Newb help - Power inventory

jrs1418jrs1418 Registered Users Posts: 5
Hello Ladies and Gents!

I have some newb questions for you. I've tried searching but havn't found my answer.

1) I'm starting a small car washing business. It will not be brick/mortar, i'll be operating under a tent in a local shopping center. It will be completely waterless and eco friendly, but the only thing holding me back from 100% eco friendliness.. is a generator that can power my equipment reliably. So i guess my first question is.. at this time is there a way to build a mobile solar power generator that can power my equipment and still be small enough to be manageable and mobile?? I will need to run a cash register, 2 small shop vacs, my laptop, credit card machine, and maybe a cell phone charger or 2.

2) Power inventory - I'm having a hard time understanding how to do this.

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this is from my laptop.. can someone break down how they would use this to make their solar power inventory.

Thanks!

Comments

  • mike95490mike95490 Solar Expert Posts: 8,463 ✭✭✭✭✭
    Re: Newb help - Power inventory

    I see the shop vacs as a problem. Too much power.

    How do you wash the cars - city water pressure, or do you have pumps?

    Other items you listed are simple, a couple PV panels and battey can manage that, for under $2K, but shop vacs are real power hogs.

    We'll need the time the vacs are ON, between :
    your start hour - 10AM
    10am - 2pm
    2pm - quitting time.

    The more time the vac's can run off the solar, and not the battery, the better. We also need the Watts or amps off the label of the vac.
    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: Newb help - Power inventory

    If you've already bought your business equipment, get a Kill-A-Watt meter. Plug it all in, and wash your car. This is the best way to get real world data on power consumption. Trying to calculate it from "plate ratings" on equipment is almost completely useless.

    One other warning, as Mike said the Shop Vacs are power hogs. Big start-up surge and often draw 1-2 HP (depending on size) which is up to 1500 Watts, not including what happens when they clog.

    Is it possible? Yes. Will it be inexpensive? Not a chance. And you may be looking at a trailer rig to house everything (with panels on the roof).

    Have you looked at the little inverter generators like the Honda EU2000i? Very quiet, very economical on fuel, very dependable. (Gee, I sound like a Honda salesman! :p)
  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Newb help - Power inventory

    In the end, you can probably run everything but the shop vacs from a couple lead acid batteries and some solar panels on the trailer (assuming you work at conservation).

    The vacuums are iffy... As the other guys said, if you use them a lot--Either a ton of batteries (actually) or genset.

    Are you towing this home at night (recharge at the shop)? Or are you leaving this at the shopping center?

    Can you / do you want to / check with the shopping center management about pulling power from a light standard? Would make things a lot easier.

    Battery sizing... Say you want 60 watts (computer, cell phone, light, printer, etc.) for 10 hours a day and you want a maximum of 50% discharge on the battery (you can recharge every night from AC power)--gives you the smallest practical battery--Probably have to replace every 1-3 years.
    • 60 watts * 10 hours * 1/0.85 eff inverter = 706 WH per day
    • 705 WH * 1/12 volt battery * 1/0.50 max discharge = 118 AH @ 12 volts
    Assuming run the 2x 1,500 vacuums at the same time, 4 hours per day. First, look at a 48 volt battery bank (high power requirements).
    • 1,500 watts * 4 hours * 2 vacuums * 1/0.85 inverter eff = 14,118 WH per day
    • 14,118 WH * 1/48 volt battery * 1/0.50 max discharge = 588 AH @ 48 volts
    A 588 AH @ 48 volt battery bank is about 20x the size of the 12 volt bank for your electronics.

    About 16-24 golf cart sized batteries...

    We have not even talked about solar array--For your electronics, assuming you only work during sunny weather (assuming 4 hours of full sun equivalent):
    • 706 WH per day * 1/4 hours of sun * 1/0.80 battery eff * 1/0.77 solar array eff = 285 watts minimum of solar array.
    We also check the battery bank for 5-13% recommended rate of charge (minimum to maximum recommended economically):
    • 118 AH * 14.5 volts charging * 0.05 minimum rate of charge * 1/0.77 solar array eff = 111 minimum for battery bank
    • 118 AH * 14.5 volts charging * 0.13 minimum rate of charge * 1/0.77 solar array eff = 288 watts maximum for battery bank
    So, roughly you are still looking at a 285 watt panel for running your business 9 months of the year in sunny weather (could be more, if you are in north east, or affected by marine layer, etc. local weather conditions).

