The last 7 days (up to Sunday) that I recorded.  Found the voltage on Friday to be interesting as it was the first day I ran the Freezer much -- I did not run it all day mind you, just ran it a few times to keep it cool enough to use as a Fridge (I know that's not the best thing for it but it works until I get the Fridge installed).

Thoughts?

I should add that Friday (-2 on the chart) we arrived about 1PM and used the Freezer (to cool it down) and then ran lights and battery chargers a lot.  Wasn't much sun out either.

Saturday (-1) we ran everything and then some all day and had very little drop by the looks of it -- it was a heavy use day as seen on the chart -- I think adding the two additional batteries will be wise if I want to run the Freezer and Fridge all the time....guess I'll find out!

My question is; is that watt hours row the watt hours going into the batteries from the panels? That's what I think it is. That indicates your system plowed 1140 watt hours into the batteries on Sat because your Friday use dragged the batteries down to a low point of 12.27 volts.  And Friday you can tell you either arrived after the best sun had gone or it was a lousy sun day; 420 watt hours.

Saturdays absorb time was very low (70 minutes) which would lend itself to a long bulk charge before the sun went away or a day with clouds or a combination.

Then Sunday when you took the snapshot the system had not yet recharged much as the max volts were still down from where iy usually peaks. Also the watt hours are still low and the absorption charge only just reached 1 minute.

Quote from: MountainDon on May 17, 2011, 05:25:12 PM
My question is; is that watt hours row the watt hours going into the batteries from the panels? That's what I think it is. That indicates your system plowed 1140 watt hours into the batteries on Sat because your Friday use dragged the batteries down to a low point of 12.27 volts.  And Friday you can tell you either arrived after the best sun had gone or it was a lousy sun day; 420 watt hours.

Saturdays absorb time was very low (70 minutes) which would lend itself to a long bulk charge before the sun went away or a day with clouds or a combination.



Then Sunday when you took the snapshot the system had not yet recharged much as the max volts were still down from where iy usually peaks. Also the watt hours are still low and the absorption charge only just reached 1 minute.

We arrived Friday just before the panels were in the shade (I need to remove that tree and make it into planks!) and the weather was mostly cloudy.  I was also surprised by the heavy usage the next day and am guessing that charging batteries (18v Ryobi's) and running the freezer, lights, etc all must have really sucked the power.

I'm still so new to all of this I'm mostly doing this: 

I think the watt hours are the amount of charge going into the bank.  One thing I noticed is that the draw down to 12.27 still put me around 60% I think (haven't done the math) which would be ok I think.

One thing I've noticed is that my fully charged bank runs about 12.9v rather then what Trojan indicates 100% should be (12.7)...thoughts on that?

Do you have a meter you know for certain is properly calibrated?  Maybe the meter in the CC is off?

Hydrometer check?

Time also! Trojan will have hidden away in there spec a resting period before you make the measurement.  Not to worry on this one!

http://www.walmart.com/ip/Danby-9.1-Cubic-Ft.-Frost-Free-Refrigerator-in-Black-with-Stainless-Steel-Door/11368635
Using the calculator I see that running this fridge (at about 1030 watt hours per day) and the freezer I previously mentioned (about half what the fridge will use theoretically) then my system with 3 panels, 6 hours of sunlight per day (summertime I can probably get more then that but in general I should be able to get 6 hours of pretty much direct sunlight at 33 degrees for the time I'm running these both) and 8-10 220ah GCB's with the 60amp MPPT controller should do it.

That's taking it to 50% of discharge according to Don's spreadsheet.

Now, am I doing something wrong?  Does it look right?  I set it to 4 days without sun which might suck if I get 5 or 6 without it but the region only gets about 15 inches of rain a year and has around 300 days of sun.....so I'm hoping anyway.

Last 44 days of monitoring the MPPT controller and I've seen only 3 days where it had little to no charging.  Rest of the time it seemed to do fine.

Also, I may not need to run them both at the same time but want to be able to.

My worry is mostly because I'm often gone ten days in a row so there will always be at least 10 days where I cannot put the generator on the system to get it back up to charge.

http://www.uakc.com/energyguides/dar1102we-danby.jpg
Found this for a fridge I'm looking at that doesn't have a freezer -- uses almost 200 watt hours less per day.

This http://www.refrigeratorexpert.com/danby-DAR1102WE.html fridge may do the trick as it's all fridge which is ok since we have a freezer already and I've been told that these use less energy (which appears to be possibly true from what I'm seeing).

I should also add that with this unit I was able to drop hours of sunlight down to 5 hours per day which still left me with 3 panels and 8-10 batteries (at 50% discharge).

It is most likely that I will only run the Fridge until late August or early September (deer season starts).

Here is the latest log from my controller.  I've hidden the days we weren't at the cabin unless they showed recovery from when we were there (more watt hours despite out no longer being at the cabin which I assume is recharging the batteries).

I have not yet checked water levels or equalized the batteries which I plan to do this weekend.

We seem to average above 600 watt hours per day which I assume is replacing energy we used while at the cabin (though the one day we used a lot more which I think is due to using the freezer more and not having much sun).

THis weekend it is supposed to be cloudy and raining so might be interesting.

I've noticed that absorption seems to run about 3 hours while float can run 7 to 10 hours -- which I assume is just as long as the sun is hitting the panels.  On days that we were at the cabin it tended to be cloudy and I'm wondering if the float times were lower because of this??

Both the bulk stage and the float stage duration can vary widely in time spent in either stage. Too bad the data display does list bulk charge as it could help explain what is going on. You may understand the following. If so good and this is for anyone else.

