Howdy, I'm looking to convert all my outdoor Christmas lights to PV

[ericcson]

Hello,

I guess I should have gone here first. Anyway, I've had this idea tickng away in my head for awhile and I thin it's worth pursuing.
Here's what I just posted to the Lighting Forum.
------------------
I want a solar powered outdoor Christmas light setup. Not the teeny lights that come with a 6-inch solar panel. I’m talking the longs runs of 120v LEDs that surround the front eves. A collection the looks like it’s running on the grid but isn’t. Also, I’d like to use it with an inverter to power my tankless water heater during a blackout. It runs on gas but uses 110v to ignite. Usage: 70 watts power.

My design is thus:
Solar Panel, 15Watt/12v, from Harbor Freight (usually on sale)
12 volt Marine battery from Costco ($72 !)
A charge controller with timer (http://www.newegg.com/Product/Produc...9SIA0U00BZ7466
100W (more?) Inverter

What do you think? On track or way off base?


New Bee

[inetdog]

Hello,

I guess I should have gone here first. Anyway, I've had this idea tickng away in my head for awhile and I thin it's worth pursuing.
Here's what I just posted to the Lighting Forum.
------------------
I want a solar powered outdoor Christmas light setup. Not the teeny lights that come with a 6-inch solar panel. I’m talking the longs runs of 120v LEDs that surround the front eves. A collection the looks like it’s running on the grid but isn’t. Also, I’d like to use it with an inverter to power my tankless water heater during a blackout. It runs on gas but uses 110v to ignite. Usage: 70 watts power.

My design is thus:
Solar Panel, 15Watt/12v, from Harbor Freight (usually on sale)
12 volt Marine battery from Costco ($72 !)
A charge controller with timer (http://www.newegg.com/Product/Produc...9SIA0U00BZ7466
100W (more?) Inverter

What do you think? On track or way off base?


New Bee

Much as I dislike Harbor Fright (sic) panels etc, your usage is simple enough that it just might work.
But you can do as well and have more for the future by using a larger solar panel. For a typical 12 volt marine battery, you really should have between 100 and 200 watts of panel, not the 15 watts you get from HF.

The inverter will not need to be very big at all for the LEDs. Check the wattage rating of the strings, but I would not expect them to be more than 4 watts/30 LED string.
And since you have grid power, using an AC battery charger occaionally so would be as simple as using solar.

[Sunking]

I've had this idea tickng away in my head for awhile and I thin it's worth pursuing.

No it is not worth pursuing, It will cost more than a brand new Cadillac. I do not care who you are, running a 6000 watt tankless electric hot water heater off solar is funny stuff.

For a few thousand you can run the Xmas lights. Just to do the lights you will need a 500 to 750 watt solar panel, 80 amp charge controller, 500 pound $1000 battery, and a 200 watt inverter. Any questions?

[ericcson]

Understood. 100-200 watts check. That's the kind of information I needed.

The idea of regular charger for the battery, so I can power the igniter on the tankless is more reasonable.
If the power is out, my wife will care a lot more about hot water than Xmas lights. A lot more.

[ckhorne]

For a few thousand you can run the Xmas lights. Just to do the lights you will need a 500 to 750 watt solar panel, 80 amp charge controller, 500 pound $1000 battery, and a 200 watt inverter. Any questions?

Wait... what?

ericcson didn't say how much xmas lights he has. I have 6 20' strands of LED lights on my house; I'll assume that his front eves are less than or equal to what it takes to go around my house. Each strand is 4 watts, so 24 watt pull. Assuming 24 watts over 12 hours == 288 watt hours.

Assuming 20% DoD, that still only requires a 120 AH battery and 144 watts of panel @ 4 insolation hours/day (even using a PWM controller).

As for the gas hot water heater, if the pilot light goes out, run an extension cord from the inverter to get it going again. From what you've said, it should be a 70w burst to light the pilot light, and should be fine with your spec'd out system.


Maybe I'm missing something, but what ericcson is looking to do seems pretty feasible to me.

[Wy_White_Wolf]

LED Christmas lights seem to run about 35 watts per 100 light string (you will need to adjust is you have a different light count).

So per string to run them for 6 hours a day you would need:

200 watts of panels
131 AH of battery @ 12v
20 amp charge controller

So how many strings of 100 LED lights do you want to run?

WWW

[Sunking]

ericcson didn't say how much xmas lights he has. I have 6 20' strands of LED lights on my house; I'll assume that his front eves are less than or equal to what it takes to go around my house. Each strand is 4 watts, so 24 watt pull. Assuming 24 watts over 12 hours == 288 watt hours.

Assuming 20% DoD, that still only requires a 120 AH battery and 144 watts of panel @ 4 insolation hours/day (even using a PWM controller).

Believe he said 70 watts and did not specify how many hours or location. Assuming 10 hours is 700 watt hours. Very few places get 4 Sun Hours this time of year an dif he were to use a PWM charger the panels would have to make 1400 watt hours.

I blew it when I said electric Water heater but he did not specify.

The point is taking the Xmas lights off-line just does not make any common sense to spend that kind of money for 5 cents worth of electricity per day.

[inetdog]

I blew it when I said electric Water heater but he did not specify.

He didn't?

Also, I’d like to use it with an inverter to power my tankless water heater during a blackout. It runs on gas but uses 110v to ignite. Usage: 70 watts power.

If the tankless gas heater he has is anything like mine, it will need power the whole time that water is being drawn, so the temperature control system can work, not just for the moment of ignition. Even then though, if he switches it on and off as needed I would be surprised if he needs to actually power the heater more than an hour a day. There should be no pilot, and if the burner may have to be switched on and off over short cycle times to regulate temperature.
I would also not necessarily believe the 70 watt nameplate rating, as it may be much lower most of the time. OP should plug the heater AC into a Kill-a-Watt meter for a week to see just what would be required.

Regarding the lights, I agree 100% based on economics. But if the price is low enough the awesomeness factor and bragging rights have some value too.