GOT to ask the stupid questions about inverter.

bmetbmet Solar Expert Posts: 630 ✭✭
I've pieced together a tiny solar system for my tool shop. The components were purchased not for solar, but since I already owned them, I figured, why not? I want to do it smarter, and like to start with choosing the right inverter.

Here's what I have, everybody cringe together.

1. Harbor Freight Tool 5 watt solar panel.
2. HQRP Solar 10A charge regulator.
3. Car Battery, new (I know I know, I'd already bought it when the engine threw a rod))
4. "Power on Demand" inverter rated @ 400 watts

I've read that deep cycling a car battery is the quickest way to kill it. I am not using the battery for anything else, so I tried to experiment with two devices. One is a Walmart 10" camping fan(DC), the other is a 11 watt LED floodlight(AC).

The inverter I have seems to suck all the battery power for itself. It's tiny fan makes a loud enough roar. When I try to operate the fan and light together, the inverter usually shuts off after about a minute. The HQRP regulator is new, and its lights indicate it's operating normally. It is mounted in between the panel and battery, about 3 feet away from each.

I can't afford a one-stop shop for a completely matched system. but rather would like to piece together the separate devices that would play well together.

My needs are to run the fan, the LED light, and a laptop simultaneously overnight.
What real world battery storage do I need to sustained this? What inverter would support these, and not hog the battery for itself?

I don't trust the inverter I currently have, but its too late to return it.

Thank you.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,994 admin
    Re: NO search tool here? GOT to ask the stupid questions about inverter.

    The Search function here works OK if you know the terms / words you are searching for...

    If you are looking for things and need a better search... Use Google and type in the words/phrase you are looking for and end it with "site:wind-sun.com"--It does a pretty good job of finding things here--I use it all the time.

    For example:
    • portable solar power battery inverter system site:wind-sun.com
    Regarding your system... There was a nice thread here where we went through an entire set of questions and project for a small / portable solar powered inverter system:

    Emergency Power


    Regarding your system... The first problem is that your car battery sounds like it is near dead---Check the resting voltage (~12.7 volts is near 100% charged, 12.0 volts in near 50% charged, etc.). Or check the specific gravity if you have a hydrometer.

    Then backing up a moment... For a good quality system, you are looking at around 4 hours of sun and 50% efficiency (from solar panel power rating to AC power to your loads)... So, a 5 watt panel:
    • 4 hours * 0.50 * 5 watts = 10 Watt*Hours of useful power a day
    10 WH is not very much--That would power my little 10" netbook computer for about 1/2 an hour. (20 watts for 1/2 an hour = 10 Watt*Hours)...

    Add the losses from the large battery and 400 watt inverter--And your 5 watt panel would not even do much more than trickle charge the car battery.

    For example, say you want run a 20 watt fan, 11 watt LED lamp, and a 30 watt typical lap top for 10 hours a night... Solar panel wise:
    • (20w+11w+30w)*10 hours a night = 610 Watt*Hours per night
    Assuming a minimum of 4 hours of noontime equivalent sun per day (solar is very location and seasonal dependent) and 52% end to end efficiency:
    • 610 Watt*Hours / (4 hours of sun * 0.52% sys eff) = 293 Watts of solar panel (~9 months of year)
    Battery size... For emergency power, you would want to discharge the battery by 50% maximum (for longer battery life and to have spare capacity for aging). If this was an off grid system with daily use--3 days of no sun and 50% maximum discharge and an 85% efficient inverter... For a 12 volt battery bank:
    • 610 WH * 1/12 volt battery * 1/0.85 * 1/0.50 max discharge = 120 AH battery bank @ 12 volts (minimum battery recommendation)
    • 610 WH * 1/12 volt battery * 1/0.85 * 3 days * 1/0.50 max discharge = 359 AH @ 12 volts (sort of maximum battery recommendation)
    Anyway, I will stop here--We really need to know more about your daily power requirements, roughly where the system would be installed, and your expectations (off-grid, emergency power, backup genset, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: GOT to ask the stupid questions about inverter.

