Trip Report (Long) Solar information

[DonF]

More information on solar
Two 6 v batteries, 232 amp hour capacity
LED lights
Computers are powered with 12 v adaptors
Refrigerator on propane if 120v power is not available and is also on propane when towing
Kindles, phones, iPad all charged through 12v to USB adaptor plugged into 12v socket
I have 1000 w inverter but have yet to use it

Data collected during this past summer (my backyard and driveway in north MS)
Used Trimetric 2030-RV monitor with 500 amp shunt (reads to x.x accuracy) to collect data.
Test # 1
· Test conditions partly cloudy skies, medium to heavy shading on panel.
· 12v load applied from dusk to dawn (Endless Breeze fan)
· Measured amp-hours used averaged 21.2 amp-hours per period
· No 12 v load applied during the daylight hours.
· Measured amp-hours replaced by the solar panel averaged 6.7 amp-hours, or 32% of the amount withdrawn
· Test stopped after 5 days, battery voltage read 12.3 volts on both Tri-metric and GoPower panels (roughly 50% of battery capacity)

End of 1st recharge cycle: Trimetric 100% GoPower 100%
End of 2nd recharge cycle: Trimetric 95% GoPower 100%
End of 3rd recharge cycle: Trimetric 91% GoPower 100%
End of 4th recharge cycle: Trimetric 86% GoPower 100%
End of 5th recharge cycle: Trimetric 82% GoPower 93%

When the test was stopped, the Trimetric meter showed a -82.2 amp-hour reading.
My conclusion under similar conditions, I could operate on battery power for about 5 days if the average daily load was around 21 amp hours.

Test # 2
The above test was repeated with the trailer parked in full sun and pointed to the east. Partly cloudy skies during the testing were considered equivalent to what was seen during the 1st test.
· 12v load applied from dusk to dawn (Endless Breeze fan)
· Measured amp-hours used averaged 29.8 amp-hours per period
· No 12 v load applied during the daylight hours.
· Measured amp-hours replaced by the solar panel averaged 24.6 amp-hours, or 83% of the amount withdrawn
· Test stopped after 5 days, battery voltage read 12.4 volts on both Tri-metric and GoPower panels (roughly 75% of battery capacity)

End of 1st recharge cycle: Trimetric 100% GoPower 100%
End of 2nd recharge cycle: Trimetric 100% GoPower 100%
End of 3rd recharge cycle: Trimetric 97% GoPower 100%
End of 4th recharge cycle: Trimetric 95% GoPower 100%
End of 5th recharge cycle: Trimetric 94% GoPower 100%

When the test was stopped, the Trimetric meter showed a -26.6 amp-hour reading.
My conclusion under similar conditions, I could operate on battery power for about 10 days if the average daily load was around 21 amp hours.

Real World Measurements during our trip.
Using the Trimetric meter, power draws were measured as noted. Items with * indicate data from the Forum as I either didn't measure them, or my meter is not able to read to more than one decimal accuracy.
Double OH Light, LED 0.20
Single OH Light, LED 0.20
Water Pump* 2.00
Propane Gas Monitor 0.10
Solar Panel Display* 0.04
Tank Monitor System* 0.04
Maxx (vent) Fan, Lo 0.20
Maxx (vent) Fan, Speed 3 0.60
Maxx (vent) Fan, Speed 5 1.20
Water Heater (lit, propane)*0.43
Water Heater (switch light)*0.10
Refrigerator Display (running on propane) 0.10
Furnace 2.30
Cabinet LED strip lights 0.30
Outside Light 0.30
Endless Breeze fan, low speed 1.40
Endless Breeze fan, medium spd. 2.10
Wilson Sleek amplifier 0.50
CPAP, Running 0.70
C's Laptop, Running 5.60
D's Laptop, Running 5.60
AA Battery charger (camera) 1.90
Canon battery charger 0.80
Kindle Charger 0.30
iPad charger 0.80
Phone charger 0.20

I've summarized notes I took while testing various setups while on our trip. Unless otherwise noted, all readings are from the Trimetric battery monitor.
Ocean Pond Campground in north Florida, 11/13/14 & 11/14
Mostly sunny conditions, no shade
Operating test using batteries only.
Typical power use for us, both computers in use for one of the two day test. Mostly sunny during the test period.
· After 44 hours on batteries
o -71.9 amp-hour reading (net after any solar charging gain)
o Battery voltage was at 12.3.
· Significant event was after a full day of solar charging with no draw other than the propane detector and refrigerator panel (refrigerator was on propane), I only gained 12 amp-hours, or 24% of what had been used in the previous day.

