How many KW from solar energy you need to run a 100W light bulb for one year?

Answer 1

It doesn't matter whether it is for a year, for a month, or for a week - 100 Watt is 1/10 of a kilowatt. - In the case of solar energy, you only get the energy during the daytime; also, you have to account for the night-time when the Sun doesn't shine, and for cloudy days. Also, some energy is lost when saving and restoring from a battery. Therefor, while the Sun shines you need several times more energy - perhaps 500 W (1/2 kilowatt) or so, to account for these losses.

It doesn't matter whether it is for a year, for a month, or for a week - 100 Watt is 1/10 of a kilowatt. - In the case of solar energy, you only get the energy during the daytime; also, you have to account for the night-time when the Sun doesn't shine, and for cloudy days. Also, some energy is lost when saving and restoring from a battery. Therefor, while the Sun shines you need several times more energy - perhaps 500 W (1/2 kilowatt) or so, to account for these losses.

It doesn't matter whether it is for a year, for a month, or for a week - 100 Watt is 1/10 of a kilowatt. - In the case of solar energy, you only get the energy during the daytime; also, you have to account for the night-time when the Sun doesn't shine, and for cloudy days. Also, some energy is lost when saving and restoring from a battery. Therefor, while the Sun shines you need several times more energy - perhaps 500 W (1/2 kilowatt) or so, to account for these losses.

It doesn't matter whether it is for a year, for a month, or for a week - 100 Watt is 1/10 of a kilowatt. - In the case of solar energy, you only get the energy during the daytime; also, you have to account for the night-time when the Sun doesn't shine, and for cloudy days. Also, some energy is lost when saving and restoring from a battery. Therefor, while the Sun shines you need several times more energy - perhaps 500 W (1/2 kilowatt) or so, to account for these losses.

Answer 2

If you live in Wisconsin, as I do, you will see 2 hours of full sunlight per day average. (I had trouble believing that also, but that is what the charts say and what my panels average.) San Francisco gets almost twice this number, so the answer is half as many panels, by the way.

Let's also assume you bought 75 watt panels, as I did. The maximum power you can possibly get from a 75 watt panel is 56 watts of instantaneous power. 56 watt/hours of usable power times the number of hours a day gives us about 112 watt/hours of MAXIMUM daily power from each 75 watt panel. (The panels are rated weird so you can never get what is rated. They multiply open circuit voltage with short circuit current to derive power out. The condition is impossible to obtain simultaneously) Your batteries and inverter will take some of your power. My losses run about 10%, because I have a very good inverter and use buss bar rather then cables. Gridable inverters reduce battery need, but also are far less efficient.

The bottom line is about 100 watt/hours per day of usable power from a 75 watt panel. (As stated before some areas can get up to twice this from a panel. Temperature also reduces power so if it is warm, you will not see as much output!) Winters mean more power for me, even though the days are shorter! One day is 24 hours so, you need 24 panels to hold that light in all the time. Two things you learn very quickly with a solar powered home. 1. Go high efficiency everything and 2. Turn off systems you are not using!!!!

Batteries are also a big factor. If you have too small a battery system, your power will be reduced because your voltage drops. (power is voltage times watts, so you want batteries to stay close to full charge, yet have room for any charge you wish to supply them) I have found that 10 days seems to be a good loading. So, in terms of amp hours for your batteries you want to have 100watts*24hours*10days= 24000 watt hours is that answer. If you go any lower then this, you will need a regulator which reduces your efficiency. Larger then this is fine, but gets very expensive. There are switching regulators (such as Morning star) that will switch your load, (rather then just reduce it) to another item, such as a hot water heater.

With careful use, and no air conditioning, we get by on 30 panels and two wind generators (400 watt/hours each). If I had it to do over, I would never have used solar. The panels are four years old and are already not putting out the power they used to. The projected life is supposed to be twenty years. I see them at 90% in ten years. I will never see the power output from these panels to break even. Maintenance is about one hour a week. I have lost three inverters in thunder storms. The system is far from being green, or even environmentally friendly.

On the plus side, they are quiet backup systems if you have power issues. That was the original attempt with my system. I tend to get carries away though once I started something. A 5000 watt/hour fuel cell cleans up any shortfalls I have in power.

Answer 3

117.72 kg coal is required.

if 1 kg coal gives 6400kcal

and 1 cal=4.18joules

then 1 kg coal gives 26.789 M joules

now 3.6 M joule =1 kwh

so 1 kg coal gives 7.44 kwh

now 100 watt bulb consumes 876 kwh in one year.

hence for 876 kwh ,we will require 117.7 kg coal,i.e to light up 100 watt bulb for one year.

08-EE-23

asad_023@Yahoo.com

Answer 4

Fascinating question!

Matter can't be 'destroyed'. I assume you mean 'converted to energy'.

(100 watts) x (365.25 days) x (86,400 seconds per day) = 3.15576 x 109 joules

E = M c2

M = E/c2 = 3.15576 x 109/(299,792,458)2 = 3.5113 x 10-8 kilogram = 0.0000351 gram

Could that possibly be correct ?

I did it again and got the same, so either it's correct or else I botched it twice.

Answer 5

It doesn't matter whether it is for a year, for a month, or for a week - 100 Watt is 1/10 of a kilowatt. - In the case of solar energy, you only get the energy during the daytime; also, you have to account for the night-time when the Sun doesn't shine, and for cloudy days. Also, some energy is lost when saving and restoring from a battery. Therefor, while the Sun shines you need several times more energy - perhaps 500 W (1/2 kilowatt) or so, to account for these losses.

Answer 6

a 100w light bulb uses 867kwh of electricity

in 365 days . if an oil burning generator uses

1 gall of oil to produce 10kwh of electricity

then it would need 86.7gallons