    Of course, all this is based on a pure SWAG on my part of how much energy you want to use/generate. You could easily use 1/2 or use 2x as much--depending on your choices and how you run the equipment.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jrs1418jrs1418 Registered Users Posts: 5
    Re: Newb help - Power inventory

    WOW! ok.. sooo It sounds like i'm out of my league here with this thing.

    I looked into the Honda generators.. which were my first choice until I thought I could try solar. Home Depot sells a mobile solar system 1800watts for $1499 + battery. So i figured for a few hundred more than the honda generator I can get a solar which will save me the $4+ per gallon of gas.

    http://www.homedepot.com/Electrical-Alternative-Energy-Solutions-Solar-Power-Solar-Panels-Kits/h_d1/N-5yc1vZbm1w/R-202548447/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

    What do you guys think of that system??

    The 2 shop vacs will be on about 5 mins max at a time and hopefully on and off lots of times during the day. I would guess they would be on 5 mins for every 15-20 they're off and thats if i'm slammed back to back cars open to close which is unlikely.

    I also didnt mention earlier but I'm in Hawaii, and for the most part a good amount of sunlight is available throughout the day.
  • russruss Solar Expert Posts: 593 ✭✭
    Re: Newb help - Power inventory

    One 140 watt no name panel and nothing UL listed - claims 'plug and play' which is not legal to do.

    A very expensive piece of junk!

    Any time they give so few details as the sites selling this thing do it is bad news - means they are hiding things.

    US 13.60$ per watt - they should wear a mask when selling the thing for that.

    Russ
  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Newb help - Power inventory

    It is probably not junk... It looks like the Xantrex 1800 Powerhub.

    The problem is that it is really just a larger version of UPS with a 200 or 400 AH 12 volt battery box (one or two external battery boxes, I think).

    The "problem" with most systems of this type is they have a rather large inverter and a small battery bank. For example, if we assume it came with a 200 AH battery, use to 20% state of charge (typical for UPS application):
    • 200 AH * 12 volts * 0.80 battery discharge * 0.85 inverter eff / 1,800 watts of inverter output = 0.9 hours of operation at 1,800 watts of power
    And a 140 watt panel, running 5 hours of sun per day would take
    • 200 AH * 12 volts * 0.80 * 1/0.77 typical charging eff * 1/140 watts panel * 1/5 hours of sun per day = 3.5 days to recharge with just solar panel
    It gets a bit more complicated--but the above math shows you some of the assumptions.

    You can work up a more accurate profile for the vacuum usage than my first guess--5 minutes per car * XX cars per day, etc... And then we can go through the math again.

    In general, the pre-packaged systems do address some issues with designing and building your own off grid system--But it is tough to hit the needs for every customer.

    We try to get people to define their needs first (average WH per day, peak Watt load, location for hours of sun, assumptions on weather--in your case, a car wash typically closes in bad weather, etc.).

    Then we start sizing the hardware and picking some possible components.

    It is possible that the Xantrex PowerHub may be useful--but with more solar panels. Or it may not be cost effective--All depends on your needs.

    For example, it is very possible that a Honda eu2000i running one vacuum and your register/electronics could operate on ~1.5 gallons of fuel per 8 hour day.

    And, with proper maintenance, you may get 2,000-6,000+ hours of service before needing to replace the genset.

    Certainly a practical short term solution until you get a better handle on your business and decide in 3-12 months on your next power system (battery, recharge at night at the shop, solar array in lot/on trailer--if possible--etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 5,022 ✭✭✭✭
    Re: Newb help - Power inventory

    I have a shop vac mini, and even it runs several hundred watts running, claimed 1hp motor as I recall, and though I use it around the house and even some around my outdoor 'shop' I'm not sure I'd try to tackle my Toyota Echo which I use more like a pickup, if I ever get down to the floor...lol.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Newb help - Power inventory
    jrs1418 wrote: »

    The 2 shop vacs will be on about 5 mins max at a time and hopefully on and off lots of times during the day. I would guess they would be on 5 mins for every 15-20 they're off and thats if i'm slammed back to back cars open to close which is unlikely.

