Solar Panel

Nishan.dj · October 26, 2012

Hi All,

I am not much knowledgeable on this but I want to make a solar charger for both 12V and 24V [12*2] Batteries. I have few things that need to understand and kindly reply to the post if you know something about it.

First of all;

A regulator and a 10W or 15W Solar Panel would be Ok for a 12V 70Amp battery solar charger as I understand and from those two I think I can make one. If I get two 5W Solar Panels [seems like its a bit cheap], can I connect them in a way that the output would be 10W and double the current?

If It is not please explain what else to do.

Second of all;

How many watts that I have to look for in the panel If I make a charger for 24V System?

Are there any places that sells only or mostly solar panels in Sri Lanka that you know?

Apart from these; I looked at building a Solar panel from solar cells kit that is a bit of a work to do rather than buying a whole panel and has anyone tried it?

After all; kindly suggest me a good way of doing it. First I want to build 12V one and then to 24V one. Appreciate your responses and thanks in advance.

Sylvi · October 26, 2012

Nishan. dj,

My advice for you is not to go for this type of low Wattage solar panels because they will not give enough Amperage to charge a battery of 12 volts.

You can buy Solar Panels in S L. As for my knowledge they are subsided for rural area people who do not have National Grid supply.

There was a news paper advertisement few months back and I have seen them on a exhibition at BMICH.

It is a long process to get one of those systems for those people, have to go behind certain authorities Palm oil them.

I long years ago before I got 3 PH power to my land had Japanese Toshiba system which I bought in Japan 1980s for Rupees 20000/= at that time.

At that time they were duty free that came in my personal luggage so no fright involved.

During day time I used to get 10 Amps to charge a battery in few hours (6 hours) because we have good sun light only for 8 hours a day 8AM to 4 PM.

This solar panels you have to have a charging controller if not battery will get over charged and go off in no time.Like automobile battery overcharging.

had a Alternator during rainy weather to charge the battery can be coupled to water pump diesel engine belt driven.

I have had this system for 20 years or more until I Got the National Grid supply. please log into link below for controller.

Working very satisfactory only changed batteries every 5 years.

http://www.ebay.com/itm/10A-solar-charge-controller-solar-power-controller-timer-and-light-sensor-/180889808191?pt=LH_DefaultDomain_0&hash=item2a1ddf6d3f

Sylvi Wijesinghe.

Edited October 26, 2012 by Sylvi

Watchman · October 26, 2012

It is a long process to get one of those systems for those people, have to go behind certain authorities Palm oil them.

You do realize "oiling a palm" is not at all the same as "palm oil" right? :rolleyes:

That's what happens when you cut class to play hokey-pokey with the boys in the drain behind the school during the Queen's English period.

So are you gonna go cry to the joint-moderator or address the issue yourself like a man?

Rumesh88 · October 28, 2012

Hi Nishan

I would be in a position to help you with your project but the details that you have given here do not reveal the whole story. For a system of this nature there are four main items.

1. Power source (Your solar panel. You can decide the capacity later based on the insights I would provide)

2. Storage device ( Your battery. You need to decide its voltage and capacity based on other items in this list)

3. Your load (You do not say anything on this in your post)

4. Regulator (This is to be decided based on the three items above and your intended usage)

As a person having long experience in the subject I would be willing to give you much needed advice but please let me have a clear picture on your intended load and the usage.

Nishan.dj · October 29, 2012

Nishan. dj,

My advice for you is not to go for this type of low Wattage solar panels because they will not give enough Amperage to charge a battery of 12 volts.

You can buy Solar Panels in S L. As for my knowledge they are subsided for rural area people who do not have National Grid supply.

There was a news paper advertisement few months back and I have seen them on a exhibition at BMICH.

It is a long process to get one of those systems for those people, have to go behind certain authorities Palm oil them.

I long years ago before I got 3 PH power to my land had Japanese Toshiba system which I bought in Japan 1980s for Rupees 20000/= at that time.

At that time they were duty free that came in my personal luggage so no fright involved.

During day time I used to get 10 Amps to charge a battery in few hours (6 hours) because we have good sun light only for 8 hours a day 8AM to 4 PM.

This solar panels you have to have a charging controller if not battery will get over charged and go off in no time.Like automobile battery overcharging.

had a Alternator during rainy weather to charge the battery can be coupled to water pump diesel engine belt driven.

I have had this system for 20 years or more until I Got the National Grid supply. please log into link below for controller.

Working very satisfactory only changed batteries every 5 years.

http://www.ebay.com/...=item2a1ddf6d3f

Sylvi Wijesinghe.

Hi Nishan

I would be in a position to help you with your project but the details that you have given here do not reveal the whole story. For a system of this nature there are four main items.

1. Power source (Your solar panel. You can decide the capacity later based on the insights I would provide)

2. Storage device ( Your battery. You need to decide its voltage and capacity based on other items in this list)

3. Your load (You do not say anything on this in your post)

4. Regulator (This is to be decided based on the three items above and your intended usage)

As a person having long experience in the subject I would be willing to give you much needed advice but please let me have a clear picture on your intended load and the usage.

I must thank to Sylvi and Rumesh for giving valuable responses.

