Solar Test - 15 Days Boondocking in the Outer Banks in NC!

[MAWilsonPE]

We just got back from a two week trip to the Outer Banks of North Carolina staying at 3 National Seashore Parks, boondocking the whole way! Five days on Ocracoke Island, 5 days at Frisco, and 5 days at Oregon Inlet.

I have the Super Solar system with 1200 watts of solar panels and just over 500 amp-hrs of lithium batteries. I ditched the Jaboni 30 amp solar controllers for the Victron 100/50 MPPT controllers. I have connected the Victron components to a Raspberry Pi (which functions like the Victron Cerbo GX at a fraction of the cost) which allows me to record performance by uploading data to the Victron VRM site.

Below is the chart showing solar charging and battery usage during our trip. The yellow bars are the total charge in kW-hrs, the blue shows min, max and average battery percentage. I thought you might be interested in some real-world performance data!

We had really good, very sunny, weather with only two days of some rain. Temps were mostly in the 70's with a few days in the mid-80's. These sites are wide open with direct sun most of the day, so a good test. As you can see, we saw a maximum of just over 7500 watt-hrs of charging per day. That is 625 watt-hrs per day per 100 watts of solar panel!

If you are wondering how I got my battery charge up on May 23 & 24, I cheated and had to run my 2000 watt Honda generator for 1-2 hours as it was really hot in the camper, we did not have as much sun, and we had to run the A/C for about 3 hours in the afternoon to keep the wife and the dogs cool. I only used the genny those two days...

Best Regards, Mike

[MAWilsonPE]

To be clear, we did run the A/C for 3 hours or so on most afternoons when the inside temp exceeded 80 degrees. I was able to recover with solar only on all but those two days.

I was also able to record weather data using my Ambient Weather station. What I really like about this model WS-2000 is that it has a solar radiation sensor that records watts/square meter. Now I am sure this is a measure of total solar radiation and no solar panel can capture all of it but it is a good relative indication of how much is available.

Best, Mike

[MAWilsonPE]

OK, just one more set of data. It looks like May 17th was my best charging day. Here is more detail from 6:00am to 8:00pm on that day. You can see I had a peak of 36 amps from one controller, that's 588 watts from a 600 watt rated pair of panels. I have seen higher but come May in NC it gets a bit hazy

The voltage jumps on the controllers when they go into absorb mode as the batteries get full.

You can see why I ditched the Jaboni controllers only capable of 30 amps.

Best, Mike

[lewy64]

edit ok just saw you posted another reply with somewhat of what i just asked.


I am a newby to solar. How many constant amps were you able to utilize on average per day, or is it just measured in wattage. Just courious if someone could be unplugged for extended periods while using the normal electrical usage?

[MAWilsonPE]

It really depends on how you define "normal usage". We went two weeks unplugged on this trip and relied totally on solar for all but 2 days. It helps that the temps were moderate, I would never do this trip in July or August

I have a 3000 watt inverter so I can draw 25 amps of 120VAC power (that is 250 amps of 12 VDC power) at any given time. Running one A/C unit will draw about 10 amps at 120 VAC (100 amps at 12 VDC). With 500 amp-hrs of lithium I could run the A/C for about 5 hours before killing the batteries with no sun. With almost 70 amps (DC) coming from the panels at their peak that is more than half the requirement and the draw from the batteries is cut way back, but that doesn't last all day.

The thing is, timing during the day matters too. In the morning, the batteries are down and the sun is not yet up. Fortunately the camper is cool and we only needed the A/C in the afternoon when it got hot inside and the batteries were well charged.

We have a coffee maker that draws as much as 1400 watts (more than the A/C unit!), but only for a few seconds at a time as it is heating the water. The total draw on the batteries for our normal 2 cups each is minimal. So no problem running that in the morning.

I hope the graphs above will give you an idea on what to expect from a solar installation. I welcome your questions

Best, Mike

[MAWilsonPE]

To be clear, what we considered normal daily power consumption on this trip...

