Seeking advice on best way to start with new RV

[rootusrootus]

I'm picking up a new RV, and it comes with a basic 165W panel on the roof (Furrion) and a 25A MPPT charge controller (also Furrion). No battery provided, aside from whatever garbage the dealer throws on. I'd like to build a decent system, ultimately capable of running a microwave occasionally (but never A/C) and big enough so we don't really worry about using lights and such when we are boondocking (typically two or three nights at a stretch is all).

I've kinda fallen down the rabbit hole. Spec'd myself out a nice big battery using eight 270AH cells (two 4S strings, staying 12V), though I haven't entirely ruled out some sort of drop-in. Expensive tho. Then I figured on a multiplus inverter/charger, and a smartshunt monitor. Not sure what I want to do with the panel on the roof. Adding another identical one would cost more than ripping off the Furrion and getting two of something else. Can only do 300W before I'd need a new charge controller.

So it starts getting pretty spendy in a hurry, and frankly, I just like to go camping a dozen times a year and I like some comforts from home. Hard not to just say 'hey wait a second, forget about the microwave, pick up a couple GC2 FLAs and call it good'. But in the long run I think I'd prefer lithium performance. And the RV has a 12V fridge, which apparently is a bit piggy and can suck down 90Ah a day.

How would you do this, to avoid draining the wallet all in one shot, and still work towards a pretty sweet setup without buying gear that will get tossed later as I upgrade?

 

[John Frum]

Start with an energy audit.
Link in my signature.

 

[HRTKD]

The 165w panel on the roof is enough to keep your system charged when in storage. For the load you want to run (microwave), that panel isn't likely to provide enough charge to get the battery bank to 100% by the end of the day.

More panels and probably a better solar charge controller. Get the specs for the Furrion solar charge controller and we'll be able to tell you how much solar wattage you can go with to replace the 165w panel without replacing the solar charge controller.

If your battery bank is fully charged before camping, you should have 540 Ah available. If you're careful with power usage, you might be able to make it all weekend with the existing equipment and then let the 165w panel charge the batteries back up over the span of a few days.

 

[Whinny]

What size/type of trailer, how much space on the roof? A 12v fridge, what brand/model? For 2 or 3 days you could go with the 540ah battery, maybe a few panels on the ground with their own controller, leave the existing as is. A 1500 watt inverter should power a microwave with no issues, we get by with ours with 1000 watt inverter. Use it with a manual or auto transfer switch or just plug in your shore cable to it. Just have to remember to turn off your existing converter. Is it a WFCO? they apparently play with lithium without issues. I really like the smart shunt............
With our type of travel I consider the solar to be a "stay extender" doesn't matter if the batteries are low when we leave. Might work for you.

 

[75west]

I have this same Furrion setup. I just purchased it with our grand design 17mke. I am very confused about adding a panel or panels. I want at least one more.

I plan on purchasing a 1000w inverter to just power the occasional luxury. No ac but maybe the small microwave every once in a while.

I plan to add two lithium batteries. 100ah

Here is what I have.

Furrion 25amp MPPT solar charge controller. I snipped a section of the specs and attached.

I have one Furrion 165 watt panel. Specs also attached.

When reading the SCC specs it states to not exceed 150watt is series. I also see it says 300 watts total.

Here is the confusing part. The installation manual shows an install with two 165 watt panels. I also sent an email to tech support and they said "the SCC is rated to handle two 165watt panels".

The install diagram (attached) shows the panels wired in series. With each panel producing 19 volts (total) 38 volts and 9 Amp would this be 342 watts and exceed the rating?

On another not the furrion panel is very expensive. I am rather certain I can get two panels equaling 300 watts for cheaper than one furrion. I welcome any feedback.

I appreciate any guidance.

 

[Jred]

Why not just purchase a couple of 200 watt suitcase panels? The renogy I just bought has a good controller.

