Classic 150SL for 1360 watts on an RV

[Jphoenix13]

Been doing a lot of reading and I've decided I want four 340 watt panels in series on top of my Bluebird Wanderlodge 40' coach. Plenty of room up there and now I'm looking at the Classic 150 as it was recommended by one of the solar supply houses. Using the the Classic sizing tool (attached) it shows Max VOC as too high, HyperVOC as always and the array wattage as excessive.

I use the coach for dry camping at race tracks on weekends, no shore power available and almost always in the Pacific Northwest in summer. So, it's unlikely these panels will ever see 100% and I plan to mount them flat, no tilt - which is why I want as much wattage as I can get in four panels. This bus has significant parasitic loads as it is old has has literally dozens of solenoids throughout the systems; totally analog machine.

I plan to install a 2000 watt pure sine wave inverter and currently have four 6VDC batteries at 225 ah each in series parallel giving me 12VDC house power. Also two very big 1100ah  12VDC start batteries for the Detroit Diesel.

Question #1: Am I OK with the Classic 150 SL because the panels will never see optimum sun? I also figured it in two parallel strings, but I'm advised to go all series because the higher voltage is more efficiently converted into the 12VDC batteries (?)

Question #2: Am I OK with the SL - do I need arc fault in an RV with solar and a 12.5kw diesel generator and shore power? I don' think I need the ethernet because there is no server in the bus.

Question #3: I do not plan to run anything big off the inverter except for short periods of a 1200 watt microwave, so total daily kwh is around 1000 max and typically I run the generator for microwave, water heater, 110VAC heaters and AC, etc. All I want to use the 12VDC house bank for is lighting, water pump, electronics charging. So, am I over-wattaging my solar needs for this daily kwh usage - keeping in mind that on a good day in June we still don't get the exposure most others do. Even this summer with zero rain for months, we have hazy days due to forest fires that likely kill some power - and my panels will be flat.

Thoughts gratefully appreciated.

Jim

[Vic]

Hi Jim,  Welcome to the Forum,

Limited time now;

Would NOT run strings of four PVs on a Classic 150,  period.

Is there a Typo on the String Sizer input ...   it says you will be running a 48 V battery bank.

Also,  that seems to be quite a bit TOO much battery charge current for the 225 Ah batteries  --  normal limit for Flooded batteries is 10 - 13% of Capacity ...

More later,   FWIW,   Vic

[Vic]

 ...   couple of additional thoughts;

Many  RVers like to run as few PVs per string as possible,   because many RVs are not parked in ideal locations  --  more strings of PVs,  with as few PVs per string  can help increase power production  with some PVs partially shaded.

Have not run the numbers,   but perhaps  three 340 W PVs in "strings" of one PV,  into a Combiner.

THree PVs will probably be too much charge current for the 225 Ah GC-2 batteries.

Later,     FWIW,    Vic

[Jphoenix13]

Yes, typo on the sizing tool. it defaults to 48v and I keep forgetting to change it.

Interesting that a bunch of guys on the Bluebird forum are installing 1000w plus on their coaches, using the Classic 200. Most have six 6V batteries in the house bank. I may increase my bank to six as I have plenty of room in the bay for them.

[Vic]

Hi Jim,

Well,  often  RV PVs are flat on the roof,  with no PV elevation,   which helps reduce the maximum PV power production  ...

The Classic can be limited in output current,   and under certain conditions,   the Classic can Limit charge current into the battery  ...   still trying to understand this a bit more.

Am not an RVer,   so,  your friends on that other Forum are much more knowledgeable than I  ...   just another drive-by post (not in an RV),   FWIW,   Vic

[ClassicCrazy]

Yes, typo on the sizing tool. it defaults to 48v and I keep forgetting to change it.

Interesting that a bunch of guys on the Bluebird forum are installing 1000w plus on their coaches, using the Classic 200. Most have six 6V batteries in the house bank. I may increase my bank to six as I have plenty of room in the bay for them.

It isn't a good practice to add new batteries with older ones - all batteries should be the same age because of charging characteristics as they age. Also it becomes more difficult to properly get a balance on the charge and discharge the more parallel strings of batteries you put in - you need to pay careful attention to how they are wired so they are balanced.

Larry

[Jphoenix13]

Larry, good point. My existing batteries are 3 years old, so I plan to replace them anyhow, they were purchased by the previous owner and not the best quality, but they've been working fine.

