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Solar panels?

Started by sbishop, May 11, 2013, 06:41:14 PM

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sbishop

Hi folks...its been a few months since i posted anything but i'm still looking around! ;)

i'm getting ready to install a couple of small solar panels 15W each. they have been sitting in the box for 2 years now..so its time to get them on the roof. i've got a 1500w inverter and charge controller. Pick up 2 deep cycle 12V 110 AH batteries last night so i'm set to go. This setup is just for a small tv and maybe a few lights at the camp.

So my first question is what size wire should I run from the panels to the controller? it will be no further then 40ft. Is 12/2 wire over kill? the reason i ask is that i have some in hand.

Second question is how long will it run a tv and sattelite receiver? each take .6amp...so total of 1.2amps, is it correct to say that it will run 12amp at 12v? if the batteries are 110AH and i've got 2 would that mean i would get approx 18hrs?

At what point will my inverter stop working? at what voltage?

any guess on how long would it take to rechage the batterries?

Thanks for all the info.
Sbishop

Ianab

I'd run the heavier wire if you have it. Heavier gauge, less resistive loss. I suspect you will want to add more panels in the near future as 30w isn't a lot of power, maybe get 2 amps @ 12 volts? The 30w is best case. When the sun isn't overhead, or there is a bit of cloud it will be less.

Your run time maths is correct in a perfect world, but the inverter isn't 100% efficient. Might lose 10-20% of the power it converts. Takes you back to maybe 14 hour run time? Still useful of course. Inverter should cut out at maybe 11 volts? You don't want to suck the battery 100% flat as that tends to kill them.

Charge time? Pretty long. Batteries also aren't 100% efficient. You probably need to charge 130 a/h into them to get the 110 back out. Two amp charge? That's something like 65 hours of good sunshine, maybe twice that amount of daylight? It will get them charged, and keep them topped up, but you are probably only going to collect a couple of hours TV time per day.

To get them close to charged in a day would need more like 200-300w of panels? Hence the suggestion to run the heavier cable now.

For the lights I'd be looking to run 12v led lamps directly off the batteries. They are very efficient, and you don't waste any extra power in the inverter. Look at the RV and boat accessory places as they are becoming pretty standard in those markets

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

sbishop

So there no extra loss for using the larger wire?

our plan is too have enough for a few hrs in the evening for the kids to watch...and me too  ;D

Any suggestions on how to mount it on a 9/12 metal roof....attach it directly or have them propped up a bit?

i know 30w isn't much but its a start..maybe add a few more panels..but hopefully some day i can run a water wheel with a PMA from the river which is only 50ft away.

Thanks Ian

Ianab

Less loss with bigger wires. Think of it the same as a water pipe. If you use a larger dia, it restricts the flow less. A pipe that's too small makes back pressure and slows the flow. Same with electricity through a wire.

Angle of the panel? Ideally you want it 90 deg to the sun. On average this would be the same as your latitude. But if you wanted to be clever you could make an adjustable mount with summer and winter positions and get a few more watts.

What you have should work if it's a weekend camp. Build up enough charge during the week to give you a few hours power in the evening. Will power a couple of small LED lamps for quite a while. 10w of LED is a respectable sort of lamp.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

jdonovan

Quote from: sbishop on May 11, 2013, 06:41:14 PM
So my first question is what size wire should I run from the panels to the controller? it will be no further then 40ft. Is 12/2 wire over kill? the reason i ask is that i have some in hand.

you can look up volt drop tables... most you find are for AC, when using them for DC double the drop the table shows.


QuoteSecond question is how long will it run a tv and sattelite receiver? each take .6amp...so total of 1.2amps, is it correct to say that it will run 12amp at 12v? if the batteries are 110AH and i've got 2 would that mean i would get approx 18hrs?

Depends... generally batteries are rated at c/20 rate. That means full discharge over 20 hours. If you pull 2x the C/20 rate, you will not get 1/2 the run time, you get less as the battery has to work harder to supply the current, and more is lost to heat.