 

[75west]

Why not just purchase a couple of 200 watt suitcase panels? The renogy I just bought has a good controller.

Had that thought a few times but I'm planning to try and use what I have. I'm also worried about theft. Anything can be stolen but being in the roof it may limit access.

 

[HRTKD]

Exceeding the wattage is usually OK. That's over-paneling. Exceeding the Max PV Input Voltage of the solar charge controller is not OK. Bad mojo when you do that.

It looks the Max PV Input Voltage for that solar charge controller may be 70 volts. As long as you stay under that (with some wiggle room for cold temperatures), you're golden. Two of those panels wired in series is well under 70 volts (23.12 Voc x 2 = 46.24 volts)

 

[75west]

Exceeding the wattage is usually OK. That's over-paneling. Exceeding the Max PV Input Voltage of the solar charge controller is not OK. Bad mojo when you do that.

It looks the Max PV Input Voltage for that solar charge controller may be 70 volts. As long as you stay under that (with some wiggle room for cold temperatures), you're golden. Two of those panels wired in series is well under 70 volts (23.12 Voc x 2 = 46.24 volts)

It is 70 volts max. I'm thinking about buying a different brand panel. Would there be an issue if it was 150watts. I would check the volts and make sure I don't exceed 70 but was wondering if there would be an issue mixing two different wattages.

 

[HRTKD]

This is a good video series on the good, bad and ugly of mismatched panels.

How to wire mismatched solar panels. Wire in parallel or in series?

Video series testing wiring mismatched solar panels in parallel vs. wiring in series to maximize solar PV output with an MPPT charge controller.

www.altestore.com

 

[corn18]

It is 70 volts max. I'm thinking about buying a different brand panel. Would there be an issue if it was 150watts. I would check the volts and make sure I don't exceed 70 but was wondering if there would be an issue mixing two different wattages.

I don't see an issue as long as it's close on Voc and Isc. That is a good controller and will work great with 300-400W of panels. What panel are you looking at adding? I looked at some 150W-200W panels on Amazon and pretty much any of them would work fine with your current panel.

 

[12VoltInstalls]

70 volts max. I'm thinking about buying a different brand panel. Would there be an issue if it was 150watts. I would check the volts and make sure I don't exceed 70 but was wondering if there would be an issue mixing two different wattages.

What I might do is get something like the epever AN40 (or better brand, although the epever is very decent quality for the money) and aim for 600- to 800W of solar. That’s usable power and especially for daytime use the microwave use recovery will be quicker.
600 to 800 watts IS overkill in 24hrs, but hour-by-hour or cloudy days you’ll be appreciative.
A pure sine 1200W inverter would be my choice over a 1000W. A little headroom or more headroom with similar efficiency, and plenty for a coffeemaker and vacuum cleaner. Just my opinions. Ymmv
I hope I don’t get shot in the streets for using the word, “power” in a colloquial manner…

 

[BretS]

I did my batteries and inverter/charger first, then solar second. You can use the one panel and SCC that you have until you see how much you use out of your bank, then I would decide whether to add to that panel, or pull it and go with new panels. I found that using my generator, and shore power for a while, I was able to track my usage and then plan better for the solar (in my case it means I don't have enough room on the roof LOL). Doing a power audit gave me some figures, but I found it better to do some actual camping and tracking my actual usage during different seasons to get a much better idea of what I needed. Just my opinion.

 

[Rocketman]

Because you are thinking of using Victron components, I would suggest getting a Victron mppt for the roof panels (probably a 150/60 or 70) - put a bunch of panels on the roof. Use the current wire. This will allow great charging into that large battery.
Remove the one panel and set it up as a portable panel you can deploy in the sun. Run that power into your current furion charge controller.
Also, look at tying all the Victron stuff together into a Cerbo. It gives excellent info on what is happening to your rig’s electrical stuff.

 

[12VoltInstalls]

Use the current wire.

