Newbie. Humor me please.....

concretefire

Ok, I'm just trying to get my head wrapped around this solar thing. I have a link to an article that states an Energy Star 42" LCD tv consumes (on average) 180.5 Kwh per year. I'm trying to reverse engineer the numbers (ballpark) and come up with a per day estimate of how much power that Tv would "consume." Assuming it was on every day.

I have my own number already figured out, but I'd like to see the real experts reverse engineer that number here. For me to see if I am close in my head.

Second question: Assuming that is the only electrical device I would be using on solar......is solar a viable solution or is it so far out the realm of being realistic that I need to look in another direction to power something like that. This also assumes an off grid situation. Nowhere near any Grid power. I have been reading this forum for about 3 days and some of the math makes sense, but I never was much good at formulas and after 3 days it's all a blur now.

The number I have in my head (my answer) I think it definitely would work but I am concerned (read don't know) what size system I would need to make that a reality. Just understanding that one device would be the proverbial light bulb in my head going on. Thanks. I'll hang up and listen.

icarus

Re: Newbie. Humor me please.....

180/365=.49 kwh/day, or in round numbers, 1/2 a kwh per day.

My rule of thumb for off grid PV is this, take the name plate rating of the PV, divide by 1/2 to account for all cumulative system loses, then multiply tht umber by 4 to account for the average hours of good sun one could reasonably expect, per day, on averge over the course of the year.

So a 50 watt panel would look like this,, 50/2=25*4=100 watt/hours/day.


So in your case you would need somewhere around 200 watts of PV to sustainably power your 500 WH load, eqc day over the year.

That same 500 WH load would translate roughly to 42 ah of battery capacity. (12 vdc) so you would want a battery of ~200 capacity if you are aiming for a daily discharge limit of 25% of capacity. That would give you better than 2 days capacity without drawing the battery below ~50% soc.

A 200 watt PV system MIT cost, complete, ~$5-10/watt or $1-2000.

You could probably build it somewhat cheaper. PV at $2/watt,$ 400, inverter $300,, batteries $300, charge controller $100, misc wiring, fuses, breakers etc $200 just as a rough guess.

Welcome to the forum, and hope this helps,, keep in touch,

Tony

niel

Re: Newbie. Humor me please.....

to be sure of the kwh your tv would need daily would be to get a killawatt meter to actually measure what that tv needs over that time period. what many places list may not be accurate even from tvs that are the same model.

it is possible to do it, but specific needs dictate what may be needed to provide this power for it reliably. address the kwh measurement and we can kick around the ins and outs of solutions with more accuracy.

Cariboocoot

Re: Newbie. Humor me please.....

How much TV do you watch every day? Some people just look at it for a couple of hours of news and maybe a movie now and the. Others turn it on AM and it's going 'til bedtime. Without knowing the time factor the 180 kW hours per year rating is meaningless.

One thing we've all found about the new LCD TV's; adjust the picture settings a bit and you can save a lot of power. I turned mine down to where it was still watchable - and dropped 100 Watts from the factory settings. With 2 hours of news per night that's 200 Watt hours * 365 days = 73 kilowatt hours per year.

jagec

Re: Newbie. Humor me please.....

concretefire wrote: »

Second question: Assuming that is the only electrical device I would be using on solar......is solar a viable solution or is it so far out the realm of being realistic that I need to look in another direction to power something like that. This also assumes an off grid situation. Nowhere near any Grid power. I have been reading this forum for about 3 days and some of the math makes sense, but I never was much good at formulas and after 3 days it's all a blur now.

Solar can be a viable solution for just about ANY situation, if you have enough money!:p

Based on a cnet chart, a lot of recent 32" LED LCDs can get down to the 50-watt range when calibrated. So if you watch 3 hours of TV a day, that's only 150 watt-hours, or 12.5 amp-hours from a 12V system (ignoring inverter losses).

So, is solar a viable solution (given that you're far from the grid)? Absolutely. You could even throw in a few LED or CFL lights and you'd still be well within the capabilities of a small solar system. You could probably get a reasonable system put in place for $1k-ish.

concretefire

Re: Newbie. Humor me please.....

Cariboocoot wrote: »

How much TV do you watch every day? Some people just look at it for a couple of hours of news and maybe a movie now and the. Others turn it on AM and it's going 'til bedtime. Without knowing the time factor the 180 kW hours per year rating is meaningless.

One thing we've all found about the new LCD TV's; adjust the picture settings a bit and you can save a lot of power. I turned mine down to where it was still watchable - and dropped 100 Watts from the factory settings. With 2 hours of news per night that's 200 Watt hours * 365 days = 73 kilowatt hours per year.

