Solar lighting system in our school

[s.xavier]

By the way, how do we know if our charge controller is sufficient to work with? How to determine the required amp-rating of our controller? Is it based on the maximum current that is flowing through the wire from the PV array to the battery? Can someone enlighten me please? Thank you.

Well if your solar panel is your typical 125w module you will only get so much current at any given time and the charge controller pumping out 30a doesn't make much sense if you module will never come close to 30a.

[Mike90250]

I'd suggest these lamps from Amazon, 1 watt LED's, using 10 SMT diodes, and a driver circuit on the backside. I have several of them, they are VERY bright
Disc Type G4 Base Side Pin 10 SMD LED
You may be able to find them locally.

If you visit the link, you will see there are 10 yellow colored "chips" soldered on the front side of the circular PCB (printed circuit board) They are called SMT (Surface Mount Technology) parts, because they do not have wire leads that poke through holes in the PCB.
Because they have a "driver circuit" on the backside of the PCB, that circuit is designed to power the LED's at full brightness, regardless of the input voltage, so they cannot be dimmed. (more photos of that on Amazon).

The internet brings global purchasing, everywhere. I'm sure these are made in china, sold in bulk to the states, resold to distributors, and mailed everywhere. If someone has a credit card at the school, It's worth a chance to try to order a couple of them.

[Sunking]

Depends on the charge controller type being PWM or MPPT

* For PWM simply look at the panel Isc rating. The controller should be equal or greater than the ISc rating of the panel. Example a 120 watt 12 volt panel should have rating like:

Voc = 22 volts
Vmp = 18 volts
Imp = 6.6 amps
Isc = 7.0 amps

You would need a 10 amp PWM controller. FWIW the max power out of a PWM controller would be 12 volts x 6.6 amps = 80 watts.

* For a MPPT take the Vmp rating of the power and divide it by the nominal battery voltage. Using the above example 120 watts / 12 volts = 10 amps. Not with a MPPT controller the max power output would be approx 120 watts minus efficiency of the controller of around 95%. So in real life about 114 watts.

[john p]

Mike one problem I see is using the LEDs you mention is they are not mounted in anything . only come on a pcb. As they are going to be used outdoors it may be hard to find something suitable to mount them in that can also keep them cool?
Importing them will also cost an unknown amount of duty, and they would have to get spares in case of failure. its unlikely they will get them locally ,I have never seen them or similar for sale there.
I dont think you understand about credit cards. Very few people there have them.. you would be lucky to find a hanful of students in the whole country that have one. And unless you live in one of the 5 major cities in the country its almost impossible to get one, and another major problem is you have to be earning more than a teacher is to get one. If im wrong and they can get one to use mabe they can tell us.
I cant even get a credit card there as the town I live in is not an"approved " town to have a bank give you a credit card,, believe it or not.

[Mike90250]

I'd not realized the CC situation was so limited. How much duty can be on a $14 light bulb ?

What about camper / RV / Truck shops ? In Japan, trucks are decked out in as many colored lights as possible! The disc bulbs are replacements for G4 base halagon lights, often used in RC campers, or likely truck cabs. Any thing can be used as a shelter for the bulb.

Since they are 1.4 watts, and have enough surface area, they need no heatsink.

Anyway, just offering ideas of something I've used and thought someone else could .

[john p]

Mike im not trying to criticize your help. its really hard but to explain for people to understand how it is in countries like Phils..
duty can be anything from 10% to 200% . true. and if the item looks "interesting" it may get "lost "in customs.. Trucks there dont have facylights like we do here in Aus and USA .. most have just the lights that the manufacturer put on(the bare minimum). and if broken get replaced at sometime in the future.. joke only.. they never get replaced. No one has money for doing anything except the bare minimum to a truck. well for any vehicle for that matter..tires are used until they burst when worn right through.

[pastmaster02]

Depends on the charge controller type being PWM or MPPT

* For PWM simply look at the panel Isc rating. The controller should be equal or greater than the ISc rating of the panel. Example a 120 watt 12 volt panel should have rating like:

Voc = 22 volts
Vmp = 18 volts
Imp = 6.6 amps
Isc = 7.0 amps

You would need a 10 amp PWM controller. FWIW the max power out of a PWM controller would be 12 volts x 6.6 amps = 80 watts.

