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Anyone using alternative energy in their home

Catwell
I remember, when I was younger, a friend of mine had a solar panel on his roof. I always thought it came in handy, provided a lot of power, saved the day in power outages, but I was wrong. My friend told me, it only gave the house a few minutes of power for only a few small devices during blackouts. That was 20 years ago, is in home generation worth it today?
 
Solar panels are more efficient today, batteries are more dense, turbines, geothermal solutions, and more, all exist for our homes. I've read of attempts to make several homes completely green, it seemed like a good effort. After they sink hundreds of thousands of dollars into making the experimental house greener, does it pay for itself, ever? My electric bill is about 80 dollars a month.  In comparison, the $100,000 spent to make a house use less electricity is equivalent to 104 years of my $80 a month. And I would have to pay all that up front.
 
But perhaps it's more about making a statement. Like voting for a third party in the USA, or diving a an expensive hybrid. It's saying, we want less dependence, we want to give back. Maybe someday less expensive solar panels will adorn all of our roofs.
 
 
 
For those who actually use alternative energy solutions, is there a lot of maintenance associated with the equipment?

Cabe
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    Hi Cabe,

     

    I managed to build a solar panel a while ago. It is not a thing I would recommend to others (the PV cell are too fragile). Anyway, the solar panel produces 250Wpeak, but the power varies mostly between 30W and 160W. The variation in output power is to unreliable to use such a device as a power source. Storing the energy in a battery pack is an alternative but it is costly and the whole conversion step from PV-power to storing energy and converting stored energy to 120VAC/230VAC is not really efficient.

     

    The best way to use solar energy is to have a grid tied inverter with converts the solar power in 1 converter to AC voltage (two conversion steps: step up to DC-Bus voltage and DC/AC conversion). You use the grid as a virtual storage device. This only works well if 'delivered' power is as expensive as 'drawn' power. In my country this is not the case, therefore it doesn't work :-)

     

    Up till now it was common to put multiple solar panels in series to have a high DC-voltage (low current). High DC-voltage is than converted in AC-voltage. In principle this is very efficient but there is a major drawback. As the PV cells act as a current source, if 1 cell is blocked by shade the whole system is down. This is very sensitive and therefore the new approach is having multiple smaller converters in your solar system.

     

    The discussion on the feasibility of alternative energy is really complex. It is not only related to technical ascepts but merely political. I live in the Netherlands where solar power is not widely spread. I see it often on remote places where something is monitored (traffics jams and stuff) and information is wireless returned to a central place. But in Germany, our neighbouring country, they have a political system in place that you receive a high return on generated alternative energy and you see lot's of solar panels over there. Here you see the difference in political climate.

     

    I think that the major benefit of having an alternative energy system in your house is that you have to think very carefully on what you spent your energy on. This is of course very bad for the economy because we have to have lot's of energy consuming stuff in our homes. :-)

     

    Best regards, Enrico Migchels

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    I agree with Enrico,

     

    Building your own PV cells is a major pain, they are EXTREMELY fragile, look at them the wrong way and they break.

     

    I think that a good experiment would be to see just how much power we can get from a PV cell by implementing an MPPT algorithm and solar tracking versus a stationary cell. My gut tells me that implementing those systems would improve the overall efficiency of the array(Obviously the MPPT hardware as well as the tracking setup consume energy however I don't think a carefully designed system would produce let power then a stand alone cell so at least some improvement would be observed).

     

    I've been wanting to perform such an experiment, but at the moment I don't have the means. The issue I see with the MPPT is that you control the input of a converter block to present an ideal load to the cell, the control loop will do whatever it takes to keep the solar cell producing peak output power therefore at the output we will have widely varying voltage(current) which wouldn't be easily usable. My solution to this would be to interface the output of the MPPT to a buck-boost topology converter(ZETA, SEPIC, Cuk, Buck-Boost, etc.) which would deal with the varying output of the MPPT.

     

    With a stable DC voltage an additional inverter would allow for the AC conversion. Obviously there are three stages here so the overall system efficiency would probably be in the 70-85% range(I don't know where I'm getting the numbers from my gut I guess)

     

    It's just an idea, and there are people much smarter than myself on this forum so I'm sure there will be lots of better suggestions.

     

    My 2 cents,

     

    Jorge Garcia

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    You don't need to spend $100k to go greener.  Have a think about how long you'll be staying in one place.  If you are a student and moving every year then you'd probably want no more than goes in the back of a car, which would be one or two large solar panels and a grid tie inverter.  That won't make you 100% green but in a houseshare, running the fridge during daylight hours might count for 1/6 of the household bills.  Meter it to be fair.  Total cost of this starter kit: less than $1000.  In a later year it is possible to replicate this kit or get a proffessional installation, but to make a statement, all you need is $1k.