# Project: Balcony Party Lights = Solar Panel → Battery → LED Strip

#### Ryan Johnston

Joined Jun 26, 2018
7
Hey guys, I'm almost about as beginner as it gets when it comes to electrical engineering (architect by profession). I understand concepts really well but the technical stuff gets me hung up on times. I'm a hobbyist at best. With that said, here's the project I have:

I want to put LED Strip lights on my balcony and power them with small solar panels that are charging a little battery. The lights would need to run for 4-8 hours after the sun goes down. I know I'm going to need two "1W/6V/150MA" solar panels wired in series, a charge controller (no idea what size/type), battery (I was thinking a 12V 8AH battery would work), a switch for on/off, and the LED Strip. All links are posted below.

I'm really looking for any advice you have on this project because I'm just starting off my solar panel adventures. Eventually I'm going to try to become an expert in solar power but for now it's just a fun project to help me understand it better. I'm viewing this project as an ultra-small-scale whole house solar powered system. Also, am I going to need an inverter to power the lights? I planned on wiring them directly and ditching the power supply that they have in the LED kit. Thank you for your help!

Link to lights (Consumption: 2.4W/m ; Input: DC 12V)
Link to solar panels (two panels in series @ 1W/6V150MA each)
Link to battery (up for suggestions) (12v 8MA)

#### MrChips

Joined Oct 2, 2009
25,066
Looks like you've done some of your homework. We're not going to do it for you.

Step 1.
Determine the voltage and current requirements of your lights.
Calculate the Ampere x hours required by the lights.

Step 2.
Choose the right battery, one whose rating exceeds ( x 2) the Ah calculated in Step 1.

Step 3
Choose solar panels that can exceed the Ah calculated in Step 1 (again x 2).

#### Ryan Johnston

Joined Jun 26, 2018
7
Step 1:
Lights require 12V and 2.4W/m so 2.4 / 12V = 0.2A) - I don't know what 2.4W/m stand for btw
0.2A x 6hours - 8hours = 1.2Ah - 1.6Ah needed per day at worse case

Step 2:
Battery should require 3Ah - 4Ah

Step 3:
and this is where I get lost.
if 1 solar panel = 1W/6V/150MA = 0.167A
if I get 6 hours of sunlight than 0.167A x 6hours = 1A
if I need 3Ah - 4Ah than I need 4 solar panels
x 2 for assurance like you said and I need 8 panels

8 panels wired in series getting 6 hours of sunlight per day should charge a 12V/4Ah battery every day

is that right/close?

#### Ryan Johnston

Joined Jun 26, 2018
7
Looks like you've done some of your homework. We're not going to do it for you.

Step 1.
Determine the voltage and current requirements of your lights.
Calculate the Ampere x hours required by the lights.

Step 2.
Choose the right battery, one that whose rating exceeds ( x 2) the Ah calculated in Step 1.

Step 3
Choose solar panels that can exceed the Ah calculated in Step 1 (again x 2).

Step 1:
Lights require 12V and 2.4W/m so 2.4 / 12V = 0.2A) - I don't know what 2.4W/m stand for btw
0.2A x 6hours - 8hours = 1.2Ah - 1.6Ah needed per day at worse case

Step 2:
Battery should require 3Ah - 4Ah

Step 3:
and this is where I get lost.
if 1 solar panel = 1W/6V/150MA = 0.167A
if I get 6 hours of sunlight than 0.167A x 6hours = 1A
if I need 3Ah - 4Ah than I need 4 solar panels
x 2 for assurance like you said and I need 8 panels

8 panels wired in series getting 6 hours of sunlight per day should charge a 12V/4Ah battery every day

is that right/close?

#### bertus

Joined Apr 5, 2008
21,766
Hello,

The 2.4W/m stands for 2.4 Watts for every meter of the led strip.
If you use 5 meter of led strip the used power will be 5 meter X 2.4W/m = 12 Watts.

Bertus

#### Ryan Johnston

Joined Jun 26, 2018
7
Hello,

The 2.4W/m stands for 2.4 Watts for every meter of the led strip.
If you use 5 meter of led strip the used power will be 5 meter X 2.4W/m = 12 Watts.

Bertus
That seems so obvious now haha thank you for helping me out

#### Ryan Johnston

Joined Jun 26, 2018
7
Revised math base on 5 meter of lights

Step 1:
Lights require 12V and 2.4W/m x 5 meters = 12W → so 12W / 12V = 1A) -
1A x running for 6hours - 8hours = 6Ah - 8Ah needed per day at worse case

Step 2:
Battery should require 6Ah - 8Ah if used every day

Step 3:
and this is where I get lost.
if 1 solar panel = 1W/6V/150MA = 0.167A
if I get 6 hours of sunlight than 0.167A x 6hours = 1A
if I need 6Ah - 8Ah than I need 8 solar panels
x 2 for assurance like you said and I need 16 panels

16 panels wired in series getting 6 hours of sunlight per day should charge a 12V/8Ah battery every day

is that right/close?

#### Ryan Johnston

Joined Jun 26, 2018
7
@MrChips I hate to be a bother but can you check my math on this?
Lights require 12V and 2.4W/m - assuming I want to power the whole 5 meters this is 1A

1A for 6 hours means the battery needs to be about 7Ah so it doesn't go totally dead

if the solar panels are 1W/6V/150Ma = 0.15A x 6hrs of sunlight = 0.9Ah per day per panel x 60% efficiency = 0.54Ah/day/panel

7Ah needed / 0.54Ah = 14 panels
Am I going to need a charge controller or an inverter on this project?
Sorry about all the questions but like I said, I'm brand new to this and don't know where to turn.

Thanks

#### MrChips

Joined Oct 2, 2009
25,066

There is another simple way of checking your math. Since your solar charge time is 6 hours and the lights are powered for 6 hours, you can simply equate the wattage requirement (and then go some more).

Lights take 12W @ 12V.
You will need the panel to supply at least 12W @ 12V. (You will need 14.5V to charge a 12V sealed lead acid battery, SLAB. I would go with a readily available 12V 7Ah SLAB ).

To make sure that the battery is fully charged, you want to look at a single 20W (or greater) 12V solar panel.

#### Ryan Johnston

Joined Jun 26, 2018
7