Our First Serious Solar Use

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Our First Serious Solar Use

June 25, 2018, 12:02:49 am

We're camped at Ten-X Forest Service campground a couple of miles south on 64 from the Grand Canyon South Gate. I'd commend this campground to anyone interested in the Grand Canyon. No electric, water fill or dump but big, beautiful campsites...and lots of them pull thus. Ours is easily 60-70 long. Water is available for drinking, washing dishes or washing hands...just not filling tanks. We came in full of water and empty tanks and can easily say a 7-10 days without worry as far as fresh water and grey/black are concerned with cooking, cleaning and daily showers.

But without power we rely on solar (640 Watts) / Battery (675 aH) and generator. Generator is allowed from 6 am to 10 pm. So far in our first 3 of 7 days solar covered 100% of our needs until today. Normally our daily deficit is about 80-120 aH which could be easily made up by solar of 120 aH daily even with partial shade. As an experiment we ran the Uline ice maker during daylight hours yesterday and ended up with a deficit this morning of about 200 aH, or SOC about 80%. We brought in about 120 aH while we were gone today but with minimal parasite draws (salesman's switch off and propane fridge on gas), we were at about 87% at 4 pm....still about 100 aH down.

Fired genny for about 2 hours but quickly reached absorption where genny power couldn't move batteries along faster than absorption needed. Shut off genny at 92% at about 6 pm. Now at 9 pm we're at 89%, 12.8 v and down about 103 aH from 100%. I suspect with small overnight draws we'll be down 140 ish by morning and solar tomorrow will bring us up into the mid 90% SOC.

It's been interesting to see that in our previous solar usage we've only been down 80-100 aH by morning so solar could easily bring us back to 100% by lunch. With additional draw to make ice and shade for part of the day we can still go 3-4 days but progressively fall behind 10% SOC without eventual genny use.

Takeaways are that ice maker + inverter not really reasonable with less than 100% full sun site. Easy to buy ice most places. Without inverter/icemaker probably no issue in maintaining 100% SOC indefinitely even with normal use and partial sun. And, even with loads that prevent solar to 100% daily it's seems rather eas9nable to go 3-5 days with minimal genny use.

Real takeaway is how long it takes to get from bulk to float.

Randy

Re: Our First Serious Solar Use

Reply #1 – June 25, 2018, 12:42:46 am

Great observations. What kind of batteries are you drawing off of?

Re: Our First Serious Solar Use

Reply #2 – June 25, 2018, 12:45:11 am

What electronic devices do you use on a daily basis? How many watts/amps does the ice maker use?
What type of batteries are you using? What type of inverter? Do you shut the inverter off at night?
I'm thinking your solar panels should keep you batteries full until close to sundown and fill them before noon on a sunny day.

Re: Our First Serious Solar Use

Reply #3 – June 25, 2018, 12:55:11 am

Seems like on all systems, Genny or Solar that last 10% takes a LONG time - always can add more Watts on roof at some point - but I like the idea of a bit of Generator use every third day or so - they are good to a HUGE amount of hours (10,000+?) need to be excsercised and are not that noisy if run during daytime - plus if you need to cool coach with AC, and you are not on a power pole, it is the only option. TO each his own, but the coach came with an expensive, efficient low maintenance long lasting generator, I have no issue using when needed. For some it is a pastime to make sure they don't use the Genny and if that is what floats your boat, all good!

Sounds like you have a nice mix of solar and sensibility.

Solar power is kind of like money - no matter how much you have, you can always find something to do with more of it.

1180 Watts on my roof, of course more would be better!!!!!

Tim Fiedler

Sure Start Soft Start - home of SureStart soft starters TCER Direct - home of Generac Approved Aluminum and Copper TCER Composite cable generator-gas-prod - home of X-Riser Gas Risers for PE installation Call me at 630 240-9139
Gen-Pro

Re: Our First Serious Solar Use

Reply #4 – June 25, 2018, 07:10:52 am

Nice results. I wonder if running your generator in the morning for 2 hours then letting the solar panels finish might not work better?

