Looking for pointers from those who are into solar

[Searching_Ut]

Originally Posted by ret60sp

Not to sound snarky here, but 100's of hours in an aged classroom doesn't count when those classroom hours were delivered more than 10 years ago. Battery technology has come a Long Way in the last 10 years.

Does sound snarky, but I'd still offer you a beer in the campground. If you're in the Tetons in the next couple weeks swing by for a cold one.


My classroom training was indeed years ago, but working with the design engineers and chemists one on one took over. New technology was pretty much my business most of my career, from test squadrons in my active duty years to defense contractors and the DOD civilian following that. I wrote or at least did a periodic reviews on much of the maintenance, and time change criteria for assorted military aircraft battery systems over the years, and was heavily involved in the design and development of many of the current systems. Also a lot of systems that are still in development. For the last 10 years or so, if your front line fighter needed upgraded, troubleshooting or repairs beyond what you could do at the base level, I was more than likely involved in pulling together the engineering and personnel to do it for you. Solving all the issues created because the design engineers and bench folks didn't understand real world use was a big part of it, with battery systems being one of those issues that sound simple but cause lots of issues. I actually have a lot of first hand experience with a wide range of battery and charger systems....

[Golfer Guy]

Originally Posted by nctrigg

If you are looking for a good custom solar/battery setup.
Contact Marvin at Precisionrv.com
He installed : 1200 Ah lithium ion batteries, BMS, 3000W hybrid inverter, and additional sub panel to compliment the 1400 watts of solar previously installed on our coach. We love to dry camp.
Best calling ever made.

Marvin set up mine too. 1200 AH, BMS, 3000W Hybrid, sub panel, 2000W raised Solar. Very slick setup. Nice new additions to be made with some of the new upgraded Bluetooth components available today.


NCTrigg, I PM'ed you

[MarylandRich]

I have a 2002 Country coach Affinity, I had 4 8D AGM battery's and no solar. I was changing out the Heart 2500 inverter to a Magnum 3012 Hy-bread inverter, and decided I would added 1200 watts of solar, and change out to 4-8D 260 AH Green life Lithium Battery's for a total of 1040AH. ( I own some Battle Borne Battery's at work and really like them, but wanted the simplicity of just changing out the 8Ds and Battle Borne did not offer that size). I added a Magnum PT100 solar controller to keep everything simple and controlled through 1 remote. I followed the blogs on Pau Hanna travel website, he did 2 installs, a 24V system on his RV with two Victron inverters and Battle Borne 24V Battery's, and a 2nd install on his father 5th wheel with the Magnum inverter and solar controller setup, and 12V AGM Battery's. My install was mostly like the fathers, but with the Green Life Lifepo4. It worked out great. I ended up with a very pro install that was DIY I learned a lot, about all of it, and saved me a ton of cash over letting someone else do it, and I never would have attempted with out the videos. I put 5000 miles on the coach out West and back right after the install, with everything working just the way it was intended.
Here are the links


https://pauhanatravels.com/solarguide/


https://pauhanatravels.com/solarguide2/

[e4services]

I do this for a retired living so here is what I ended up with after trail and error over the years.
As it has been said, no "12V" panels. You will need more "Potential" Your Inverter Charger can produce using 120VAC 100 amps of 14V charge current. I am using now 24V panels and a charge controller that can handle upto 100V in and a 12V battery out, mostly because of the panel size but the solar charges are cheaper at <100V. I bought a pallet of 340W 24V panels. THey are 6 1/2 feet long and can fit on the roof.
One panel provides enough subsystant charge for 8 golf cart batteries. But more could provide high use draws.

[fratermus]

Not to break anyone's spirit here, but the technical research and data points I've made...

Ladies, you're both pretty.