[harryn]

Pretty much all I do is RV projects, installing solar panels, LiFe battery packs, and inverters.

On a home, full size panels provide a lot of benefit.  On an RV, especially if you are manually lifting them up there, full size panels are challenging to work with.  Before you make the investment, consider to cut a sheet of 3/4 inch plywood to each size (RV size and full size) and hoist some up there.   In some ways, it is more hazardous on an RV roof than a conventional home roof.

There is no question that full size panels are cheaper per watt, but you might find that the 180 ish watt size are worth it.

The vast majority of projects, we either initially install as 48 volt or set them up for conversion to 48 volt, usually LiFe.  As you can see from the PDFs you generated, the benefits are substantial.  Even 24 volts is much better than 12.  With the LiFe setup we use, 4 size 27s are equivalent in capacity to 10 of the T 105s and you can run air conditioning if you use the right inverter.

For 12 volt loads, just use a converter.

24 and 48 volt inverters are more efficient than 12 volt under most loads, and you can drop the wire size substantially.

Just MHO.

Harry


 

[Sunshine]

Putting 4 of those panels in series on a CL150 would be a bad choice. If you over voltage your controller, you will ruin it and over voltage is not covered under warranty. You can over PV on the amp side, which is a fairly common practice and in the event you do receive enough sun to go over your max on amps, your charge controller will not be damaged it will just run a bit warm. Of course you want to keep this within reason because heat can cause premature failure over time but will not just ruin your controller like over voltage would.

[Jphoenix13]

So, studying and reading a bit more, I see the Classic sizing tool says max two modules in series, so it's clear to me now, that the only way to go is two panels in series, paralleled to another two panels in series.

I did see that limiting my battery bank to 12v vs. 24 or 48 makes it less efficient - but I'm not sure what I would do with a 24v system in a 12v bus, much less 48 - so is there some clever step-down transformer or something that the 48v aficionados use to get 12v to feed the systems?

I'm willing to spend the bucks on higher wattage and better quality panels (I'm only buying 4 after all) to maximize my energy harvesting up here in the land of low light. So, I'm linking the 330-340 watt offerings from Canadian Solar, LG, Panasonic and BenQ - any others out there that are just as good or better? (Sorry, maybe wrong topic for this post.

I am a bit surprised that there are so many solar related manufacturing companies up here, but only one retailer I can find in Mount Vernon - and they still want to charge me shipping - even if I drive up there to pick it up - because they need to ship the panels in from somewhere else.

Best proces I've seen so far is on altE and even shipping from the east to teh west coast is almost same a shipping from CA. Even cheaper if I pick it up at the local freight dock just down the road.

[ClassicCrazy]

So, studying and reading a bit more, I see the Classic sizing tool says max two modules in series, so it's clear to me now, that the only way to go is two panels in series, paralleled to another two panels in series.

I did see that limiting my battery bank to 12v vs. 24 or 48 makes it less efficient - but I'm not sure what I would do with a 24v system in a 12v bus, much less 48 - so is there some clever step-down transformer or something that the 48v aficionados use to get 12v to feed the systems?

I'm willing to spend the bucks on higher wattage and better quality panels (I'm only buying 4 after all) to maximize my energy harvesting up here in the land of low light. So, I'm linking the 330-340 watt offerings from Canadian Solar, LG, Panasonic and BenQ - any others out there that are just as good or better? (Sorry, maybe wrong topic for this post.

I am a bit surprised that there are so many solar related manufacturing companies up here, but only one retailer I can find in Mount Vernon - and they still want to charge me shipping - even if I drive up there to pick it up - because they need to ship the panels in from somewhere else.

Best proces I've seen so far is on altE and even shipping from the east to teh west coast is almost same a shipping from CA. Even cheaper if I pick it up at the local freight dock just down the road.

You can get a DC to DC voltage converter to change higher voltage DC to 12v . Samlex makes some good quality inexpensive ones - depending on your amp requirement. I put a 20amp converter  on my 24v system recently and it works great. They have other voltage and current rated models too.

https://www.solar-electric.com/samlex-sdc-23-dc-voltage-converter.html

Larry

[Jphoenix13]

You can get a DC to DC voltage converter to change higher voltage DC to 12v . Samlex makes some good quality inexpensive ones - depending on your amp requirement. I put a 20amp converter  on my 24v system recently and it works great. They have other voltage and current rated models too.

https://www.solar-electric.com/samlex-sdc-23-dc-voltage-converter.html

Larry

OK, not that's interesting. I can buy four 6v batteries, series them into 24vdc and more efficiently feed an inverter? The CC would like 24 volts better than 12 as well since he panels I'm looking at are 72 cell. Then take any DC load I need and run it through the converter. They are surprisingly inexpensive.