* For a MPPT take the Vmp rating of the power and divide it by the nominal battery voltage. Using the above example 120 watts / 12 volts = 10 amps. Not with a MPPT controller the max power output would be approx 120 watts minus efficiency of the controller of around 95%. So in real life about 114 watts.

I'm sorry sir but what do you mean by the panel's Isc and Imp? Also with Voc and Vmp? What are those and how do I determine them? Thanks!

[Sunking]

I'm sorry sir but what do you mean by the panel's Isc and Imp? Also with Voc and Vmp? What are those and how do I determine them? Thanks!

Look at the spec sheet for the panel being used.

Vmp = Voltage @ max power
Voc = Voltage open circuit
Imp = Current @ max power
Isc = Current short circuit.

[s.xavier]

international shipping is a pain in the behind but with that said, great beaches in the Philippines clearest water and excellent people there.

definitely get a smaller controller to save money. now yah just need to figure out the racking portion

[pastmaster02]

Look at the spec sheet for the panel being used.

Vmp = Voltage @ max power
Voc = Voltage open circuit
Imp = Current @ max power
Isc = Current short circuit.

What is the significance of these 4? If ever these values are not indicated in the product, how can we measure them? Thanks!

international shipping is a pain in the behind but with that said, great beaches in the Philippines clearest water and excellent people there.

definitely get a smaller controller to save money. now yah just need to figure out the racking portion

Thanks for your compliments sir. What rating of charge controller in amps is safe if for example I have a current of 7 A. Is 10 A enough (with the 3 A allowance) or should I get a higher rating e.g. 20 A? 30 A charge controller as everyone said is a little too much to handle the current and costs about 5000 pesos (118 $). I think 10 A would cost only 2000 pesos (47$). That's already a big saving for us.

What do you mean by racking portion?

[john p]

a 10a charge controller will be fine, for the panel you intend to use it with..

[s.xavier]

What is the significance of these 4? If ever these values are not indicated in the product, how can we measure them? Thanks!

Thanks for your compliments sir. What rating of charge controller in amps is safe if for example I have a current of 7 A. Is 10 A enough (with the 3 A allowance) or should I get a higher rating e.g. 20 A? 30 A charge controller as everyone said is a little too much to handle the current and costs about 5000 pesos (118 $). I think 10 A would cost only 2000 pesos (47$). That's already a big saving for us.

What do you mean by racking portion?

The racking = the stuff that will hold up the panel, battery and charge controller

Look at the spec sheet for the panel being used.

Vmp = Voltage @ max power
Voc = Voltage open circuit
Imp = Current @ max power
Isc = Current short circuit

W

These values are the technical specifications for your solar panel. All modules should have that and is your basis to configure the rest of your system

[john p]

The racking = the stuff that will hold up the panel, battery and charge controller WHAT ??? you cant put the panel and the battery and controller together.. Water in controllers is not good and for best results you need the panel outdoors.

[s.xavier]

The racking = the stuff that will hold up the panel, battery and charge controller WHAT ??? you cant put the panel and the battery and controller together.. Water in controllers is not good and for best results you need the panel outdoors.

well i was hoping he had considered that side of the system.. pastmaster02 you have all you need to go. have fun make sure you get an A for all your work....

azure water.... jollibee.....

[pastmaster02]

The racking = the stuff that will hold up the panel, battery and charge controller

These values are the technical specifications for your solar panel. All modules should have that and is your basis to configure the rest of your system

well i was hoping he had considered that side of the system.. pastmaster02 you have all you need to go. have fun make sure you get an A for all your work....

azure water.... jollibee.....

Oh ok. Well in that case, we still have to plan on that racking. I'm still confused as to what tilt angle our panel would be positioned or if we would lay it out flat on the roof of our catwalk using specialized mounting structures, and by that I think we would buy fabricated steel or whatever material that can handle our panels. The roof's like an inverted V. Probably has a slope of 50 degrees (I'll check on it later when I get to school). Yes I do hope we get high grades for this project.

Jollibee.. my favorite fast food chain.

a 10a charge controller will be fine, for the panel you intend to use it with..

The racking = the stuff that will hold up the panel, battery and charge controller WHAT ??? you cant put the panel and the battery and controller together.. Water in controllers is not good and for best results you need the panel outdoors.

Noted. 10 A would be enough. As for the controllers and the batteries, we are planning to put it overhead, inside under the roofs supported by those wooden trusses and encased by probably stainless steel cover or whatever material suitable for the job. Thank you.