Help! - Solar questions - I hope I'm not beating a dead horse

[Joe & Cherie]

I'm looking at adding solar to my all electric EggCamper this early spring. This may get detailed so I started a new thread instead of adding this to my EggCamper journal thread. Once I understand - I'll add what I learned and add the install to the journal.

Usage: I dont have or want an inverter. When boondocking we will be running the fridge (12v compressor fridge pulling 2.5a for 50% of the time), some LED interior lights, possibly the maxxfan on low sometimes but not often, and the water pump occasionally - that's it!!

I would like a system that can keep up with these demands assuming the sun shines moderately. I also like to overkill a bit. So here is my thoughts and I want you guys to tell me if I'm on track. I've been reading but I really dont know squat about solar. I also want a relatively simple system.

I plan to use (2) 6v Trojan T-105 wet cells (225ah@20hr rate). (2) Renogy 100w 12v fixed panels (200 watts total) on the roof running in parallel for 12v or in serial for 24v (I dont understand which is best setup yet), a Trimetric TM-2030-RV monitor, and an SC-2030 12v/24v solar charger also from Trimetric (Bogart Engineering).

http://www.trojanbattery.com/product/t-105/

https://www.amazon.com/dp/B00AQQAAQW...ing=UTF8&psc=1

http://www.bogartengineering.com/products/trimetrics/

http://www.bogartengineering.com/pro...solar-charger/

What are your guys opinions on this setup? I realize the solar charger is PMW and not MPPT (whatever that means) but I read a few threads and also Bogart Engineering webpage stating the PMA will perform well.

I'm also adding the "charge wizard" pendant to my existing Progressive Dynamics 9130 shore power converter/charger to make it a smart charger instead of a 1 stage.

So to keep it simple - and because if it gets to technical, I wont understand.....lol.....what your guys thought?? Also, how does solar come into play when plugged in? I assume I just put a switch in place so I'm not charging from both solar and shore power at same time?

Thank you VERY much for the help on this!

[Raspy]

I don't have any real hard numbers to throw into the calculation, but I think your collector sizing is about 1/3 what you'll actually need. I would expect the fridge to run more than 1/2 the time, especially if you add warm items to it, open it once in a while or camp where it's hot. Do you have real world use records to show it will only run 1/2 the time? Your fixed roof array will not be oriented optimally to the sun and won't produce it's rated output. I don't know if you've factored in the energy lost while charging the batteries as not all power is saved.

The weather won't always be perfect and you'll find you want more power for other uses that you don't expect. It seems usage always rises to meet what is available. For instance, you might want to run a laptop more than you expect now, or charge your phone more, or listen to music. I know you said you don't want an inverter, but you might find a small one that plugs into a cigarette lighter socket is a very useful tool. I always have one handy for charging battery operated tools, camera batteries, my laptop and my phone.

Are you planning to heat water with propane? If you will have propane, are you sure you don't want a propane fridge?

I have tended to keep my solar systems very simple with the collectors set out, when I'm not plugged in, and connected with a cord to the batteries. This keeps the roof clear, allows excellent orientation and easy collector cleaning, and it allows me to park the trailer in the shade.

[milt]

Originally Posted by JWScarab

I'm looking at adding solar to my all electric EggCamper this early spring. This may get detailed so I started a new thread instead of adding this to my EggCamper journal thread. Once I understand - I'll add what I learned and add the install to the journal.

Usage: I dont have or want an inverter. When boondocking we will be running the fridge (12v compressor fridge pulling 2.5a for 50% of the time), some LED interior lights, possibly the maxxfan on low sometimes but not often, and the water pump occasionally - that's it!!

I would like a system that can keep up with these demands assuming the sun shines moderately. I also like to overkill a bit. So here is my thoughts and I want you guys to tell me if I'm on track. I've been reading but I really dont know squat about solar. I also want a relatively simple system.

I plan to use (2) 6v Trojan T-105 wet cells (225ah@20hr rate). (2) Renogy 100w 12v fixed panels (200 watts total) on the roof running in parallel for 12v or in serial for 24v (I dont understand which is best setup yet), a Trimetric TM-2030-RV monitor, and an SC-2030 12v/24v solar charger also from Trimetric (Bogart Engineering).

