.

    I would throw in a couple more of those 100 watt panels.

    Yea--A 1,000 WH per day would give you "lots" of power for an off grid cabin--But would best be used behind 4x 6 volt 200 AH batteries--If you plan on using that much energy... And you may want more panels, larger MPPT charge controller, etc...

    Power usage is a highly personal set of choices--If you have kids and lots of electronic games/devices--You can easily need a 1kWH+ per day system. If you are up there to be "off the grid" and/or just need some power (much during daylight/sunny days--some computer use, pumping a bit of water, a small fan to keep the air moving during warm afternoons/evenings, etc.--A smaller system may be just fine.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    BB. wrote: »
    I think I am clarifying here:



    Note, that a typical ~15" laptop may use 20-30 Watts average power when the battery is charged... May use 60-100 Watts when running+battery charging. My old laptop would use ~500 WH (0.5 kWH) per day of AC power when used much of the day (moderating forum, reading, etc.). The heavier loads you place on a laptop, the higher the draw may be.



    I think SolarPowered also intended Watt*Hours per day above--But this is highly variable. The new 120 VAC LED lights can run from something like 5 watts to 20 Watts or so--* hours of day you need lights.

    15 watts * 6 hours of lighting at night = 90 Watt*Hours of energy. That is probably around a 70-100 Watt equivalent to Filament Lamp.

    If you had filament lamps--An old nightlight may use 4-7 watts, and 40-100 Watts are (where typical) * Hours per day of usage, per lamp.



    Yea--A 1,000 WH per day would give you "lots" of power for an off grid cabin--But would best be used behind 4x 6 volt 200 AH batteries--If you plan on using that much energy... And you may want more panels, larger MPPT charge controller, etc...

    Power usage is a highly personal set of choices--If you have kids and lots of electronic games/devices--You can easily need a 1kWH+ per day system. If you are up there to be "off the grid" and/or just need some power (much during daylight/sunny days--some computer use, pumping a bit of water, a small fan to keep the air moving during warm afternoons/evenings, etc.--A smaller system may be just fine.

    -Bill

    Thanks for the clarification, its appreciated. When it comes to forum talk, I tend to jibber jabber, rather than in depth express the variable terms.

    My 19" Dell Laptop requires 220Wh, some of the alienware gaming laptops require much higher up to 400Wh
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?
    My 19" Dell Laptop requires 220Wh (Watts, not WH), some of the alienware gaming laptops require much higher up to 400Wh (Watts, not WH)

    Yea--Desktops, especially "high powered" desktops really suck the power... Running a 400 Watts * 24 hours per day as a server = 9,600 WH = 9.6 kWH per day--That is as much power as my entire 3 bedroom, 4 people suburban home uses per day (or more, in a moderate climate--I have natural gas for heating/cooking/hot water).

    Power usage is a highly personal set of choices... But when looking at off grid solar--It can be an expensive set of choices.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    My 19" Dell Laptop requires 220Wh, some of the alienware gaming laptops require much higher up to 400Wh
    I think you mean W rather than Wh. To run all day on only 220Wh would be exceptional. And 220Wh/h is just 220W.
    SMA SB 3000, old BP panels.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?
    inetdog wrote: »
    I think you mean W rather than Wh. To run all day on only 220Wh would be exceptional. And 220Wh/h is just 220W.

    Now he has me mixing up WH and W... ;):p

    Went back to fix.

    This stuff is easy to mix up... We are used to Miles per Hour and Miles -- The electrical equvalent is Watts (a rate) and Watt*Hours (an amount).

    Watts is already Joules/Second (like Miles per Hour). There there is the whole Seconds vs Hours math (a factor of 3,600 seconds per hour convertion factor--In power, we just stay with "Hours" instead of seconds--The numbers are 1/3,600 times smaller). :roll:

    -Bill

    Then there is the whole "plural vs singular argument"... I think it is 120 Watt, not 120 Watts according to the standards folks. :-)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?