[freestyle_freddy]

I'll just address something I haven't seen anyone else address. If you're going to spend extended time in one place, you might want to add tilt bars so you can maximize the angle of the panels to the sun. Most tilt bars come with only a couple of tilt angle choices, but I drilled multiple holes so I can tilt my panels every 5 degrees from about 20 deg to 55 deg. Also, if you're going to run two rows of panels lengthways down the roof, keep the two rows far enough apart so if the panels are tilted, one won't cast a shadow on the other row's panel.

[WyGal]

I am considering using the Tesla battery for my solar. Would that be a better option than the batteries listed. Now I am considering going back to the generator idea.

[bobwilcox]

ISAM, asking this group about batteries (or solar in general) is like asking opinions on religion or politics!

But since you asked, IMO, if I was you, adding solar, I would stick with the AGM's until they start to fail, or they aren't able to support your lifestyle. You may get another year or 2 out of them, the price of LiFePO will continue to decrease, and then you can shift to the new technology.

Good luck on your project!!

[bobwilcox]

Originally Posted by WyGal

I am considering using the Tesla battery for my solar. Would that be a better option than the batteries listed. Now I am considering going back to the generator idea.

Better option as in cheaper? Yes
Safety? Possibly Equal, but...

Make sure to do all your homework, The limitations discussed about temperature and voltages above still apply. A battery management system (BMS) is necessary, to protect the batteries and yourself.

I went with a Nissan Leaf battery bank in my RV (48 volt), so you could look into it or others, as alternatives to the Tesla setup.

[roccovw]

One of the consideration for solar is the ability to keep your house batteries charged during periods of storage when not using your rv. We only boondock and minimize our battery usage to the point were a half hour run with our generator will top up our house batteries but during the off season our motor home is parked in a compound across the street from us without the ability to plug in to shore power. A moderate sized solar setup keeps the batteries topped up, saves the hassle of removing the batteries and hooking the batteries up to a trickle charger.

[dmg111]

Some time People like you just tell it like it is
A GOOD JOB!!
You are right on. I all so have a CCI with all the things you talked about. The coast of doing it right. Can pay for a lot of fuel!
One should think first about what he or she getting after doing the solo thing.
For me it summer it's hot i run the Gen.
Good Luck with what ever you do?
I have been full timing 25 + year.Capt Dan

[Ivylog]

We have not heard from IASM since post 1, although he has been active in other threads. We still do not know how he would use a solar system.
WYGal does not own a RV yet.

[Itinerant1]

Maybe he forgot he started a thread or should atleast participate as the OPer.

[ret60sp]

To stay true to this thread:


There are three sources of power to consider:

1) Engine Alternator – 300 amp Delco Remy 40Si
2) Generator- Onan 7500, split into 30 amp/20 amp
3) Solar Two Solar World 290 watt panels

How much power can be generated by each of these sources for a bulk charge situation?
For the sake of simplicity, I’ll be using 13.5 Volts DC in the calculations. Yes, I know charge voltages are higher, however battery voltages are lower, so for the sake of some simple math I’ll be using 13.5 VDC across the board in the calculations. Save your harpoons for something else.
1) The engine driven alternator will output 100% of its rated power if the detected* voltage is below 13.5 VDC.
a. * Alternators with Remote Sense have additional features and are more capable of charging batteries faster than conventional alternators.
b. 300 amps @ 13.5 VDC = 4,050 watts.
i. *Remote Sense Alternators are capable of 300 amps @14.5 VDC or 4350 watts.
c. Engine ECM’s typically consume 30 amps from the alternator. If the radio or any other DC electric accessory is “on” after engine start (i.e. running lights), that power must be subtracted from the potential energy going to recharge batteries.
i. Subtracting 40 amps from the alternator output to run the ECM and other hidden DC loads reduces the mean effective charging output of a 300 amp alternator to 260 amps or 3510 watts.