Re: Our First Serious Solar Use

Reply #5 – June 25, 2018, 09:03:01 am

Batteries are 3 Deka 8G8D @ 225 aH each. Uline manual says 2.5 amps running, Xantrex 3012 says 3 amps and normal parasitic draw seems abou5 3 amps but we also used the coach during the day in question, ie showers, led lights, etc.

Included in parasitic draw are 2 phone chargers, 2 iPads and 2 surface computer tablets, TV, etc runnin* 9n an 800w Victron inverter that's on 24x7.

Re: Our First Serious Solar Use

Reply #6 – June 25, 2018, 09:12:58 am

Morning is not always the most convenient time to run the gen but it makes sense to let it push big amps in when your batteries are lower in charge and more accepting to new amps. Unless you are using Lithium batteries, normal batteries do best when they get fully recharged on every cycle. That last 5-10% can take all day.

All of the chargers and the rest of the small stuff are pretty small loads. The Victron 800VA inverter has an economy mode which will put it into a very low level use state. In this state it looks for loads and powers up when needed.

You can add 12v powered stable USB charge ports for phones, tablets and those kinds of things. They use almost nothing not charging, less than a 120v charger plugged in on an inverter circuit doing nothing. We have three of these.
Amazon.com : Blue Sea Systems Dual USB Charger Socket : Cell Phone Car...

It is really nice to be able to be off-grid for a week or so and be generator free or only need to use it for a couple hours.

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Our First Serious Solar Use

Reply #7 – June 25, 2018, 10:34:38 am

Randy,

We have about 420 Ah for our six batteries but 1140 watts on the roof. The big differences are that we shut down the inverter at night or if not using it. In the morning, it runs the microwave fine for lattes and we are up to float by 11am. We are almost all LED including the big screen and use propane for the fridge. No ice maker. Would be nice to have! Never any generator use except if we venture down to lower elevations in summer and need AC.

I think one more panel on your roof would get you to float much quicker. Right now, the sun is as high as it's going to be in the sky and you are pretty far south in the U.S. As you travel to higher latitudes and summer turns to fall, your panels won't be able to squeeze as much out of the sun. Plus, cloudy weather drops the efficiency down a bit so you may need to shut your inverter down part of the time.

How many watts will your controller handle? Low percentage daily discharge on the batteries will extend their life. Sort of like a Toyota Prius that has been modified so it drops battery voltage 20 percent or so before the engine starts. They may be able to get to work and back but at the expense of battery life. Our AGMs have gone past eight years now. Keeping fingers crossed.

Heading to Oh Ridge Campground at June Lake in a couple of hours where we will go a week dry. They do have water available and there is another RV park with showers an easy walk away.

Pierce

Re: Our First Serious Solar Use

Reply #8 – June 25, 2018, 11:12:46 am

the specs for my 86 GV say I have a 75 amp converter so I mistakenly thought it meant 75 amp battery charger. Wrong....I was told that it might be 5-7 amp charger which seems very inefficient for charging with the generator for bulk charging. I would think installing a 50 amp DC charger to bulk charge and let the solar power take care of the float would be the way to go. Any corrections?

Wantabe
1986 Grand Villa 33'
chevy 454 front

Re: Our First Serious Solar Use

Reply #9 – June 25, 2018, 11:28:38 am

I agree with Pierce. More watts on the roof will make a difference. With our residential refrig we are pulling more out of the batteries all day but with 900 watts of solar we were at float in the early afternoon in the summer. Not so easy in the winter with shorter days and lower sun angles. I just added another 300 watt panel to help out.

Re: Our First Serious Solar Use

Reply #10 – June 25, 2018, 12:15:45 pm

Quote from: Roger & Susan in Home2 – June 25, 2018, 11:28:38 am

I agree with Pierce. More watts on the roof will make a difference. With our residential refrig we are pulling more out of the batteries all day but with 900 watts of solar we were at float in the early afternoon in the summer. Not so easy in the winter with shorter days and lower sun angles. I just added another 300 watt panel to help out.