    No, it could well be 220 Watt hours.
    All depends on how much power it draws over what amount of time.
    My wife's laptop pulls <35 Watts but is on 12 hours a day so ... 420 Watt hours or less.
    My netbook pulls <12 Watts and is on about 14 hours a day so ... 168 Watt hours or less.
    If you had a laptop using an average of 22 Watts on for 10 hours a day: 220 Watt hours.
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    BB. wrote: »
    The numbers are 1/3,600 times smaller). :roll:
    Now you got my attention again, Bill.
    3600 times smaller gives you a smaller number. But (1/3600) times smaller makes the number 3600 times as large. :)
    SMA SB 3000, old BP panels.
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    No, it could well be 220 Watt hours.
    Not in the context of an Alienware gaming machine being 400 (whatever). That sort of machine could easily pull 400W, so 400Wh would mean that you only use it 1 hour per day. And if you are a serious enough gamer to buy that kind of computer, you will certainly have it powered on more than one hour per day. :)
    SMA SB 3000, old BP panels.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Inetdog;

    About those reading comprehension skills ...
    Thanks for the clarification, its appreciated. When it comes to forum talk, I tend to jibber jabber, rather than in depth express the variable terms.

    My 19" Dell Laptop requires 220Wh, some of the alienware gaming laptops require much higher up to 400Wh

    He did not say his laptop was an Alienware, nor did I. He did say that those use a much larger amount of power.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?
    inetdog wrote: »
    Now you got my attention again, Bill.
    3600 times smaller gives you a smaller number. But (1/3600) times smaller makes the number 3600 times as large. :)

    Come on InetDog, you know by 1/xx convention.

    (1/3,6000) times a "number" is a smaller number

    9.6 kWH * 1000 W/kW * 3,600 seconds/hour = 34,560,000 Watt*Seconds per day

    And then there is the whole Centimetre–gram–second system of units -- Where 1 Joule equals 1×107ergs...

    Anyway--Enough math fun. :D It has been too many decades.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    BB. wrote: »
    Come on InetDog, you know by 1/xx convention.

    (1/3,6000) times a "number" is a smaller number
    Yes, but the convention is common English is that when you say "N times smaller" or "Smaller by N" you divide by N, not multiply by N.
    Would you agree that "3600 times smaller" is good usage and means 1/3600 of the original?
    If you accept that, then "1/3600 smaller" would have to be 3600 times the original.
    A lot like double negatives, another favorite subject of mine.

    A story is told of a paper at a linguistics convention about the use of double negative in different languages. In some (Russian, French) the double negative is just a more intense negative, whi.e in others (English) a double negative becomes a positive. Anyway, during the Q and A afterward the author remarked that at least there were no languages where a double positive became a negative. And an audience member yelled out, "Yeah, right!"
    SMA SB 3000, old BP panels.
  • Steve961
    Steve961 Solar Expert Posts: 93 ✭✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Soulearner:

    I have something similar to you, a weekend cabin where power was mostly a convenience. Unlike most on this forum though, I have found that I actually use LESS power than I thought I would. Having bought some of my equipment before I knew what I was doing, I now have two separate arrays and controllers - a 128 watt roof array w/ PWM, and a 190 watt ground array w/ MPPT that's removable to prevent theft. I rarely use the ground array now, except when it's hot and I need to run my Vornado fan or my Coleman Stirling cooler for an extended period of time. I only have a 110 AH Concorde AGM battery, and I have never even been close to draining it below 50%. To be fair though, I typically only visit my cabin over a weekend when the weather is nice.

    This has been possible through both energy conservation and the extremely efficient Morningstar SureSine inverter. My entire cabin is lighted with CREE 6 watt (40 watt equivalent) LED bulbs. Other loads are: HP Mini netbook at <30 watts, 22" LED TV at 25 watts, T-Amp powered stereo, 12 Volt Shurflo water pump, small vacuum cleaner, rechargeable tools, and various portable electronics that my kids recharge. While not a coffee drinker myself, my wife NEEDS it, and uses a French press to make it.

    If I had to do it all over again from scratch, I would get the following:

    Single ~200 watt grid tie panel - higher voltage allows for smaller/cheaper wire and longer runs
    MidNite Kid 30 AMP MPPT controller - would allow another 200 watt panel to be installed
    ~200 AH 12 volt battery - I use AGM since it's indoors and I leave it unattended over winter
    Morningstar SureSine 300 watt inverter - my favorite part of the system

    Steve
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    Steve961 wrote: »
    If I had to do it all over again from scratch, I would get the following:

    Single ~200 watt grid tie panel - higher voltage allows for smaller/cheaper wire and longer runs
    MidNite Kid 30 AMP MPPT controller - would allow another 200 watt panel to be installed
    ~200 AH 12 volt battery - I use AGM since it's indoors and I leave it unattended over winter
    Morningstar SureSine 300 watt inverter - my favorite part of the system

    Steve

    Critique:

    You don't need that much charge controller for the current needed to recharge 200 Amp hours of battery. So spending $300 on a controller may not be a good choice financially.
    You may want more than 200 Watts of panel even with an MPPT controller as the charge rate from that would be just above 5% which is cutting it thin.