2) Generator – almost all generators above 5Kw service have split power, and all 50 amp service RV’s have split service. This means the power circuit of your 7.5Kw – 15Kw generator is split into two different 120 VAC circuits. Few of the manufacturers actually externally wire the genset-to-coach to operate at 100% of its rated power. If you have a 7.5Kw system it is more than likely wired to produce 6,000 watts or 7,200 watts, but not 7,500 watts. Look at the line breaker coming off of the genset to determine your load capacity. If you have a 30 amp and a 20 amp breaker you have 3600+2400=6000 watt service. If you have two 30 amp breakers you have 7,200 watt service. Just note that you only have the power of each circuit separately on a split system, and in this example you are limited to a charge current of 3600 watts minus the line losses and inverter inefficiencies. Most charger/inverters are limited to 100 amps of DC charge current, which means they can only charge the batteries at 100 amps x 13.5 VDC = 1,350 watts. Inverter/Chargers rated for 120 amps produce 1,620 watts of charge current. Rare and very expensive Inverter/Chargers that output 150 amps produce 2,025 watts of charge current. The average RV inverter charger outputs 1,620 watts of charge power maximum (or 120 amps DC).

3) Solar – Although solar is sold to the public as watt/hr rated panels, to achieve their sales rating the panels must be oriented perfectly facing the sun, on a cloudless day, with no obscurations or diffusing humidity to achieve their rated power. They do not produce power at night. As in my personal life’s example, we have seventeen 245 watt panels on the roof of our home with a “rating” of 4.1Kw of power. They have produced 36.46 Megawatts of power, or 36,460,000 watts of power over the last 2240 days (since installation). The simple math and the exact amount of power they have produced each day is 16,277 watts/day or 16.27 Kw. Take that and divide it by 12 hours of sunlight (an average) and we have the exact production of 1,356 watts per hour, or 1.36Kw/hr in the 12 hours of power production. That’s a far cry short of the salesman telling us it’ll produce 4.1Kw/hr. In reality we are getting 1/3 of the rated power when averaged over a 12 hour solar day. You should expect the same performance, or less, on roof mounted RV solar panels.

a. We have two 290 watt Solar City panels mounted flat on top of the RV. They do not produce 580 watts of power. In fact I’ve never seen them produce more than 510 watts of power. The average power production of these panels over a given solar day is 2,280 watts. That means they average 190 watts per hour over the 12 hours of solar production.
b. If you have 1,200 watts of solar panels, and you are operating them in a setting similar to ours (here in the SE United States with diffused sunlight, high humidity and high temperatures in the summer) you should expect 33% of your rated power on average, meaning your 1,200 watts will produce (on average) 400 watts of power per hour over the 12 hour span, or 4,800 watts of power. The average RV with a solar installation has less than 600 watts of potential power, and even at 600 watts (maximum) the potential energy to expect from those panels would be no more than ½ of that rating over a 12 hour solar day or 3,600 watts for two 300 watt panels.
Now to compare all three for charging your house batteries. Starting with a set of eight 207Ah rated AGM batteries, discharged to 50% SOC, requiring no less than 11,178 watts to recharge them:
A) The 300 amp engine alternator has a charge rating that is not limited by the inverter/charger and therefore it can recharge the depleted batteries at a rate of 3510 watts/hr.
a. 11,178/3510 = 3.18 hours.
B) The120 amp Inverter/Charger is limited to 120 amps and is therefore capable of 1,620 watts output maximum.
a. 11,178/1,620 = 6.9 hours
C) The typical solar system is capable of 3,600 watts per day.
a. 11,178/3,600 = 3.1 DAYS* assuming you do not interrupt the recharge by using the power from the batteries, and assuming that there are no losses overnight between the charge days.
Obviously tripling the size of your solar array from 600 watts to 1,800 watts means you can recharge the eight 207 Ah AGM batteries in 1 Day. However, to achieve this feat, one must NOT use any power from the batteries or from the charging solar array during the daylight hours or it will lengthen the charging time necessary to achieve 100% SOC. You’ll need to operate your generator or engine driven alternator occasionally to achieve this.


