Update a small DIY project for a shed

SystemSystem Posts: 2,511 admin
I have a small back yard shed that I am powering via a DIY solar system. I need some assistance in increasing the solar panels in this system.

I am fairly new at this, having had a 5.3 Kw roof top grid tied system professional installed on my house.

Power usage:
Standard 120 volt
1 65 watt fluorescent yard light that comes on at dusk and off at dawn, every night.
1 27 watt fluorescent compact bulb inside turned on when needed, maybe 2 hours per week in the summer maybe 4 hours per week in the winter.
1 fan (to be determined) to be used as needed, maybe 6 hours per week, aprox 200 watts.

Power storage:
2 Trojan T-105 6 volt wet cell batteries in series for 12 volts nominal.

Inverter:
1000 watt Xantrex Xpower inverter.

Charger:
Blue Sky SB2000E MPPT charge controller.

Current PV panels:
4 Sunforce 50032 15 watt solar battery charger, purchased as part of Sunforce 50044 Solar Charging Kit.

According to the SB2000E controller, the 4 panels are putting out about 2.2 amps peak at the high point of the day. (About 3 PM) Currently, I am having to charge the batteries overnight with a AC powered 3 level (10 am, then 6 amp then 2 amp) charger every 4 days, with the charger showing about 25% remaining capacity on the batteries when I begin to charge it.

It appears I need to add about 200-250 watts of panels to this setup to cover average normal daily usage.

Cost is a factor to be considered.

I would like to verify which one or 2 panels I should purchase as well as what cables/connectors and how to connect to the controller along with the current panels. The connectors on the current panels and included wiring is the rubber plug in where on terminal is male (negative on the cable end going away from the panels) and one is female (positive on the cable end going away from the panels.)

Comments

  • mike95490mike95490 Solar Expert Posts: 8,471 ✭✭✭✭✭
    Re: Update a small DIY project for a shed

    What is less expensive for you, PV panels, or LED lighting ?

    If you can reduce the power used by lighting, that will help.

    Smaller fan will be better too

    Go for a SureSine 300W inverter, it's pure sine will reduce the draw by the fan, and it has low standby losses, and high 92% efficiency.
    http://store.solar-electric.com/mosu300wasiw.html
    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 ,

  • System2System2 Posts: 6,290 admin
    Re: Update a small DIY project for a shed

    Can not change the yard light, as the unit in place is the most energy efficeint for the yard. It is one of those 65 watt usage 500 watt output equivalant pole mount yard lights. Plus, an LED equivilant for the yard would be expensive. Putting money into the panels, the power gets put into the batteries for other uses if desired. Money put into the LED yard light is fixed to that. Yes, I could go with LED for inside, but that will only be used infrequently.

    As for the fan, I do not have one yet, but am going to look for one. This will be used only while I need to be in there for a while, say 15 minutes or longer. If there are any recommendations for a low power usage fan, that would be great. The shed does have passive non-powered ventilation.

    That inverter looks good, although a bit pricy. However, I can use the 1000 watt inverter I already have for my pickup.
  • BB.BB. Super Moderators, Administrators Posts: 29,736 admin
    Re: Update a small DIY project for a shed

    If cost is a factor--and since you already have 5.3kW of roof-top grid tied solar--I would suggest that it will be cheaper for you to rent a trencher and lay down some direct burial cable and even some 2"+ ABS pipe (phone, alarm, network, cable TV, etc.--whatever makes sense to you).

    Solar off-grid usually only makes sense for small loads and places where it just does not make sense to run AC power. Or for emergency power with periods of long outages (such as to supplying a fridge/freezer, and a few lights).

    If you are doing the solar to be green--Your grid tied solar connected to your back shed is probably greener (less resources, batteries, etc.).

    If you are building the system to learn, then costs are not really a key design factor--since off-grid solar is going to cost you ~5x+ per kWhr more than your grid tie system.