Most battery makers have discharge charts available and you can use it to approximate what your battery might do.

QuoteAt what point will my inverter stop working? at what voltage?

RTFM.  Usually about 10.5 volts.

BUT you really really don't want to discharge them that low. A battery is good for X full discharges. But if you only discharge to 50% you may get 300% more life.

Quoteany guess on how long would it take to rechage the batterries?

Figure your panels will put out about 4-5 hours of 'equivalent' hours of charge on a sunny day. So 1 15Watt panel will put about 3-4 AH per day into the battery. You've got a loss of about 10-20% when charging, vs direct use from the panel.

Hopefully you're using a deep cycle/marine battery not a starting battery. A starting battery might only give you 50-100 discharge cycles before its done. A deep cycle might give you 10 times that.

trapper

what about dc tv.  My buddy has one in his cabin.  Inverter not needed.
stihl ms241cm ms261cm  echo 310 400 suzuki  log arch made by stepson several logrite tools woodmizer LT30

mad murdock

Quote from: trapper on May 12, 2013, 08:30:43 AM
what about dc tv.  My buddy has one in his cabin.  Inverter not needed.
good point. If you are running a limited circuit anyway, if you can stick with DC all the way, you will not take such a hit on efficiency.
Turbosawmill M6 (now M8) Warrior Ultra liteweight, Granberg Alaskan III, lots of saws-gas powered and human powered :D

Ljohnsaw

I plan on doing all 12v in my cabin.  The power company wanted $1,000 to just look and give me a proposal for power.  Their average installation was between $10k and $45k!! :o

So, I'm doing LED throughout, no microwave and propane stove/oven and water heater.  What else do you need?  There is no TV reception but I will probably have an RV TV with DVD/BluRay for the evening/bad weather days.

At the rate the solar panels are improving, by next year, I figure two large panels (3x5 or so) will put out 300w each.  I'll run a 24v system to the batteries (to lessen losses) and no more than 25' to any power outlet/light.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

mad murdock

Lehman's even sells kerosene refrigerators if propane is not readily available. Amazing the things that are had these days to lessen ones need on electricity.
Turbosawmill M6 (now M8) Warrior Ultra liteweight, Granberg Alaskan III, lots of saws-gas powered and human powered :D

John Mc

Quote from: ljohnsaw on May 12, 2013, 12:50:46 PM
At the rate the solar panels are improving, by next year, I figure two large panels (3x5 or so) will put out 300w each.

SunPower already makes 345 watt panels.  However, they're a lot more expensive per watt than the more commonly available 250 watt panels.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

maple flats

What is the rating schedule on your panels? There should be a label showing Pmp (power, maximim power, in watts), Vmp (volts at max power), Imp, amps at max power, Isc, amps short circuit and Ptol, power variation panel to panel. I believe your 15 watt panels are going to be something like Pmp 15W, Vmp 15V, Imp 1amp, Isc 1.1A and Ptol maybe 0%/-5%. Am I right. If yes, you can figure 30 watts (connect in parallel) at 15V to calculate loss. At 40' if these numbers are correct you will lose2.6% with 16 ga, 1.63% with 14 ga, 1.02% with 12ga and .64% with 10 ga.
Regardless of whether my label guesses are correct, you can see the relationship as the wire ga gets larger. Bigger wire has less loss. These numbers are at 40' and they change as that number gets bigger or smaller. The main thing it to realize that at 30 watts you have very little you can afford to lose. The heaviest wire you can afford will net you the most usable power. The second thing is how you use it. If you are all DC you lose nothing in inverting to AC.
At best you will maybe be able to run an hour or 2, but only on days that had good sun. If you draw a battery down too low you ruin it. I would really suggest you try to get a bigger panel. Did you buy these thru Harbor Freight? You can do better. Go to a solar vender site and just look up their best price for several small size panels (I use a 50 watt just to charge my tractor batteries, both 12V, and I use a MPPT charge controller to regulate the charge and I only charge one at a time, I also have 6320 watts solar that sends excess power to the grid along with 1480 of those watts connected to a MPPT (maximim power point) charge controller to maintain a 48V battery bank for backup  but it normally sells excess to the grid., overcharging will ruin a battery too.grid. If you are small, you can connect directly and use no charge controller. If you get a bigger panel be careful to determine if it can overcharge the battery.
Be careful, if you just want to keep it simple, go with very basic system approach, everything you add will refine the system, but also starts making the price climb rapidly. (point in case, I first ordered 1 panel at 150 watts, 5 yrs later I had 6320 watts, grid connected and had spent over $32,000 US before tax credits and incentives that only happen if you are grid tied.)
logging small time for years but just learning how,  2012 36 HP Mahindra tractor, 3point log arch, 8000# class excavator, lifts 2500# and sets logs on mill precisely where needed, Woodland Mills HM130Max , maple syrup a hobby that consumes my time. looking to learn blacksmithing.