T-105 | Trojan Battery Company

https://www.amazon.com/dp/B00AQQAAQW...ing=UTF8&psc=1

TriMetric Model Descriptions, Present and Past - Bogart Engineering

SC-2030 Solar Charger — 30 Amps Max- 12 or 24V PWM type - Bogart Engineering

What are your guys opinions on this setup? I realize the solar charger is PMW and not MPPT (whatever that means) but I read a few threads and also Bogart Engineering webpage stating the PMA will perform well.

I'm also adding the "charge wizard" pendant to my existing Progressive Dynamics 9130 shore power converter/charger to make it a smart charger instead of a 1 stage.

So to keep it simple - and because if it gets to technical, I wont understand.....lol.....what your guys thought?? Also, how does solar come into play when plugged in? I assume I just put a switch in place so I'm not charging from both solar and shore power at same time?

Thank you VERY much for the help on this!

150 watt panel laying flat; output 12.9 volts 3.6 amps. panel raised at 45 degrees, facing south 13.0volts 8.6 amps.at 10.30 am.At 12 noon 12.9 volts 8.8 amps.Hope this helps. Milt

[John in Michigan]

JWScarab,

- the Renogy 100w max output is about 5 amps at 18 volts per panel, and should be wired in parallel thus providing max combined output of 10 amps at 18 volts
- PWM controllers cut off voltage at 12 volts instead of converting, thus not using all of the power; MPPM controllers convert voltage, thus using all power (i.e., MPPM in theory converts 10 amps at 18 volts to 15 amps at 12 volts)
- With an MPPM controller, better chance of powering the fridge w/2 100w panels

EDIT: assuming 5 peak sunlight hours per day, 2 100w panels w/PWM produces 50 amp hours per day and w/MPPM produces 75 amp hours per day
Fridge running 2.5 amps 50% of time uses 30 amps hours per day

[Paul Braun]

Good points in the prior posts. I too have opted for portable folding panels. One of the places I camp for two - two week stays will only get solar for 3 hours, I cannot fill up the batteries once I have a rainy day. The Trojans are great, I find the TM-2030 very putsy but it does the job. The SC-2030 is fairly recent so I went with a Blue Sky 30, it has worked very well.

As you probably know you have to use small gauge wire. One drawback of the Blue Sky is it only accepts 8 gauge. In that case you would have to make an immediate transition to a thicker gauge.

[John in Michigan]

I just updated wiring in my Trillium 4500 to accommodate solar panel. I use a SPDT switch to switch between battery power and shore power source for 12vdc loads. I plug the solar charge controller cable to the battery cable when boondocking; uplug solar charge controller cable and plug in the battery charger cable when on shore power.

[Jon Vermilye]

If your refrigerator uses the amount of power stated, that will be 30 amp hours per day. The rest of what you have described is minimal, probably no more than 5-6 amp hours more.

I use about the same (35 - 40 amp hours per day). I have 2 roof mounted, non tillable panels (a 100 watt & a 95 watt) and a pair of interstate 6v, 232 amp hour batteries. I have dry camped for as long as 93 days.

During the summer with long days & high angle sun, the combination will keep the batteries charged as long as there are less than 3 - 4 cloudy days in a row. The winter is a different matter. The sun is lower & the days are shorter (and often cloudier). I, like Milt, find that the performance of the flat mounted panels in winter is dismal.

I've added a port to the input of my controller for a portable 160 watt panel that I add during the winter. It will almost always produce more output than the two rooftop panels because it is aimed at the sun. During winter months, I have still had to cut back on my electrical usage after 4-5 cloudy days, even with 355 watts of solar.

My concern with your system is it is minimal for your needs. I can cut back on my electrical usage to make up for poor sunlight conditions; with a 12V refrigerator, you can't. Unless you carry a generator or run your tow vehicle (not too efficient) to recharge the batteries, a string of cloudy days may require a visit to a campground with hookups.

If you are going to do extended dry camping, I'd consider tilting panels, adding one more 100 watt panel, and, if you can deal with the weight & space, another pair of 6V batteries.

One more point - you do not need to shut off the solar system when plugged into a pedestal. There is no problem with multiple charging sources - while driving, your tow vehicle & solar panels will both help recharge the batteries.

[Timber Wolf]

You are describing basically the same set-up I have (partially installed). I have a Truckfridge, two generic 6V batteries, the Trimetric meter and Bogart charge controller, three (3) 100W Renogy panels and a 100W folding (2-50W) Renogy panel. I have not finished installing it all (still playing/learning), and the Bogart controller is still sitting in the box.