120VAC appliances: coffee in the morning, A/C for 3 hours in the afternoon, if necessary, microwave for lunch or dinner, charger for battery powered fan, charger for e-bikes, 2 laptop computers and a large monitor for 4-5 hrs/day, streaming 3-4 hours of TV in the evening, occasional central vacuuming to get up some of the sand

When it was cool enough not to need the A/C unit I was able to run my ice-maker for 2 days straight and collect about 40lbs of ice to store in the freezer

12VDC: power for RV fridge control (cools with propane), fresh water pump, a few hours of stereo system, LED interior lights, LED under carriage lights at night, chargers for jetpack, iphones, ipads and camera.

Best, Mike

[twindman]

How did you only use 10 amps for A/C? Mine always have used 14-17 amps per the ems system.

[Daryles]

We LOVE OBX especially Ocracoke. We spent 5 days there last year and 10 days in March of this year. Weather was pretty cool this spring.
We have 400W solar into a Victron 100-30 MPPT. I wish I had installed a 100-50 now. We don't carry a generator but I installed a Renogy 60A DC-DC charger.
We had 3 straight days of rain. I had to run the truck twice a day for an hour to charge the batteries back up.
We had one full propane tank and 60% in the other. We ran out. There is no propane fill on the Island. We had to buy a 20lb BBQ grill tank to get us through the last couple of days (cold!).
I did learn how to tweak the MPPT programming to maximize the output.

[MAWilsonPE]

Hello Twindman,

I guess I should be more careful with my math. When running the A/C I see about 100 amps of DC power being drawn (once both fan and compressor are running). I used a lazy conversion of AC amps = 1/10 DC amps (12VDC/120VAC) but in reality the lithium voltage is closer to 13.5-14 volts so 100 DC amps is closer to 11-12 AC amps.

My model is a 2021 and they installed "high efficiency" AirXcel Coleman Mach model "MACH 15 Powersaver" heat pumps and air conditioners. According to the AirXcel website this heat pump draws 11.3 amps when cooling and 15.6 amps when heating (AC). I am not sure if Keystone is using these units on all models or when they started with them. I have never looked at the amps on my EMS on shore power but I will

Both the heat pump (living room) and air conditioner (bedroom) have soft starts installed. If you have not seen these in action see the DC amp curve below. This was for the heat pump starting in cooling mode. Note the soft start does not control the fan start up (first dip) but only the compressor.

Best Regards, Mike

[MAWilsonPE]

Hello Daryles,

It had been about 20 years since we went to the OBX. We took the 2.5 hour ferry from Swan Quarter to the southern end of Ocracoke. I like that I could make a reservation on that ferry. When we left north to Hatteras the southern ferries were down with mechanical issues and we had to wait over 3 hours to get off the island... but that one is free.

Ocracoke is great. Sites are big, at least on the beach side. The sand spurs are minimal and seemed to be last year's left overs and kinda soft. I thought the best feature is the 4.5 mile sidewalk all the way from the campground into town. We took our e-bikes multiple times and tooled around town and got lunch. Nice not to have to worry about the vehicles on the road. We never ran our heat so 2 full 30# tanks of propane was plenty, I think we emptied just one.

Frisco NPS campground is much more wooded. Well spaced sites but the ticks were heavy, we saw a cottonmouth snake on our site the first day and the sand spurs were extremely heavy. I could not take two steps off the pavement without picking up 4-5. Had to be real careful walking the dogs. Frisco Woods campground is not far up the road and they refill propane tanks. We drove through and they have full hookups but it was tight, crowded and not well maintained.

Oregon Inlet NPS campground was great. Sites a bit close together. No trees, so no ticks. Minimal sand spurs. Need to plan a fishing charter next time to go yellow tail tuna fishing. I went to fill my water bladder near the pier at 10am one morning and one boat was back in already with 17 fish! With a 2 hour ride out to the gulf stream and 2 hrs back they must have all caught their limit in less than an hour!!

Hope to visit the OBX again soon!

Best, Mike

[Daryles]

We stayed at Oregon inlet before. We had electric and water connections at that time.
I have a Dometic Blizzard NXT air conditioner that I installed a SoftStartRV in.
Mike Sokol of
RVELECTRICITY FB group
https://www.facebook.com/groups/rvel...ity/?ref=share
Did a test on the SoftStartRV. He has detailed his results here.
https://www.rvtravel.com/rv-electric...ft-start-caps/

Here's screen shots of my tests. The AC really draws down the batteries. You can see in the last screen shot the current draw increase and the voltage drop.

