Battery usage percentages

Topic: Battery usage percentages (Read 2722 times) previous topic - next topic

Re: Battery usage percentages

Reply #50 – March 01, 2014, 04:07:13 pm

Bob,

None of the larger panels are 12V. Ours are 36V with some available at 48V. Look around on Craigslist. Our 280 Watt panels were $170/ea new and work great. Same as the new operational solar field in the Mojave. The controller costs as much as the four panels. No need to pay anywhere near $1/watt as the prices have really come down. Still others trying to soak buyers though. Very pleased how our system works. Never start generator except for exercise perhaps every two weeks.

Pierce

Re: Battery usage percentages

Reply #51 – March 01, 2014, 04:21:02 pm

Quote from: Pierce & Gaylie Stewart – March 01, 2014, 03:58:52 pm

So far in winter in Arizona, we peaked out at about 50% of the total potential in the middle of the day. Less up north where we live. Even at half your potential, it can replenish the batteries especially if you have converted to LEDs for lighting. Another plus is in case of generator failure, it can bring all batteries up for any kind of emergency starting, etc.

Summer sun will be a lot higher so will take less time to bring the batteries back up.

Pierce

This is part of the reason I chose the 30A mppt controller when two panels could supply 22A to the batteries, three panels 33A, and four panels 44A. Most of the time the current will be limited by the sun, once in a while by the controller.

This controller can handle 150 volts from the panels, which is safely above the open circuit voltage of three in series. These are 33volt nominal panels, and if I go to four panels, they will be connected series-parallel.

Re: Battery usage percentages

Reply #52 – March 01, 2014, 04:29:08 pm

Pierce,

Not trying to hijack but, that's a great price on those pannels

Question, can you mix wattage? I have a C40 charge controler.

I have 12-75w. Could I replace 2, 3, 4 with the higher wattage?

Re: Battery usage percentages

Reply #53 – March 01, 2014, 05:29:44 pm

Quote from: Pierce & Gaylie Stewart – March 01, 2014, 04:07:13 pm

Bob,

None of the larger panels are 12V. Ours are 36V with some available at 48V. Look around on Craigslist. Our 280 Watt panels were $170/ea new and work great. Same as the new operational solar field in the Mojave. The controller costs as much as the four panels. No need to pay anywhere near $1/watt as the prices have really come down. Still others trying to soak buyers though. Very pleased how our system works. Never start generator except for exercise perhaps every two weeks.

Pierce

Glad to hear prices have come down. Can you recommend a good primer for learning what to buy to set up solar? There is so much hype out there, it is hard to sort the facts from the fiction. Clearly, one small panel is better than NO panel at all, and two is better than one. But where should one start if they wanted to build a system progressively as needs expanded?

Re: Battery usage percentages

Reply #54 – March 01, 2014, 06:04:46 pm

John,

I would take a photo of the label on the back of the panel with all the specs and then contact the C-40 controller retailer like Northern Arizona Sun and Wind or one of the other companies and see what they recommend. There are a lot of factors here and a lot of installation companies make major mistakes in installation. A large company did my neighbors and really botched the job.

Brad,

The 280 Watt panels have dropped another $10 each. Now $160 for each 280W panels. Here is the site: 280W SOLAR PANELS

My best friend has been in solar panel development for his business for many years. I asked him for information as he is always at one of the big Chinese factories and he said Yingli panels are top quality and the price is the lowest a very large solar company here in the states could get if they made a large volume purchase. The seller is part of a crew that installed 80,000 in the Mojave. 500,000 of these panels have been installed in the U.S. No tax on these panels, what you see is what you pay.

So, total was $170 x 4 (or now $160 x 4) plus about $610 plus $12 shipping, no tax for the MidNite Classic 150 plus wires, aluminum for roof standoff mounts, fittings. Using the best quality materials available, about $1600 total for 1140 watts up top. The efficiency goes way up if they can be tilted toward the sun but I didn't want to have to climb up and possibly fall off sooner or later.

Our 102" U300 was perfect for the installation of four with only the batwing having to be turned 90 degrees and the rear radio antenna removed. Other coaches, even though longer or different floor plan may not be as easy. It took a LONG time to figure out all the details. Glad to help with the issues I had and always have time to answer any questions over the phone or with a PM. I just went to a lot of forums, sites, did a ton of reading and tried to weed out the fact from the fiction.

Glad to try and arrange for panel purchase from this guy. Have been to his house several times and watched as trailers would stop and pick up 10 or 20 panels. He has a LOT more than 10 for sale!

I purchased my batteries the same way just watching Craigslist.