Long Pine Key Campground, Everglades National Park, 12/27 & 12/28
Partly cloudy, light shade from high pine tree canopy
Operating test using batteries only.
Similar power use for as during the Ocean Pond test. Mostly sunny during the test period
· After 44 hours on batteries
o -84.9 amp-hour reading (net after any solar charging gain)
o Battery voltage was at 12.3.

If I understand battery use correctly, for longest life they shouldn't be allowed to drop below 50% capacity on a regular basis. With 232 amp-hours available, the magic 50% number is 116 amp-hours. When I was seeing a 2 day use of around 80 amp-hours, that was telling me I only had 36 amp-hours left to work with; less than one days typical use for us. That led to the conclusion I made in the original trip report.

Other measured draws
11/03/14
· 6 hour period, daytime use
· -23.3 amp-hours
12/21/14
· 12 hour period, nighttime use
· -13.9 amp-hours
12/29/14
· 16 hours nighttime use
· -43.2 amp-hours (Endless Breeze and MaxFan on all night, it was hot!)
12/29/14
During 8.5 hour tow, gained 40.6 amp-hours, (replaced 50% of what was used over the previous 2 days). Battery at 13v and 87% capacity.
01/29/15
· 10 hours nighttime use
· -18.4 amp-hours (furnace on quite a bit, it was cold!)
· Trimetric showed battery voltage at 95%, GoPower showed 100%
01/29/15
After towing for 6 hours on a sunny day, amp-hours were -2.7; 93% of amp-hours had been replaced.

[kvermeulen]

I must give you an A on your report card for such a nice review.

How big is your solar panel??

Ken

[kvermeulen]

I see on your previous post it is 95 watts. Probably not enough. I think it looses about 30percent of its efficiency, so it might put out 10 to 15 amp hours in a nice sunny day. If you change the controller to mppt it will run at about 97percent as the mppt controller converts excess voltage into more amps into the batteries instead of letting it go to waste.
I would add a portable panel (try borrowing one) and see if that helps. Just my 2 cents.

Ken

[padlin]

Hi Don, nice work. After all this what do you figure your average daily Ah usage is?

[cpaharley2008]

Thanks for the update and data so we can do comparison. With a gain on 12 a/h for a full day in the sun with no draw, that seems very low. That equates to about 1.5 hours of charge? There may be something amiss here. Have you discussed these numbers with the solar panel company, they appear to be very low.

[fudge_brownie]

You have given a very thorough report. I know there will be a number of solutions posted and look forward to hearing them all. My suggestion is based on your batteries and what is considered a full charge. I assume you have the Interstate batteries provided by Escape and their standard GoPower controller. I contend that with the GoPower solar controller or the built in WFCO shore power controller you are never obtaining a full charge on your batteries. You are never getting your batteries up to 232 Ah. I do not have the GoPower but it is rated at the same charge rate as the WFCO. Both units charge at a rate of 14.4 but the GoPower has a higher absorption rate.

This past summer I performed a similar test using a Trimetric monitor and found that charging with the WFCO I was only able to get the batteries to 204 Ah. I was able to determine this value by charging with shore power for 24 hours, then switching to a charge via solar and my Blue Sky 30 controller with a 120 watt panel at the recommended charge voltages from Interstate. That Interstate charge voltage is 15.3 volts for two hours. The solar charger added nearly 30 Ah to the batteries after the WFCO charge before switching to float/trickle/ storage mode.

As mentioned above, this testing was not done with the GoPower controller but I believe it is giving you a similar deficit. Your measurements are all correct but the starting point of your batteries is closer to 200 Ah than the 232 Ah you are assuming.

Even with a different solar controller it is going to be very difficult to obtain the necessary voltages with a flat mounted, roof top panel at 90 watts. My 120 watt portable panel will do the proper charge in midsummer with frequent tending to keep the panel in full sun and at the best angle. It will take the full day.

Here is the link to a previous post on this topic.

[hotfishtacos]

Originally Posted by cpaharley2008

Thanks for the update and data so we can do comparison. With a gain on 12 a/h for a full day in the sun with no draw, that seems very low. That equates to about 1.5 hours of charge? There may be something amiss here. Have you discussed these numbers with the solar panel company, they appear to be very low.

The numbers were pulled during November and December when the sun is very low and if the 95 watt panel is between the air conditioner and MaxiFan then it will experience shadowing in the morning and evening as well. It all contributes to loss. These numbers would be much higher during the summer. ...and if the MaxiFan is opened that will also shadow the panel during part of the day...and as was mentioned by Paul, the GoPower controller is not supplying all of the available power from your panel.

