Trying to build a simple solar system, but need some help

[zcapozzi]

Hi all,

My goal is to create a simple system with one panel that can power a laptop (90W) for at least one hour per day. My current equipment plan is:

RENOGY 100 Watt 100w Monocrystalline Photovoltaic PV Solar Panel Module 12V
Concorde Sun Xtender PVX 340T AGM Solar Battery (34Ah)
Morningstar SunSaver SS-10-12v Charge Controller 10A 12V
Samlex America (SSW35012A) SSW 350W Pure Inverter ---- OR ---- MORNINGSTAR SURESINE INVERTER-300W, 115V 60HZ UL

I'm not trying to spend a ton as this is more for experimenting and so that I can learn how these things work in advance of perhaps one day installing a whole home system.

Assumptions:
1. Because I'm powering a laptop, I need to use the pure sine inverter
2. Morningstar is a superior brand (in terms of quality) to Samlex
3. AGM batteries are the best type for simplicity and lack of maintenance requirements
4. This set up will provide me with at least 90Whrs per day to run the laptop assuming at least 2 hours average sun (I live in Chicago)
5. The inverter is the most important component to choose from a quality and reliability perspective

I'd love to get some feedback on my assumptions so that I can start to adjust my plan as necessary. Again, my primary goal is to generate electricity from a solar panel and run my laptop off of it for at least one hour per day. This is not a system that needs to power a home.

Thanks in advance.

- Zack

[Sunking]

Zack I will try to help out here and maybe save you a coin or two.

First point I want to make is it is extremely unlikely your laptop uses 90 watts. If it does it is the only laptop on the face of earth that does that. I assume you got this information off the Power Brick. Th epower brick is over sized so it can do two jobs at once. One function, th ebig on eis recharge the battery in only a few short hours. Second function is to power the laptop while th ebattery is also being charged at the same time. In reality the laptop only uses 20 to 30 watts at most.

Second point or suggestion is to dump the inverter idea. You do not need it to run your laptop. Any Laptop sold today has an optional Power Brick to run off 12 volt DC. The Power Brick I have has two power inputs. One for 12 volt DC with a cigarette lighter plug to plug into a car power port as they are called today. Seems Cigarette Lighter is not Politically Correct today and changed the name to Power Port.. It also has a standard 120 VAC input. All you have to do is get one of the DC power bricks, and cut off the Cigarette Plug and wire it directly to the 12 volt battery terminal post.

So now if you use the 100 watt panel, and 10 amp controller, with a 35 AH battery you will be able to run your laptop for a lot longer than 1 hour per day. Even with a 2 Sun Hour you are looking at around 5 to 6 hours.

[zcapozzi]

Thanks Sunking,

Didn't even consider that the 90W would be a peak estimate, not an ongoing need. But you make a very good point about the brick needing to charge as well as power. I've always been impressed with how quickly the battery on this thing gets back to 100%; I guess that's why.

So that changes my scope a bit. Your recommendation about not needing the inverter makes a lot of sense, but if I'm going to have excess electricity to use, I'd rather use it to charge electronics (cell phones, iPads, etc) than run the laptop longer. If I'm going to be using chargers and potentially small appliances like lights, then I would need an inverter?

I think this is my biggest remaining question:

I want to have a high quality, reliable system, even though it's going to be small. I'm more concerned with having a good system than with saving a few bucks (although let's not get crazy). So assuming that I need an inverter, do I need the $250 Morningstar SureSine 300W ( or comparable ) or will something like the Samlex SSW 350 meet my needs. I'm struggling to understand whether the difference in price is based on quality/reliability or whether it is based on features. If it's features, will I need the features that come with the Morningstar product?

Other questions to get to later:
1. What is the deal with wires? I assume it's more than picking up a standard wire from a hard ware store.
2. Best vendors to buy this stuff from (I've seen suppliers like AltE Store, MCM Electronics, Rakuten.com, BackwoodsSolar, Northern Arizona Wind & Sun, Impact Battery, The Energy Conscious)

[Wy_White_Wolf]

...I'd rather use it to charge electronics (cell phones, iPads, etc) than run the laptop longer. If I'm going to be using chargers and potentially small appliances like lights, then I would need an inverter? ...

