Solar lighting system in our school

[john p]

YES All will workfine. You only need a 10a charge controller
#12v wire will be ok for the lights

[pastmaster02]

YES All will workfine. You only need a 10a charge controller
#12v wire will be ok for the lights

Yay thanks for the positive feedback. I'm still aiming to provide lighting for more than 4 hours.

[john p]

To get 4 or more hours is no problem you just need to scale thing up from the present system.

[pastmaster02]

To get 4 or more hours is no problem you just need to scale thing up from the present system.

Can I reduce the lamp wattage and increase the number of hours?

[Sunking]

The purpose of that project it to cut the electric expenses of the school by a little.

Well you have learned by now, going off grid will not save any money huh, in fact cost a great deal more money.

[john p]

Yes of course you can vary the lamp watts up and down and the hours they can run will vary the same.
ie 50w lamps =4 hrs
25w lamps = 8 hrs

[Mike90250]

A 30a controller, with a 100w panel is fine. Lets hope you bought good components. there are a lot of rip-off parts out there, and with the $ invested in solar, you don't want to have to buy it twice.

[john p]

Mike they wont have a lot of choices as solar is not big business in Phils as components cost at least double in USA or Australia. and not many have any money to spend on solar at all.
And as for guarantees .. ??? well???? dont ask.

[Mike90250]

Can I reduce the lamp wattage and increase the number of hours?

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.

[s.xavier]

Thanks again for your reply.

Total power of lamps: 50 W
Number of powered hours: 5 hours (from 12 down to 5 hours)
Energy spent in 1 night: 50 W x 5 hours = 250 W-hr

Battery: 250 W-hr x 4 = 1000 W-hr capacity. Is this equivalent to 1000 W-hr divided by 12 V = 83.3 Amp-hr? (does multiplying the energy spent by 4 mean we are using only 25% of the battery capacity? Is that good enough?)

PV array: 250 W-hr x 2 = 500 W-hr capacity (assuming the the sun is giving full power for 7 hours, is the power our array gives equal to 500 W-hr/7 hrs = 71.43 W?

You are on the right track. The batteries should always be optimized to prevent it from discharging too much or you will shorten its life = yah will have to buy more batteries. Mike is correct you should add an additional battery.

My only question is, "have you thought about the 50w LED solar light fixture itself?" From my experience and depending on the light itself, 50w LED fixture is pretty bright and aggressive (depends on what type of light). For any lighting application you want to keep in mind what you want to do, take a look at this article on commercial solar lighting - for any lighting applications running 12 hours may not be suitable considering I'm pretty sure no one will be running around 4am near your school... unless schools are different nowadays, i do not see a need to run 12 hours during night time

School of hardknocks..hehehe..

[john p]

s xavier they are not running one 50w LED lamp ALL the lamps come to a total of 50w.

[s.xavier]

I think pastmaster02 went with a single LED lamp at 50w but he will need to clarify on that matter...

A 30a solar charge controller is a little much imo.. You can probably get away with a smaller one that maximizes the charge and will cost less.

I have however seen some LED lights that provide functionality where you can dim after x amount of hours to reduce the brightness of the light saving you energy which may work for your application. For example, basically you get 5 hours of max brightness and then dims at 50% for the remainder 7 hours that help save energy consumption

Good project and have fun with it in my opinion... never had these interesting projects when i was in school

[john p]

We are about to use 10 pieces of 5-watt bulbs for a total of 50 W. My classmates decided to put a single LED lamp in every post in our catwalk.
I said to use a 10a charge controller then Mike said a 30a one.

[s.xavier]

We are about to use 10 pieces of 5-watt bulbs for a total of 50 W. My classmates decided to put a single LED lamp in every post in our catwalk.
I said to use a 10a charge controller then Mike said a 30a one.

IMO comes down to what they want to do in the future and the quality of the controller... 30a makes sense if they were to upgrade in the future and such ... also they need to take into account the quality of a 10a charge controller...

Personally, if they find something in the 10a range (and quality-not a throw away put together) and do not expect to upgrade in the future 10a should work and save a buck or 2 considering they have limited resources....

[pastmaster02]

Thanks to all of you who took time to answer my queries.

Well you have learned by now, going off grid will not save any money huh, in fact cost a great deal more money.

Yes sir I've learned well enough that our investment is a not very good one but for us to pass the subject, even though our project may be a little too much for students, we should still comply.

Yes of course you can vary the lamp watts up and down and the hours they can run will vary the same.
ie 50w lamps =4 hrs
25w lamps = 8 hrs

Okay. I'll just do some balancing in the calculations to make it work. Thanks!

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.

Excuse me sir, but what are SMT diodes? We're not much familiar on how things work on online stores especially those that are outside our country.

You are on the right track. The batteries should always be optimized to prevent it from discharging too much or you will shorten its life = yah will have to buy more batteries. Mike is correct you should add an additional battery.

My only question is, "have you thought about the 50w LED solar light fixture itself?" From my experience and depending on the light itself, 50w LED fixture is pretty bright and aggressive (depends on what type of light). For any lighting application you want to keep in mind what you want to do, take a look at this article on commercial solar lighting - for any lighting applications running 12 hours may not be suitable considering I'm pretty sure no one will be running around 4am near your school... unless schools are different nowadays, i do not see a need to run 12 hours during night time

School of hardknocks..hehehe..

I think pastmaster02 went with a single LED lamp at 50w but he will need to clarify on that matter...

A 30a solar charge controller is a little much imo.. You can probably get away with a smaller one that maximizes the charge and will cost less.

I have however seen some LED lights that provide functionality where you can dim after x amount of hours to reduce the brightness of the light saving you energy which may work for your application. For example, basically you get 5 hours of max brightness and then dims at 50% for the remainder 7 hours that help save energy consumption

Good project and have fun with it in my opinion... never had these interesting projects when i was in school

We're planning to use 10 pieces of 5 W LED lamps for the project. I like your idea sir of having a dimmer to control the power consumption but for now, we would like to consider in simplifying the operations of our system. Maybe in the future if we would like to upgrade our system then we could add additional components like what you suggested. Thanks!

IMO comes down to what they want to do in the future and the quality of the controller... 30a makes sense if they were to upgrade in the future and such ... also they need to take into account the quality of a 10a charge controller...

Personally, if they find something in the 10a range (and quality-not a throw away put together) and do not expect to upgrade in the future 10a should work and save a buck or 2 considering they have limited resources....

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.