Yes. Randy and Co are doing very well with 640 watts. Watt rating can be misleading as it is measured with the sun 90 degrees over the panel and test temperatures. The panels will lose efficiency in summer heat. I measured voltage at different angles before installing ours. The voltage really jumps up with the sun perpendicular. I did see a fellow that installed a reflector on his. Wattage really increased. Bottom line is that you can never have too many watts up top especially if traveling in the off season.

Pierce

Re: Our First Serious Solar Use

Reply #11 – June 25, 2018, 12:38:50 pm

OH, if only one could park under the parking lot lights at Walmart and siphon/actuate the solar panels to charge the batteries.
What a wondrous improvement it would be. Just think about it. All these solar panel equipped coaches gathered and jockeying for position under the lights like bugs attracted to a Colman gas lantern!

Old guys on the outskirts crawling up on their coaches trying to tilt their panels for maximum gain. Ambulances racing to the scene.
Oh, the wonder of FREE charging at night!!

Re: Our First Serious Solar Use

Reply #12 – June 25, 2018, 01:00:14 pm

Nitehawk,

And for those intrepid people, lay out long strips of a conductor under big power transmission lines and charge by induction.

Avoid the Walmart crowds!

Pierce

Re: Our First Serious Solar Use

Reply #13 – June 25, 2018, 01:06:21 pm

This voltage chart has been posted before. It's a great reference...

Re: Our First Serious Solar Use

Reply #14 – June 25, 2018, 01:11:14 pm

A quick rule of thumb is to take the total watts x 10 hrs x 25% to get an average day real world output.

640 watts x 10 hrs x 0.25 = 1.6kw on an average day. Maybe more in the summer, less in the winter, more in all sun, less with some shade but it seems to be a good ball park estimator.

In Randy's case assume his average volts are 12.6, divide the 1600 wats coming in from solar during the days by 12.6 to get 127 amps pushed back into his batteries over the course of a day. About right.

Keeping your batteries above 75% SOC or 12.4 volts will significantly extend their life. SOC is relative to what the batteries are actually capable of doing. It is rarely what the manufacturer says after a few years of use.

Re: Our First Serious Solar Use

Reply #15 – June 25, 2018, 06:20:36 pm

The Deka 8g8d's should not be hurt at the use in a partially discharged state unlike agm's which if sulfated enough would require equalization that other than the lifelines cannot be performed.

Good point about maybe running the gen first to get the bulk charge stage finished then allow the solar to finish the charging if possible.

The Deka gels are designed to be bulk charged at 1/5th C. Which was how the coach was shipped new. The other way is 1/20th C.

I understand the 1/5th C bulk charge restores the batteries SOC better as they cannot be equalized.

Mine take around 115 amps at bulk. Then switch to absorption at 85%. Old freedom 25 switched at 90%. Why? No idea.

Now that I think about it the batteries( at least the oem gels) may well need the 1/5th C. Charge rate. The lifelines I think are 1/4 C.

How much solar would it take to input 1/5th C into 675 amp hours?

That's how the oem alternator and oem Charger were setup and the long term results posted here show that it was correct.

Slow charging to less than float may or may not be as long term reliable.

If you consider the necessary charge rate needed to restore the SOC for the longest life it's likely the gen for bulk.

That's how I use our small solar now. Gen or alternator for bulk. Alternator turned down to 13.6 volts to partially offset its non temp corrected nature.

Then let the solar finish at roughly 1/20th C with both the engine and batteries combined.

Re: Our First Serious Solar Use

Reply #16 – June 25, 2018, 08:22:44 pm

Going to stop in Eugene in early August to have fluids changed at Oregon Motorcoach and then have appt at AMSolar to have the entire solar system evaluated. Their initial response by was that our 2-48v panels would be hard to match and that adding different panels would require a second controller. I'm considering changing our outback contr9ller t9ma Victron which I can monitor b6 Bluetooth and will also price out simply changing the array on top at the same time.