Everything listed can be either run from 12VDC or charged from 5VDC. Going from 12vdc to 5VDC might not be the most efficient but it will be better than an inverter for such small loads. Dump the inverter unless you absolutely need it.

WWW

[zcapozzi]

Everything listed can be either run from 12VDC or charged from 5VDC. Going from 12vdc to 5VDC might not be the most efficient but it will be better than an inverter for such small loads. Dump the inverter unless you absolutely need it.

WWW

Interesting. And with a DC-to-AC adapter, I wouldn't need to worry about waveforms, correct? So I guess what you all are saying is that until I need to run something that needs it, just use an adapter rather than an inverter? Can you give me an example of something that would require an inverter? Also, just trying to ball park an adapter set up like this; does $24 sound right for the two products listed below?

A quick search found these products:
http://www.cpapsupplyusa.com/UV-7019...FbDm7AodBlgAtw (for connecting to the battery)
http://www.rakuten.com/prod/dc-to-ac...ingId=94443158 (for converting that into a socket)

Are there any risks that I run from using a DC-to-AC adapter rather than a DC-to-AC inverter?

[Sunking]

Are there any risks that I run from using a DC-to-AC adapter rather than a DC-to-AC inverter?

Huh? They are both the same thing.

[zcapozzi]

Huh? They are both the same thing.

My understanding is that yes, they both will take in 12V DC and provide an outlet for a typical charger so that I could charge a laptop or phone. But obviously, they are designed to do it in two different ways ( and at 2 different costs ).

Two options would be:

DC to AC Universal Power Car Charger Converter Adapter is designed to plug into a car battery outlet in a vehicle. It costs $5.
On the other hand, the Morningstar SI-300-115V-UL SureSine Inverter still provides the connection between DC and AC, but it costs $200.

I assume for $200 you get either reliability, safety, efficiency, or something, right?

[inetdog]

DC to AC Universal Power Car Charger Converter Adapter is designed to plug into a car battery outlet in a vehicle. It costs $5.

If you look at the specifications, that DC to AC Universal Power Car Charger Converter Adapter has an output power of only 5 watts. That is not enough to reliably run most AC input chargers for cell phones, etc.

Since most cell phones these days are designed to be compatible with charging from a USB connection on a computer or other charging power supply, you would be much better off getting a unit which plugs into the car battery outlet and gives you a USB (power-only) outlet to connect the cell phone charging cord to.

[zcapozzi]

If you look at the specifications, that DC to AC Universal Power Car Charger Converter Adapter has an output power of only 5 watts. That is not enough to reliably run most AC input chargers for cell phones, etc.

Since most cell phones these days are designed to be compatible with charging from a USB connection on a computer or other charging power supply, you would be much better off getting a unit which plugs into the car battery outlet and gives you a USB (power-only) outlet to connect the cell phone charging cord to.

Good point. Is the unit that you described ("plugs into the car battery outlet and gives you a USB (power-only) outlet") a similar type of adapter to the one that you linked to or is that an inverter (i.e. Samlex SSW or Cobra)? Any chance you could share a link describing one of those?

I found out that a buddy might have a Cobra inverter that he doesn't use. His is 400W and has an extra 5V USB outlet also. So I'd be back to a modified square wave inverter, but at least it's going to give me the wattage I need to charge phones and run laptops. I was a little excited that I might not need an inverter at all yet, but at least I've got an option.

[inetdog]

Good point. Is the unit that you described ("plugs into the car battery outlet and gives you a USB (power-only) outlet") a similar type of adapter to the one that you linked to or is that an inverter (i.e. Samlex SSW or Cobra)? Any chance you could share a link describing one of those?

This is the cheapest one which showed up on a Google search (car to usb charger adapter), but I am not recommending it or saying anything beyond that. There are also some which cost up to $30 in the same search.
Look specifically at the output specifications, whether they are listed for iPhone, iPad, etc. The iPad takes a lot more current to charge or operate than the iPhone.