    The good news is that these days the >200 Watt panels are the best Watt per $ which makes it more practical to buy them, sometimes even if you 'waste' half the power using a PWM type controller.

    As it is the OP is on-track for a viable system with just a little tweaking.

    Never lock yourself in: always think about the future and what changes you may want. Try to evaluate what you buy now for how it will fit with what you want then.
  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    inetdog wrote: »
    I think you mean W rather than Wh. To run all day on only 220Wh would be exceptional. And 220Wh/h is just 220W.

    That was exactly my point according to the OP to spread the energy distribution there could only be 220Wh used for the laptop in that configuration, which means 1 hour not all day.

    Dead of winter with perfect pitch will be lucky to yield 110 watts from 200watt panels, so I was speaking hypothetically if that was my set up. Then in the summer there are temperature issues that will probably only make the system yield 185watts at best, doesn't matter where in the world or what insolation factors there are, 200watt in panels simply is not enough.

    Think about it, its more than charging a cell phone at 88watts, then you need a hotspot which is another 88watts if the smart phone doesn't offer internet, and honestly a laptop is pointless without internet connectivity.
  • Soulearner
    Soulearner Registered Users Posts: 18
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Most of the replies were outside my 'concept zone'. I read all 3 times to sink it in.
    (goodness; reading you guys is like Disney's Chip-n-Dale talking. LOL!)

    @BB. & Cariboocoot: I get it! That makes sense; I will add one 100w panel. The Suresine 300 fits the system profile needs better than the Cotek, thanks.
    Question: If I use the Iota DLS 30 for battery charging....does it work off of the gen, and PV...or just the gen? I ask because I possess a quality 120v bulk/absorb/float battery charger that I was going to use just for the gen-to-batt, and figured I just needed something for the PV.

    @Steve; sounds like a good system for basic needs - kinda of what I will do. We have a Flojak hand pump to pressurize the tank from the well - so water needs are all set. As is heat with a new Drolet wood stove and a huge supply of split wood.
    The 35 watt laptop is our DVD player for cozy nights together.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Iota's are AC powered battery chargers: connect to the generator to charge batteries when the PV won't do the job.

    PV charges batteries through a charge controller. Different device and not interchangeable.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?

    The Iota is 120 vac input from the ac generator or from the grid/utility power.

    DC side connects to the +/- battery bus, usually with a fuse or breaker at the positive battery bus connection to protect the charger wiring from short circuit fed by the battery.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Soulearner
    Soulearner Registered Users Posts: 18
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Of course. Then, I admit I am now betwixt on PV charge controller choice. For 3 100w panels, may I request recommendations.
  • Steve961
    Steve961 Solar Expert Posts: 93 ✭✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    You don't need that much charge controller for the current needed to recharge 200 Amp hours of battery. So spending $300 on a controller may not be a good choice financially. You may want more than 200 Watts of panel even with an MPPT controller as the charge rate from that would be just above 5% which is cutting it thin.

    While you may not need that much controller now, I believe it is a wiser long term investment. An MPPT controller will allow you to use the less expensive and higher voltage grid tie panels that will save you money up front. It will also allow you to use a lower gauge wire which can also be a substantial savings if you need to run your wires any distance. The next less expensive MPPT controller would be the Morningstar 15 Amp SunSaver at just a 60 dollar savings. Considering that the MidNite is 30 Amps at 12, 24, and 48 volts, that extra $60 provides a lot more options for growth in the future.

    Battery banks and solar panels seem to grow over time. It would be nice to have a charge controller that wouldn't need to be replaced every time too.
  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    Soulearner wrote: »
    Of course. Then, I admit I am now betwixt on PV charge controller choice. For 3 100w panels, may I request recommendations.

    I'm pretty sure Renogy sells basic 2 or 4 panel kits with charge controller. For a small set up that's the route I would go, make sure monocrystalline panels. Just make sure 25 year power warranty or don't buy.
  • Soulearner
    Soulearner Registered Users Posts: 18
    Re: Small PV For Convenience. What Can Be Improved Upon?