Not unhappy with what we have...simply trying to become familiar enuf to know exactly what we can do. This 6 month trip will tell is a lot about our solar needs. So far our favorite camping has been forest service dry campgrounds and they don't alway provide optimum sun exposure.

Re: Our First Serious Solar Use

Reply #17 – June 25, 2018, 08:32:21 pm

The higher voltage is commercial. Needs a conduit for safety

Re: Our First Serious Solar Use

Reply #18 – June 25, 2018, 10:16:14 pm

That is the big difference between LA/AGM vs LiFePo4 battery tech. With lithium you can cram those amps in, and never have to fully charge, but with LA, its a different story.
Sounds like solar is working well for you. The real problem for longer term boondocking as I see it is water and sewer capacity.
I am contemplating switching to a composting toilet to free up the water needed to flush, and it would add grey water tankage.
Bob

Re: Our First Serious Solar Use

Reply #19 – June 25, 2018, 10:42:22 pm

As an aside to the solar topic of my post, and in note of Bob's comment, our current finding are that we can easily go 7-8 days dry camping when starting with a full fresh tank and empty black/grey. This assumes no outside water add d, daily showers formbot( of us and 70-80% of our meals in th coach with non-paper/plastic utensils.

In the end the limiting condition is fresh water, not black/grey in our experience.

And at the end of our 8 day run we had not completely drained fresh water nor filled the tanks. Even though a composting toilet would increase grey capacity, it couldn't increase fresh water capacity. And more grey would still require dumping.

Our experience only...your experience may differ.

Re: Our First Serious Solar Use

Reply #20 – June 25, 2018, 10:43:25 pm

Obviously the li-ion has many advantages. Some you mentioned.

Seriously considered several systems. The $6-12k was a consideration but the deal breaker for me was the narrow temp range in both charging and use.

I have been at more than -30 F and over 120F. Many times. Plus dry storage outdoors.

A microphor toilet has a adjustable knob to control how much water is dispensed.

You only need enough to cover the seal.

Re: Our First Serious Solar Use

Reply #21 – June 26, 2018, 12:03:13 am

In regard to water usage, there are many ways to conserve. Pretend water costs $1,000 a gallon -- or that 100 gallons needs to last 60 days -- and see what you come up with.

Re: Our First Serious Solar Use

Reply #22 – June 26, 2018, 12:25:19 am

On our 16 day vacation dry camped at Oh Ridge in the Sierra's, used the generator 1 hour a day solar gave over 5 kw every day with shade at 3:30 cutting watts back to less than one hundred. Peak was between 998 and 1210 watts during that time. Left home with fresh full and holding tanks empty. Returned home and dumped at the house with fresh water left and the old monitor system had black under 50% grey at 70%

Re: Our First Serious Solar Use

Reply #23 – June 26, 2018, 03:27:18 am

Quote from: floridarandy – June 25, 2018, 10:42:22 pm

And at the end of our 8 day run we had not completely drained fresh water nor filled the tanks. Even though a composting toilet would increase grey capacity, it couldn't increase fresh water capacity. And more grey would still require dumping.
Our experience only...your experience may differ.

But it would. A composting toilet uses no water. So more of the water in the tank is then available for other uses, like showering. The black tank can be used for urine only. Not for everyone for sure. But if your in the mood to stay out for longer periods of time, it is one way to do it.

Re: Our First Serious Solar Use

Reply #24 – June 26, 2018, 03:30:41 am

Quote from: Dakota Slim – June 26, 2018, 12:03:13 am

In regard to water usage, there are many ways to conserve. Pretend water costs $1,000 a gallon -- or that 100 gallons needs to last 60 days -- and see what you come up with.

Great way to look at it. One of the things I liked about sailing off to parts unknown, was the ability to make fresh water from salt via a reverse osmosis watermaker. Can't do that in a Foretravel so you have to conserve. At $1K per gallon, won't be taking much in the way of showers or down the black tank for sure.... would be used mostly for drinking and cooking, with a bit left over for cleanup.

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