Solar Data

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Solar Data

March 02, 2018, 08:33:23 am

Finally took the time to figure out how to view daily data logged on our Outback Flexmax 80 connected to 2-320w panels.

Looks like daily data ranges over the last two weeks or so of 0-118 AH, .2-1.6 kWH with peak input volts 77-102 and peak output .6-32 aH and .07-.45 kWH.

Panels don't tilt.

Not exactly sure what this will mean boondocking but looking for input.

Thanks

Re: Solar Data

Reply #1 – March 02, 2018, 11:32:33 am

I have the same controller you and 2 420w 73v panels. Never looked at all that data. We dry camp almost all the time, 1000w inverter on all the time, tv on till 11pm most nights, heaters propane on when needed to keep a reasonable temperature 68-70. Our 3 8d agms are back full by 1pm with the panels laying flat. With that said we are careful with power usage, use the generator for large loads, coffee with old style stove top pot. We never need to run the generator to charge batteries. What it all means park east to west to maximize your charging, stay away from shade, you'll be fine enjoy the piece and quiet. Hard to find much real boon docking back east not a lot of open public land, and the need for AC. We spend all of our time west of the Rocky Mountains.
Happy travels

Re: Solar Data

Reply #2 – March 02, 2018, 06:03:45 pm

Bruce or Andy, What brand and model of panels are you using?

Re: Solar Data

Reply #3 – March 02, 2018, 06:52:24 pm

Forgot what mine are and the tags are gone, they are 128 cell.

Re: Solar Data

Reply #4 – March 17, 2018, 01:34:24 am

My average over the last month has been 92AH a day (max 127AH, Min 45AH), and most days recharged by 2pm while making coffee off the original 1500W inverter this coach was born with. Installed a separate 300W inverter for the entertainment center that usually runs 10AH with TV, Computer, ROKU, and a Kodi Box running all day. Max input I've seen is 35amps off my 2 Sunniva 295W panels. Max output is when making coffee, 57amps. I too watch TV until 11 or 12, and it's been a little cold the last couple days so the heater has kicked on a few times each night.

I have a Morningstar MPPT-60 and 4 Trojan T-125's. I religiously equalize every 30 days and check water every 15.

Looking for a way to shift additional amps the panels are bringing in toward the engine batteries in the afternoon.

Re: Solar Data

Reply #5 – March 17, 2018, 09:04:10 am

Ken, we have 3 Renesola 300 watt panels. Lower sun angles at this time of the year mean less output. Still with variable clouds we are doing 1.6 KW to 2.3 KW each day ( @12.5 volts that is about 128-184 anp hrs per day). In the summer it goes up to 2.4 KW to more than 5KW (190-400 amp hrs)

A OK approximation to what to expect from panels is to take the total watts x 10 hrs x 25% to get an average expected output over the year for different shade and sun angles.

To figure out what you need you have to know what you use. That takes some measurements. With a residential refrigerator we use about 2.8 KW per day. (@12.5 volts, 225 amp hrs). It can easily go up over 4KW if it is warm, fans are on and the big inverter is on but generally if that is the case you may be getting more solar.

Every coach and every user is different. And everyone's objectives are different too.

Re: Solar Data

Reply #6 – March 17, 2018, 10:15:22 am

Chuck the new coaches in the industry all use auto combiners to tie both battery banks together under charge from either side.

Sealand ACR connects at from 13 to 13.6 volts defending on how long that amount is detected and disconnects when either bank drops to 12.7 volts for a short period.

The ACR is magnetic. No power consumed. In your case as the solar puts out its power in the morning you would hear the click from the auto connect function if the front switch is set to auto and at night as your house batteries(or engine) drop to 12.7 volts in use you will hear the click again from the auto disconnect.

There is a manual connect and disconnect also.

My Control switch is where the boost switch was. Did not bother to run the switches internal lighting which verifies the functions operation.

No isolator, ACR installed where the isolator was. Isolator consumes power and needs fins to dissipate its heat and the oem boost consumed 3 amps when on.

No heat with the ACR and less power consumed and no power consumed by the solenoid in the old boost switch system.

Not aware of any isolator use anymore.

Seems a no brainer to me other than the cost of the ACR and the install but I am not aware of any other fool proof way to address this issue?

Re: Solar Data

Reply #7 – March 18, 2018, 09:54:10 am

Still parked next to the house but trying to monitor use/solar recharge. Yesterday evening I turned on propane fridge and 800w secondary inverter with Apple TV on but TV off. By 8 am total drain was 70 amp hours at a drain rate of about 5 amps. Obviously doesn't include other normal camping loads like LED lights and water pump.