Pierce

Re: Battery usage percentages

Reply #55 – March 01, 2014, 08:23:29 pm

Quote from: Pierce & Gaylie Stewart – March 01, 2014, 06:04:46 pm

...
So, total was $170 x 4 (or now $160 x 4) plus about $610 plus $12 shipping, no tax for the MidNite Classic 150 plus wires, aluminum for roof standoff mounts, fittings. Using the best quality materials available, about $1600 total for 1140 watts up top.

I just want to dip my feet into solar at this point. I'm not sure how much that means, and I am confused as to why they use watts as the measurement instead of amperage. I could understand if I was told that a particular solar array that would put (up to) 25 amps into my battery bank in a 5 hour day, but with the different panel voltages being cited...like 36 volts...48 volts... I am a bit lost. If you have "1140 watts on top", what does that mean in terms of amperage fed back into a 12 volt battery in a day? I have not been back out since installing my Trimetric, so I am not really sure how much I use in a normal day yet...i.e., what I would need to replace. At this point, I would just like to reduce generator time a bit, but I'm not seeking to completely eliminate it yet.

Re: Battery usage percentages

Reply #56 – March 01, 2014, 08:40:46 pm

Watts are no more than the result of multiplying Amps times Volts. Just divide the Watts on the roof by 12 or 13 (volts in the battery) to see how many Amps it can theroetically pump into the battery under the best of conditions. If you get a MPPT solar charge controller, it makes no difference the voltage of the panels so long as it is below the maximum the controller can handle. If you get a lower-cost PWM controller, some of that power will be lost.

I bought a MPPT comptroller that can handle a maximum of 150 volts from the panels. This way, I can wire three of the 33volt nominal, 42volt open circuit, panels in series and not exceed the capability of the controller. Everything the panels can deliver will be converted to 12-13 volts and pumped into the batteries, up to the maximum of the controller, which is 30 Amps.

If I am every fortunately enough that the panels are trying to supply a full 136 watts each, that would give me 31.8A to the batteries at 13 volts. At this point, the controller would have hit it's limit of 30A, and the batteries would not get that last 1.8A the panels want to supply. Too bad.

I may go with four panels, in which case they would be hooked up in series-parallel in order to not exceed the maximum panel voltage. In this case, bright sunny days would frequently see me limited to 30A, but for more hours than I would see 30A with fewer panels.

Re: Battery usage percentages

Reply #57 – March 01, 2014, 08:48:27 pm

Watts = Amps X Volts

Watts is a measure of power. A panel that produces 12 amps at 12 volts produces 144 watts of power. A panel that produces 12 amps at 24 volts produces 288 watts of power. Using only amps to compare panels doesn't provide enough information to rate the power the panel can deliver under ideal conditions.

My understanding is that the MPPT controllers can take power at a voltage higher than 12.6 VDC (nominal, it takes about 13-14.5 volts to actually charge the battery) and convert it to the best combination of voltage and current for charging your battery.

I offer this as a start to add to your education (confusion?). Others may be able to explain more clearly.

Re: Battery usage percentages

Reply #58 – March 01, 2014, 10:15:18 pm

I have a pretty good understanding of Ohm's Law (WA7QOK), but the missing piece to me was that whatever the voltage of the panels, I am now understanding that the controller is used to transform it into the 12-14volt range to fit the need. That makes it quite a bit clearer. Thanks!

Re: Battery usage percentages

Reply #59 – March 01, 2014, 11:36:41 pm

Quote from: Brad & Christine Slaughter – March 01, 2014, 10:15:18 pm

I have a pretty good understanding of Ohm's Law (WA7QOK),

K5ERP here. Originally KN5ERP in 1955. Held novice, technician, general, advanced, and now hold extra. I haven't been active, but I do keep the license up. That doesn't mean I know or understand anything, but I was able to pass the test and copy code up to 20 wpm.

I'm pleased a couple of us were able to clarify the issue regarding panel voltage.

I like the idea of solar and was able to see it in use during my brief adventure to Quartzsite. We seldom boondock and are "part timers," so solar power for us is like the whole "motor coach" adventure: interesting and fun, but not economically sound.

Re: Battery usage percentages

Reply #60 – March 02, 2014, 12:40:49 am

Quote from: J. D. Stevens – March 01, 2014, 11:36:41 pm

K5ERP here. ...

so solar power for us is like the whole "motor coach" adventure: interesting and fun, but not economically sound.

I was KN7YAX to start with. 1963, I think, at age 14. I stopped at Advanced and am waiting to either die or get grandfathered to Extra. Christine is N7QOK.

Boy, that is exactly correct. Not economically sound...but a lot of fun and adventure. That is sort of where I am at. I'd just like to play a bit with it, but not to the level of 1140 watts.

