Not engine or oil related...solar electric panels?

[deeter16317]

Since we've got a new house, I've wanted to add solar panels for auxiliary lighting, landscape lighting, and for charging things like cell phones, laptop, etc. (if the power goes out)... I have a generator for the big stuff, this is just something to play with and so I don't need to run the generator "all the time"...so I'm not looking at something large to power the house, or to tie into the grid.

I need some input...I'm looking at Northern Tools, they have Sharp 80-Watt panels (they have good reviews), a 30-Amp controller, and the AGM batteries (staying with an all 12-volt system). I'm considering (as a entry level, to start) two panels (160 watts total), the controller, and a 200 Amp-Hr battery. It would cost about $1400 to the door, which I don't consider too bad.

Does this sound like a good start? I would be able to add at least two if not three more panels before I exceed the capacity of the controller. I guess I just can't wrap my head around the draw versus the charge rate...two panels should produce around 10 amps (assuming 160 watts * 90% efficiency = 144 watts /13 volts = ~11 amps). A 10 amp battery charger will charge pretty much any battery (even fully discharged ones) overnight in my experience...and a 200 amp-hr battery should run a lot of LED lighting overnight??

For the smaller systems, what's everyone finding works?

 

[cchase]

Where is the 90% efficiency number coming from?

 

[A_Harman]

How long will it take the solar panels to generate enough electricity to save you $1400 in energy cost from your power company?

 

[deeter16317]

Originally Posted By: cchase
Where is the 90% efficiency number coming from?



From what I've read, panels typically lose some of their effectiveness with age...the Sharps are warranted to around a 90% efficiency for 25 years. That's where I got that number from...

 

[deeter16317]

Originally Posted By: A_Harman
How long will it take the solar panels to generate enough electricity to save you $1400 in energy cost from your power company?



I don't care...

 

[JHZR2]

I dont have a good answer to you, but Ill be watching this thread. I like your approach. We have a four-sided roof that gets pummeled with PM sun, and my thought was that it would be nice to have a few hundred watts up there just to offset the draw from an AC or the refrigerator.

Why not? If nothing else, I enjoy learning and doing stuff like this, so it would be a fun hobby. Surely better for me and my brain than spending $1400 on beer.

Thing is, all the companies want to sell a HUGE system that cuts your bill to zero and generates all youll ever need from your roof. Have a smaller roof with the right angle (like mine), and it is essentially a situation they dont even want to talk to you about.

Personally, the spot where I see a bad scenario for ROI is in getting batteries. The weight, HAZMAT, etc to me isnt worth it. I'd just want to backfeed to keep my electrical use offset, and then if my load is low enough, allow my meter to run backwards (with the correct protection against backfeeding when the grid is down, of course).

 

[JTK]

I think your about right with your thought process deeter, but that's a lot of infrastructure and cost to power some LED lighting.

You'd need more panels and batteries to reliably power anything with a motor or heating element.

Joel

 

[A_Harman]

Then you are a model customer for photovoltaic panels.
Go for it.

 

[deeter16317]

That's it for me...a hobby, something different to play around with...$1400 over 25 years? That's cheap...

I figure piecing this together will allow upgrading (essentially doubling) the output if I want to in the future...the system I'm thinking about will never be large enough to back feed our house circuit, but I can have 12-volt lighting options inside and outside. I'm thinking about when the power is out...you can shut the genset off at night, and still have enough light to see what's going on without candles burning, and enough to run a radio, charge cell phones, etc..

 

[deeter16317]

Originally Posted By: A_Harman
Then you are a model customer for photovoltaic panels.
Go for it.



What is different about this, or someone spending $14000 on a boat that they use twice a year? They enjoy it when they do, and that's all that matters. If it bothers you, then you should be belittling everyone who buys anything they can't get a ROI. Its no different than all those "projects" you have listed in your signature...same thing, you spend money on a project car, I spend money on a project house...

I don't really care if my way of thinking doesn't fit your model...

 

[deeter16317]

Originally Posted By: JTK
I think your about right with your thought process deeter, but that's a lot of infrastructure and cost to power some LED lighting.

You'd need more panels and batteries to reliably power anything with a motor or heating element.

Joel



But if I install it...the labor is cheap.

I'm thinking of even interior lighting (LED), the pump in my small fish pond, exterior lighting on the house, etc. Probably 40 to 50 lights, maybe more?

 

[JHZR2]

Originally Posted By: deeter16317
Originally Posted By: A_Harman
Then you are a model customer for photovoltaic panels.
Go for it.



What is different about this, or someone spending $14000 on a boat that they use twice a year? They enjoy it when they do, and that's all that matters. If it bothers you, then you should be belittling everyone who buys anything they can't get a ROI. Its no different than all those "projects" you have listed in your signature...same thing, you spend money on a project car, I spend money on a project house...