    When you say that your "needs are to run the fan, the LED light, and a laptop simultaneously overnight", exactly how many hours are you talking about and what is the total watts for each device?

    This is probably the single most important piece of information when trying to put together a power pack.

    Smoove
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: NO search tool here? GOT to ask the stupid questions about inverter.

    Bill and Smoove,

    Thank you for the quick eye opener. My needs at this point are hypothetical because I am a solar idiot. I have a fully-insulated tool shed, and I need to run a small fan, plus a light when the door is closed. It would be a bonus to power a small laptop/radio, or recharge an iPod. When I am working in the shed, it is usually an all day affair, and I sometimes run a couple of hours into night.

    I'll switch to DC powered LED lights, something like these http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=%2Fspecs%2Fslm.htm
    Once in a while I need something brighter to work by, and I own these. http://www.esplighting.com/liofampoledf1.html /They are very bright for the electricity they use.

    I don't know how many watts the camping fan uses, I connect that to the regulator since it has an output for a device, and supposedly uses LVD. The inverter is directly clamped onto the battery, and is supposed to shut off at 11.5 volts.

    I live in SW Texas where we get plenty of sun. The shed is just a 12' x 12' building, and has no hook-ups of any kind. The solar system is for my convenience, and I had most of the pieces, just not the proper ones. As you surmized, the panel keeps a tractor battery charged, the inverter was for the now-dead car (battery too). The only new purchase was the regulator. At this time, all these component are place-holders, allowing me to finalize the layout without starting completely over.

    The panel faces south over the door, tilted at about 22 degrees. Its wire runs 3 feet inside to the regulator. 3 feet away from that is the battery. No long runs, and I am using a solid core, insulated copper wire that is approx. 10 gauge in size.

    It is hard to know what direction to go. A 20-something watt panel for occasional use, or one of the 100+ Watt Kyocera's I keep reading about. If one is going to buy, then why not look to the future?

    Thank you for your time.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    From an off-gridder's POV: you're going to have to spend money.

    1). 5 Watt solar panel - this won't produce enough power to charge anything. 5W / 12V = < 0.5 Amps. On a good day it might protect a car battery that's not being used from self-discharge losses. Unfortunately HF equipment is known to be of poor quality, so it might not even be that good.

    2). 10 Amp charge controller. This should work for up to 100 Amp hour battery, or even 200 if you go with a slow charge rate. It would need 170-180 Watts of panel to get it to maximum output.

    3). Car battery. Okay, you already know this is no good and doomed to fail. :p

    4). Suspect inverter. I'm guessing MSW, el cheapo which probably will use a lot of power for its own needs. At "full power" this thing will drain a 100 Amp hour battery in just over an hour.

    So it comes down to this: get a good handle on the loads. How much power for how long? And then see if your budget can handle the strain. Your experience is another example of why I wrote this post:
    http://forum.solar-electric.com/showthread.php?t=9310
  • mike95490mike95490 Solar Expert Posts: 8,234 ✭✭✭✭✭
    Re: GOT to ask the stupid questions about inverter.
    HQRP Solar 10A charge regulator.

    What is it, who makes it, did you buy it at horrible freight too ???

    Skip the off brand parts, and get a quality controller from Trace or morningstar and you are likely to get better luck. Some no-name controllers consume more power internally, than the panel provides.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • KeithWHareKeithWHare Solar Expert Posts: 140 ✭✭✭
    Re: GOT to ask the stupid questions about inverter.
    mike90045 wrote: »
    What is it, who makes it, did you buy it at horrible freight too ???

    Skip the off brand parts, and get a quality controller from Trace or morningstar and you are likely to get better luck. Some no-name controllers consume more power internally, than the panel provides.

    The HQRP charge controllers are marketed by HQRP. The info for the 10 amp controller is:

    http://hqrp.com/solar-10a-charge-controller-regulator-12v-24v-10-amp-with-battery-charger-monitor-by-hqrp.html

    Last December, I purchased a couple of HQRP 20 amp controllers through Amazon and sent them to Haiti for my brother Mark to test. Then an earthquake caused some distractions, and I haven't heard anything about how they worked.