[padlin]

"Data collected during this past summer (my backyard and driveway in north MS)"

[cpaharley2008]

Perhaps this explains why the 95 watt panels were "upgraded" to the 165 watt units? due to the poor output? I just can not keep up with progress.....

[padlin]

My take on Your testing and real world results.

On a clear day at home you should see a gain of 35 amps in full sun in July. Solar Irradiance - calculate the solar energy available on your site, I used Memphis as your location.

In the 1st test scenerio, the panel is under partly cloudy skies, medium to heavy shading and gained 6.7 Ah.

In test #2 it's in full sun and pointed to the east, which with a flat mount shouldn't matter. UnderpPartly cloudy skies which you considered equivalent to what was seen during the 1st test, you gained 24.6 Ah. Both test results sound reasonable to me. Parking the trailer in full sun on a clear day would give you a better control number that hopefully would be closer to what the calculator calls for.

Ocean Pond CG in November...
Should see a gain of 19 Ah in full sun, I used Jacksonville Fl as location.
Mostly sunny, actual gain was 12 Ah.

Long Pine CG in December,
Should see a gain of 20 Ah, used Miami.
Partly cloudy, light shade from high pine tree canopy. Hard to tell but it looks like the gain was close to nothing. Don't know how much to expect in real life when parked under light shade.

Looks like your average usage is about 45 Ah a day. Using the worst solar month of December, parking in full sun in Miami, you'd need a little over 2 - 95w panels. Obviously from your results all bets are off in the shade.

[DonF]

Thanks for the input everyone.

Couple of more items to address some of the questions/suggestions.

I've no doubt the low solar gain at both Ocean Pond and in the Everglades was influenced by the shadowing effect of both the a/c shroud and the MaxFan being raised. No secret that shadow on even a small portion of a solar panel reduces efficiency of the panel. Considering the location of the 95w panel, shadowing at some time of the day is a fact.

I have seldom see a 5 amp output from the solar panel for any length of time (theoretical max is 5.3). Angle of the sun, shadowing on the panel, shade, haze, partly cloudy skies generally kept the output below 5 amps. I usually see a slightly lower amp input reading on the Trimetric than I do from the GoPower controller.

I do have the Interstate GC2-XHD batteries. I did change out the main board on the WFCO 8955 and replaced it with a PowerMax Boondocker 4 stage converter/charger. The 4th stage of the Powermax is a "desulfation mode" which raises the voltage to 14.6 once a day for 15 minutes when the battery is in the storage (float) mode. Still less than the 15.3v equalizing voltage recommended by Interstate, but it's what I have. At the completion of my solar testing at home, I used the converter/charger to recharge the batteries. It required 9.5 hours to return to the 96% charged state and an additional 24 hours to reach 100% charged (as measured by the Trimetric monitor).

The average use during the periods tested while we were traveling was around 45 amp-hours per day.

No question I'll have to add more solar panels and likely change the controller. I'm comfortable with doing most anything, but mounting solar panels on the roof isn't on my comfort list right now.

I will be contacting AM Solar in Springfield, OR to see what they would recommend (gives us a reason to head west again ). I'm going back and forth between roof mount and portable. Maybe I should just mount a panel(s) on the Pilot's roof racks and make them adjustable so they could act as air deflectors and improve my MPG at the same time.

[fudge_brownie]

At the completion of my solar testing at home, I used the converter/charger to recharge the batteries. It required 9.5 hours to return to the 96% charged state and an additional 24 hours to reach 100% charged (as measured by the Trimetric monitor).

How does the Trimetric know what is 100%? My impression is this is determined and remembered by the Trimetric once it successfully achieves a full charge. What determines a full charge? It appears the settings that you enter for P1 and P3 but the user manual does not clearly explain how these settings interact.

I use the following settings:
P1 = 15.28
P2 = 4.64
P3 = 232

The P3 setting is obviously the goal for 100% but it appears that you could set P1 for say 14.6, then the Trimetric would flash "full" once that voltage was achieved, since it was measuring your battery as full it would assume 232 Ah based on your P3 settings but in fact you would not be at that level of charge.

My point is, the Trimetric is pretty dumb, everything is based on what you program. If you program low charge rates it will indicate full battery when indeed it is less than full. I might argue that the setting for P1 should be the figure Interstate recommends for a charge rate.

The downside to all this is, if you are not charging your battery to the full amount, then based on a reading from the Trimetric you discharge the battery to 50% you are actually discharging it much lower, perhaps to 40% or less depending on the starting point or actual full charge.

I know there are not may owners of Trimetric battery system monitors on the forum but if anyone can dispel my myths or add a comment it would be welcome.