How are you using DC power that you've harvested?

Discussion in 'Off Grid' started by timber, May 27, 2012.

  1. timber

    timber WindyNation Engineer

    I think we all tend to concentrate on how to get the most out of our wind and/ or solar systems but I see much less discussion about how to best use that harvested energy.
    This would apply to grid-tie as well as off grid of course, however, with off grid systems there may be some additional things to consider. For example, do you use 12, 24 or 48V directly for lighting, fans plug-ins etc. or do you rely on inverted 120VAC to easier distribute power to load?
    I know some of you use both direct or inverted power, perhaps using an isolated DC circuit for outdoor lighting or using contained units like attic fans or single outdoor lights etc and using inverted power to supplement an on-grid system via separate circuit.

    What I'm most interested in here are DC circuits, DC lighting and fans or other means of using DC power directly or via DC power tracks (think track lighting, cable lighting etc).

    I appreciate any ideas or how you use DC power.
    I would like to work on saving energy as I work to improve harvesting it.

  2. Minnesota

    Minnesota WindyNation Engineer

    Here's a clip I did just yesterday showing how I run our refridgerator off the DC collected and then use the excess to null-out our utility usage. It's a hybrid setup. I'm working on a means to make it work automatically.
    ecar likes this.
  3. timber

    timber WindyNation Engineer

    Nice setup Minnesota!
    I really like that you have the means to charge the battery bank or go to grid per individual panel, that gives you a lot of flexibility. (And makes for a great test bed).
    Keep us posted on your progress of automating the switching process.

    Having the refrigerator backed up via battery bank is reassuring, should the grid ever go down for more than an hour or so; not to mention being able to virtually run from the sun a good part of the time.
    I have two off-grid circuits wired in here, One goes to where I use my laptop as well as to an auxiliary receptacle behind the refrigerator to act as backup for power outages.
    The other circuit goes to my office where my modem and wireless router are located as well as to the bedroom for lighting or laptop.
    I'm guessing your inverter is a pure sine, mine is not (but really should be) although I've never had a problem using it with this refrigerator.

    I'm weighing out the usefulness of adding a DC circuit for some sort for interior lighting. I like the overhead cable lighting with halogen or LED spot lights although I'm not sure my wife will readily agree. I like the ability to place lights wherever along the cables and add, subtract and direct as needed. Plus I just like the high-tension look
    One option I am considering is powering the cables directly from the DC panel instead of the norm (using a transformer powered from grid).
    I doubt the lights will care that the DC varies somewhat between ~12V to ~14V.
    Minnesota likes this.
  4. Minnesota

    Minnesota WindyNation Engineer

    Yes, my setup is to get real hands on experience and do a lot of testing so I can talk intelligently in this subject area. Since running the refridgerator with batteries for the last 3 months, you get to appreciate how much power they take and how much solar watts and battery capacity you need to keep just this one "steady" appliance running for a day (or two). In the morning the batteries tend to be down to 50%, but having the tracker it starts recharging right at dawn, where my fixed panels don't see light until many hours later when the sun is in the southern sky. That's is a key benefit of a tracker for me - early morning power.
  5. I just use it all what comes from my system , sure use DC direct would be more efficient for lights , perhaps fridge , but AC products are more easy to find ....
  6. timber