[Foldbak]

I have a question. The Victron Connect app shows your solar production history. I've noticed that my production while stored on shore power in the sun shows very little production compared to when the rig is being used. Especially while boondocking. I've concluded that the app is not showing production but rather draw. Is this correct?

[rames14]

Foldbak, it only charges when you need it. So, when in storage, you have minimal draw so it will only charge what it needs to stay at 100%.

Mike, glad your solar is working well. We were able to stay at 100% by the end of the day while in the SW during February. We replaced the Jaboni 30’s with Victron 50’s also. Plus, replaced the PD Transfer Switch with a a Hughes Watchdog. We also had our AC controllers changed out thanks to your posts last year on the load shedding. Safe travels.

[Foldbak]

Originally Posted by rames14

Foldbak, it only charges when you need it. So, when in storage, you have minimal draw so it will only charge what it needs to stay at 100%.

I was referring to the Victron app that shows solar history. It's a bit misleading.

[rames14]

Foldbak, this is my VictronConnect chart, if that’s what you’re referring to (and I might be misunderstanding, so if I am, I apologize). This is my graph. I have been on 50 amp, so Solar Charge Control did not allow any charge to the battery. Today, I disconnected and drove 4 hours. Plus, I had my DC-DC charger connected. When I get to our Boondocking site, I anticipate seeing significantly more. The Victron app is only showing what it is providing to the battery, not how much the panels are seeing. Am I answering your question?

[Foldbak]

Originally Posted by rames14

Foldbak, this is my VictronConnect chart, if that’s what you’re referring to (and I might be misunderstanding, so if I am, I apologize). This is my graph. I have been on 50 amp, so Solar Charge Control did not allow any charge to the battery. Today, I disconnected and drove 4 hours. Plus, I had my DC-DC charger connected. When I get to our Boondocking site, I anticipate seeing significantly more. The Victron app is only showing what it is providing to the battery, not how much the panels are seeing. Am I answering your question?

Yes you did. Thanks!

[MAWilsonPE]

Hello Foldbak,

The summary information above is for solar production and is gleaned from the Victron Controllers, not the battery monitor. This is evident as you cannot see the juice I pushed in using my generator on May 23 & 24.

You will not get much production when stored if the batteries are full. What you see above is mostly "bulk" charging which is the max available amperage. At about 85% battery charge or so, the controllers switch to "absorb" charging which is slower. As it nears 100% it virtually stops charging, even in full sun (which makes me want more batteries )

I had the Victron MPPT controllers set to the stock Lithium battery settings using the dip switch. I found this resulted in a low charge voltage during absorb charging. I switched to "expert" settings to allow me to up this voltage to closer to what Futures Sales recommends in their setting sheet for absorb charging.

I hope this helps.

Best, Mike

[rames14]

Mike, is the expert setting in the Magnum panel? I will look today, but believe ours is already set there.

[MAWilsonPE]

Hello Ron,

Glad to hear you are enjoying your solar system! I had to replace my PD transfer switch, they replaced it under warranty so I just swapped it out. I hardwired my generator into the generator side of that switch so it works as intended. Will see how long this one lasts.

I did install a hardwire Progressive Industries 50 amp EMS to add more AC protection.

Glad to hear you got your shed control working.

The last problem I am still having relates to poor connections for the two relays (the ones with red lights) in the SSF box. These tell the PCS that power is being supplied by the inverter (it should say 25A Generator). I had corrected this for a time with some conductive grease but they still manage to shake loose causing the system to shed all its loads and reset them 2 minutes later. Most of the time the PCS just says 30A Service indicating a failed connection.

I talked to Matt about this and he agreed this is a problem. They had tried tie wraps around the relays but they still shake loose. He has another solution now, a "circuit board that mounts on the inverter" that he is sending me to try. I will let you know when I can give test it out.

Overall I am real happy with the system. But now I want MORE... maybe another 600 watts solar and 1-2 more batteries

Best, Mike

[MAWilsonPE]

Ron,

No, the expert settings are accessed using the Victron app for the controllers. It overrides the dip switch setting. When set to its stock Lithium battery setting I believe the absorb voltage is 13.5 VDC or so, I raised to about ~14.3 in expert mode. This is closer to the 14.5 Matt recommends for the Magnum charger absorb voltage.

Don't hold me to these settings, they are from memory. I will double check them tonight.

Thanks, Mike