sbishop

Sorry guys for not replying...my back gave out shortly after this post and i'm just getting around..feeling a lot better today.

Looks like i should get a few more bigger panels...again i'm just trying to recharge my batteries during the week while i'm not there....i plan on not running my batteries below 12.0V...every year i'll add a battery or two and make this a little bigger each year..thanks all that responded!

jdonovan

Quote from: sbishop on May 30, 2013, 08:28:00 PM
Looks like i should get a few more bigger panels...again i'm just trying to recharge my batteries during the week while i'm not there....i plan on not running my batteries below 12.0V...every year i'll add a battery or two and make this a little bigger each year..thanks all that responded!

mixed age batteries are not a good plan. The when the older battery starts to fail it can damage the whole bank of batteries.

240b

I own an off the grid house which I lived in full time for 6 years up until last year. My advice is figure out what you think you need and double it as far as capicity. Than install that much. It will only cost you more in the end trying to piece meal it.
(guess how I know).  Juice off the grid is the best thing going. If I was able I'd tap into it. But it was over 150k to run the service. The property was unique enough to bother building on..    Also I'd recommend a mix of wind and solar if the site is suitable..( the wind usually blows when the suns not out)

beenthere

240b
Where was that at?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

thecfarm

Same price for power here too. About 25 years ago.  ::)  4-5 people went in on it and paid to put it in. Than 15 years later I had a home built here.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

240b

VT, guy from co-op ball parked it for me.  Its about 3/4 mile thur woods to service, but they will only run new lines along the town ROW now. which makes it a most 5 miles to nearest pole.  Plus if I brought it in that way most likey a few new houses are going to pop up on the road. I am 3/4 mile past end of town row and the town road is a class 4 dead end.  Plowing snow stinks but its the price u pay.

SwampDonkey

I see no fairness in the first guy taking the hit to install power. The power company up here rebates the first guy for each additional transformer from others coming in. Which is a fair system I'd say.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

John Mc

Power company here does the same thing. It's been almost 12 years since we put in the line, but if I remember correctly:   If someone taps on to the line you put in, you get a rebate based on home much of your line they used.  For example, if they tapped in 2/3 of the way down, and were the only other person on that line, they would pay 1/2 of the cost of that 2/3 of the line. 

There is a time limit, if I recall.  What sticks in my mind is 7 years, but I may be off on that.