By 10 am 11.9 amps in (net of above load) and consumed Ah down to 65.

Will update as day goes on.

Re: Solar Data

Reply #8 – March 18, 2018, 10:55:13 am

It helps only to speak in common terms, which is WORK that the system must generate. This is measured in KWH (KiloWatt Hours). The daily consumption my U270 had while boondocking is about 5 KWH. About half of this power is overhead: just to keep the inverter and related 115VAC systems running. The largest consumer of the remaining power is the original compressor icemaker, which is on 24x7. We use the convection / microwave oven once every day. It draws a maximum of 1500 watts for 30 minutes, or .75 KWH. The propane fridge and furnace was used, with outside temperatures reaching a low of 40 degrees. Overall, their usage is negligible since propane is the main power source.

If the icemaker was switched off, the consumption could be reduced to about 3.5 KWH.

Having spoken to many RV owners, most keep the inverter off most of the time. With big solar and 48 Volt lithium, the inverter can easily run 24x7, assuming:

- Boondocking in a sunny area of the country
- One cloudy day every four days
- Minimal trees blocking the solar arrays (E.g. at Mammoth Cave and Big Bend National Parks)
- Only 80% DOD (Depth Of Discharge on the batteries), thereby extending the life of the batteries to about 20 years

Re: Solar Data

Reply #9 – March 18, 2018, 11:18:15 am

What would explain this change?

At 10:15 battery monitor showed 13.7 amps in (net of fridge and small inverter) and 13.4 volts. At 10:30 6.o amps and 13.3 volts. At 11 am 1.6 amps and 13.2 volts. No discernible change in sun.

Outback flexmax 80 shows 66.2 v in and 2.1 amps. 13.3 volts out and 5.9 amps.

Battery monitor now shows a discharge of 1.6 amps.

Trying to undrerstand what is being reported.

Charge controller is set to absorb at 14.4 and float at 13.6.

Now at 3:15 after being away net charge around the amp.

Re: Solar Data

Reply #10 – March 18, 2018, 03:36:47 pm

Quote from: Roger & Susan in Home2 – March 17, 2018, 09:04:10 am

Ken, we have 3 Renesola 300 watt panels.
Every coach and every user is different. And everyone's objectives are different too.

I quoted you, Roger cuz you seem to have the largest amount of wattage (3x300=900w). Everyone seems to have 800w or so. Is this the norm? I have a mere 300w (3x100=300w) of panels on my roof. While I do use our Kuerig (4 cups total a day in the morning) We always seem to be around 12.2v in the morning, after two days. Making a cup of coffee pulls the voltage down to 11.8 and is forever setting off my Victron BMV 702 monitor's alarms. Am I way under solar powered? Should I get more panels up there or get a bottle of pine sol and scrub the heck out of them? My DW does love TV and I never shut my Magnum MS2012 off.

I surfed over to AMSolar and most of their panels are 100W and the largest is 180w. A little guidance please.

Ed

Re: Solar Data

Reply #11 – March 18, 2018, 04:02:35 pm

Photos below taken at 4 pm today with current readings and so far today readings taken from charge controller.

Shouldn't I be expecting more?

Re: Solar Data

Reply #12 – March 18, 2018, 06:03:45 pm

I fail to see how the computer keeping track of SOC can accurately determine SOC without letting the batteries rest for an hour. To do so, the computer would have to match the battery's load to equal the solar charge. Or it should disconnect the battery from the RV for an hour and measure the voltage, which is not feasible.

I corresponded with Morningstar Corporation about this and they are clueless.

Re: Solar Data

Reply #13 – March 28, 2018, 10:30:21 pm

Still working to determine real life usage and recharge on our coach with propane fridge and hot water. Here's where I am.

Parasitic draw seems to be about 2.2 amps with nothing "on"...no inverters...or a total of 50-60 amps per 24 hours with no charging of any kind.

Until we have a chance to play with "normal" usage of led lights, water pump and small 800w inverter powering electronics I'll assume another 50-60 amps per 24 hour period or a daily total usage of 100-120 amps per day. Our 3 - 225 ah batteries at 50% max discharge would give us 338ah or about 3 days with no recharge.

Solar Recharge - we have 2 - 320w panels mounted flat. Our Outback Flexmax 80 reports the following over the last couple of days:

Today - 151 ah (2.0kwh)
-1 day - 107 ah (1.4 kWH)
-2 day - 85 ah (1.1 kWH)
-3 day - 43 ah (.5 kWH)
-4 day - 42 ah (.5 kWH)

5 day average - 85 ah (1.1 kWH)

In this 5 day average the first 2 days were along side our house and the last 3 were out front.

