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Published on January 21st, 2013 | by Nicholas Brown

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Solar-Powered Bulbs Illuminate Off-Grid Homes



Photo Credit: Discovery

More than 1.4 billion people in the world don’t have access to electricity, and therefore, lighting is a bit of a problem for these people, most of whom live in Africa and India.

How do they study in the evenings after school, and how do evening schools operate at night in geographic locations stricken with this problem?

Wireless Solar Power

I said “wireless” because solar-powered light bulbs are usually wireless, so that they don’t have to be tethered to a costly power transmission line (transmission line infrastructure can cost up to $80,000 per mile to construct).

Everything is integrated into one unit in the case of the solar-powered light bulb that Evan Mills, a researcher at the Lawrence Berkeley National Laboratory (LBNL) envisions could be a “boon for literacy,” improve women’s safety, and improve the productivity of businesses that are using ineffective flame-based lamps.

Integrated into these light bulbs is a small solar panel, an LED (since these are efficient), and rechargeable batteries. Typically, the solar panel would recharge the batteries, and the batteries would power the light bulb at night.

My Experience with Solar-Powered Lights

After Hurricane Sandy knocked out my power supply, I used a 10-watt solar panel to charge an old discarded battery which I used to dimly light two rooms until the power was switched back on. I used it to power one 4-watt, 450-lumen Bridgelux LED module, which was more than bright enough to use as a desk lamp to illuminate my work. (450 lumens is the brightness of a typical 40-watt incandescent light bulb.) It was a very simple setup, and it worked very well.

Source: Discovery

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is: Kompulsa.com.



  • Bob_Wallace

    I think the best idea is what is being installed in thousands (millions) of homes in Bangladesh, India and other countries in SEA and Africa.

    Small solar systems – a panel, controller, battery and some LEDs. Enough to give a good light source and charge a cell phone.

    http://cleantechnica.com/2011/12/30/cheap-solar-home-systems-bringing-light-new-opportunities-to-millions-in-rural-bangladesh/

    Dedicated solar lamps are less flexible. Once the lamp battery is charged the panel output is wasted. Better to feed it in to a central larger battery where it can be used for multiple purposes.

    For on grid people who need something for when the grid goes down what might be most useful is a solar panel attached to a battery/cell phone charger. Then one could charge AAs, AAAs whatever is needed for lights and radio.

  • Danny

    I just don’t under stands that too, why connect to the grid
    with solar power; it doesn’t support self efficiency or independents. There are
    a lot of people out there that are only connecting to the grid in order to make
    money when the can afford to be independent, and not sending the nation bankrupt.

  • Mark

    Sound like a good idea, get off the grid and move to a stand alone solar power system. I agree that the cost to the national grid is to high, more people should be independent and not be connecting to the grid with solar power, as it only add more cost to the network.

    • Bob_Wallace

      I’ve been off the grid for over 20 years.

      My advice – if you can hook to the grid, hook to it. Put some panels on your roof so that you make as much electricity as you use in a year.

      Work out a plan so that if the grid goes down for several days you can still run your basic needs from your panels.

      A single 12 volt deep cycle (marine) battery that you normally leave on a trickle charger would be enough to run lights and radio at night. Battery powered “boom boxes” use very little electricity. Make sure your most important lights are LEDs or CFLs.

      Have an inverter that will let you run your refer from panels during the day and the turn it off when the Sun goes down. Throw a couple of blankets over it and don’t open it until your panels are producing. (If you keep the spare space in your freezer filled with plastic bottles full of water you can move a couple into the refer part when you shut down in the evening and refreeze the next day.)

      Let the grid provide your “storage” and “backup generator”. It’s a dirt cheap and butt-simple way to take care of these problems.

      I just brought home 30 gallons of generator gas to (hopefully get through the rest of the winter). I need to change the gen oil tomorrow before the weather turns bad again. And I’m going to have to fork out $2k for a new set of batteries this summer.

      Independence is not always the best way. There’s a lot to be said for sharing.

      Ideally, drive an EV or PHEV that you can use as a “rolling battery bank”. The LEAF, for example can store enough power to run a house for 2-3 days. A Volt or Prius PHEV would also work but won’t hold as much power. You could use them as generators to recharge the batteries if necessary.

      You can recharge from your panels during the day. You could, if necessary, drive to a rapid charge point and get a refill.

      • Rod

        Just reading what you said, I know that living on the grid would be the easy way out far cheapest; however some places around the world now are paying just for electricity alone is $3,000 per quarter or $12,000 dollars a year. Given that amount of money in which the utility company demand each year, it would be better to invest that $12,000 dollars in solar panels and battery and go off the grid. I don’t know what you pay per unit kw/h in the USA, but in Australia the utility bills have been loaded up with ongoing cost of wind/solar power taxes which turn utility bills from around $200-300 on average to $3,000 per quarter and they are continuing to say that $3,000 will rise even more this year by $500. I have taken consideration what you said about cost of replacing batterys, what is the life of the battery I don’t really know.