Unfortunately, there is no such provision for roads.  The town would not open up the 400' of their right-of-way, to the point where our driveway splits off, so we got to do that one on our own (We also get to maintain it).  When someone else built and used about 375' of that road, we got nothing.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

240b



Unfortunately, there is no such provision for roads.  The town would not open up the 400' of their right-of-way, to the point where our driveway splits off, so we got to do that one on our own (We also get to maintain it).  When someone else built and used about 375' of that road, we got nothing.
[/quote]

The joy of sharing a class 4 road. The section I share only gets fixed enough to be passable and the rest which I don't share is better than the town highway.  Yeah the power co-op will pro rate the cost if some one taps into it with seven years, but you still have to lay out the $$ to start with and I know of two people who are waiting out the seven year period to the day.

maple flats

When my brother and I built an office, workshop several hundred feet down a road from the grid power, we had to pay $5500 back is 1990. I think it was about 700' down the road. We got 1/3 back for each of the first 2 new homes to build, which followed 3-5 yrs later. There are now 4 others on that road. We never got more back than the 2/3 of the original.
That price is now much higher. Last year I had to pay a little over $28.00 per ft to run new lines to my sugarhouse for a 240' run. I got the 1st 100' free and had to pay $28.00+ per foot for the next 140'. I then ran another 230' underground to my sugarhouse, connected solar power to net meter into the grid. Even though I have carried a net flow toward the grid all but 1 month, I still have to pay a line delivery charge to the grid of $22.93 each month. It seems like they should be paying me, it is flowing towards them more than towards me. The utility just has total control, and charge for as much as the public service commission (PSC) allows. It seems like the PSC should not allow them to charge me to deliver power to them.
logging small time for years but just learning how,  2012 36 HP Mahindra tractor, 3point log arch, 8000# class excavator, lifts 2500# and sets logs on mill precisely where needed, Woodland Mills HM130Max , maple syrup a hobby that consumes my time. looking to learn blacksmithing.

John Mc

That $22.93 is most likely what you are paying them to maintain the lines, read the meter, and handle the account administration for your account.

Here in VT, if you generate more than you use, the credit can be applied to the flat monthly charge, as well as to any future net electrical usage. Any crdit more than 12 months old basically becomes a gift from you to the utility.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

JSNH

In New Hampshire the monthly fee is $11.50 if you use no electricity. Any surplus you build up a khw credit for the future. None can be applied to your monthly bill. I had 1500khw of surplus but used it up over the winter. I am back to overproducing and building up a credit again.

maple flats

I was at 1400 KWH credit about 2 days ago. In the months since I installed the system my only month that was not in the credit balance was last December. My system was activated on net metering Nov 26, 2012. Once we build our home there the tide will turn.
logging small time for years but just learning how,  2012 36 HP Mahindra tractor, 3point log arch, 8000# class excavator, lifts 2500# and sets logs on mill precisely where needed, Woodland Mills HM130Max , maple syrup a hobby that consumes my time. looking to learn blacksmithing.

mad murdock

If you are running LED lights on 12V, you can purchase standard service 115VAC LED's and put in a Joule lamp (Oscillating Tesla Coil), that will effectively run in the instance linked, up to 12 LEDs, and pull only about 22-24 watts of power.  Very effective way to increase light without breaking the potential of your off grid system
https://www.youtube.com/watch?v=3C-WW9gd8SM

and the 2nd part of this how to
https://www.youtube.com/watch?v=GWq5uDdiQzE:
This guy has a lot of how to's that he has posted on youtube, and I have found his videos very instructional and realistic.  He admits right off that there is no such thing as something for nothing, so he is not claiming unreal results, IMO.
Turbosawmill M6 (now M8) Warrior Ultra liteweight, Granberg Alaskan III, lots of saws-gas powered and human powered :D

Ljohnsaw

This is a really nice video / build.  Looks very doable.  My question is, why?  With the availability of LEDs for automotive (12v dc), why bother converting 12v to 120v?  Yes, you can use smaller wire to carry the amps but the LEDs draw so little, current draw should not be a problem.  I replaced 5 incandescent lights in my trailer with LEDs - Brighter and use less than one of the old bulbs.

Also, I wonder what the power curve looks like.  Is is a sawtooth 120v pulse at some crazy frequency?  Probably useless for any other purpose than lighting a light bulb.  But still, really cool idea.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Thehardway

Lot's of good advice here.  I would chime in on doing as much with straight 12V as possible.  It is much more efficient. You can run all of your lights, TV, a DVD/blu-ray and an array of other appliances made specifically for 12V.  A good source for these is an RV supplier. 