So if I have this right using the average of 85 aH solar recharge against 120 amps/day usage in 5 days we'd use 600 amps and solar would replenish 428 for a net deficit of 172 amps or about 25% of capacity. This assumes no microwave, hair dryer or Vitamix and no generator or driving to recharge.

QUESTIONS:

1. We have an 8000w generator and a Xantrex Freedom SW 3012 inverter. What is the amps/hour we could expect generator driven charger to replenish in the absence of solar?

2. If we are driving, what are the amps/hour we'd expect from the alternator in the absence of solar or generator.

Hopefully my ignorance on this subject makes this post understandable.

Thanks

Randy

Re: Solar Data

Reply #14 – March 28, 2018, 11:26:33 pm

Quote from: Lance Camper – March 18, 2018, 03:36:47 pm

I quoted you, Roger cuz you seem to have the largest amount of wattage (3x300=900w). Everyone seems to have 800w or so. Is this the norm? I have a mere 300w (3x100=300w) of panels on my roof. While I do use our Kuerig (4 cups total a day in the morning) We always seem to be around 12.2v in the morning, after two days. Making a cup of coffee pulls the voltage down to 11.8 and is forever setting off my Victron BMV 702 monitor's alarms. Am I way under solar powered? Should I get more panels up there or get a bottle of pine sol and scrub the heck out of them? My DW does love TV and I never shut my Magnum MS2012 off.

I surfed over to AMSolar and most of their panels are 100W and the largest is 180w. A little guidance please.

Ed

Hi Ed, the only way to know what you need is to know what you use. And this varies significantly over the course of a year and with the equipment you are using. Without using our big inverter and none of the appliances it powers (Microwave, toaster, coffee maker) but using a smaller inverter to power the residential refrigerator, tv, DirecTV, PCs, mobile devices etc and 12 volts for lighing and our Aquahot, we average around 2.8 KW per day. 900 watts for solar panels for 10 hrs per day at about 30% efficiency gives us 2700 watts per day from solar, aveage over the year. In the winter with lower sun angles, on cloudy days, in shady areas, cooler weather when we will use the AH more we usually fall a bit short every day. After four days we will run the generator for four hours or so to catch up. In the summer, better sun angles, a longer sun time, maybe less clouds, less shade, less AH time and we are making 2,700 to over 5,000 watts per day and we can pretty easily be somewhere for close to a week without running the generator. If it is hot and we want AC then it a whole different ball game.

If you want to be land line and generator independent you need more average solar capacity then your average use, probably by 20% more or more. If you want to be able to get through a period of no solar (like a long, cold winter overnight at a WalMart) then you need battery capacity to do that.

If your batteries are at 12.2 volts, resting with minimal load, then they need to be recharged.

You need to know what you use.
You need to know what your real world solar capability is.
You need to know what your battery capacity actually is.
You need to know what your charging systems can do and how well they are working.

Is 900 watts enough? For many, yes. With a residential refrigerator like we have just barely. I have one more panel that I will add for 1200 watts total. Some have much more than that. What that gets you is faster recharge time. It is a bit of a balancing act initially based on a lot of power use estimates and capacities. Good equipment will help you have a much better understanding or want your world really looks like and options to get towards a better balance.

I am no expert in this field but I have done a bunch of research and talked to many folks who have a much better understanding of how this works. I learned as much as I could and then applied it to what I wanted to achieve, to my expectations and what I perceived my needs to be. I think I came pretty close and am glad I have an extra panel to make an adjustment based on experience. The more you know and understand about this subject or any other will help you understand how to evalutate other points of view and make better choices for yourself.

Bottom line, we are really pleased with adding a solar component to our coach. It extends our generator and landline free time to many days. Having solar reduces electric charges at places where the electricity is metered. The extra battery capacity makes many no added power duration much longer.

I hope that helps.

Roger

Re: Solar Data

Reply #15 – March 28, 2018, 11:47:35 pm

Randy,
I think you are going to find that typical average power use is going to be closer to 2,000 watts, maybe more per day. At 12.5 volts that is more like 160 amp hrs.

A pretty good solar estimate is total watts x 10 hrs x 25-30% efficiency. So 640x10x0.25 = 1600 watts per day. Lots of days it will be less. Some days more. What can go back into your batteries is what is left over after what you use.

Any charger, from your inverter/charger, solar panels or alternator will push more amps when the voltage is low. This quickly drops off as voltage comes up. So if you are at 50% SOC when you start off on a typical days drive or run your generator for four hours you will most likely not recharge to 100%. If you start at 80% SOC you will get pretty close.

