DIY Solar Panel Off Grid questions + further progress

[jpsulisz]

Hey guys I'm new to this forum!
So by the title you can tell what I'm wanting to do, a off grid small solar panel kit. Now I'm just doing this for the experience and fun, this could be used for camping or selling it to make something bigger. So the reason for this post is to firstly keep you guys updated on the project and to ask some questions! I should firstly say my parts list, these of course are the main parts to a build. The frame, wiring, and other parts not listed can be bought cheaply or made elsewhere. So here are some parts:

When stated : Other options considered :

Solar Cells 6x6 100W option (25PCS)$50.00: http://www.ebay.com/itm/10W-20W-30W-...item35ca289066

750 Watt Power Inverter (Off-Grid) (Other options considered) -$40.00: http://www.harborfreight.com/750-wat...l#.UxKa_3k7XjI

Marine Battery -$50.00 (Other options considered): http://www.walmart.com/ip/EverStart-...ttery/16782694

So here is my first question which should i get a PMW or a MPPT, and which model?

PWM: http://www.ebay.com/itm/20A-12-24V-A...item48574c2fe3

MPPT (Varies amount of models): http://www.ebay.com/itm/12V-24V-5-10...item54037d90be

Im aware MPPT's are much better but its a smaller system so it may be that there isn't a difference.

I will be posting further questions and progress on this. Please give me any advice that you have on DIY solar panels and whether my parts are good.

[Mike90250]

avoid building your own panels. Buy them pre-made with 20 year warranty. DIY panels end up costing as much, or more as commercial panels, and seldom last past 2 years.


What are you planning to power with it ? The HF inverter is cheap, but you pay for it being inefficient, and draining the battery. Quality inverters in the 300w range are more balanced for a single battery and small panel system.

this link http://www.solarpaneltalk.com/showth...715#post100715 is a more compact system someone else put together.

[jpsulisz]

avoid building your own panels. Buy them pre-made with 20 year warranty. DIY panels end up costing as much, or more as commercial panels, and seldom last past 2 years.


What are you planning to power with it ? The HF inverter is cheap, but you pay for it being inefficient, and draining the battery. Quality inverters in the 300w range are more balanced for a single battery and small panel system.

this link http://www.solarpaneltalk.com/showth...715#post100715 is a more compact system someone else put together.

Im aware you can buy them pre made but thats not the point, I want to do it myself for the experience and satisfaction that I've built it and it customized the way I want it to be. This is a 100 watt set of solar cells so I'm going to say it will actually output 80-90 after everything. The most I'd want to charge is my laptop (45 watts), a couple lights maybe, or a camera for a trip. I don't want to live off the grid or anything but this would be for a camping trip or to use in the garden. Again Im not looking as this to live off grid. So paying a lot of money isn't what I'm looking for.

[inetdog]

Im aware you can buy them pre made but thats not the point, I want to do it myself for the experience and satisfaction that I've built it and it customized the way I want it to be. This is a 100 watt set of solar cells so I'm going to say it will actually output 80-90 after everything. The most I'd want to charge is my laptop (45 watts), a couple lights maybe, or a camera for a trip. I don't want to live off the grid or anything but this would be for a camping trip or to use in the garden. Again Im not looking as this to live off grid. So paying a lot of money isn't what I'm looking for.

A fair analysis. But what Mike is trying to tell you is that for a total output of 100 watts, building a panel yourself from cells you buy on Flea Bay will end up costing you more for a lesser end result.
As long as you realize at the start that this will be an educational process, you can have fun and learn some things (often the hard way) building your own panels.

But the expensive part of the system will then be the charge controller, the batteries and the inverter.
If you work out a way to use a 12V DC input charger or supply for computer, phone, camera, etc. you can save the cost and inefficiency of the inverter. But you will still need batteries and a charge controller (CC).

If you look carefully at a Harbor Fright system, you will see that it does not deliver very much for the cost, although it does give you a complete system to play with.