12V LED lights can be found for low voltage outdoor landscape lighting in an array of styles.

Size your panels, charge controller and battery bank for your average load, not your peak load.  Use a small generator for your large incidental peak loads.  For example, trying to size a solar system to run my welder, saws or my planer would be silly.  It is much more cost effective to have a small generator available and a few AC circuits to power large, short term loads and stuff that does not run continuously.

There are some youtube videos out there which show how to convert some old UPS units to work as an inverters.  This is a cheap way to get useable AC power from a battery bank if you are not grid tied.

There are some tricks to getting grid power run to your house more affordably.  One is installing 4" conduit on your own.  If it buried to the appropriate depth and has pull points at correct distances, they will usually run the wire at cost.  This can offer significant savings and also keeps them from having to maintain large power easements trimming trees, etc.  Some basis of the cost calculation is done on the potential for electric sales.  This means when you do your load calculation, don't skimp.
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

mad murdock

Quote from: ljohnsaw on August 04, 2013, 12:32:22 PM
This is a really nice video / build.  Looks very doable.  My question is, why?  With the availability of LEDs for automotive (12v dc), why bother converting 12v to 120v?  Yes, you can use smaller wire to carry the amps but the LEDs draw so little, current draw should not be a problem.  I replaced 5 incandescent lights in my trailer with LEDs - Brighter and use less than one of the old bulbs.

Also, I wonder what the power curve looks like.  Is is a sawtooth 120v pulse at some crazy frequency?  Probably useless for any other purpose than lighting a light bulb.  But still, really cool idea.
They are stricly to power lights, the reason you would want one is that they will light the same number of bulbs on about 1/3 the power. 
Turbosawmill M6 (now M8) Warrior Ultra liteweight, Granberg Alaskan III, lots of saws-gas powered and human powered :D

OlJarhead

I run 615watts of solar with 880ah of battery bank and a 2500watt modified sine wave inverter -- I expect to get 2-3 days without sun, perhaps 4 if I'm not too greedy.

Just a quick read of your system and I'm thinking:  no.  It's not nearly enough to run a TV for a few hours in the evening.

There are calculators out there which can help with sizing but I think you are asking a lot of what you're putting together.

Just my 2c
2016 LT40HD26 and Mahindra 5010 W/FEL WM Hundred Thousand BF Club Member

Ianab

I just looked at our little TV in the bedroom, new Akai 22", with a DVD player built in. Low and behold, it runs on 12V (3 amps) and has a little laptop type brick to power it.  So it would work fine of a 12V system, no inverters, no power loss etc.

This is just a standard LCD TV that you can buy from any appliance store, nothing fancy or expensive.

Same with lighting, go 12v LED there too. LEDs are inherently a low voltage device, each individual LED needs about 3 volts applied across it. So a 120V LED will have some fancy electronic in there to step the voltage down. Extra cost and wastes some power. A 12V led lamp is more likely to just use 4 x individual LEDs in series, and some very simple circuitry to prevent an over-current meltdown.

Now whether your panels will supply enough power to keep the batteries topped up is debatable, but I'd think that a week of charging would have them pretty much topped up. Then if your TV and lights are only drawing about 5 amps (?) that's plenty of run time for the weekend.

