Solar UV water disinfection

SystemSystem Posts: 2,511 admin
Hello,       I am researching solar powered UV water treatment and have been looking at the iota 12 volt ballast.
Can anyone offer help in matching the proper ballast to lamp. I do safe drinking water development as a volunteer.
Being a good fabricator but a poor electrician I need some advice.

1.1 billion people in the world do not have access to safe drinking water

thanks

Rusty

Comments

  • mike95490mike95490 Solar Expert Posts: 9,014 ✭✭✭✭✭
    Re: Solar UV water disinfection
    rusty wrote:
    Hello, I am researching solar powered UV water treatment and have been looking at the iota 12 volt ballast.

    Do you have a link to their site ?

    What's needed is how much power the unit draws, and the duty time. Then we can figure out how much power (in watt hours) is needed, and can caculate panel size and battery bank size

    Mike
    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: Solar UV water disinfection

    Mike,

    Here is a link to the site with the Ballast. They don't have much info online. The initial challenge is determining what lamp would go with what ballast. I think I have a supplier for UV lamps. Just found these ballasts today. I know so little about electrical components I don't really know where to start asking questions. It is my understanding that all fluorescent bulbs are AC. These ballast converts the 12 volt DC to AC I think. Hope this helps.

    Rusty

    http://store.solar-electric.com/12vodcbaforf.html

  • mike95490mike95490 Solar Expert Posts: 9,014 ✭✭✭✭✭
    Re: Solar UV water disinfection

    The units I've seen, for water treatment, are sealed packages, with the quartz UV tube inside the water jacket. I don't know if I like the idea of cobbleing something together out of parts, without having it somewhat enginered, to have acceptable illumination per flow rate. ( http://www.nemw.org/Balsurv2_UV.htm has a fair description of the flow rate vs length of exposure, for huge systems, without the hyperbole of comercial sites ) The ballast has to be matched to the tube, and both contribute to the overall power usage. So are you looking at a 10W tube, or a 100W tube?
    Frankly, the idea of mateing High Voltage and Water scares me a bit.
    Ballasts are usually pretty efficient, so say you are using a 40W tube, I would guess the ballast would consume about 50, maybe up to, but no more than 60 watts. Then what is the run time, 24/7 ? 6 hours a day ? Will you be batch filling a tank at noon, or trickle useage all day long ??
    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: Solar UV water disinfection

    You are right about having acceptable illumination for the flow. Possibly using a 10 watt tube for a prototype. Housings would be easy for me to fab. with a lamp inside a quartz sleeve closed on one end. A system that would produce 2-5 gallons per minute would be a good start. I am not sure if a 10 watt tube could handle this amount of flow. 100 watts would take care of more flow but may require a lot of energy. Trickle usage would be good batch filling could be a good way to go also. In the villages where they have wells they are used all day long. Many times the well water is contaminated. UV on river water without prefiltering river is not always 100% effective because of the turbidity of the water. The particles shadow the bacteria. In appropiate technology you have to adapt to the conditions that are in each area.
    For arguments sake lets say we would require 60 watts and run 6 hours a day. What would you estimate would be needed as far as panels and batteries.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar UV water disinfection

    you can use the 10w uv light if the source pipe is divided into many pipes that would encircle the area of the uv light. the multiple paths would slow down the flow of the water and expose more area to the uv rays longer.
  • mike95490mike95490 Solar Expert Posts: 9,014 ✭✭✭✭✭
    Re: Solar UV water disinfection

    60W @ 6 hrs = 360 watt hours. That's not too much. How many cloudy days do you expect to need to run through, 2, 3, 4 ?? It's gotta rain sometime. Also, in desert areas, washing the layer of dust off the panels may be usefull, say every other month ?

    Say a Diehard Deep cycle battery is rated for 100A, and you need 3 days shaded run time.
    360 WH x 3 days = 1080 Wh needed from a battery. Call it a 12.5V battery. that is 86 A hours, more than a single 100A battery can supply, without going below it's 50% discharge. (50% discharge is the magic number where battery life starts to drop quickly) So 2 batteries (each 100A rated) should easily run this for 3 days.
    Now, to get that much power back into the cells, flooded cells need 120% recharge to replace what you took out, and you still have to run the UV while recharging the battery, you need to get about 1800 watt hours in say - 2 days of sun, following 3 cloudy days. That would be 900Wh per day, and to really fine tune this, you would need to factor in exact location - and consult solar charts. I'd guess of 6 hours of daylight, 4 of them would be really useable for charging - so 900WH / 4 = 225W of solar panels. On those long summer sunny days, you will have LOTS of leftover power, and I'd set the panel tilt for most efficient winter sun angle, and waste some in the summer. I'm thinking of putting them on a tall pole, avoid some vandalism. Will there be a shed the water treatment will be located in, or is it all out in the open?
    So my guess is a couple panels, a couple batteries, and a charge/load controller should do it, run for 3 cloudy days, and recharge in 2 sunny days.
    Your mileage will vary, and I'm just pulling a lot of this out of the wild blue, as a first guess.