Also, since the cells you linked to, like all silicon based cells, have an open circuit voltage of .5 volts, 25 of them will not be enough to charge a 12 volt battery. To allow for losses and the required 14+ volts required for battery charging, you will need to make a 36 cell panel.

[jpsulisz]

A fair analysis. But what Mike is trying to tell you is that for a total output of 100 watts, building a panel yourself from cells you buy on Flea Bay will end up costing you more for a lesser end result.
As long as you realize at the start that this will be an educational process, you can have fun and learn some things (often the hard way) building your own panels.

But the expensive part of the system will then be the charge controller, the batteries and the inverter.
If you work out a way to use a 12V DC input charger or supply for computer, phone, camera, etc. you can save the cost and inefficiency of the inverter. But you will still need batteries and a charge controller (CC).

If you look carefully at a Harbor Fright system, you will see that it does not deliver very much for the cost, although it does give you a complete system to play with.

Also, since the cells you linked to, like all silicon based cells, have an open circuit voltage of .5 volts, 25 of them will not be enough to charge a 12 volt battery. To allow for losses and the required 14+ volts required for battery charging, you will need to make a 36 cell panel.

Ah, I see what you mean. I've seen 3x6 cells give the same amount of voltage and assumed that a panel twice the size would give me twice the voltage. That was stupid of me to not even check that. Sorry about that. But I do know what you guys are saying. I will look into more solar cells to see what I can get for under $50.

Also, I had been looking at Charge Controllers on "Flea bay" and the "MPPT" controllers (Most under $50) are just PWMs. So I'm just going to get a PWM for the kit, even knowing the energy loss.

As for the batteries, good Gel-Based car batteries are $100, So I did some video watching and going through many forums and one man had said he bought the car batteries at places like Auto-Zone or car part stores near him half off. He asked for the batteries that have had sat on the shelves for too long and they keep them in the back until they safely dispose of them. He said they are safe, just old, and you only lose a year off your battery life. If this true or not I don't know. It does not hurt to ask though.

[Mike90250]

....
As for the batteries, good Gel-Based car batteries are $100, So I did some video watching and going through many forums and one man had said he bought the car batteries at places like Auto-Zone or car part stores near him half off. He asked for the batteries that have had sat on the shelves for too long and they keep them in the back until they safely dispose of them. He said they are safe, just old, and you only lose a year off your battery life. If this true or not I don't know. It does not hurt to ask though.

You are free to believe what you like. Gel batteries have NO place in solar, they will be quickly ruined by the solar 5 hour charging regime.
And battery life is directly related to care, if they are being sold for half off, they will give you half life.

[russ]

So I did some video watching and going through many forums and one man had said he bought the car batteries at places like Auto-Zone or car part stores near him half off. He asked for the batteries that have had sat on the shelves for too long and they keep them in the back until they safely dispose of them. He said they are safe, just old, and you only lose a year off your battery life. If this true or not I don't know. It does not hurt to ask though.

Ain't youtube wonderful - you can find any kind of baloney you want there!

[jpsulisz]

Ain't youtube wonderful - you can find any kind of baloney you want there!

YouTube, The video version of Wikipedia.

[russ]

YouTube, The video version of Wikipedia.

I have heard my wife's cousin who is a teacher complaining about students doing their research with the Wikipedia - bad things she says!

[jpsulisz]

I have heard my wife's cousin who is a teacher complaining about students doing their research with the Wikipedia - bad things she says!

I have finally ordered some parts. 40 3x6 solar cells cost me $25 on ebay. Not bad

[Shockah]

You are free to believe what you like. Gel batteries have NO place in solar, they will be quickly ruined by the solar 5 hour charging regime.
And battery life is directly related to care, if they are being sold for half off, they will give you half life.

Thank you for confirming this, Mike.

A local solar-supplier tried selling me Gel Batteries for an Off-Grid Solar Project.