Re: Battery usage percentages

Reply #61 – March 02, 2014, 12:42:09 am

Brad,

You are just starting to grasp the complexity of all the possibilities in setting up a complete solar system from the PV panels to the batteries. Just understanding a MPPT controller takes a while to only partially figure out. Once you have studied it, installed it and it works as expected, it's a real feeling of accomplishment. A larger system is not really much more complicated than a small one.

For us, running the generator took away part of the reason for being outside in nature. I just never completely relaxed with it running. With so many campgrounds here mixing tents with RVs, I always expected a dirty look when I looked outside. Part of it was that some motorhomes ran their generators well past the campground hours and started them an hour or two before they were supposed to. The other part is being sort of a pioneer in harnessing the sun's power to live without constantly depleting our resources. Everyday, more and more homes and vehicles are now using this technology. It still seems a little magical touching a button and getting mostly pollution free electricity. Might be one of the good things that came with high oil prices.

Pierce

Re: Battery usage percentages

Reply #62 – March 02, 2014, 02:48:24 am

MPPT Tracer3215RN 30A 150V Solar Battery Charge Controller Regulator US Stock $167

2 x 136 watt Flexible Solar Panel Peel & Stick by Uni-solar. PVL136 Unisolar $310

These two eBay purchases make up the core of my first foray into solar. If needed, I can add another panel or two.

I don't expect to boondock totally generator free in the winter when the propane furnaces and more hours of lighting take a toll on the batteries, but I want to use the generator less and let the solar panels top off the batteries each day. In the summer, with no use of the furnaces and more daylight, the generator should see little use except for air conditioning.

Re: Battery usage percentages

Reply #63 – March 02, 2014, 07:57:01 am

Try to keep in mind that the amperages, etc, in the advertising is just that...advertising. In the real world you'll never get the full output even if you tilt and track the sun. Light dust, degradation of the surface, loss over connectors, etc, will drop you down at least 10% on your best days. We have 465 watts of solar and are very happy getting 26 amps at the controller. in theory it should be 465/13.8 or 33.696. That's never going to happen. We have a 30 amp controller and all's right with the world.

Re: Battery usage percentages

Reply #64 – March 02, 2014, 08:10:51 am

Hey Larry,

Can I ask you something about my set up?

900w in 12-75w panels, 40A controler

Looking at removing 2-4 panelsand updating with these 270w panels.
Can you mix wattages? $:-\$

Re: Battery usage percentages

Reply #65 – March 02, 2014, 09:33:13 am

JD,

In for a penny, in for a pound ... ;o)

best, paul

Quote

like the idea of solar and was able to see it in use during my brief adventure to Quartzsite. We seldom boondock and are "part timers," so solar power for us is like the whole "motor coach" adventure: interesting and fun, but not economically sound.

Re: Battery usage percentages

Reply #66 – March 02, 2014, 09:41:55 am

Tom,

I'm not sure the amount of solar you're considering will top off the batteries.

Others here are more knowledgeable and can chime in.

best, paul

Quote

I don't expect to boondock totally generator free in the winter when the propane furnaces and more hours of lighting take a toll on the batteries, but I want to use the generator less and let the solar panels top off the batteries each day. In the summer, with no use of the furnaces and more daylight, the generator should see little use except for air conditioning.

Re: Battery usage percentages

Reply #67 – March 02, 2014, 09:52:46 am

Quote from: Dave M – March 02, 2014, 05:48:23 am

Like other lurkers, been giving some thought to the solar idea, but since my setup is Gel, I have to ask how tuneable are the controllers as to max voltage limit (14.2VDC Gel).

Very tuneable for all voltages including even the display voltage. Check the owner's manual for ours at: http://www.midnitesolar.com/pdfs/classicManual.pdf Lot of good YouTube videos too.

Pierce

Re: Battery usage percentages

Reply #68 – March 02, 2014, 11:10:57 am

Brad, we will most probably be going thru L havusa on way down to Lukeville this next weekend so can stop for a coffee if you want to look at our set up. Not as big as Peirce's but we live off it mostly as we do not use AC (open windows and use fan) but do have residential fridge on all the time. We do not have a cell so would have to call you once there or meet at your place. Up to you.
JohnH

Re: Battery usage percentages

Reply #69 – March 02, 2014, 12:01:27 pm

Quote from: lgshoup – March 02, 2014, 07:57:01 am

Try to keep in mind that the amperages, etc, in the advertising is just that...advertising. In the real world you'll never get the full output even if you tilt and track the sun. Light dust, degradation of the surface, loss over connectors, etc, will drop you down at least 10% on your best days. We have 465 watts of solar and are very happy getting 26 amps at the controller. in theory it should be 465/13.8 or 33.696. That's never going to happen. We have a 30 amp controller and all's right with the world.