    I have done a few sizings in earlier threads in the last couple weeks... So I will avoid the details and just go for the end results. Assuming Long Beach CA, off grid system (0.52 derating factor), and default fixed panel:

    Amount of power per day:

    (65 watts * 12 hr + 27 watt * 0.5 hr + 200w * 1 hr) * 1/85% invert eff = 1,168 W*Hr per day...

    Battery (T105 225 A*H):

    1,168 W*H * 6 = 7,008 W*Hr of battery.
    7,008 W*H / (6v*225AH) = 5.1 -> 6x T105 batteries

    Solar panels (off grid using Long Beach and 0.52 derating) and that you will solar power from February through November (2.667 kWhrs per day for 1kW of solar panels) :

    [1.168 kWhr per day / 2.667 kWHr per day] * 1kW of solar panels = 440 Watts of solar panels...

    Just for solar panels + batteries, this system would cost $2,200 solar panels + $700+ for batteries... Easily over $3,000 for the system (+ charge controller, + mounts, + wiring, +...)...

    I would suggest that you spend less than $1,000 for buried cable and, if you want, look at adding a couple panels to your existing system (if you need it). Or just save the $2,000...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Update a small DIY project for a shed
    BB. wrote: »
    If cost is a factor--and since you already have 5.3kW of roof-top grid tied solar--I would suggest that it will be cheaper for you to rent a trencher and lay down some direct burial cable and even some 2"+ ABS pipe (phone, alarm, network, cable TV, etc.--whatever makes sense to you).

    Solar off-grid usually only makes sense for small loads and places where it just does not make sense to run AC power. Or for emergency power with periods of long outages (such as to supplying a fridge/freezer, and a few lights).

    If you are building the system to learn, then costs are not really a key design factor--since off-grid solar is going to cost you ~5x+ per kWhr more than your grid tie system.

    While cost is a factor, learning is also a factor. This is indeed only a small load. Any power needed for tools and such I will run my 10 GA 100 ft extension cord out there from the house. The problem with tying it to the house is the first 15 ft from the house. In both of the two locations, one is slab and the other already has a myrid of pipes making a major job to try to run a new electrical conduit under all of them.
    BB. wrote: »
    1,168 W*H * 6 = 7,008 W*Hr of battery.
    7,008 W*H / (6v*225AH) = 5.1 -> 6x T105 batteries

    Please explain why 6 batteries. The current 2 hold enough power to run 4 days with the current PV providing only about 25 watts during the peak time of the day. I am investigating purchasing 2 used ones, but they are from a client and have been used maybe 40 hours total.
    BB. wrote: »
    Just for solar panels + batteries, this system would cost $2,200 solar panels + $700+ for batteries... Easily over $3,000 for the system (+ charge controller, + mounts, + wiring, +...)...

    I would suggest that you spend less than $1,000 for buried cable and, if you want, look at adding a couple panels to your existing system (if you need it). Or just save the $2,000...
    -Bill

    Since I already have the controller, 2 batteries and half the cable, it appears my additional cost would be say another $100 for the cables and mounting brakets for the additional panels and then what ever the cost of the panels would be plus the inverter recommended earlier by another poster.
  • mike95490mike95490 Solar Expert Posts: 8,471 ✭✭✭✭✭
    Re: Update a small DIY project for a shed
    jst3751 wrote: »
    Charger:
    Blue Sky SB2000E MPPT charge controller.


    Again, Morningstar has hit the market with a favorably reviewed small system MPPT controller - SunSaver 15 Amp http://store.solar-electric.com/mosumpsochco.html
    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 ,

  • BB.BB. Super Moderators, Administrators Posts: 29,736 admin
    Re: Update a small DIY project for a shed
    jst3751 wrote: »
    While cost is a factor, learning is also a factor. This is indeed only a small load. Any power needed for tools and such I will run my 10 GA 100 ft extension cord out there from the house. The problem with tying it to the house is the first 15 ft from the house. In both of the two locations, one is slab and the other already has a myrid of pipes making a major job to try to run a new electrical conduit under all of them.

