Connecting Portable Solar Panels

[obiwancanoli]

As I've been exploring an upgrade of my entire electrical system, I'm contemplating adding additional solar, and looking at options.

I have plenty of room on the roof for a few more panels, though I probably need only 2, at around 300-600W added to my current 480W panels, and a 120W portable. Four Battle Born Lithium batteries are probably installed by now, along with a Victron 100A/50 MPPT controller, and 712 Voltmeter. Given those hot days when you'd prefer to be under some shade, it seemed having a portable would be prudent for those times when you need to be more judicious by having solar you can actually point at the sun.

Thus, I am thinking it might be prudent to add at least ONE portable, maybe up to 300W perhaps, and I had a couple questions for y'all... first, does it make sense for me to consider an additional portable, and if so, how long of an extension cord should I consider? Is 20 ft sufficient, or is 30 ft a more practical length?

Second, can two - or more - portable panels be tied together so that only one lead goes to the batteries? I've looked on Amazon, but amongst the multitude of pages I must sift through, I confess my patience was challenged, and I gave up before having any success in finding a 2-into-1 fitting that combines the two...

[Gdetrailer]

pianotuna wrote:
Gdetrailer,

Thanks for the detailed explanation of Diesel Idle.

Solar for certain is better.

Yep, I have Diesel tractor myself.

Always keep it above well above idle if not working it for long periods of time.. Will shut it off if I need to pause for more than 10-15 minutes, no sense in wasting fuel and it IS noisy when running so sometimes it is a relief to turn it off when not needed.

[pianotuna]

Gdetrailer,

Thanks for the detailed explanation of Diesel Idle.

Solar for certain is better.

[Gdetrailer]

pianotuna wrote:
Michael,

One other thought. Some diesels do NOT like to be idled. I do not know this from experience. I think you have to use "high idle". This is a "skating on thin ice" comment as it is outside my area of certain knowledge.

WET STACKING

Can occur with Diesel engines under extended low idle and light load conditions.

Generally for extended idling some folks have done a high idle mod to avoid this condition.

From Web site above..

"What causes wet stacking?

Like all internal combustion engines, to operate at maximum efficiency, a diesel engine has to have exactly the right air-to-fuel ratio and be able to sustain its designed operational temperature for a complete burn of fuel. When a diesel engine is operated on light loads, it will not attain its correct operating temperature.

When the diesel engine runs below its designed operating temperature for extended periods, unburned fuel is exhausted and noticed as wetness in the exhaust system, hence the phrase “wet stacking.”
The effects of wet stacking

When unburned fuel is exhausted from the combustion chamber, it starts to build up in the exhaust side of the engine, resulting in fouled injectors and a buildup of carbon on the exhaust valves, turbo charger and exhaust.

Excessive deposits can result in a loss of engine performance as gasses bypass valve seatings, exhaust buildup produces backpressure, and deposits on the turbo blades reduce turbo efficiency.

Permanent damage will not be incurred over short periods, but over longer periods deposits will scar and erode key engine surfaces.

Also, when engines run below the designed operational temperature, the piston rings do not expand sufficiently to adequately seal the space between the pistons and the cylinder walls. This results in unburned fuel and gasses escaping into the oil pan and diluting the lubricating properties of the oil, leading to premature engine wear.
Why avoiding wet stacking is essential

In addition to the adverse engine effect, the designer and user of a system have to consider:

Expense- Excessive wet stacking will shorten engine life by many years and before planned replacement.
Pollution- Many urban areas restrict the level of smoke emissions wet stacking produces.
Power- Even before an engine is damaged, deposits will reduce maximum power. A prematurely worn engine will have a lower maximum power than it was designed to produce.
Maintenance- An engine experiencing wet stacking will require considerably more maintenance than an engine that is adequately loaded."


Personally, I am not a fan of extended idling of a large expensive ($3,000-$4,000) gas engine in a vehicle to do the job that a small MUCH CHEAPER ($400-$1,000)single cylinder gas engine generator.

Sort of like swatting a fly with a tank..