[zcapozzi]

Thanks all for the tips. I appreciate all the advice.

Next round of questions. A big part of the reason that I'm excited about this is being able to see how much power I've used/created from my solar set up (and didn't need to pull from the grid). Are there any components that I can use to log the amount of power that I pull off the panel and store in the battery?

Ideally, it would be something that transmits usage statistics to a web server that I have set up. Any suggestions?

[inetdog]

Thanks all for the tips. I appreciate all the advice.

Next round of questions. A big part of the reason that I'm excited about this is being able to see how much power I've used/created from my solar set up (and didn't need to pull from the grid). Are there any components that I can use to log the amount of power that I pull off the panel and store in the battery?

Ideally, it would be something that transmits usage statistics to a web server that I have set up. Any suggestions?

You will find several types of battery monitor or energy monitor described in various threads here, and you can also search the solartown.com website. But all of the ones that I am aware of will be quite expensive.
If you are an electronic and computer hobbyist too, you can use a small dedicated computer such as one of the Arduino family, with open source software, to collect data from voltage inputs from the battery voltage and the voltage across a current shunt. Not simple or cheap, but less expensive and more customizable than a commercial product.

[zcapozzi]

You will find several types of battery monitor or energy monitor described in various threads here, and you can also search the solartown.com website. But all of the ones that I am aware of will be quite expensive.
If you are an electronic and computer hobbyist too, you can use a small dedicated computer such as one of the Arduino family, with open source software, to collect data from voltage inputs from the battery voltage and the voltage across a current shunt. Not simple or cheap, but less expensive and more customizable than a commercial product.

Very interesting. I've got a programming background, so that would be perfect. Once I get up and running, I'll definitely invest in one of the Arduino components.

On to wiring:

Wanted to make sure I'm not going to put too much current through my wires. I understand that I need to wire the panel to the controller, then the controller to the battery. There would be separate alligator clips and wires for connecting my adapter/inverter to the battery, but that's a separate issue.

I'm planning to put the solar panel about 15 feet from my charge controller and battery. The panels are 100W (12V; 8.5 amp), the battery is a 34 aH 12 V AGM (Concorde Sun Xtender), and the charge controller is a Morningstar 10A 12V PVM controller. The charts that I've seen suggest a 15 gauge copper wire for this set up, and it would be the same gauge for both panel to cc and cc to battery.

Also, I'm a bit unclear about grounding. I'll be installing this panel on a patio with lots of metal railing that go to the building and in theory to ground. My thought was to connect some part of the metal frame to a metal railing via a covered 15 gauge copper wire. I've also got an ohm meter, so I'll be able to check some of the other wiring components once they are on. However, I've never used an ohm meter before, so any tips there would be appreciated.

- Zack

[Mike90250]

.... I've got a programming background....

......The charts that I've seen suggest a 15 gauge copper wire for this set up, and it would be the same gauge for both panel to cc and cc to battery. .... Don't forget the fuses!

....Also, I'm a bit unclear about grounding. ......However, I've never used an ohm meter before, so any tips there would be appreciated. - Zack

You should really look into a basic electricity followed by a basic electronics class. Maybe there is something on-line you can do. (MIT has a whole bunch of stuff online, free)

Trying to cover this is way beyond the scope of this website. We can say things, and tell you how to do them, but you need to have some basic knowledge so we can communicate.

[zcapozzi]

You should really look into a basic electricity followed by a basic electronics class. Maybe there is something on-line you can do. (MIT has a whole bunch of stuff online, free)

Trying to cover this is way beyond the scope of this website. We can say things, and tell you how to do them, but you need to have some basic knowledge so we can communicate.

Thanks for the tip Mike. I was an engineer in college, so I went through EE classes and have the basic (if not a little rusty) understanding of how everything works. I also worked a summer with an electrician, so I'm fully aware of the seriousness of electricity and how it works.

Is there something in particular you sensed I didn't understand (perhaps my grounding idea)? I was pretty confident in my plan and looking for validation more than anything, but if you think there's something I need to go understand better, happy to do it and then come back.