Rumesh, kindly read the following;

1. Power source - I was considering to buy a 10W - 15W panel which may give 0.6AMP - 1AMP current. [without having any idea whether it will be enough as Sylvi mentioned]

2. Storage device - 12V 70AMP Battery [There may be 2-3 batteries connected together that gives 12V but more amperage based on the capacity that the panel can support]

3. Your load - My idea is basically to use the 12V DC power for lighting the house instead of using 220V AC main line. Currently there are 4 to 12 CFL bulbs (20W) are switched on at night but mostly it is like 5 bulbs that are on for longer period. [However equipment that require more power such as fridge, water pump ...etc are to be powered by 220V AC]

4. Regulator - think that 10AMP is enough but kindly appreciate your response.

So what would be your suggestion? appreciate your response. Thanks.

Edited October 29, 2012 by Nishan.dj

Sylvi · October 29, 2012

Nishan dj,

Thanks for your reply.

I think Member "Rumesh88" has much more experience according to his post on Solar Panels. It is better if you get his advice on this subject from him.

Sylvi Wijesinghe.

Nishan.dj · October 30, 2012

Nishan dj,

Thanks for your reply.

I think Member "Rumesh88" has much more experience according to his post on Solar Panels. It is better if you get his advice on this subject from him.

Sylvi Wijesinghe.

Thank you sir,

I could manage to contact few people who have had solar house lighting system and now taken 220V AC supply for their homes. If I am to get one of those [used panels] I will have to check the amperage of those with the original amperage to check the status of the panel. To do so, All I have to do is to measure the amp with a meter or is there any other process to check those panels?

As this is not a final decision I still expect that Rumesh88 will reply to the post that I publish above. Thank you.

Rumesh88 · October 30, 2012

Hi Nishan

Although the subject is not in line with this forum, I will give you the required information.

Assuming you operate all lights for four hours each night and further five lamps for another two hours your to total energy consumption would be (20X12X4+20X5X2) 1160 watt-hours. A battery having a capacity of 12V 70AH can provide only a maximum of (12X70) 840 watt-hours under IDEAL conditions. As a rule of thumb you can go for a 70% discharge of the battery each night hence the available energy from one battery is (70%X840) 588 watt-hours. Assuming a conversion efficiency of 80% when you convert this to 240V you will end up with (588X80%) 470.4. Hence, working back on the same formula if you want to end up with 1160 WHs you need to keep in store at least (1160/0.7/0.8) 2071 WHs. Basically you need around 180AH battery of 12V or 90AH battery of 24V. My advice for you is to go for a 24V system but keep in mind that above calculation is only for the storage for ONE NIGHT! If you need more back up time you've got to increase the battery capacity.

Then comes the question of solar panel. assuming you expect your 24V 180AH battery which is discharged by 70% charged back in ONE day of full sunshine (ie four hours from 10am to 2pm of full solar panel output, which is reasonable unless you have a motorized solar tracker in which case you can add another 3 hours or so, and a lot more investment!!!), you need a solar panel which can provide something like 30A at 24V. (I am using round figures here). Hence the regulator may have to handle something like 40A. However, you can bring down above figures if you intend to use this system only as a back up in the event of a power failure.

The most important point of above explanation is to show you that it is not that easy to go for a total solar solution for a house that has been on CEB power all along unless you are prepared to invest a lot. However, if you can change your load, ie if you can change to 10watts CFLs instead of 20watts an reduce the number of bulbs etc...

Good luck..

Rumesh88 · October 30, 2012

One thing I forgot was that the battery used for this type of repeated charge-discharge cycles should be of a special type NOT the regular vehicle types. You can use vehicle batteries but then the should not be discharged down to 70% or else you would be compromising its service life.

Nishan.dj · October 30, 2012

Thanks Rumush88 for the detailed explanation.

What I am thinking is that, getting the DC power for several bulbs that are switched on most of the times such as 3-4 CFLs [18W or lower]. Then I can be able to get the work done from the set of existing equipment without investing much on it. Thanks so much on your reply.

XBeat · October 30, 2012

If you can invest on 4W LED instead of 18W CFL you can reduce your system capacity significantly and save the cost. There are several local LED manufactures who offers the bulbs at lesser cost than at Pettah market with a warrenty

Or else if you are interested you can assemble LED bulbs yourself. 1st cross street vendors have all the components with them for sale. It is a bit tedious task since you have to spent time in soldering the bulbs

Edited October 30, 2012 by XBeat

Nishan.dj · October 30, 2012

If you can invest on 4W LED instead of 18W CFL you can reduce your system capacity significantly and save the cost. There are several local LED manufactures who offers the bulbs at lesser cost than at Pettah market with a warrenty

Or else if you are interested you can assemble LED bulbs yourself. 1st cross street vendors have all the components with them for sale. It is a bit tedious task since you have to spent time in soldering the bulbs

Thanks XBeat for the suggestion. I already have got 5W LED [with heat sink] and its good. The only drawback is that the light is sharp and feel little uncomfortable to see but with the costs that incur with the investment to make, its not a big issue. Anyway will try it and post. Thanks.

Sylvi · October 31, 2012

Thanks XBeat for the suggestion. I already have got 5W LED [with heat sink] and its good. The only drawback is that the light is sharp and feel little uncomfortable to see but with the costs that incur with the investment to make, its not a big issue. Anyway will try it and post. Thanks.

Nishan dj,

Please Log into this web sites you can get solar cells as for your requirement.

http://www.dcac-powe...price list.html

http://www.dcac-powe...ly 120-140.html

I have requested CIF Colomo S L.

The cost is very cheap I think you have to do It your self.

Sylvi Wijesinghe.

Edited October 31, 2012 by Sylvi