I can leave the start bank on the alternator and existing 110vac smart charger, which is plenty for what little use that bank gets - but how do I charge the 24vdc house bank off the 110vac generator (or shore power) - another 110vac to 24vdc smart charger? I guess that would work, but this is getting complicated just to use 24vdc. I think I'm OK with leaving the house bank 12vdc using four 6vdc in series/parallel.

Is it worth adding the converter and additional battery charger in  terms of efficiency gained? Likely only talking 3 or 4 hundred bucks, maybe.

So, unless I'm way off here, I think I can buy four 340 watt panels, 2 parallel strings into a combiner, then to the Classic 150SL(need arc fault for this application or not?) then into the house bank. Ignore the start bank.

Will the  MNSPD115 SPD work for this application?

Feed a 2000 watt inverter off the house bank.

[Jphoenix13]

With a 24v system, I need more than 24v from the Pv to charge the batteries, not sure I will see that with horizontal panels in the dark days of winter up here - but I don't really know.

[Vic]

Hi Jim,

PV modules are Current Sources (not voltage sources).

As long as the PVs have sufficient STC string voltage ratings for the system battery voltage,   the Charge Controller (CC)  will work well with the available power from the PVs.

Most 72 Cell PVs wired in strings of two should be fine into an MPPT CC,  like a Classic,   for a 24 volt Flooded battery bank.

Yes,   12 V systems are somewhat less efficient than are 24 and 48 volt battery based systems.   24 and 48 volt systems make much better use of the CC,  as CCs are rated by output current.   A 24 V system will generally allow about twice the PV power of a 12 V system,   and likewise a 48 V system  twice the PV power of a 24 V system.

One main factor in deciding on what battery voltage is appropriate for a system,   is the power that the system needs to supply in a day.   This power is based upon calculating the loads that the system needs to supply,   and when these loads occur.

For two 72 cell PVs in series the 115 V SPD should be fine.

FWIW,   Vic

[ClassicCrazy]

You can get a DC to DC voltage converter to change higher voltage DC to 12v . Samlex makes some good quality inexpensive ones - depending on your amp requirement. I put a 20amp converter  on my 24v system recently and it works great. They have other voltage and current rated models too.

https://www.solar-electric.com/samlex-sdc-23-dc-voltage-converter.html

Larry

OK, not that's interesting. I can buy four 6v batteries, series them into 24vdc and more efficiently feed an inverter? The CC would like 24 volts better than 12 as well since he panels I'm looking at are 72 cell. Then take any DC load I need and run it through the converter. They are surprisingly inexpensive.

I can leave the start bank on the alternator and existing 110vac smart charger, which is plenty for what little use that bank gets - but how do I charge the 24vdc house bank off the 110vac generator (or shore power) - another 110vac to 24vdc smart charger? I guess that would work, but this is getting complicated just to use 24vdc. I think I'm OK with leaving the house bank 12vdc using four 6vdc in series/parallel.

Is it worth adding the converter and additional battery charger in  terms of efficiency gained? Likely only talking 3 or 4 hundred bucks, maybe.

So, unless I'm way off here, I think I can buy four 340 watt panels, 2 parallel strings into a combiner, then to the Classic 150SL(need arc fault for this application or not?) then into the house bank. Ignore the start bank.

Will the  MNSPD115 SPD work for this application?

Feed a 2000 watt inverter off the house bank.

If you have 24v battery system you will need a 24v input inverter. If you get an inverter/ charger then you can also charge your batteries via the inverter using your 110v AC generator (  or other 110v AC input source ) .

So yes you would still need a DC to DC converter to run anything 12v in your present 12v system. Not sure what is run on 12v - but wouldn't be too difficult to just change it over to 24v if you can convert anything on it to 24v - if small loads under about 2 amps you can get small DC to DC converters on ebay for a dollar or two and put them right at the device.  Changing lights over to LED 24v would be easy enough too. So depends on what all in there is running on 12v and if it is easier to convert to 24v or to just get larger 12v DC converter and wire into existing appliances. If your lights are 12v incandescent then changing those over to LED  would be the smart thing to do to reduce your load and save energy .

Larry