You can always upgrade to a ~300w panel, and would then have plenty of power for a light electrical load.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

maple flats

Panels are cheap now. My first panels were $3.00/watt (5-6 yrs ago), non UL panels, last year I added 4830 watts @ $1.75/watt, UL panels. I now have 6.32 KW solar dual system. Check the prices carefully. Don't buy from the so called cut rate companies, their prices are much higher than many other sources. PM me and I'll give you a link to compare prices across the board, hundreds of panels and dozens of vendors.
Adding more panels is by far the cheapest way and keeping away from an inverter if possible helps. A top notch MPPT charge controller is between 95-98% efficient, a PWM controller is at best 50-60% efficient. A cheap inverter is less than 50% efficient, a good pure sine wave inverter is about 97% efficient. These efficiencies however don't come cheap. My first good inverter (an Xantrex 6048, 6000 watts constant, 12,000 watts surge) now on 1480 watts with a battery bank and set to sell excess power by net metering ran $3400+ frt 4 yrs ago. My second inverter is a Fronius 5KW , no battery bank, inverts to 240V was about $2800 + frt. Both of these inverters are at or above 95% efficient, the higher efficiencies are when the inverter is at higher wattages in it's rated size range. Before I got the XW 6048, I got educated in solar, (school of hard knocks + the internet) I bought a cheapo 2500, 5000 surge watt inverter for $279+ shipping. Efficiency, ~40%!
Anytime you can stay with all DC you lose none of these inefficiencies in the inverters. To make the most of your array you do need a MPPT (maximum power point tracking) charge controller, without one you will throw away about 1/2 of the energy the panels generate.
Next, make sure you mount the panels in full sun. Any shade radically drops the power generated. You might think if 25% is shaded you will get 75% of the watts, not so, even a 10% shading drops the wattage produced by over 80%. Full sun is needed. Try to face the panels towards solar south and mount them at the degrees of latitude for your location for tilt. I.E. 43 degrees latitude is mounted at 43 degrees tilt angle for year round, if you use this mostly in the summer, lower the angle about 10 degrees and if mostly in the winter raise it about 10 degrees. When I first started my solar system I was off grid, last year when I added 4840 watts of sloar, I also went the whole shot and brought grid power in, at a cost of about $5000 to the grid and another $2500 in wiring, panel, meters and misc. I now generate excess power and net meter it to the grid. I only have my sugarhouse (for maple syrup production) there, but we will build a new home there someday. The solar system is designed to power the home to be built.
logging small time for years but just learning how,  2012 36 HP Mahindra tractor, 3point log arch, 8000# class excavator, lifts 2500# and sets logs on mill precisely where needed, Woodland Mills HM130Max , maple syrup a hobby that consumes my time. looking to learn blacksmithing.

John Mc

Maple Flats gives some good advice.  It's good to think about your intended uses - the seasons of use, as well as you electrical loads.  If the site will get year round use, some off grid folks will mount their panels on a rack with adjustable tilt to maximize the output.  This may be too much hassle for some, or may not be possible for some types of mounting systems, but may be something to consider.

This is off the topic for the OP, who is off grid, but I'd also like to point out that for grid-tied systems that are doing net metering, what you typically want to do is maximize ANNUAL production.  (Most states net metering laws let you carry your surplus generation as a credit on your bill month-to-month for up to a year.)  If you are mounting a fixed tilt array, this can often mean setting the tilt at something other than your degree of latitude.

For example here in VT I'm at about 45˚ latitude, but the ideal tilt for a fixed, grid-tied array is closer to 35˚.  This is because the summers have longer days, and historically there are more sunny days than in the winter.  If you want to maximize total production, you tilt to favor the summer.  However, this may be exactly what you DON'T want for an off-grid array used year round: you may need to make the most of what little sun there is in the winter to meet your wintertime needs (shorter days often mean more need for artificial lighting, for example).

On a roof mount system, the question may be moot.  Generally, roof mounts in this area just match the angle of the roof.  Fortunately, most roof pitches in the area from 6 to 12 pitch (26 to 45˚), and 7 to 10 pitch roofs are very common.  These make decent mounting platforms, though you do giv eup a bit from the "ideal" tilt. (It's possible to mount at a different tilt than the roof slope on some roofs, but that can dramatically increase the wind loading if you are in a high wind area, not to mention complicating the mounting system.)