    Keith
  • mike95490mike95490 Solar Expert Posts: 8,234 ✭✭✭✭✭
    Re: GOT to ask the stupid questions about inverter.
    KeithWHare wrote: »
    The HQRP charge controllers are marketed by HQRP. The info for the 10 amp controller is:

    http://hqrp.com/solar-10a-charge-controller-regulator-12v-24v-10-amp-with-battery-charger-monitor-by-hqrp.html


    Something seems strange, terms i've never seen before:

    Product Description:
    All HQRP controllers at the final stage of charge use the so-called pulse-width modulation (PWM) charging current.
    Type of Charging: Series PWM & stat of charge(SOC);
    4 Stages: equalization, PWM, Boost and Float, temperature compensated charging;
    Electronic protections: Short circuit and over current-solar and load; Reverse current at night;
    Limits high voltage to protect loads;
    Lighting protection;
    Terminals: for wire sizes to 2.5mm2;
    Tropicalization: Conformal coated printed circuit board;
    Self-consumption: 6mA maximum.
    200 days warranty!


    Well, at least you don't have to pay a lot for them.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: GOT to ask the stupid questions about inverter.
    mike90045 wrote: »
    Something seems strange, terms i've never seen before:

    Let's see if we can translate from the Copy Writer's native language (Gibberish):
    Product Description:
    All HQRP controllers at the final stage of charge use the so-called pulse-width modulation (PWM) charging current.

    "so-called"? Okay, it's a PWM controller, not an MPPT. We knew that already.
    Type of Charging: Series PWM & stat of charge(SOC);
    4 Stages: equalization, PWM, Boost and Float, temperature compensated charging;

    Yes, yes; it's a PWM. Redundancy thy name is "advertising"! I'll bet "boost" was as close to "Bulk" as they could get, translating in and out of Cantonese or Mandarin. Not in the right order, either. I'd be worried about that emphasis on equalization; when does it do this? On its own? Nice to know it's temp compensated.
    Electronic protections: Short circuit and over current-solar and load; Reverse current at night;

    Contains fuses and a diode.
    Limits high voltage to protect loads;

    Good; the "LOAD" terminals are Voltage limited. Unless that's not what it means.
    Lighting protection;

    Also contains at least one MOV.
    Terminals: for wire sizes to 2.5mm2;

    10 AWG
    Tropicalization: Conformal coated printed circuit board;

    "Tropicalization"? That's a new one. Coated circuit board. Meh. So what? No guarantee against failure.
    Self-consumption: 6mA maximum.

    Good; low power. Unlike a BZ which consumes more than it produces. :p
    200 days warranty!

    Less than one year, but more than one minute!

    Well, at least you don't have to pay a lot for them.

    Nor would you want to.
    It probably works okay. :cool:

    On the whole, I'd say this is the one item on the OP's list of what he's already got that isn't totally worthless. :roll:
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    Okay, thanks for the running commentary on my bad choice. I knew coming in that this wasn't the proper way to do it, but now I have better information to work with.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    Hey! You didn't make any bad choice. You had this stuff lying around, kind of accumulated over time, and you were wondering what you could do with it. Unfortunately the answer is "not much".

    Some people go out and buy a 45 Watt Harbor Freight solar panel and a BZ charge controller and two "deep cycle" RV batteries and a 10,000 Watt AIMS inverter - and then ask: "How come I can't run my AC from this?" That's making bad choices!
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    Normally I wouldn't have given that regulator any consideration, but the Osprey name is what changed my mind. I installed it a week ago, and have not been to the site since. The battery had been sitting with just the panel on it for a couple of days, and the voltage never rose past 12.3V

    I'll be back there in a couple more days, and I hope the regulator will have managed to get to the float stage.
  • BB.BB. Super Moderators, Administrators Posts: 28,994 admin
    Re: GOT to ask the stupid questions about inverter.

    You really need to get that battery recharged on an AC charger pretty quickly... The battery setting below ~75% state of charge for weeks/months at a time will sulfate and die on you.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    A very slow charge?
  • BB.BB. Super Moderators, Administrators Posts: 28,994 admin
    Re: GOT to ask the stupid questions about inverter.