    I also didnt mention earlier but I'm in Hawaii, and for the most part a good amount of sunlight is available throughout the day.

    I think you should do like Cariboocoot suggested and buy a Kill-A-Watt meter. They sell them at Home Depot for about $35.

    Plug everything into a power strip and plug the power strip into the Kill-A-Watt . Let it run for an hour and do a couple simulated cash register/ CC sales. Do NOT run the vacuums. After an hour read off how many KWH you've used and multiply this by how long you plan on being open each day.
    This is your base load KWH.
    Next reset the display on the Kill-A-Watt (you can just unplug it) and then clean a car. Read off the KWH, this is how much you use to clean a car. Multiply this by the maximum number of cars you ever expect to clean in one day.
    Add the base load to the cleaning KWH and that is how many KWH you'll need for one day.
    To maximize battery life you don't want to drain them more than 50%, so pick a set of batteries that will give you at least twice as many KWH as you came up with above.

    Assuming you want to run off solar power as much as possible, divide the KWH you need for a day by 4 and that is approx how many watts of solar panels you'll need. On cloudy days you'll end up running almost entirely on batteries, but you can recharge them at home if you need to.
    You could actually get by with about 1/2 as many solar panels, but then you'll probably end up having to recharge a bit at home every day.

    Since you'll have enough batteries to run on even with out solar, you could start with just the batteries and inverter and then add the panels as business picks up.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Newb help - Power inventory

    Oh yeah, another possible solution.

    Size a smaller solar array just to run the laptop, cash register, etc.

    Use the Honda generator just for the vacuums. That way the generator only has to run while the vacuums are on and the rest of the time you don't use any gas or have to listen to the noise (albeit not much noise)
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Newb help - Power inventory

    Peter took the idea right out of my head. That is what I would do - solar for the small stuff and use the genset sparingly for the big stuff. If you used a gallon of gas a week I would be surprised. If you will be operating during dark evening hours or if it gets especially dark under the tent during cloudy/rainy days you should include a few CFLs in your solar system power estimate (maybe you did and I missed it).

    Going down this path, you might consider oversizing the battery bank slightly and get a 2 kw inverter, even though you'll use the solar system for the low-powered stuff most of the time. Oh, and keep the smaller PV array that is sized just for the low-powered stuff. My reasoning is if your generator goes down when you have several customers lined up you'll have the capacity to do a few vacuum sessions from the solar system while someone else runs out for gas or parts or a rental genset to get you back to full capacity. If this ever happens you'll have to use the genset to charge the battery bank some but that isn't a big deal. Also if you ever have a long power outage or the business doesn't work out you'll have everything you need for a good emergency backup system for your home.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • jrs1418jrs1418 Registered Users Posts: 5
    Re: Newb help - Power inventory

    I like this idea. Except I dont know if turning the generator on and off multiple times a day will create a lot of wear and tear on it versus just leaving it on.

    for the idea of having just a battery bank and inverter(charging at home), then adding solar panels later as business increases:
    What kind of batteries are best for this type of usage? How many batteries do you estimate? I wont be open during dark hours so no need for lighting, Just laptop, register, credit card machine, cell phone. also do you think i'd be able to run the 2 shop vacs on this setup?

    thanks for all the help guys!

    Peter_V wrote: »
    Oh yeah, another possible solution.

    Size a smaller solar array just to run the laptop, cash register, etc.

    Use the Honda generator just for the vacuums. That way the generator only has to run while the vacuums are on and the rest of the time you don't use any gas or have to listen to the noise (albeit not much noise)
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Newb help - Power inventory

    The only extra wear would be on the rope-pull assembly, once the generator starts up the first time and warms up the additional starts through the day will have minimal internal wear. The biggest wear on engine parts is when you first start an engine cold and little oil is left on the moving parts after sitting all night. The oil will be warm and coating everything after you get that first start.