I am actually running a 20A Tracer MPPT controller that came with one of the panels in a package deal from Renogy. The only time I tried to boondock off solar (middle of March in N. Florida, panels laying flat on top of the truck's camper shell) two 100W panels did not keep up with the fridge and lights. We only were out three days so the batteries did not get below 50%.

I studied this a couple of years ago until my head hurt and can't remember what all I finally decided. I seem to recall that I was figuring I would need all three 100W panels, and possibly two more 6V batteries to truly and safely achieve complete independence from anything but solar. As I have a Honda 2000 bought for camping/hurricane/construction use anyway, I may just install two of the panels and see how it goes.

Good luck with your project. Please proceed, and report back with your empirical findings.

[Joe & Cherie]

Good info guys! It gets me thinking and learning - which is what I need!

A few things - here is Trimetric answer to the PWM vs MPPT and why they feel the PWM works better - I read it but dont understand it......lol.

Also, they say their PWM works in 12? OR 24V? so maybe its ok cause I can get 24V out of it in serial?

Frequently Answered Questions - Bogart Engineering

Q/A #C1

Also, a few thing: my fridge is 12V only, it is one of those smaller 12V compressor fridges like those used in semi trucks. It is very efficient, unlike the 3 ways on 12V. It works great! Also, my water heater is 110V only. I do not have LP at all. To swap out the fridge and water heater and add LP would be cost prohibitive - Id think I'd just buy a new camper now.

That being said what I forgot to mention is I want this solar to do the trick most of the time. And we are not retired so our boon docking will most likely be just 4-5 days max. Id love to buy 4 batteries, thought about that. Also love to have huge solar. But cost and weight - idk - maybe I should consider the 4 batteries.

But lastly, I am also thinking about running a generator - as in having BOTH. I'd like to get a Honda eu2000i for when the solar wont quite do the trick. Plus with the generator I can do hot water and A/C. I'm thinking about mounting the generator to the tongue, and running it off a 20lb propane tank with a propane conversion for the Honda. Now in the "hopefully very infrequent" times of needing more power, I can run generator and charge batteries. Also have ability to take a hot shower or use AC. Currently we are just "vacation campers". When we retire, we will buy a bigger camper with LP - most likely a 5.0TA (since its the only other FGRV I can stand up in).

Which also lends to the last option I've considered: just buying the generator and skipping the solar. But I hate to be one of those guys running the generator...... If it charged the batteries in 3-4 hours, and I was good for 3 more days - maybe that's the best bet......uuggggg......idk!

[John Linck]

Joe,

I have used a 100 watt fixed panel for three years, camping mostly in Winter with fewer hours of low angle sun. We can go about 4 days in deep shade with our LED lights, water pump and occasional furnace use.

I think your system sounds pretty ideal. I only wish I had bought your compressor frig instead of Scamp's 3 way offering. My frig does work, but temperature control is a real crap shoot and I don't like the huge hole in the side of my camper.

The only problem with reserve capacity that I see is if and when you have no sun. We like to camp under trees and in the off season too. This limits your stay.

One change I would consider is to maybe make one panel tilt-able and portable to chase the sun around a partially shaded campsite. Most days you will not need it anyway. Another choice may be to carry extra Trojans in the tow vehicle depending on your camping choices.

Cheers, and happy camping, john

[Raspy]

To me, the fridge is the real problem. I had a 12 volt compressor one in my boat with a very well insulated top loading box. It drove me crazy with it's constant cycling and relentless power use.

The fridge must always get power, unlike some other optional loads, so no matter what the conditions, it has priority and is alway drawing power.

I designed and installed a holding plate system next and it was way better. Still 12 volt compressor, but it only ran for 20 minutes every six hours. Then I was more able to manage the load and allow it at more convenient times if needed. On the boat, a propane fridge was not an option.

Propane fridges just make a lot more sense to me for extended camping. If you are willing to have a propane converted Honda running to support the fridge, why not just have a propane fridge running on it's own 30 lb cylinder? It would not need any infrastructure in the camper, just an external connection that could also be used to run an outside stove. While traveling, the fridge could run on 12 volts from the TV (12 volt heating element, not compressor), so it will always be working and use nothing from the batteries ever.

Now your solar system can be much smaller and if you run out of power, you won't lose any food. With no fridge pulling the system down, you could go for days with no sun on a relatively small battery bank. Then you can expand your system as needed, if needed.