Well, I'm not sure I understand how to answer that question because I'm not entirely sure I understand watts vs watt hours. Example : I saw his guy on youtube and he was showing his solar panels bought from HERE and he was saying he now "had a 540 watt system." It was either 540 or 550 something real close to that. Anyway my point is...does that mean he's producing that much that instant? Or over the course of the day?

I understand the batter bank plays a huge part as well and I guess that's the math part I'm struggling with. I haven't studied Tony's response yet but I'm positive there's some light shedding information in his post.

I can live without a lot of things, but my TV and my Computer are not those 2 things. Lol. Everything else I can get by with some other means. Heat, Water, Fridge...etc.

I'd honestly probably run my TV an average of 8 - 10 hrs a day. But if I could just the formulas down for just 1 hour figured out in my head then wouldn't it be simple addition from there? Or multiplication? I'm going to study Tony's response. Thanks

Cariboocoot

Re: Newbie. Humor me please.....

Ah Youtube: source of some of the finest misinformation in the world.

A Watt = 1 Volt * 1 Amp.
A Watt hour is supplying that power for an hour.
So a television that uses 150 Watts and is on for two hours will use 300 Watt hours in that time.

People have many definitions of "a 540 Watt system". None of them are particularly useful. It usually means they have 540 Watts of panels. On average those panels will actually produce about 415 Watts, and will do so for around four or five hours a day: 1660 to 2075 Watt hours per day (before the losses from converting to AC).

concretefire

Re: Newbie. Humor me please.....

Cariboocoot wrote: »

Ah Youtube: source of some of the finest misinformation in the world.

A Watt = 1 Volt * 1 Amp.
A Watt hour is supplying that power for an hour.
So a television that uses 150 Watts and is on for two hours will use 300 Watt hours in that time.

People have many definitions of "a 540 Watt system". None of them are particularly useful. It usually means they have 540 Watts of panels. On average those panels will actually produce about 415 Watts, and will do so for around four or five hours a day: 1660 to 2075 Watt hours per day (before the losses from converting to AC).

I definitely agree about the youtube comment however, this guy had a 6 or 7 part series and it was some of the most informative vids I've ever seen. AND he highly recommended NAWS as HE had ordered the Kyocer(?sp) 135 watt panels and definitely recommended going with a proven manufacturer. Anyway, I am quite confident he put it more of the way you put it. I believe he did say that the last panel he ordered gave him 540 watts of panels. I quoted when I shouldn't have. He went through the whole process really. I know a BS'er when I see one and he definitely had no agenda. Other than to help others. I would name him but I don't know if he would appreciate that so I won't. He probably visits and posts in these forums. Great guy.

To Tony... .490kWh is the same as 490 watts, yes? If so then I came up with the same number which is nice. I just didn't want to say and be waaaay off and look like an idiot.

BB.

Re: Newbie. Humor me please.....

concretefire wrote: »

To Tony... .490kWh is the same as 490 watts, yes? If so then I came up with the same number which is nice. I just didn't want to say and be waaaay off and look like an idiot.

"K" does stand for Kilo--or 1,000x ... so 0.490kW = 490 W, and 0.490kWH = 490WH (notice that the units are not the same, Watts vs Watt*Hours).

When designing (and paying for) off grid systems, conservation is going to be your friend. It turns out that designing a system to run a microwave oven for 20 minutes per day is "cheaper" than doing one for a typical TV that runs for 10 hours per day. For example:

• 1,500 Watts * 20 min / 60 min per hour = 500 Watt*Hours per day for Microwave used 20 minutes per day
• 150 Watts * 10 hours per day = 1,500 WH per day for a TV used for 10 hours a day

So, first, conservation. Purchase something like a Kill-a-Watt Meter to measure the power used by your TV/computer or even take it to the store and ask to measure the display TV (may be set to bright and use more power).

So, say your TV uses 150 watts for 10 hours per day. Then to figure out your power needs.

Using PV Watts, for Raleigh North Carolina, 1 kW (1,000 watt) array, 0.52 derating, fixed array, we get:

"Station Identification"
"City:","Raleigh"
"State:","North_Carolina"
"Lat (deg N):", 35.87
"Long (deg W):", 78.78
"Elev (m): ", 134
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 35.9"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 8.5 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.73, 58, 4.93
2, 4.66, 66, 5.61
3, 5.38, 81, 6.88
4, 5.76, 82, 6.97
5, 5.55, 78, 6.63
6, 5.77, 77, 6.54
7, 5.53, 77, 6.54
8, 5.58, 77, 6.54
9, 5.35, 73, 6.21
10, 5.33, 78, 6.63
11, 4.34, 63, 5.36
12, 3.51, 53, 4.50
"Year", 5.04, 866, 73.61

Toss the bottom 3 months and we see February gets and average 66 kWH per month or:

• 66,000 WH / 28 days per month = 2,357 WH per day per 1,000 watts of panels

Your "TV" usage is 1,500 WH per day, so solar panel wise:

• 1,500 WH load / 2,357 WH per 1,000 of panels = 636 Watts of solar panel minimum

And for the other three months, you might want to use a backup generator (cheaper than buying a whole bunch more panels for winter power).