Even worse with the newer more modern vehicles when you add in all the computers/electronics on board and toss in a $3,000 transmission idling all that time also..

Don't like the noise of a gen? Fill up on as much solar as possible that will fit on your roof.. You can buy one heck of a solar array for what it can cost of repairing or replacing your vehicle engine/transmission and electronics..

[pianotuna]

SamanthaNicols,

How are you determining 100% state of charge? What is the capacity of the battery bank in amp-hours?

[obiwancanoli]

Now there's something I had never considered... and if I didn't have the acreage on the roof, I might more seriously consider something like this... a novel idea, to be sure, particularly since they can be removed and placed where needed. Congrat's on a most interesting innovation!

[Tom_M1]

My solution for storing portable panels:


The panels can be left in place and tilted or removed and set in the sun.




I have two 40ft extension cables with Anderson SB50 Powerpole connectors:

[jaycocreek]

I dislike generators, but relying 100% on solar may not be wise.

I think they compliment each other especially if your only camping is in a national forest..I actually have five generators lol..Kinda a hobbie for years and I just can't seem to sell any of them..If a guy bought a $350 inverter generator and had a decent charger,he needs nothing else..But what fun is that...lol

I swore I would never get into solar but here I am..It is addictive and expensive..There's no end to upgrading a system and everything depends on the sun..Enter lithium batteries and there pros and cons,especially in the winter for me....

Hobotech(Tom) on YouTube,who was full-time in a van,has a roof full of solar panels and two portable solar panels with like 40ft of cable but he also has a small inverter generator for when the sun fails all that solar and his four BattleBorn batteries and it does and did...All this is very interesting to me..

[pianotuna]

Michael,

One other thought. Some diesels do NOT like to be idled. I do not know this from experience. I think you have to use "high idle". This is a "skating on thin ice" comment as it is outside my area of certain knowledge.

Consider putting the description of your system in your signature--that makes it easy for others to refer to it when making comments.

[pianotuna]

Michael,

800 watts would more or less eliminate generator use. Except for running the roof air conditioner. For that "condition" I use the trip planner at https://freecampsites.net/ and set the filter to electricity. Depending where you are it is possible to get power for free, or at extremely low cost.

Your system is great because you have adequate storage, and excellent equipment (Victron? iirc). Another reason is that you took advice from many of the excellent folks on RVnet.

Do wire the jars in a balanced manner.

400 is on the border line of not being quite enough. In a lead acid system it would not be enough, because of the need to equalize and fully recharge every cycle--but LI do not care about being fully recharged. It may be wise to fully recharge every 30 days or so--so that the internal cell balancing can do its job.

[obiwancanoli]

pianotuna wrote:

obiwancanoli wrote:

pianotuna wrote:
you will soon tire of deploying portable panels.

That may be, but if it's the only way to charge the batteries, best to be able to tap into the sun

I dislike generators, but relying 100% on solar may not be wise.

If you are in a class C or class A with a v-10, it can safely be idled to recharge the batteries. Equip it with a dc to DC voltage boost device, and limit current to 1/4 of maximum alternator output.

If not equipped with a V-10, then a small generator may be a good back up source.

I do get six amps of charging at solar noon in leafy shade.

I do get three amps of charging at solar noon in the rain.

My solar farm is tiny at 256 watts, in comparison to your rather magnificent system, but now that I'm back to part time, it will be more than adequate when I upgrade to 600 amp-hours of SiO2 jars. My OEM system had ~437 amp-hours usable. (875 Amp-hours, total). I had no generator at all for 5 years. I never had to idle the v-10 in those 5 years. I ran out of fresh water before I ran out of power--and I cooked 100% electrically.

You seem to have deep pockets--so why not max out the solar panels on the roof--they are the cheapest part of the system, in terms of cost per watt. My cost per watt was $5.50 in 2005, for the panels.

Then, if you find you need them--buy some portable panels.