If you take the Honda, the extra panels and extra batteries out of the budget, it seems like the propane fridge would end up being much cheaper initially. Plus, I still think you are seriously underestimating the real world amp use, and thus, the size of the system to support it. On hot clear days the solar will be much more powerful than when it's cold and overcast, but the fridge power demand will also be higher. It will have a harder time keeping cool and getting rid of it's waste heat, plus you might be more likely to want to cool down some drinks, make ice or refrigerate some foods that could otherwise be left out. That will increase it's power use. And finally, there is the bad weather amp use that continues even though the solar is not working. Firing up the Honda or the TV to support the fridge will be very tiresome.

[Gordon in Idaho]

I think you're on the right track. My 12v fridge is large, and draws 3.5-5.5 amps. It's on from spring to fall and runs about 1/4-1/3 of the time. That's about 30-40 amp hours per day, every day. The other big draw is the furnace blower at about 3 amps. I love that blast of heat on a cold morning (and my dog does, too). But I also have a tv/dvd, big sound amp, and over 400 dimmable led's on light strips and 3 different circuits to control the level of light that I want.
I'm using 3 100 watt panels in parallel, fixed to the roof of my scamp13, and 185 amp hours of battery storage. The panels are set at different angles and at any given time of day, one panel is always doing more work than the others. I did pretty well with 2 panels, but I added the third as insurance for the colder/shorter days of early spring and late fall. If I were to camp in the dead of winter (like now!), I think a portable panel added to the system would be a good idea. An interesting thing (at least to me) that I've learned is that on a misty morning (in a cloud, waiting for the sun to break through), the panels draw amps very well. It's something to do with the diffusion of light hitting all the panels equally. Neat.
I've used this setup for 3 years of full-timing, 5 months each year, no shore power, just the sun.
It doesn't hurt to run the formulas available online to determine what you require for your energy needs, but I follow the path of over doing it. You never know what you might want to use in the future. And, there's no fun in worrying about running out of juice.
I've spent countless hours online trying to weed out fact from fiction when it comes to batteries. I'll never be an expert, but there are a couple of things that I often read here that I believe to be misleading or just wrong:
1. Don't panic when your voltage drops below 12v, especially when in use. A consensus of the charts I've studied for determining 50% state of charge lies between 12.06 and 12.2 volts. You will not ruin your battery by occasionally going below 50% SOC. You MAY shorten the battery's life by a few days of its lifespan, however. I've never found a definitive answer for this issue. And, or course, the variables are numerous.
2. Two batteries of the same voltage, connected in parallel, do not have to be a matched set. Different capacities can be combined. I know because it works for me.
3. Inverters are only efficient when matched to the appliance you're using. for example, running a small television from a 2000 watt inverter is a terrific waste of your battery's stored energy.



Well, that's just touching the surface of this endlessly fascinating topic.
I wish you well. Have fun.

Gordon

[ShelbyM]

I don't know what you have for a tow vehicle, but an extra pair of 6V in the tow, maybe charged by the tow and /or solar might give you enough for your anticipated # of days.

[David B.]

Joe, we are in a similar situation as you are, with our Lil Snoozy, but I did add a propane furnace and two burner stove to it. We use the Truckfridge 12 volt danfoss refrigerator, LED lights, TV/DVD, XM Radio, Cell Phones, and lap top. We use 50-60 amp/24 hrs. I have a 150 watt Renogy panel mounted flat on the roof, and a 2000i generator as backup and to give us hot water (takes approx. 20 minutes), blow dryer, micro wave, or air conditioning if needed, but not all at the same time. So far parked next to the garage with the refrigerator on, the panel is keeping the 225 amp hour battery topped off at 13.2 volts each day. I will see how this works out with us in the mix at the Quartzsite gathering next month, and decide if I will place another 150 watt panel on the roof, or use it as a portable unit to chase the sun. Best of luck.
Dave & Paula

[Huck]

I have 2 100 watt solar panels. It will run my refrigerator during the day but not overnight.

[Glenn Baglo]

Warm beer for breakfast?

[David B.]

Originally Posted by Huck

I have 2 100 watt solar panels. It will run my refrigerator during the day but not overnight.

What refrigerator are you using? Is it a gas absorption (3 way/2 way) or a compressor style, and if so, is it 120 volt running on an inverter or a 12 volt danfoss compressor refrigerator?
Dave & Paula