John Mc

If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

OlJarhead

I adjust my panels for summer (15 degrees up) spring and fall (48 degrees) and winter (15 degrees down) to maximize year round production.  If I move to my cabin (which I may well do soon) then I'll tweak that a little more.  I can also rotate the panels into the sun if I need a little more production (no tracker) but for the most part I leave them facing true south.


As I haven't needed much power this summer I've left the panels at 48 degrees but again, I'm not living there right now or spending as much time as I could there.  Raising them would increase production but again, no need for me at the moment.
2016 LT40HD26 and Mahindra 5010 W/FEL WM Hundred Thousand BF Club Member

doctorb

What time of day was that picture taken?
My father once said, "This is my son who wanted to grow up and become a doctor.  So far, he's only become a doctor."

OlJarhead

Quote from: doctorb on August 07, 2013, 12:48:13 PM
What time of day was that picture taken?

Early morning before the sun popped up over the trees.  The panels are usually in full sun by 10am and stay there until after 3pm.  At the time of the pick the MPPT controller was actually charging with about 59watts despite the shade.
2016 LT40HD26 and Mahindra 5010 W/FEL WM Hundred Thousand BF Club Member

Thehardway

Maple Flats brings up some good points on efficiency reduction and decreased production from shading.  There are some ways around this which can be helpful especially if you want to build out your system panel by panel and not take the hit of buying a big, expensive inverter all at once. 

Using microinverters such as the Enphase product

Enphase uses an individual inverter for up to two panels.  The DC power is converted locally at the panel to AC and allows each panel in the array to operate independent of the rest, as such, if one panel in the array is shaded, it does not effect the output of the remaining panels as it would when you have the panels in a string. Other pros include the ability to use a cheaper, smaller gauge wire from the inverter directly to AC breaker panel, no single point of failure (one inverter can fail and the rest continue to operate supplying critical power), ability to stage panels for time of day specific needs, and the ability to add panels and inverters as budget and needs increase and allow without major changes to wiring etc.

Note that these are only beneficial when you are setup as a grid-tie system.  The biggest drawback to Enphase microinverters IMHO is that they require input from the grid to power on.  This is a safety measure.  It disconnects the inverter from the grid in the event of power loss from the grid to prevent back feeding current during a power outage and electrocution of line workers.  The down side of this is that in the event of a power outage, you can't use the power you are generating on site with your PV panels!  What a bummer.  I understand there are several homebrew and creative workarounds for this but approval is a bit sketchy.  They need to make an autoswitching circuit which transfers to DC mode and charges a battery bank if the AC feed sense is lost or there is no AC load present. 

Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

Thehardway


Maple Flats brings up some good points on efficiency reduction and decreased production from shading.  There are some ways around this which can be helpful especially if you want to build out your system panel by panel and not take the hit of buying a big, expensive inverter all at once. 

Using microinverters such as the Enphase product

Enphase uses an individual inverter for each panel. The DC power is converted locally at the panel to AC and allows each panel in the array to operate independent of the rest, as such, if one panel in the array is shaded, it does not effect the output of the remaining panels as it would when you have the panels in a string. Other pros include the ability to use a cheaper, smaller gauge wire from the inverter directly to AC breaker panel, no single point of failure (one inverter can fail and the rest continue to operate supplying critical power), ability to stage panels for time of day specific needs, and the ability to add panels and inverters as budget and needs increase and allow without major changes to wiring etc.

Note that these are only beneficial when you are setup as a grid-tie system.  The biggest drawback to Enphase microinverters IMHO is that they require input from the grid to power on.  This is a safety measure.  It disconnects the inverter from the grid in the event of power loss from the grid to prevent back feeding current during a power outage and electrocution of line workers.  The down side of this is that in the event of a power outage, you can't use the power you are generating on site with your PV panels!  What a bummer.  I understand there are several homebrew and creative workarounds for this but approval is a bit sketchy.  They need to make an autoswitching circuit which transfers to DC mode and charges a battery bank if the AC feed sense is lost or there is no AC load present.
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

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