    No--5-13% of the 20 Hour Amp*Hour rating... You need enough energy to "mix the electrolyte" and get over the self discharge rate of an old battery (1-2+% per day for an old forklift battery).

    A 100 AH battery, 5-13 amp charger...

    And around 5% for the Equalization (battery 100% charged and you are looking to equalize the the specific gravity between cells).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.
    Let's see if we can translate from the Copy Writer's native language (Gibberish):
    "Tropicalization"? That's a new one. Coated circuit board. Meh. So what? No guarantee against failure.

    I don't know what that means either, but apparently Morningstar, a product supported by this site's host, uses that same term.

    After re-educating myself with all your good information, I can see that my needs in the shop can be met by a small system based on one of the 135W panels. During the day I don't really use anything but the 10" camping fan, my iPod, and the occasional power tool which I can recharge from my car. It's only after dark that lights and the netbook come into play, and only for a couple of hours while I finish whatever I am working on. Here's my list of items:

    11W LED Light Input: 110VAC
    Netbook AC adapter: Input: 110VAC @ 1.0 A
    Output: 12VDC @ 3A or 36W
    iPod adapter: Input: 110VAC @ 0.15A
    Output: 5VDC @ 1A or 5W
    10" Camping Fan Don't know the wattage since the adapter is at the remote site. However, I did look up the ideal conditions of a D size battery from this site, given a number of 20.83Wh . Multiplying that by 8 batteries comes to 166.6 Wh(Using fan for one hour would equal to 167 Watts?)

    My total output so far: 166.6 + 36 + 11 + 5 = 218.6 Watts per hour. If I work a couple of hours past sundown then that would be 218.6 x 2hrs = 437.2 W .

    This is with everything going at once, and with cooler weather the fan may not be used at all.

    According to a few different web sources, my area (around San Antonio) gets an average of 4.5 hours of "good sun equivalent" per year. (For this month it's 5.5)
    From the same sources, I need a fixed tilt of 29.5 degrees, facing due south.

    The system could be supplied by a single Kyocera 135W panel, my existing charge controller, and a Deka 104 Amp Hour battery.

    The inverter, which has yet to be decided, will be one of the the true sine wave kind in the 300 watt range.

    What else am I missing? Thanks.
  • BB.BB. Super Moderators, Administrators Posts: 28,994 admin
    Re: GOT to ask the stupid questions about inverter.
    bmet wrote: »
    I don't know what that means either, but apparently Morningstar, a product supported by this site's host, uses that same term.
    That is another term for conformal coating of circuit boards.

    From a user point of view--Can be a really nice way to reduce that chances of mist/moisture and bugs (i.e., real bugs) from shorting out the electronics.

    From a manufacturing and repair point of view--A real nightmare to repair and upgrade boards with engineering changes (cuts and jumps).
    10" Camping Fan Don't know the wattage since the adapter is at the remote site. However, I did look up the ideal conditions of a D size battery from this site, given a number of 20.83Wh . Multiplying that by 8 batteries comes to 166.6 Wh(Using fan for one hour would equal to 167 Watts?)

    A D Cell alkaline battery is around 1.25 volts average output and around 10-18 Amp*Hours depending on current levels. So, around 12-20 Watt*Hours.
    • 8 batteries * 12 Watt*hours = ~96 Watt*Hours
    Or, assuming the fan will run 10 hours on a set of batteries, around 9.6 watts average power.

    To address the confusion between Watts (a rate like miles per hour, gallons per hour) and Watt*Hours (an amount like miles driven or gallons pumped):
    My total output so far: 166.6 + 36 + 11 + 5 = 218.6 Watts [no watts per hours--just Watts]. If I work a couple of hours past sundown then that would be 218.6 Watts x 2hrs = 437.2 Watt*Hours .
    According to a few different web sources, my area (around San Antonio) gets an average of 4.5 hours of "good sun equivalent" per year. (For this month it's 5.5)

    From the same sources, I need a fixed tilt of 29.5 degrees, facing due south.