    Mike
    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 ,

  • mike95490mike95490 Solar Expert Posts: 9,014 ✭✭✭✭✭
    Re: Solar UV water disinfection
    you can use the 10w uv light if the source pipe is divided into many pipes that would encircle the area of the uv light. the multiple paths would slow down the flow of the water and expose more area to the uv rays longer.

    This has to be all quartz, to pass the UV, and somehow shielded to not sunburn eyes & skin. There is no fancy glass that will pass UV - only quartz will do it, and it must be kept spotlessly clean
    Home systems run in the $700 range, with enginered flow rates and easy to change bulbs.
    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: 31,048 admin
    Re: Solar UV water disinfection

    Using UV to sterilize water is a pretty complex issue... From suspended solids, to type of contamination, water chemistry, keeping the quartz envelope clean, temperatures, water flow, reflective surfaces, detecting weak/failed lamps, etc...

    I maintain a couple 40 watt UV lamps in my father-in-laws 2,000 gallon fish pond. They only last about 1 year of on time--and seem to fail much quicker if you cycle them on and off several times a day--and you cannot really tell if one has failed just by looking at the "color" of the end of the UV tube (it may still look like it is generating UV--there is an arc in the tube--but it is not enough kill the algae and other pathogens.

    And, I would want to fully characterize the ballast over voltage/temperature to ensure that the bulb was being correctly driven across the battery voltage...

    Remember that a 12 vdc battery system may output from 10 vdc (pretty much dead) to over 15 volts (cold during battery equalization). That is actually quite a wide range to design electronic equipment to operate over--not all "12 vdc" devices will properly manage that range.

    My suggestion would be to use a good true sine wave inverter that provides stable 120 VAC 60 Hz (or what ever is best for the area of the world this system will be used) to power the lamps, electronics, pumps, etc.

    If you can find a "home system" for $700 and setup solar panels/inverter/batteries to run it--you would probably be ahead of the game (unless you are trying to start your own company).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar UV water disinfection

    Yes those are all good points to consider. There are answers just have to work on them. In the mean time I have plenty to do.
    I did talk to a co. last week who is in the process of developing a solar ballast and is in the UV business.
    It can't be that difficult.
    The Stainless Steel housing is as important as anything. I already know how to make those so I am half way there.
    I will check out the inverters>
  • mike95490mike95490 Solar Expert Posts: 9,014 ✭✭✭✭✭
    Re: Solar UV water disinfection
    rusty wrote:
    the Stainless Steel housing is as important as anything. I already know how to make those so I am half way there.
    I will check out the inverters>

    If you are investing capitol, you may want to have designed, a ballast that WILL work 12 - 15 VDC, and stay high efficiency thru the range. Why pay 2 conversion penalties - 12VDC - 120VAC & 120VAC to ballast.

    Till you have calculated, and then proven via testing, and submitted samples to the testing lab (much like getting a UL label) for destructive testing, it won't likely be certified, and you would have no market. You may find it better to incorporate certified UV components, a pole mount solar rack & panels, and halfway up the pole, a cast battery box with charge controller, timer & AGM batteries. Another cast box near the base with the UV gear in it, and you have a package to drop at a village, that requires only monthly pre-filter changes, and annual UV tube replacement. Auger a hole in the ground, plant the pole, fill with cement, half day install. Add a 3rd solar panel and you could turn it into a street light too.
    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: 31,048 admin
    Re: Solar UV water disinfection

    A typical ballast needs to run around 120 vac already--there should only be one conversion required in either case (the 120 vac ballast would not need another up conversion).

    One would need to characterize a 12 vdc "ballast" to understand if it is more or less efficient than a regular inverter.

    Also, depending on location of water and light--it would be easier, cheaper, and may be less prone to theft of copper if the "power system" needs to be mounted in a different location than the filter/pump system. Also, if one can source parts/repair items from the local supply chain (like 220 vac 50 Hz pumps/ballasts/etc.) there likely stands a better chance of the equipment being maintained for the longer term.

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