    May I ask which of these charge controllers you would think best suited to my needs? Also gentlemen, I am certain we will not expand the system later on.
    Renogy 30A PWM $28
    Renogy 40A MPPT $200
    My reading indicates that the Vmp difference between PWM and MPPT can be huge - up to ¼ loss. Which makes me wonder why anyone would choose a PWM controller for long term usage. What am I missing?
    Stupid Questions:
    1) Should 3 panels be wired in parallel to the controller?
    2) Is a 24 volt battery setup more efficient use of harvested PV than 12 volt?
    3) Does the inverter get wired to the Load terminals of the charge controller?
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    Soulearner wrote: »
    May I ask which of these charge controllers you would think best suited to my needs? Also gentlemen, I am certain we will not expand the system later on.
    Renogy 30A PWM $28
    Renogy 40A MPPT $200
    My reading indicates that the Vmp difference between PWM and MPPT can be huge - up to ¼ loss. Which makes me wonder why anyone would choose a PWM controller for long term usage. What am I missing?
    Stupid Questions:
    1) Should 3 panels be wired in parallel to the controller?
    2) Is a 24 volt battery setup more efficient use of harvested PV than 12 volt?
    3) Does the inverter get wired to the Load terminals of the charge controller?

    There's no Vmp difference between the controllers per se, it is the difference allowable in the array. For a 12 Volt system using a PWM type controller the array Vmp needs to be around 17-19 Volts which would be all of the panels in parallel in this case. An MPPT type controller can accept higher Vmp and will down-convert the Voltage into charging current. With the arrays matched there is a small current increase from MPPT type controllers (retailers often exaggerate this). Their biggest advantage lies in the flexibility of design they offer.

    A 24 Volt system is definitely more efficient than 12 Volt. As a rule you should not choose 12 Volt unless it is required for another reason (as in a mobile application).

    Never wire an inverter to the LOAD terminals of a charge controller. Those terminals are meant for low current, usually the same or less than the controller's output rating. Inverters usually draw more than that.
  • Soulearner
    Soulearner Registered Users Posts: 18
    Re: Small PV For Convenience. What Can Be Improved Upon?

    I am unable to thank you all commensurate to what I have received. Please know we are grateful. We can now obtain a system for our cabin that will be far more efficient AND less expensive than had you not been so generous.

    Then my best system option, given our limited funds, I believe is this:
    2 - Renogy 100 watt panels (wired in series)
    1 Renogy PWM controller
    2 12 volt deep cycle FLA (also in series)
    1 Suresine 300 Watt inverter
    We will place a fuse near the Pos terminal. And 12 ga wire should be fine for the 16 feet from array to batteries.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Small PV For Convenience. What Can Be Improved Upon?
    Soulearner wrote: »
    I am unable to thank you all commensurate to what I have received. Please know we are grateful. We can now obtain a system for our cabin that will be far more efficient AND less expensive than had you not been so generous.

    Then my best system option, given our limited funds, I believe is this:
    2 - Renogy 100 watt panels (wired in series)
    1 Renogy PWM controller
    2 12 volt deep cycle FLA (also in series)
    1 Suresine 300 Watt inverter
    We will place a fuse near the Pos terminal. And 12 ga wire should be fine for the 16 feet from array to batteries.

    Whoa. No.
    The Suresine 300 is a 12 Volt inverter; it will not run from a 24 Volt system (two 12 Volts in series). You would need a 24 Volt inverter like this Samlex/Cotek: http://www.solar-electric.com/inverters-controllers-accessories/inverters/sasiwain1/samlex-pst-series-pure-sine-wave-inverters/sa300wa24vos.html

    Also be sure of the Amp hour capacity of those 12 Volt batteries in respect to the available charge current: with only two 100 Watt panels (in series) you would have about 5 Amps @ 24 Volts charge current. That's pretty low for most batteries. 100 Amp hours at most.
  • Soulearner
    Soulearner Registered Users Posts: 18
    Re: Small PV For Convenience. What Can Be Improved Upon?

    (slap - hand to forehead) GEEZ, am I glad you chimed back at me, Cariboocoot! My poor eyesight causes me to miss a lot!
    Thanks! And thanks for reminding of the battery deficit. I know we are running one, but, I will NOT damage those batts, and will use the gen to boost them to full every sunset when we're there. When we leave they will be full and will sustain on the panels.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Small PV For Convenience. What Can Be Improved Upon?

    When you leave, disconnect ALL LOADS, and leave the solar charger+battery connected and you should be fine (assuming the charge controller does its duty).

    If you have loads when away (alarm system, etc.), you do need to make sure that the minimal array + battery bank is still getting sufficient solar every--especially if you get a week of bad weather.

    Even small loads in winter can kill a battery bank. :cry:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Soulearner
    Soulearner Registered Users Posts: 18
    Re: Small PV For Convenience. What Can Be Improved Upon?

    Gotcha, appreciate it.