Is this ok?

[John117]

So, I am a solar enthusiast, I have been wanting to make my solar system for a long time now, so far, I have read 1 book and watch some YouTube videos, so I don't know much... I want to start small. I would like to install a path lights on my house because it gets really dark outside and I think it will be best for security. I am tired of the small solar path lights they sell online because they don't give much light and the solar panel will fade in a year. So, I decided to make a wired path light, but my house does not have an outlet outside, so this is my chance to make my first solar system and hopefully learn!! I used online calculators, watched some videos and finally came with what I think is a system, but even trough this is a very small off grid solar project, according to my calculations is over 500.00 USD and I would prefer not to mess it up. So I drew my "schematic" and would like help from more knowledgeable people here. I want this lights to be on 6 hours during the night, ideally it will be more... but I know I would have to scale up on solar panel and possible battery. Also, If I don't install a regulator the amps will fry the lights right? Anyway, thanks in advance!

Oh, the total cable run for this is around 50 feet, I choose a very expensive 10 gauge pure copper wire. Also, the lights are wired in series, I know if one goes bad, the others will also, but I accept that because I don't want to deal with a more complex ground cable installation.

 

[RCinFLA]

If you are going to use an MPPT controller with '12v' panel make sure it is a 36 series PV cells panel (about 18v Vmp).

MPPT controller needs some overhead voltage above battery highest voltage.

There are a lot of '12v' panels out there that are only 30-32 series PV cells.

A 50w PV panel is not really worth the extra money for MPPT controller for what you gain over cheaper PWM controller.

Also just noticed, how does a '12v panel with 10 amp be a 50 watt panel?

 

[HRTKD]

With such a small panel, you could use a PWM controller instead of MPPT. But if you're going to expand later, MPPT might be the way to go.

A disconnect (dual pole DC circuit breaker) between the PV and solar charge controller is helpful to turn off PV power to the solar charge controller when you do maintenance.

A breaker between the solar charge controller and the battery is also recommended.

Size the breakers for 1.25 times the expected amperage.

There may be an issue with running the LED lights in series instead of parallel connections. Be sure you wire them the right way.

 

[John117]

If you are going to use an MPPT controller with '12v' panel make sure it is a 36 series PV cells panel (about 18v Vmp).

MPPT controller needs some overhead voltage above battery highest voltage.

There are a lot of '12v' panels out there that are only 30-32 series PV cells.

A 50w PV panel is not really worth the extra money for MPPT controller for what you gain over cheaper PWM controller.

Also just noticed, how does a '12v panel with 10 amp be a 50 watt panel?

Thank you for help!

I think I may have seen it wrong, this is the panel I am thinking of buying, and the charge controller is included. This was the only charger I found that the seller says it works with LifePo4 batteries, the others will not say that or will be more expensive.

https://www.amazon.com/dp/B09F68PD93/?coliid=I3APCXDMJD0TAM&colid=2TAQXMRTBUH93&ref_=lv_ov_lig_dp_it&th=1

 

[HRTKD]

At that price point, the solar charge controller is usually PWM. There are a lot of "MPPT" controllers out there that are labeled as such, but it's been shown that they're really PWM. Maybe that one is and maybe it isn't.

I look at most kits with a healthy dose of skepticism. Building from components gives me exactly what I want without compromise.

50 watts of PV isn't much.

Look around for a used 250 watt panel and then find a quality MPPT solar charge controller to work with it.

 

[John117]

The thing is, the panel have to be mounted in a pole in the front of the house, so I have limitations on the size, i can still put a 100w panel in a pole but it will look huge... 50 w panel size is the sweet spot for discrete, so I have to built around him. I dont mind if the charger is mppt or not, but i am concerned about the lifePo4. Most chargers that size will not accept that battery.

 

[RCinFLA]

If you are going for a 50 watt panel size, just use a cheap PWM charge controller. You will not gain much with MPPT controller.

 

[HRTKD]

When you power it up, keep a real close eye on the voltage that the charger is sending to the battery. Ideally, charging a LiFePO4 battery to 14.6 volts every day isn't what you want.

 

[John117]

When you power it up, keep a real close eye on the voltage that the charger is sending to the battery. Ideally, charging a LiFePO4 battery to 14.6 volts every day isn't what you want.

Thanks for the advice, I had no idea, when I build it, I will check that! But you think it will work? also, I am unsure about the regulator, will I burn the light without one?

 

[John117]

If you are going for a 50 watt panel size, just use a cheap PWM charge controller. You will not gain much with MPPT controller.

Thanks for the advice, I am more concern about the battery type, most cheap controllers are not labeled to work with LifePo4 batteries.

 

[John117]

This are the components I am choosing for this project.

 

[HRTKD]

Can explain why you are using a regulator? The entire system is 12 volt, so what's the problem?

 

[John117]

Can explain why you are using a regulator? The entire system is 12 volt, so what's the problem?

I don't know if there is a problem, my understanding is that volts and amps are different values and if the light are 2 watts each and 12 v. Having those values, we can assume the amps for each light is 0.16, and they will be connected to a 12 v 20 amp battery, will this fry the lamps? or is ok because they are 12 v? I don't know that part. Do I have to lower those amps? Or it will be fine?

 

[HRTKD]

If the LED lights are 12 volts, you don't need anything further to power them. The lights draw amps, the batteries don't push amps.

 

[John117]

If the LED lights are 12 volts, you don't need anything further to power them. The lights draw amps, the batteries don't push amps.

Ohh ok!! Awesome, I had no idea!!
So I can take that out now, thank you for your knowledge and time!!

 

[chrisski]

You also have the 8 LEDs drawn in series pulling 1.25 volts each in series, instead of in parallel for 12 volts.

 

[John117]

You also have the 8 LEDs drawn in series pulling 1.25 volts each in series, instead of in parallel for 12 volts.

Sorry, I am very noob at this... I was under the impression that they will use 12 v each no matter what installation?... So do I have to do this in parallel ?

 

[Rednecktek]

Drop the regulator, you don't need it.

Get a larger panel, you'll need the extra watts in clouds/winter/rain/etc.

Run all your wiring in parallel, easy enough to do.

Do you have a way of keeping the battery above freezing?

Use a basic 20a or so PWM controller. Some of them (you'd have to do a little reading) will turn on their load ports when the solar stops shining thus acting as a day/night switch. Just make sure the PWM can handle the 20a of draw from the lights. Much cheaper than an MPPT and you'll get the same amount of power to the battery.

 

[rodrick]

Everything in the light description says 12 volt ac and their transformers no mention of dc anywhere did they do something to limit it to ac only might check?

 

[John117]

Everything in the light description says 12 volt ac and their transformers no mention of dc anywhere did they do something to limit it to ac only might check?

Thank you, you are right, i will check that