The sweet spot: In the morning before your solar panels actually start producing any significant amount of power (6am – 8am), start your quiet generator and let it put two hours of energy into your batteries, or 1,620 x 2 = 3,240 watts towards the 11,178 depletion. This brings the number down to (11,178 – 3,240 =) 7,938 watts remaining. Then start your engine driven alternator for an hour (8am – 9am) and it will bring things down much faster by inputting 3,510 watts into the recharge leaving (7938 – 3510 =) 4428 watts remaining. At 9am let the Solar system take over and during the course of the day it will erode away another 3,600 watts of the remaining 4,428. At lunch time again start your genset to use your microwave or air conditioner, and as long as you are not trying to operate multiple air conditioners your Inverter/Charger should still sense a bulk charge need and dump in 100% or 1,620 watts of power for that lunch hour. Between the genset lunch hour (1620 watts) and the 12 hours of solar charging (3600 watts) the overall remaining 4,428 watts needed to return the battery bank to 100% SOC should be achieved before sunset. If you do not want to start your engine and use the alternator, you can achieve the same by operating the genset again for two hours during dinner, where it will again produce almost as much recharging power during those two hours of operation as the engine driven alternator does in 1 hour.


Note: If you have two banks of eight AGM batteries (16 in total) and a 12.5 Kw genset with two inverter/chargers, and a 350 Ah alternator, the generator and the alternator are about equal in their capacities in this scenario, and there is no advantage to operating the engine driven generator while sitting stationary at a campsite. You’ll be better off in this scenario by operating the genset, but your Solar array would need to be rated beyond the capacity of your roof surface area. In other words you would need about 215 square feet of solar on your roof to achieve (11,178 watt x 2 demand) the power demand to recharge sixteen AGM batteries using your generator for 5 hours and your solar array for the remainder if you were sitting here in Georgia. You might be able to achieve a full recharge if you live in the Desert SW or in a high mountain situation west of the Mississippi river and you operate your generator and both inverter/chargers for at least 4 hours of run time in addition to having a higher output solar day.
This discussion does not factor in the losses of the differences of inefficient equipment, batteries resistance to charge/discharge.


Note 1: eight 207 Ah AGM batteries do not produce enough start (surge) power to start a 15,000 btu air conditioner. The maximum (safe) output that eight 207Ah AGM batteries can produce is less than 12 amps @ 120 VAC. It typically takes in excess of 18 amps (surge) to restart an already loaded air conditioner compressor. Units without an installed easy-start system can surge beyond 30 amps (3600 watts) to start a loaded air conditioner compressor. Therefore it is not possible to use your 15k air conditioner on batteries alone through your inverter without doubling or even tripling the number of conventional batteries needed to achieve the necessary surge current.


Note 2: This original scenario (sixteen AGM batteries) could be duplicated with four 12.8/300 LIFEPO4 batteries made by Victron Energy and arranged into two banks of two 300 Ah batteries (600 Ah in each bank).
a. If you were to increase the battery bank size to six 12.8/300 LIFEPO4 batteries, three in each bank or 900 Ah in each bank, the ability to operate one or more air conditioners without continually operating a generator, engine alternator, or being connected to a shoreline becomes possible. However, the power consumption of operating an airconditioner (even one air conditioner) does exceed the solar space limitations on an RV roof and you MUST use your genset, engine driven alternator, or a shoreline to recharge your battery bank. It is not possible with current solar technology to completely outfit an RV roof with enough solar power to operate one air conditioner for more than a few hours.


Hopefully I haven't hurt anyone's feeling.


If anyone needs proof of the data just PM me and I'll gladly send you the current data sheet from our solar array.


The 4th source of Power - Hopefully everyone realizes that a 50 amp shoreline connection negates the concern all together because a 50 amp shoreline connection has a 12,000 watt capacity and could recharge your entire bank back at whatever rate your Inverter/Charger is capable of - typically 2-3 hours if your charger is mean enough.





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