I'm in a Class A diesel, and a DC to DC makes sense. I do have a portable generator, though can't imagine needing it, given the upgrades occurring as I write... It's not that I have deep pockets, but as a newly retired financial planner, I've prepared well for my afterlife, and have always been of the opinion that if I want the best built house on the street, it starts, in part, with the best tools. And if I can afford the house, I can certainly afford the tools, albeit not all at the same time... cash flow... still, I'm patient, and as I continue to learn, from you and other generous contributors, I may even want to do things I haven't yet considered. One thing I HAVE considered is adding more solar. Maybe another 400W, but after all the other upgrades are done, I'll monitor for a while, and determine how much to add...

For the moment, I'm good. I do want to avoid using my generator, though occasional exercise will be practiced, to keep the wheels greased, as it were... but you've followed my posts and responded often enough that I'm sure my current setup is not unknown to you. I noted it in my initial post.

And thanks for the magnificence compliment! I actually never came close to thinking that, being the 2017 rookie that I am - how about merely impressive?

Thanks!
Michael

[BFL13]

Ground based portable solar gets shaded by the RV at times, so it must be moved to keep it in the sun. BTDT. This means the battery connection is at one end of your RV and sure enough the sun is at the other end, so you need long enough wire to reach past the the length of your RV at the very least.

You need enough wire to pull the array back from the RV far enough so the sun is above the roof on the other side of the RV, or else move the array to the sunny side.

A slide out one side and the awning out the other side of your RV makes good shade on a wide arc, so that means you move the array to the sunny side of those when the sun gets to there.

Didn't happen where we were doing this, but I can imagine that the place your portable would have to go would be out of your site's area, so now you have to have no neighbour that close.

I don't bother when parked in the woods. For us that is in the darker half of the year when solar is poor anyway, so it is generator and charger. I can understand trying to get some solar if parked in the woods in the summer. The trick is to find the open spot away from the RV that you are "allowed" to use for your array, and that will stay open to the sun long enough as the sun moves around and up and down to make it all worthwhile for any amp hours. AH does have that H in it., so time matters.

[pianotuna]

obiwancanoli wrote:

pianotuna wrote:
you will soon tire of deploying portable panels.

That may be, but if it's the only way to charge the batteries, best to be able to tap into the sun

I dislike generators, but relying 100% on solar may not be wise.

If you are in a class C or class A with a v-10, it can safely be idled to recharge the batteries. Equip it with a dc to DC voltage boost device, and limit current to 1/4 of maximum alternator output.

If not equipped with a V-10, then a small generator may be a good back up source.

I do get six amps of charging at solar noon in leafy shade.

I do get three amps of charging at solar noon in the rain.

My solar farm is tiny at 256 watts, in comparison to your rather magnificent system, but now that I'm back to part time, it will be more than adequate when I upgrade to 600 amp-hours of SiO2 jars. My OEM system had ~437 amp-hours usable. (875 Amp-hours, total). I had no generator at all for 5 years. I never had to idle the v-10 in those 5 years. I ran out of fresh water before I ran out of power--and I cooked 100% electrically.

You seem to have deep pockets--so why not max out the solar panels on the roof--they are the cheapest part of the system, in terms of cost per watt. My cost per watt was $5.50 in 2005, for the panels.

Then, if you find you need them--buy some portable panels.

[jaycocreek]

2oldman wrote:

obiwancanoli wrote:
how long of an extension cord should I consider? Is 20 ft sufficient, or is 30 ft a more practical length?

The longer the cord the more loss. Consider a series hookup if much over 20'. A 300w panel will likely be 24v.

While this is true,it can easily be a non issue by buying quality portable solar panels with 23-25% efficiency compared to the cheaper 18% or so..Some of the top names are not the top performers.

If the op is serious about portable solar,I strongly suggest he looks up Hoboteck on youtube and watch as he compares the portable solar panels one on one/side by side..Quite interesting...

[2oldman]

obiwancanoli wrote:
how long of an extension cord should I consider? Is 20 ft sufficient, or is 30 ft a more practical length?

The longer the cord the more loss. Consider a series hookup if much over 20'. A 300w panel will likely be 24v.