    Certainly a consideration--your choice.
    Please explain why 6 batteries. The current 2 hold enough power to run 4 days with the current PV providing only about 25 watts during the peak time of the day. I am investigating purchasing 2 used ones, but they are from a client and have been used maybe 40 hours total.

    Perhaps I did not understand your loads--over half of your load seems to be the 65 watt light fixture running 12 hours per day (just a guess)... The 25 watt panel(s) itself can only run your 65 watt light about 1 hour per night (guessing for Long Beach)... Your batteries, can supply the load for:

    6v * 2 * 225 amp*hours / 65 watts * 1/85% inverter efficiency = 35 hours...

    Or for about 3 nights until the batteries are dead (add another couple hours per day for the solar panels)... The batteries, if you want a long life out of them, should not be operated below 50% capacity--and should be recharged above 75% capacity by the next day--as setting below 75% for days will cause battery sulphates to harden and also lead to early battery failure. For long battery life--you would really prefer that the batteries stay above 75-85% state of charge for daily use and long life...

    So, by the time you added your other loads (27 watt light and 200 watt fan used intermitantly), and 2x the three day load to keep the charge state of charge about 50%--you get "5.1" batteries recommended--but since they are 5 batteries, you would round up to 6.

    However, with plenty of solar power, and monitoring to avoid prolonged deep discharge--you could also use 4x batteries too--the numbers are not exact--just recommended starting points.
    Since I already have the controller, 2 batteries and half the cable, it appears my additional cost would be say another $100 for the cables and mounting brakets for the additional panels and then what ever the cost of the panels would be plus the inverter recommended earlier by another poster.

    Plus the solar panels themselves--The 440 watts at $5.00 per watt is, again, just an approximation... You can use less power/load. Or only plan to draw the larger loads during the summer... (but, of course, a dusk to dawn light will draw more power in the winter--when you have less solar power).

    Again, this is all an approximation. You can use fewer batteries and fewer panels (or find some on sale/used for less price) which will put you closer to the edge (over discharging of your batteries, loss of the security light at night)...

    Or you can look at attaching a motion detector to your security light and have it only turn on for 5-10 minutes when somebody is actually out there. Now you have the advantage of only requiring (guess) 1/10th the amount of solar/battery power, and the added feature of a light turning on when somebody is prowling--generally considered a better security deterrent because the person does not know if somebody turned on the light or while be attracted by the light.

    In the end, defining your loads and seasonal use first--will pretty much give you a firm requirement for the amount of solar power you will need to generate. Also, defining the loads will help you decide if you need backup power too (generator, alternate lighting, low voltage disconnect to protect the battery, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,358 ✭✭✭✭
    Re: Update a small DIY project for a shed
    mike90045 wrote: »
    Nobody seems to be really happy about the BS series (unfortunate acronym , but true) of products. Yeah, they work, but they are not real efficient from what I've heard.
    Again, Morningstar has hit the market with a favorably reviewed small system MPPT controller - SunSaver 15 Amp http://store.solar-electric.com/mosumpsochco.html

    Mike,

    I think you may be confusing BS (BlueSky) with BZ. BlueSky has a pretty good rep. BZ on the other hand has a horrible rep.

    Tony
  • mike95490mike95490 Solar Expert Posts: 8,471 ✭✭✭✭✭
    Re: Update a small DIY project for a shed
    icarus wrote: »
    Mike,

    I think you may be confusing BS (BlueSky) with BZ. BlueSky has a pretty good rep. BZ on the other hand has a horrible rep.

    Tony

    Noted, and I edited my original post, you can leave yours as is, as a brain refresher for me.
    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 ,

  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Update a small DIY project for a shed

    As for the fan, look at a 12v auto fan. If you need to move alot of air, look at a auto radiator fan, a small 10" will draw about 5-8 amps DC. This will let you down size the inverter to just run the outside lamp.
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