You should be able to find a chart that shows what the inverter/charger puts out (volts and amps) relative to the battery voltage and time.

I am sure there will be other opinions on this.

Re: Solar Data

Reply #16 – March 29, 2018, 07:19:32 am

Trying to answer my 2 questions in my last post:

1. Xantrex Freedom SW 3012 data sheet says "Peak output current = 80 amps". Is it safe to assume that running the generator for one hour would add 80 amps to battery bank? If so and using Rogers 160 amp daily usage from his post above, could be replenished in a 2 hour gen run time? I do understand that adding 80 amps from 50% SOC is easier than from 80% SOC. I'm just trying to be sure I understand what the 3012 can put out.

2. Now for the engine alternator I think I've read FT used a 160 amp alternator. If this charges battery bank directly it would seem to charge twice as fast as Xantrex charger? Or, doe engine alternator require Xantrex charger to be turned on so it can use the Xantrex charger?

Re: Solar Data

Reply #17 – March 29, 2018, 07:39:34 am

Randy, when my batteries are down to 12.3 volts in the morning and I start the generator, I get 150 amps bulk for a short time then stops dropping . I have the Xantrex SW 3012 also. I have my battery type set to AGM and my capacity set to 750 as I have 3 of the Lifeline AGM's Where do you read the max output as 80 amps.

Re: Solar Data

Reply #18 – March 29, 2018, 07:46:58 am

Oops...you're right Chuck. See attached. I was looking at inverter output not charger.

So, what about the engine alternator? Does it also charge it's 160 old rate or is it powering the inverter charger?

Re: Solar Data

Reply #19 – March 29, 2018, 07:53:59 am

It is going to the isolator and charging both house and chassis.

Re: Solar Data

Reply #20 – March 29, 2018, 08:09:37 am

I think the basics are beginning to sink in.

Wyatt posted this a long time ago and it also helped so I'll repost for others who may bebefit:

"How many amphours does it take to recharge a 700 amphour battery bank.

With a 700 amphour battery bank, each 10% of discharge provides 70 amphours.
The charge efficiency is 90% at 50% charged but only 50% at 95% charged.

Recharging from 50% to 60% requires 80 amphours.
Recharging from 60% to 70% requires 95 amphours.
Recharging from 70% to 80% requires 110 amphours.
Recharging from 80% to 90% requires 125 amphours.
Recharging from 90% to 100% requires 140 amphours.

So recharging using your generator works well from 50% to 80%, however, above 80% charged, the charge rate must slow down and you are burning fuel for your generator but using only a small fraction of the available power. While the amphours required to recharge goes up as the battery charge percent increases, the amps going into your battery bank reduces, therefore the amount of time to recharge from 95% to 100% is much higher then the time required to charge from 50% to 55%.

Such is the nature of a battery."

Thanks Wyatt.

Re: Solar Data

Reply #21 – March 29, 2018, 08:24:44 am

Agrees with the real world dry camping experience reported by some Forum members. They (we) favor the routine of running generator first thing in the morning, both to get the recharging process started and to operate high load appliances like the microwave. Then, after a couple hours, we shut down the generator and allow the balance of the recharging be handled by either solar panels (if stationary) or by alternator (if driving). On the sunny days (in our coach), either option will (usually) result in 100% charge by the time the sun goes down. When stationary on cloudy or rainy days, of course, the generator has to handle (almost) the whole recharging load.

Re: Solar Data

Reply #22 – March 29, 2018, 08:39:32 am

We've always dry camped with no solar, so in the morning I charge until charging amps gets below 50 and shut off the generator. Same goes for evening. after 4 days I let it go to float in the morning to minimize damage to the battery. I will have the 1160 watts of solar on soon and hopefully can top batteries off during the day on our June trip this year.

Re: Solar Data

Reply #23 – March 29, 2018, 10:21:36 am

With a potential of 1140 watts and all LEDs, we watch a 50 inch TV, use the microwave and latte maker in the morning and are always up to float by about 11am in the morning in winter. We never start the generator except for occasional AC as we are usually up at altitude. We only have six 68 ah batteries so we could not use a residential fridge.

Pierce

Re: Solar Data

Reply #24 – March 29, 2018, 11:19:45 am

Quote from: Pierce & Gaylie Stewart – March 29, 2018, 10:21:36 am

...are always up to float by about 11am in the morning in winter.

Pierce,

What is your % SOC when your PV system first goes to float?

One of the problems I've noticed with running our generator in the morning is the battery bank voltage will be high at generator shut down. This "fools" the solar controllers into thinking the batteries are near full charge, and they quickly switch to float, thus "wasting" much of their capability during the middle part of the day when they should be at max performance.

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