    The system could be supplied by a single Kyocera 135W panel, my existing charge controller, and a Deka 104 Amp Hour battery.

    The inverter, which has yet to be decided, will be one of the the true sine wave kind in the 300 watt range.

    What else am I missing? Thanks.

    The missing thing (I think) is that you are not including the various losses... A solar panel + Charge controller will run around 77% of the solar panels marketing rating (STC--Standard Test Conditions). And the flooded cell batteries will be around 80% efficient (charge/discharge cycle). The AC inverter will be around 85% efficient... All together:
    • System Derating = 0.77 * 0.80 * 0.85 = 0.52 overall system derating
    So, for a 4.5 hour "full noontime equivalent sun day", a single panel 135 watt off-grid system would produce:
    • 135 watts * 4.5 hours of sun per day * 0.52 derating = 316 Watt*Hours per day average
    For a very nice TSW 300 watt 12 volt inverter--The Morning Star:

    wind-sun_2125_16971475Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC

    Would be a great place to start... Also includes a "search mode" (turns off most of the time if less than 6 watts of AC loads) and a simple DC inhibit digital input (draws very little power when inhibited).


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    Should I be looking for a different capacity battery?
  • BB.BB. Super Moderators, Administrators Posts: 28,994 admin
    Re: GOT to ask the stupid questions about inverter.

    This is the $64 question... We can size the battery to your loads, to your solar panels, or size the solar panels to your battery, etc...

    Roughly, if you want to charge the battery from your 135 watt solar panel only (no genset, no grid backup power)--We recommend a 5-13% rule of thumb for battery charging current... Assuming a 135 watt solar panel and 77% efficiency at charging, 14.4 volt battery charging voltage:
    • 135 watts * 0.77 derating * 1/14.4 volts charging * 1/0.05 min charge rate = 144 AH @ 12 volts maximum battery
    • 135 watts * 0.77 derating * 1/14.4 volts charging * 1/0.13 max charge rate = 56 AH @ 12 volts minimum battery
    So, your 104 AH battery is somewhere in the middle--So, if your requirement is to run from solar power only--You cannot go with a battery that is very much larger...

    And remember a larger battery does not give you more power from the sun--it just lets you store a bit more power. You still need to recharge the battery from the existing solar panel or alternative power source.

    If you wanted, you could almost double the 135 watt solar panel with your existing 104 AH battery and be pretty much OK (about the maximum amount of solar panel for a 100 AH battery).

    Remember it is the solar panel that is trying to keep up with your daily loads--if you have more loads than the panel can supply energy for--Then a bigger battery is (usually) not going to help anything (unless you work mostly on weekends and then you let the bank recharge during the week).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    bmet;

    I'm going to suggest you get a Kill-A-Watt meter (about $30) and get some "real world" power consumption figures, rather than go by the data stamped on devices. Info such as "110 V, 1A" is usually a maximum draw figure and not very closely related to what the unit actually uses.

    Case in point: Laptop power supply. 1 Amp @ 110 Volts = 110 Watts. Hardly likely. Especially when you read the output specs: 3 Amps @ 12 Volts = 36 Watts. Now, we can't believe the power supply itself is using up 74 Watts! ;)

    It's very important to have some accurate load info for planning an off-grid system, especially if it's a small one. A few Watts one way or the other is quite a large % if you only have a few Watts to begin with.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    On my visit to the remote site, I found that the battery had taken a charge of about 12.8 volts. This is a half-volt better (with regulator) than with the panel alone. The panel's voltage was 12.9 volts- I plugged in my various small devices:

    iPod and charger
    cell phone and charger
    9” Netbook and power supply
    10” camping fan (high)
    11 watt LED light.

    On the POD Inverter (being a modified sine wave) I don't know how test equipment gets a reliable measurement. I have a Kill-a-Watt EZ meter, and it never did show a consistent Hz rate, usually between 30-40 Hz. One time it even displayed DC and stayed there.

    The amps also fluxed a bit, varying between .5 and 1.1 Amps at any given instant.