    timber WindyNation Engineer

    True Billi,
    AC devices are easier to find and much less expensive in general.
    After pricing several DC lighting systems I soon began to look at various alternatives.
    Fortunately, MR-16 bulbs and sockets are fairly reasonable, where complete systems using track or cables etc are quite pricy.
    I'm doing some renovation so plan on incorporating DC lighting into certain areas such as walk-in closet which happens to be near my DC panel.
  7. This is a good topic Timber. Using DC energy without any further processing seems like it should a cheaper and efficient way to go. I started out that way too. Once you get to the next level with more wattage from wind or solar, then you will find the dc powered stuff really isn’t as cost efficient or worth the hassle as the already mass produced ac powered appliances. While you might think a pure sine wave inverter is way too expensive, when I first started with wind and solar, the cool thing I purchased was a 12 volt 15 pound square wave inverter by Tripp Lite. It was probably only 50 percent efficient if that. I wired the house for 12 volt lighting, those fixtures sure were expensive. Noisy too. They’ve been recycled into something better.
    If you check prices for dc powered appliances, motors….you would be cheaper off going to inverter powered stuff. More fun too. My wife is fully supportive of my goal to stick it to the power company and a few others. She brought home a bread maker from Goodwill. It is rated at 550 watts, has a motor to knead the dough. Don’t know how it would work with a modified sine wave inverter. One 2 pound loaf takes .28 kwh to make. Yeah, had a few sunspots on the crust, and it tasted funny too, it didn’t have that fillers and byproducts taste I’m used to.
    I wonder if this somehow helps offset the costs of investing in wind and solar.
    Anyway, IMO DC is good only to charge batteries, and run electric heating elements.
  8. timber

    timber WindyNation Engineer

    I appreciate your input Ecar, what you say makes a lot of sense. Perhaps I should concentrate more on energy efficient 120VAC lighting including more florescent lighting, led bulbs etc. instead of using DC directly. The savings can be put into more power generation. I'm learning the mindset of being a watt-watcher, unplugging unused wall warts, using more florescent type light bulbs and, of course, shutting off lights where not needed. I heat primarily with wood heat and have ducting with in-line fans to distribute the heat throughout the house although I do use an oil filled radiator to keep the bedroom a consistent temperature during winter months.
    Lots of home improvement projects going on currently, once I get these completed it will free up funds to get some solar panels and perhaps another turbine in the air.
  9. If you really need a good lesson on energy conservation and knowing what’s going on around you, drive a battery powered vehicle. I built several back in the 80’s when gas was dirt cheap. I no longer have them, but I still drive the 2.2 ecotech like I have only a half a gallon of gas in the tank.
    Home improvements will give you an awesome payback. You will get along with a smaller wind and solar system then. My current house was built in 1930. It is very efficient to heat and cool now. Remember, electricity is considered a premium energy . Oil filled electric radiators are……! If your cold, then you need to get one of these corn feed Midwestern women.
    Maybe a bit off topic, the project I have going on now is using my surplus solar energy, to run a pure sine wave inverter powering a cheap fan , on a even cheaper AC powered timer, to warm up and store the summer heat in my basement using Thermal Mass.
  10. timber

    timber WindyNation Engineer

    The only battery powered vehicle that I've built was an electric bike back in 2007. It was a fun project and I learned a lot in doing it.
    If I had it to do over I'd do a few things different but that's all part of the learning process.
  11. I have been running two kitchen lights, two living room lights , and one plug through a 400 watt inverter hooked to generator transfer switch. Would like to run more but need a pure sine wave inverter cause tvs, fans and other appliances don't like my inverter.
  12. Just found this forum. Was looking for pure sine wave inverter to use in Ford conversion van - and like places that don't blindly adhere to strictly "status quo"!

    In ref to thread topic (and quote above) have been experimenting for some time now with using solar DC (have a 3.6kw / 48volt off-grid Outback system) to STORE EXCESS ENERGY AS HYDROGEN. Has anyone messed with this at all?

    Currently have 4 stainless-steel plated, series connected dry cell hydrogen generators that produce what is more commonly known as 'browns gas' which is a broken down mix of two parts H / one part O ('water' of course).

    The chief problem is attaining complete SEPARATION of these two basic elements which is the only safe way to STORE them for later use. I currently use the hydrogen/oxygen mix to supplement my carberated CNG powered 7kw house Generac because work won't let me hook them up to my diesel truck's C13 CAT engine.

    Am unsure what effect aspirated hydrogen would have on the CAT's Jacobs Brake system.
    Last edited: Feb 5, 2017

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