    If you can transport the battery bank every day you certainly could size it and the inverter(s) to run everything. But you'll probably need 6-8 100 amp batteries to handle that load. You will need deep cycle batteries, I would recommend cheap ones to start with until you are comfortable with your system performance. When I priced around 2 years ago Wal-Mart's deep cycle batts were the cheapest but I'm sure nothing is cheap out there in the Pacific. If you need to run the small stuff and 2 vacs I would recommend getting 3 inverters. One small one for the electronics, maybe a hundred watts depending on your actual measured load. Then two 2 kw models for the vacs. This will keep the power sag/surge the vacs will create when they are turned on away from your electronics since they are on a separate inverter, and you can keep wiring sizes to reasonable levels for the 2 big inverters. If you tried to get one 4500 watt inverter for everthing you would need massive wires (and many here wouldn't recommend it even though there are inverters available in that size). Another advantage, with two 2 kw inverters if one of them fries you'll still have the other one to keep up with your workload. You could even buy two completely different brands - different designs, different failure points, less chance they would both fry within a few days of each other if there was a design flaw. In order to size this system properly you'll need to run a test with your Kill-a-Watt by repeatedly turning a vacuum on and off (and letting it run for the length of time you expect to run it each time), for let's say 15 minutes. Then multiply that by the actual time you expect both vacuums to run over a busy day.

    However, I would still go with the other option. If the PV is too expensive to start, take your idea of charging at home and combine it with the "solar for the small stuff" idea, and design a battery-only system to handle your electronics during the day but charge it at home at night (might only be 2 batteries vs. 6-8 ), and use a genset for the vacuums.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Newb help - Power inventory
    jrs1418 wrote: »
    I like this idea. Except I dont know if turning the generator on and off multiple times a day will create a lot of wear and tear on it versus just leaving it on.

    for the idea of having just a battery bank and inverter(charging at home), then adding solar panels later as business increases:
    What kind of batteries are best for this type of usage? How many batteries do you estimate? I wont be open during dark hours so no need for lighting, Just laptop, register, credit card machine, cell phone. also do you think i'd be able to run the 2 shop vacs on this setup?

    thanks for all the help guys!

    The best type of batteries will be deep cycle batteries. Golf Cart or L16 size batteries.

    How many batteries you need will depend on what numbers you come up with from measuring your loads.
    We could guess, but if we guess wrong and you run out of power 2/3 of the way through the day, who are you going to blame?
    The info I provided below on measuring your loads will let you get a better estimate of how many batteries you need.
  • jrs1418jrs1418 Registered Users Posts: 5
    Re: Newb help - Power inventory

    Thanks a lot guys! You've definately given me the best and most knowledgable advice i've gotten in quite a while! I'm going to do what you guys suggested with the battery bank charged at home, then add solar as business picks up. I'll report back after I do the Kill-A-Watt thing!
  • jrs1418jrs1418 Registered Users Posts: 5
    Re: Newb help - Power inventory

    Ok, just to make sure i'm on the right track.

    I bought the KillAWatt.. $28.xx @ home depot

    Plugged BOTH my shop vacs in, turned them on and got .35 KWH for 15 minutes of straight use. Multiply x4 per hour, X10 hour days and I get 14 KWH's if I ran those 2 shop vacs full time day to night. Is that correct?

    i figured i'd get the KWHs for them being on full time in hopes i'll be that busy one day and wont be worried about running out of power.
  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Newb help - Power inventory

    That is how it works... You should also note the VA/kVA (volt*amps). Depending on the type of motor, they will require heavier wiring and inverters than that watt reading alone would suggest (power factor is one term from AC power).

    That is quite a bit of power... Approaching 2.5-3.5 kWatts of solar panels (several hundred square feet) for a grid tied system--An off grid/battery system would be much larger.

    For off-grid solar power, you are better off supporting average loads with solar array and extraordinary power with genset or Grid Power (have you talked with the parking lot owner about installing AC power?).

    Starting a business and planting money in solar array+batteries seems to be stretching things financially.

    And running an "obvious" genset might also get you complaints if you are in an area with power available (noise, smoke, smell, etc.). As well as a visit from the fire inspector about fuel storage, and the local hazardous chemical inspector looking for double wall tanks, etc....

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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