    The Kill-a-Watt EZ meter read a maximum of 46 watts for all of these, but it wasn't a consistent reading. A lot of the time it read 39-40 watts.

    The Inverter's output voltage was in the range of 121-123 VAC.

    The car battery I am playing with is a Duralast 35DL, rated 500CCA & an 80min reserve.

    For the purpose of measurement, everything was run off of the inverter, no separate DC loads.
    Afterward I did try the 'managed' output from the regulator, and it did turn on & off via push button on the face of its box. I did not run the battery down far enough to LVD.

    Total batt run time was about 30 minutes(voltage drop, 12.8 to 12.1V). Since our calves had unplugged our only charger, and ruined it while being zapped, I could only put the car battery back in the car, and it started normally.

    The one test I couldn't get was the power being consumed by the inverter. My EZ meter doesn't do DC, and my cheapo voltmeter maxes at 250mA.

    Thank you for all your feedback, and for taking several steps back to educate me with this experience.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    The evolution of my power pack.

    My upgrade is just about complete. A MorningStar 10 amp controller completes the hardware. Then I found these to assist me with the alignment of the panel.

    http://www.northerntool.com/shop/tools/product_200430683_200430683

    They connect the bottom corners of my solar panel, to my shed above the entrance door. The top corners of the panel connect to the shed's roof with short aircraft cable so that it will float. Adjusting the angle is quick and easy.

    I thought these rods might be very handy for RV'ers and their ground mounts.
  • 2manytoyz2manytoyz Solar Expert Posts: 370 ✭✭✭
    Re: GOT to ask the stupid questions about inverter.

    I can give you details about the Walmart fan. I'm was using a couple of these at home to help cool the garage and attic.

    chinafan1.jpg

    This fan draws a little under 450mA at 12V. A 5W solar panel isn't large enough to run the fan directly. But a 15W panel will spin it up nicely.

    Here's a video of mine in action: http://www.youtube.com/watch?v=ULQmLXw4-8E

    I don't bother with a battery or a voltage regulator. The fan puts enough of a load on a 15W panel that it self regulates the voltage & speed. Starts spinning when the sun comes up, shuts down at dusk.

    The only issue with this fan is the RF noise it produces. It will prevent my garage door opener from working with the remote if the fan is on! I put some capacitors on the motor, and even put copper foil over the motor housing. No improvement.

    img_1452.jpg

    So now I've put a different fan (brushless motor) in the attic. It's only a 6" muffin fan, but works fairly well.

    The Walmart fan is now in the attic access door in the garage ceiling. Has a switch. I power it up when at home, power it off when going out (and need to use the remote opener).

    dscn5409.jpg

    My conclusion is it takes a 15W panel to run this fan, with little power left over to charge a battery. It does work well, but it'll take more than the 5W panel initially mentioned.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    Thank you for sharing your experience with that camping fan. I sought out a brushless DC fan similar to yours, matching the mA rating of the panel. It's much faster, and will become the vent 'sucker' to move air through my shed, a 10' x 10'.

    My main issue at present is the MorningStar controller I purchased. It does not produce the 14.4 VDC required for a wet lead acid battery. No matter if the Battery Select jumper is On or Off, the measurement is 14.1 VDC. I've contacted both the vendor and MorningStar Support for assistance, but neither one have yet to respond.

    I'm not sure if I even like the SunSaver. It has a single green LED that indicates everything's OKAY, but apparently it can't tell me that the Battery Select voltage is low. This, and the fact that MS support hasn't responded, make it difficult to believe the hype for this product.

    Thank you for your time.
  • icarusicarus Solar Expert Posts: 5,124 ✭✭✭✭
    Re: GOT to ask the stupid questions about inverter.

    The fact that the controller is not putting 14.4 volts may not be a controller question. It may be that you don't have enough PV to bring the battery up to float voltage, or the battery is too far discharged. Morningstar controllers, in all their derivations have good reputations.