I don't really care if my way of thinking doesn't fit your model...



Well-said.

I figure that since the electric grid is "stiff", and a generator backup can be somewhat so, depending upon loads and transients, the solar will offset your demand to some extent. Not a bad thing to do. No rule says you have to offset it all, every last Wh of energy...

 

[JTK]

Originally Posted By: deeter16317
That's it for me...a hobby, something different to play around with...$1400 over 25 years? That's cheap...

I figure piecing this together will allow upgrading (essentially doubling) the output if I want to in the future...the system I'm thinking about will never be large enough to back feed our house circuit, but I can have 12-volt lighting options inside and outside. I'm thinking about when the power is out...you can shut the genset off at night, and still have enough light to see what's going on without candles burning, and enough to run a radio, charge cell phones, etc..


Good points. Put that way, it's not a whole lot of money.

Joel

 

[meep]

i did similar years ago, and grew to wind generation and then used an inverter to power all the lamps and TV in our basement.

1. solar panels are rated funny. They give you voltage, and amps. but amps is at full short... and wattage calculations are under ideal circumstances, ie, aiming and cold temps.

not sure what the sharp panels you are looking at are, but the black-colored single-sheet cels are the least efficient of the bunch, and the long-term use of the plastic housing is sketchy. You're much better off buying a single name-brand panel with better cells in it. If the money is too high, consider buying just the panels used for solar-powered attic fans. good output, well-built, more reliable, more durable.

2. battery. i don't think you need a 200AH AGM battery. save the money for something else--- buy a decent local marine deep cycle for $100 or so, unless you specifically want a sealed gel-cel.

3. check out homepower magazine. they've been around forever, as a grass-roots start, and have lots of advice for where you are starting.

4. a quality charge controller is important!! any diode in a controller will drop .7 volts which when dealing with solar panels is a HUGE gash in efficiency. I'd see what else is out there.

5. fuse, fuse, fuse. you are pseudo-permanently installing a power system into the house.

6. if your area has a yearly average of 6knots or greater windspeed, consider a small (1 meter) turbine. they start at $400 and go up. much more amps per dollar.

7. 24V systems are more efficient than 12.

8. flooded cels are more forgiving than gel

9. imagine a 12V or 5v distribution throughout the home. charge all of those ipods, cel phones, usb devices, power the cordless phone, whatever. even LED night lights. Low voltage wiring does have some guidelines but much easier than utility wiring.

10. a 1000W inverter is nice to have to tie in if the power goes out. xantrex cheaper models start ~ $150.

 

[wrcsixeight]

I think that 1600$ number is pretty high, even with delivery.

AGM battery in this instance will only save you the hassle of watering it occassionally. The benefits of little self discharge, variable mounting positions, and no offgassing under normal charging conditions are not worth the extra 60% $$$ for AGM.

With a flooded battery you can stick in a hydrometer and see when they are truly at full charge.

Your best bang for the buck will be 6 volt flooded golf cart batteries wired in series for 12 volts. They are a true deep cycle design. Marine batteries are hybrids, excelling at neither starting or deep cycling.

Ideally you want the solar array to be able to recharge a battery at 5 to 13% of it's rated capacity, so 2oo amp hours should get at least 10 amps, but would prefer 26.

Doing the math on my 130 watt panel, the most I have seen is 122 watts under ideal conditions, and this is with a Mppt charge controller. There is only a few hours a day when the panel can approach it's rated output, and unless you live in the desert you cannot count on the sun shining for all daylight hours.

I'd shop around for individual components. The kits are overpriced and designed to take advantage of the less knowledgeable, who will have gained said knowledge by the time it is fully installed

 

[deeter16317]

Originally Posted By: meep
i did similar years ago, and grew to wind generation and then used an inverter to power all the lamps and TV in our basement.

1. solar panels are rated funny. They give you voltage, and amps. but amps is at full short... and wattage calculations are under ideal circumstances, ie, aiming and cold temps.

not sure what the sharp panels you are looking at are, but the black-colored single-sheet cels are the least efficient of the bunch, and the long-term use of the plastic housing is sketchy. You're much better off buying a single name-brand panel with better cells in it. If the money is too high, consider buying just the panels used for solar-powered attic fans. good output, well-built, more reliable, more durable.

2. battery. i don't think you need a 200AH AGM battery. save the money for something else--- buy a decent local marine deep cycle for $100 or so, unless you specifically want a sealed gel-cel.

3. check out homepower magazine. they've been around forever, as a grass-roots start, and have lots of advice for where you are starting.

4. a quality charge controller is important!! any diode in a controller will drop .7 volts which when dealing with solar panels is a HUGE gash in efficiency. I'd see what else is out there.