Battery wise, 1-3 days of no sun and 50% maximum discharge, and 1,500 watt*hours per day, assuming a 24 volt battery bank:

• 1,500 WH * 1/24 volt battery bank * 1/0.85 inverter eff * 2 days of no sun * 1/0.50 max discharge = 294 AH minimum battery bank

You may also want to use a 12 volt battery bank with 2x the AH rating (588 AH)--But that is getting pretty big (large AH battery banks need heavy cables to carry the load and charging currents).

Just to give you something to aim at--a reasonably size/cost solar PV system with decient hours of sun per day would give you around 3.3 kWH per day or ~100 kWH per month. That will power an entire off-grid home with fridge, lights, water pump, washer, laptop computer, etc...

Of course, you can do with less, or build a much larger system... But do it on paper first so that you can make the design trade-offs and figure out your costs... Grid power is around $0.10 to $0.20 per kWH and off grid power (all costs, ~20 year life including battery and electronics replacement) will run around $1-$2+ per kWH.

So almost anything you spend to conserve electricity/energy will save you money when laid against the costs of your off grid power system.

For example, I have a 17" laptop computer + a USB digital TV receiver that averages ~30 watts or so power consumption... Works well for a whole lot less power than my TV.

-Bill

bmet

Re: Newbie. Humor me please.....

You've got to be careful with some of these youtubers. They work hard, and document carefully, yet at the end they won't give any real measurements of their system. I've tried to ask several of them for real data, and receive nothing. If after all that hard work they won't, or cant' produce what they expected, them something went wrong, and all we have, is a nice video of their mistakes.

concretefire wrote: »

I definitely agree about the youtube comment however, this guy had a 6 or 7 part series and it was some of the most informative vids I've ever seen. AND he highly recommended NAWS as HE had ordered the Kyocer(?sp) 135 watt panels and definitely recommended going with a proven manufacturer. Anyway, I am quite confident he put it more of the way you put it. I believe he did say that the last panel he ordered gave him 540 watts of panels. I quoted when I shouldn't have. He went through the whole process really. I know a BS'er when I see one and he definitely had no agenda. Other than to help others. I would name him but I don't know if he would appreciate that so I won't. He probably visits and posts in these forums. Great guy.

To Tony... .490kWh is the same as 490 watts, yes? If so then I came up with the same number which is nice. I just didn't want to say and be waaaay off and look like an idiot.

rgk1

Re: Newbie. Humor me please.....

Just some real world number differences. Since the TV is one the main things you want to power, do as Cariboocoot suggested and adjust the tv settings. My sattelite reciever, clock radio, and 32" LCD TV consume about 150 watts per hour. If I make the simple adjustment of turning off the light sensor on the TV that automatically makes the screen brighter in a well lit room or dimmer in a dark room, that number drops to about 100 watts.

icarus

Re: Newbie. Humor me please.....

To keep it simple! Watts multiplied by time equal watt hours. (or watt minutes, kilowatt hours are just multiples of 1000 watt hours)

For example, a 100 watt bulb load, run for 10 hours is 1000 watt hours, or,, 1 kwh!.

You need to understnd some basic electrical info. For example, power is measured in watts. Watts is the measurement of voltage combined with current, or Volts *Amperes=watts. Knowing how many watts a load draws is useful, but until you know how long that load will be powered it will not tell you much.

So, a 100 watt tv, running 8 hours a day, will "consume" 800 watt/hours.


Think of watthours as a quantity,like gallons. When you drive your car,you consume a gallon of gas to go someplace. How fast you burn that gas is related to the rate of burn.

Keep reading and asking questions, you will gt. it.

T

ggunn

Re: Newbie. Humor me please.....

rgk1 wrote: »

Just some real world number differences. Since the TV is one the main things you want to power, do as Cariboocoot suggested and adjust the tv settings. My sattelite reciever, clock radio, and 32" LCD TV consume about 150 watts per hour.

Watts are a measure of rate of flow, not a quantity of energy. Your appliances cannot consume 150 Watts per hour; that makes no sense. 150 Watt-hours (0.15 kWh) per hour, maybe? That's what they would consume per hour if they were a steady state load of 150 Watts.