    Tony

    PS 80 watts of PV is likely to put out ~4 amps on average, just about 5% of your 75 ah battery. Depending on how you are loading your battery, you may be chronically undercharging it.

    t
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    The panel has been producing 19.1 VDC, averaging 3 Amps into the SunSaver. Even out of optimal alignment, it still was putting 1.5 - 2 Amps into the controller. The battery is new from Costco, only a couple of months old. The wiring is 8 feet of new #10 AWG stranded copper.
    The Costco marine battery has been maintained by my previous cheap controller at 13.2 volts. If anything, shouldn't the SunSaver be trying to push 14.4 volts into it? There is no load on the battery if I am not there. Every couple of weeks I get out to the address and use only minimal electricity, a radio, usb charging, a camping fan, and a 11 watt LED lamp on an inverter.
  • icarusicarus Solar Expert Posts: 5,124 ✭✭✭✭
    Re: GOT to ask the stupid questions about inverter.

    Like I said before, 2 amps into a 75 ah battery is not very much. How much is your daily draw? 2 amps * 4 hours= 8 ah, or ~100 watt/hours. Not much, enough to run your stated ~ 40 watt loads for a bit over two hours hours. I would also posit that the net book probably draws more than that 40 watts all by it self, especially if it it charging it's battery.

    I think, again, that you may be under charging your battery.

    T

    PS In case you haven't seen these, I suggest that you read the following:

    http://www.batteryfaq.org/

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: GOT to ask the stupid questions about inverter.

    That controller just connects the solar to the battery, if you not getting 14.4, its due to your loads. The SS will blink the green led when in absorb or float I believe, so solid means it hasn't reached that state. Remove all loads to the battery and see if it can complete a charge cycle.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.

    I don't run unattended loads. I've metered the inverter with it's switch in the OFF position, get a reading of 00.04. Is that 40 mV of load, or just the resolution limit of my meter?

    Tony,

    IF I was running this everyday, I'd believe. The shed sits locked for two weeks at a stretch, everything is turned off except for controller.

    What about this? We've recently experienced a large number of overcast days. Maybe the controller doesn't get a chance to finish a cycle before it starts over?
    That controller just connects the solar to the battery, if you not getting 14.4, its due to your loads. The SS will blink the green led when in absorb or float I believe, so solid means it hasn't reached that state. Remove all loads to the battery and see if it can complete a charge cycle.
  • BB.BB. Super Moderators, Administrators Posts: 28,994 admin
    Re: GOT to ask the stupid questions about inverter.

    If that is the voltage at the DC input of the inverter when the DC switch is turned off--more than likely, that is a little bit of stored voltage on the input caps of the inverter.

    Nothing to worry about.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: GOT to ask the stupid questions about inverter.
    That controller just connects the solar to the battery, if you not getting 14.4, its due to your loads. The SS will blink the green led when in absorb or float I believe, so solid means it hasn't reached that state. Remove all loads to the battery and see if it can complete a charge cycle.

    Yesterday I went out and re-aligned my panel. I went outside at 12:30 pm, stuck a right-angle tool on the glass, and adjusted the pitch until it cast no shadow. Then I took a bubble level and centered it from East to West. After that, the reading across the Solar terminals was 20.4 VDC. The Battery Select voltage was still low, 14.1 volts. There were no loads on the battery, I'd disconnected the inverter, just in case. The measured Current from panel was a mere 300 mA.

    I think I have a defective unit.

    From the Operator's manual:
    remarks in red are mine.

    The green LED indicator will light whenever sunlight is available
    for battery charging. --no flashing-- The green LED will turn off at night.

    "Because the SunSaver uses a PWM constant voltage charging
    process, there is usually some amount of energy going into the
    battery at all times. --measure the charge current to know if it is charging or floating-- Although the charging current falls to very
    low levels when the battery reaches full charge, the green LED
    will continue to stay ON (during the daytime). This is to indicate
    that the controller is working and that energy is available
    from the PV array for charging"

    The manual explains why my panel's Current is low, but if the wet SLA battery isn't getting the extra 3/10 of a volt, should I be concerned? Should I settle for less than spec?

    I'm still hoping MorningStar support will get around to me.
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