Bulk charge is the first stage, the state the CC begins every day with. Duration of the bulk charge stage will vary because of factors such as; how deeply the batteries are discharged, the intensity of the sun on the PV modules (clouds, smoke, snow, etc.) as well as how much power is being used at the same time the batteries are being charged.

Absorption charge is next. This is the only charge state that can be programmed for duration. The manual shows 150 or 180 minutes, depending on battery type (page 36). Those times may be modified by the CC under certain circumstances.

Then the unit will switch to float charge.

So, on a cloudy day the CC may remain in bulk charge for a longer duration than "normal". Since the length of the absorption charge is fixed, on a bad day the CC may never even reach float. That occurred three times in that chart.

It is also possible for the CC to reach absorb and switch back to bulk if some heavy demand is placed on the batteries. That is determined by the battery voltage falling below a certain value and remaining low for a period of 30 minutes. There is a low voltage point that will actually cance; the float charge for that day

Thanks Don, I even went and double checked about the Bulk charge period which lead me to call Morningstar -- I've not yet had a reply yet but will bug them until I do -- also want to understand the lights and why they don't repflect the charge correctly but I think that may be a setting and I'm planning on working on the setup when I get there this weekend.

Thanks again for the response, it helps me a lot!

I have figured out the lights

It seems that while you can make changes to the controller via their software and tell it exactly what you want it to do, it will not do those things unless you switch the dip switches to 'optional' which sets the controller to run on your specific programming.

Thus the lights were showing stock indicators rather then my trojan adjusted ones.  So that's solved

I'll post another set of data collected off the controller, what is interesting is the 'input' and 'output' power.  Neither of which appears to be raw panel power.  I do get array voltage and amps but if I want to see the actual 'wattage' of the panels I have to do some math (which is ok of course).

Anyway, so far I've seen pretty good production from the panels and my only weak point might be the batteries.

One interesting thing is the voltage on 6/30.  I see no reason why this is so low???  The ONLY thing running during that time was the 12vdc fan on the composting toilet and the Charge Controller.

However, I've also noticed that the controller is set to a time that does not match my time zone and I have not discovered the mystery of how to change that just yet -- hmmm.....

Beyond that I've noticed that 'Max. Output Power Watts' appears to be the amount of power produced by the controller and sent to the batteries and not the power coming off the array (that may sound silly as one cannot be different from the other, but in fact it can.  After all 60vdc off the array at 11amps is ~660watts where as 14.8vdc from the controller at 45 amps is ~666watts right?).

Quote from: OlJarhead on July 05, 2011, 12:29:45 PM
Output Power Watts' appears to be the amount of power produced by the controller and sent to the batteries and not the power coming off the array .....

The difference between power from the array and the power into the batteries is the loss in the charge controller. There are small losses usually noticeable at the CC heat sink fins. I think that into the batteries figure may also reflect some of the battery charging loss inherent to lead-acid batteries. Not + on that though.  IMO, what goes into the batteries, and what is taken out is what is most important.

Turns out I have a Surflo 9325 Well pump that with 24vdc power can pump as much as 100 gallons in an hour or more.  It's down ~80 feet into the well which puts it about 40 feet below the last known water level (when the well was drilled).

So, I'm now in the market for a ~100 watt solar panel to power the well with as the 60 watts of 12vdc solar I was using is inadequate -- though I could rewire it to give me 24vdc it's just a tad shy of the recommended size and I could use it elsewhere.

So, if anyone finds a sub $200 panel that might work please let me know!

http://www.sunelec.com/sun-laminate-118-watts-2430-vmp-p-785.html
I'm hoping to get this panel for my well solar...if I can get close to the price they were offering for 10 of them.

Quote from: OlJarhead on July 19, 2011, 10:01:52 PM
http://www.sunelec.com/sun-laminate-118-watts-2430-vmp-p-785.html
I'm hoping to get this panel for my well solar...if I can get close to the price they were offering for 10 of them.

Didn't notice the 'Laminate' part and didn't really understand it.  These do not have frames so I won't want them.  Looking at other options now.

Another weekend another log

This one is broken up a bit because of my messing with the controller.  Each time it is reset it restarts the log (I was doing firmware updates and programming changes).

With the new Fridge running full time, running two battery chargers, a DC fan and 3 lights at night we used a lot of power!  Drew the batteries down around 65% of charge (which isn't bad I think) and exercised things a bunch. v:)

I'll see what it's doing when I get there this weekend (I think) to see what happens when no lights or chargers etc are running and the fridge is on #3 setting (we had it on #4.5 when we were there).

All in all though, I couldn't be much happier!

Am I correct in taking the 65% to mean you drew the batteries down to have 65% capacity remaining? That's not bad but doesn't give much wiggle room for clouds if that was a typical single day.

Regarding the refrigerator. One thing I've noticed with our propane fridge is that while we are using the cabin the fridge maintains 35 to 40 F on our number 5.5, but when we leave the cabin for several days the fridge will freeze some things. So then our number 4.5 seems to work best. It would be interesting to see how the temperature in yours runs.

Random thought, sort of, directed towards those who are contemplating installation of a alternative power system.

From talking with people with PV systems already in use, both here, other places on the web and in person, the biggest single "failure" item seems to be insufficient storage capacity.

Temperature Compensated Battery State of Charge Chart, 12 volt. Being temperature compensated this might save someone some time and math.




or for 24 volt (below)




EDIT 09/25/2011    Made the spreadsheet the pictured charts were taken from available for download. Also expanded the flooded wet cell charts to include a 48 volt system. Separate download for AGM batteries.

... for 48 volt (below)

The above images are from a spreadsheet. It can be downloaded from below.

There are two flavors, flooded cell batteries and AGM sealed

The AGM charts
12 volt


24 volt