        • Bob_Wallace

          Yes, if you are paying $1,000 per month then setting up your own solar system could make a lot of sense.

          A stand-alone system made sense for me as the utility company wanted $300,000 to hook me up. (Five zeros is the correct number.)

          I’m using “golf cart” batteries. They are deep cycle, thicker lead plates than starter batteries. Trojan has recently released a “EE” series that is optimized for off-grid use so my next set will be a bit different than standard golf cars. I’ve been getting about seven years service from a set of batteries. Call it $300/year, $25 per month. The EEs should last ten years.

          I have no air conditioning needs so my system probably wouldn’t be adequate for someone living in a hot zone.

          I do well with 1.2kW of panels and 12 6 volt 350 amp-hour batteries. I have to fall back on a generator when the Sun doesn’t shine for a couple of days in a row.

          For a lot of the year 1.2kW is more than I need. On a sunny day (if I’m not recovering from a cloudy one) my batteries are generally full before noon. Three to four hours of potential go unused.

          We’ve got other battery options coming. I recently exchanged some emails with Electrovaya who is marketing a lithium-ion battery system for off grid. Let me share their reply…

          “(F)or a 26V system, and around 3 kWh, we are looking at a price of about $13,000. As for 48V systems and say at 6 kWh, the price would be around $18-19,000. Yes, the price is higher, but occupies much lesser space, has greater energy density and works longer.”

          I’m in no position to evaluate Electrovaya’s product, just offering this as an indication that the market isn’t likely to stay with lead-acid.

          • Rod

            Best to have an inverter that has auto start for loads like the refrigerator to conserve power, these new type flat pack inverter without transformer seen to blow-up under load only good to run lights, I’ve been looking a number of inverter sine-wave, & modified at 24vdc all tend to used above 5 amps per hour on standby 2800watts for the 24 hours. Battery I’ve seen are flooded deep cycle 6v @ 225 amp or 1330 watts cost around $ 250 each , I think it better if I have 24 deep cycle 31kw of battery power cost is around $6000 taking in to account of the inverter standby waste of energy.

            24vdc Solar panels can buy around $1 to $1.50 a watt, so I think that if I get 5kw of solar panels should give me on cloudy days at lest 4 to 8 amps per hour just for light and the refrigerator.

            Solar regulators not sure but still looking at what the best that could handle 5kw, I’ve have seen an simple one that uses a big relay solenoid on eBay which claim that can handle 500amps for around $400.

            There is not much in the way of energy meters for DC monitoring that works with a shut, mainly ac power monitoring is available but only works with sine wave inverter.

            I have seen some solar regulator that have dc monitor watt hour or amp hours which seem ok but doesn’t monitor out put energy like the inverter standby.

          • Bob_Wallace

            My bad. 225 amp-hours not 350. I was thinking about L-16s.

            Sorry.

            Here’s one place that is selling the Trojan T-150 EE for around $150. I found two or three places advertising around this price. I haven’t checked to see what my local dealer is charging. I can get these shipped for about $6.50 each. That’s how I made my $2k estimate.

            I had problems with something (forgot what) not working when I used my inverter on stand-by. I just leave mine on all the time. The draw really isn’t that much.

            I’ve got an earlier model of the XM 4024. This one pulls under 8 watts, about 1/3rd amp in search/standby.

            http://www.wholesalesolar.com/products.folder/inverter-folder/xantrexxw4024.html

            I’m using a Tri-Metric meter. They will work with modified sine wave inverters. That’s what I had in my previous house.

            If you’re going to run any shop tools make sure you get an inverter with a large surge capacity. And make sure you use a larger shunt on your meter.

            I’m using a Trace controller for the panels. I’m not convinced that power point tracking gains that much for the extra money.

            You can split your 5kW system over two or more controllers. I’m going to split my system as one set of panels gets some shade during the shortest daylight days (about four weeks) a year. That will let the full Sun rack keep pumping full power and not get pulled down.

          • Ronald Brak

            Lithium-ion electric car battery packs are apparently down to about $500 a kilowatt-hour, so I don’t think lithium-ion for home energy storage will remain at eight and a half times that price for long. Fingers crossed that your current batteries last long enough for you to pick up some low cost, high quality replacements.

          • Bob_Wallace

            Lead-acids are a bit over $100/kWh.

            Apparently lithium-ions will be down to about $250/kWh next year but that will be for large volume (EV manufacturers). I expect I’ll do one more round of lead-acids and by then I should have a much better option.

            For off-grid use lead-acids aren’t bad. I only have to move a set once ever 7 to 8 years. They’re not that heavy. And I have to check and top up the water every three months.

            When I can buy a set of lithium-ions for around $300 that will feel sweet. With their higher cycle life and ability to be discharged much deeper without damage I can buy a smaller set and use them a lot longer. I expect much better options in 2020.

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