Check the solar wire specs.
I don’t know this brand/model but I’ve seen a surprising number of ‘factory’ solar panel cables barely big enough for their $600 suitcase or rooftop panel options. (worked at a trailer service ctr for a while)
Some were 10ga which is ok but others were as tiny as 16ga and one was even labeled 5A at the sae port.

 

[PerryB67]

Our camper came with a single 170 GoPower panel, GoPower SCC, and two 220 amp 6v AGM batteries. Our batteries failed at 90 days (replaced under warranty), so the first additional item purchased was a Victron BMV-712 to see what was really being drawn. For example, two phones charging all night use 1.8 amps an hour (.9 per phone). That was an eye-opener. Last winter, after two years, the batteries failed again. The 712 showed us that the WFCO charger would occasionally send 21 volts to the batteries. How many batteries would we have replaced before figuring out the WFCO was at fault? Since we have solar, the WFCO was, and still is, disconnected. We purchased 220 usable amp-hours of batteries (270 total) and they're fine as long as we have some sun.

Solar panels have changed in the last few years. This spring, in a conversation with Northern Arizona Wind & Sun, one reason solar farms are exchanging their panels is because today's panels are much better at harvesting sun early in the morning and late in the afternoon, one of the traditional major reasons for wiring in series. Before talking to NAW&S I was going to add another set of wires to the roof for 300 additional watts. Mixing our existing 170 watt panel with three 100 watt panels in series gave a loss of 65 watts, but in parallel only a 5 watt loss, giving us 465 watts on the roof. No way was an additional loss of 60 watts going to make up for the theoretical gain from series in our case.

I didn't want to cut a hole in our roof or remove our fridge to bring the second set of wires into the camper anyway, so I chose parallel, and replaced our dumb GoPower SCC with a smart Victron 100/30 controller. We have a seasonal site .8 mile from our condo and I'm down there all the time. On December 1 I went down to the camper about a hour before dusk and our solar was still charging the batteries with 22 watts @ 18 volts. I've seen the same thing early in the morning. We chose Renogy Compact panels, but I understand that their Eclipse panels (at twice the cost) are even better at harvesting energy. Knowing what I know know (don't we all wish) I would have spent the extra $300.

Our 10 awg wire can handle up to 25-30 amps. Since our panels are flat on the roof, and nothing is perfect, our realistic goal is to provide 15 amps down the wires at under 4% wire loss. Our 465 watts on a sunny day easily meet that requirement. The most I've seen is 22 amps, at high noon, the end of June, for a 10 awg wire loss of 5.6% (for jollies, I flipped the panel breakers off the previous night and on again at 12:30 daylight time) That extra loss means nothing to us, since the batteries will be full by noon under those conditions anyway.

There is no free lunch, or you get what you pay for.

Things I've learned:

• First and foremost, buy a battery monitor that keeps history (NOT an Alibaba).
  
  
• Don't buy panels based on price, especially if you have limited roof space like ours. More than likely you're buying older, less efficient technology.
  
  
• If a small camper, under 500 watts on the roof, don't worry about parallel.
  
  
• Our Victron BMV-712 works together with our Victron 100/30, our Victron 100/20 (we have a 100 watt Renogy portable, that hopefully we'll never need again), and other Victron products.

Because of our new panels and batteries, a 1500 watt inverter, recommended by Will, was installed last month for our toaster. The electrical run for the kitchen goes right past the inverter, so I disconnected the romex from the previous outlet and it's connected to the inverter. Except for the toaster, everything else is 12v.

Remember, there is no free lunch. We slowly improve our camper and have read too many disappointments with cheap products. Buy wisely my friends.

Enjoy,

Perry

 

[12VoltInstalls]

t harvesting sun early in the morning and late in the afternoon, one of the traditional major reasons for wiring in series.

Not everybody gets that. Someone tried to tell me that wasn’t a thing, even had charts and math to prove it.

But series most definitely helps !