So, to try to understand this, if you see 26 amps at your controller, and if you get that for 4 hours a day of bright sun, are you then sending (up to) 104 amps total to the battery in that 4 hour period? Do I have it right?

John, sent you a PM. Thank you!

Re: Battery usage percentages

Reply #70 – March 02, 2014, 12:23:46 pm

Quote from: lgshoup – March 02, 2014, 07:57:01 am

Try to keep in mind that the amperages, etc, in the advertising is just that...advertising. In the real world you'll never get the full output even if you tilt and track the sun. Light dust, degradation of the surface, loss over connectors, etc, will drop you down at least 10% on your best days. We have 465 watts of solar and are very happy getting 26 amps at the controller. in theory it should be 465/13.8 or 33.696. That's never going to happen. We have a 30 amp controller and all's right with the world.

Well aware of that. This is one reason why a tri-metric battery monitor is going in at the same time as the solar, and also why I got the controller that can use a third panel wired in series or two more panels paralleled with the first two. Once I have some real world experience, I can see if another panel or two is called for.

Re: Battery usage percentages

Reply #71 – March 02, 2014, 12:33:05 pm

Quote from: Paul Smith – March 02, 2014, 09:41:55 am

Tom,

I'm not sure the amount of solar you're considering will top off the batteries.

Others here are more knowledgeable and can chime in.

best, paul

Me neither. Again, this is why the tri-metric is an essential part of this experiment. I can always run the generator a little more or try and use less power and see how it goes, and I have kept my options open for adding more panels. We'll see how it goes.

And keep in mind that this is in the winter when I use the mist electricity and see the least sun. I believe summer use will be just fine.

And another reason for having solar is for storing the coach and accidentally losing shore power, I won't come back to dead batteries (again).

Re: Battery usage percentages

Reply #72 – March 02, 2014, 12:39:16 pm

Quote from: Brad & Christine Slaughter – March 02, 2014, 12:01:27 pm

So, to try to understand this, if you see 26 amps at your controller, and if you get that for 4 hours a day of bright sun, are you then sending (up to) 104 amps total to the battery in that 4 hour period? Do I have it right?

John, sent you a PM. Thank you!

Yes, 104 Amp-hours in.

Keep in mind that you will get more than that, as the solar power is adding Amps all day long, just not as strongly when the sun is lower in the sky. I read somewhere that the total of those 4 hours plus the rest of the day is equivalent to 6 hours of bright sun in the winter, much more in the summer.

Re: Battery usage percentages

Reply #73 – March 02, 2014, 12:40:00 pm

Caflashbob

I bought five 250 watt panels for $240 each from Solar Mike Gohl at the Slabs. He has more. Panels are available online for less than $1.00 per watt.I replaced fourteen 55 watt panels to reduce the size of the footprint and can walk around them easier now. Mike took my 55 watt panels in trade so I did not have to sell them - easier for me.

Many solar controllers today are able to convert up to 150 volts DC from panels to battery recharge voltage (13.4 to 14.6 volts). The advantage of higher voltage is it allows using smaller wires. The disadvantage of higher voltage is that the efficiency of the controller is reduced by higher voltage (higher input voltage means less watts into the batteries). It also means there is an increased shock risk. One of my friends here has wired four 29 volt (MPPT volts) in series to bring almost 120 MPPT volts off the roof (152 VOC). I wired five panels in parallel bring 29 volts off the roof but had to use much heavier wires then he did.

This statement is correct:
I am starting to see the advantages of 1000 watts of solar to allow the three phase charging of the batteries as the last ten percent takes the longest time.

I recharge batteries with the generator once or twice a year.

Here is some practical numbers for designing a solar system. A 100 watt panel will provide up to 6.3 amps into a battery. If panels are installed flat on the roof, a 100 watt panel will provide about 3 amps into a battery for 6 hours, so about 18 amphours per day. With 1200 watts, I have up to 220 amphours available each day. I often run a roof fan on low (5amps) for 10 hours (50 amphours) which leaves 170 amphours per day for battery charging. In the morning my amphour meters show 40 to 140 amphours used overnight (all LED lights and LCD TVs). The only days that my batteries are not fully charged by 3pm is when it is raining.

You could by being power frugal get along quite well on 600 watts which will provide 110 amphours per day. I just do not wish to be that frugal.

Re: Battery usage percentages

Reply #74 – March 02, 2014, 01:05:16 pm

I contacted the seller listed here for the 240 watt 36volt yingli panels. No reply yet. Flat on roof the capacity should work better with four?

Would have enough capacity to run a household refer with maybe a fourth 8g8d. Not intending to as not needed yet.

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