5. fuse, fuse, fuse. you are pseudo-permanently installing a power system into the house.

6. if your area has a yearly average of 6knots or greater windspeed, consider a small (1 meter) turbine. they start at $400 and go up. much more amps per dollar.

7. 24V systems are more efficient than 12.

8. flooded cels are more forgiving than gel

9. imagine a 12V or 5v distribution throughout the home. charge all of those ipods, cel phones, usb devices, power the cordless phone, whatever. even LED night lights. Low voltage wiring does have some guidelines but much easier than utility wiring.

10. a 1000W inverter is nice to have to tie in if the power goes out. xantrex cheaper models start ~ $150.






The Sharp panels are glass with aluminum frames, they have a good user review on several sites...

High-power solar module using 125mm square multicrystal cells with 12.60% module conversion efficiency

Modules come with bypass diode to minimize the power drop caused by shade conditions

Textured cell surface to reduce the reflection of sunlight and BSF (Black Surface Field) structure to improve cell conversion efficiency: 14.11%

I was figuring the 200Ahr battery for those cloudy days...its actually the best bang for the buck. I can't use a non-sealed battery that's off gassing because I have propane appliances with pilot lights...I have three large lead-acid batteries sitting in my garage right now, but can't use them for that reason.

I do understand fusing, that's not a problem...but I want to stay with 12-volt because its easier for me to adapt to it.

I was planning on running 12-volt into the rooms for backup lighting, etc...not just outside. Where I live, we either have 70mph winds, or nothing...I don't think wind will work for us. I have a small inverter, will probably pick up a larger one later on...this will be a work in progress as we see the need.

 

[deeter16317]

Originally Posted By: wrcsixeight
I think that 1600$ number is pretty high, even with delivery.

AGM battery in this instance will only save you the hassle of watering it occassionally. The benefits of little self discharge, variable mounting positions, and no offgassing under normal charging conditions are not worth the extra 60% $$$ for AGM.

With a flooded battery you can stick in a hydrometer and see when they are truly at full charge.

Your best bang for the buck will be 6 volt flooded golf cart batteries wired in series for 12 volts. They are a true deep cycle design. Marine batteries are hybrids, excelling at neither starting or deep cycling.

Ideally you want the solar array to be able to recharge a battery at 5 to 13% of it's rated capacity, so 2oo amp hours should get at least 10 amps, but would prefer 26.

Doing the math on my 130 watt panel, the most I have seen is 122 watts under ideal conditions, and this is with a Mppt charge controller. There is only a few hours a day when the panel can approach it's rated output, and unless you live in the desert you cannot count on the sun shining for all daylight hours.

I'd shop around for individual components. The kits are overpriced and designed to take advantage of the less knowledgeable, who will have gained said knowledge by the time it is fully installed



This is individual components...not a kit. I was looking at the kits, and I wasn't impressed with the quality of the individual components. Edit: Its $1400 shipped to my door.

As noted above, I need a sealed battery...don't really have the option. Its either a AGM that sits in my basement at a controlled temperature or its a lead-acid that sits outside in temps ranging from -20*F to 105*F.

 

[deeter16317]

Ok, they changed the rating of batteries since I last looked.

Assuming a 20 watt draw, how long would a battery rated at 100 amps @ 20 hours last (useable)?

 

[wally6934]

For run time on battery’s go here.

http://www.donrowe.com/inverters/inverter_faq.html

On that page search for this about 60% of way down.

How long can I run the inverter on my battery?

They have a handy dandy calculator that says 25 hours run time for 20 watts draw on a 100 amp Hour battery.

 

[deeter16317]

Originally Posted By: wally6934
For run time on battery’s go here.

http://www.donrowe.com/inverters/inverter_faq.html

On that page search for this about 60% of way down.

How long can I run the inverter on my battery?

They have a handy dandy calculator that says 25 hours run time for 20 watts draw on a 100 amp Hour battery.





See that's how I know the ratings...you have a capacity in Amp-Hrs, and with so much draw its a simple calculation for duration of use. But I'm seeing these new batteries rated at 100 Amps @ 20 hours, one I saw was compared to 24 hours...or doesn't that really mean anything different?

Someone mentioned MPPT technology for the charger...that nearly triples the cost of the charger. However, I found a place selling kits (I know, individual components) in the 450 watt range, with the MPPT technology charger, Kyocera panels, wiring, and breakers for about the same money as my component 160 watt kit...short the battery. So it offsets, and I essentially triple the power output...

So we may go that route. That would require the battery, based on comments in this thread, to be about 200 amp-hr (assuming 450 watts at 13 volts is about 34 amps produced (this is just a rough number)...that would be a little less than 20% of the batteries capacity (if I understood that description)?

What does everyone do for mounts? Buy or build?