Advice on RV Set up & Wiring?

[Carv]

Thanks Sensij -I have a kill a watt on the way but I wanted to run my calcs and see how close the two where (I think they'll be pretty close but testing will decide). I also realized I ran my Wh incorrectly and it should be 1,040Wh based on a 1/3 run time. So based on your loss formula above it comes out closer to 1,459Wh and based on a 5 area factor it leaves me at 291.93PVw

Based on your estimations and fudge factors with the 1,459Wh/ 292PVw, if I had a 330W panel, the panel would need 4.42 hours of full sun to run the fridge and charge the batteries? And if I had 2 -330PVw panels it would take 2.21 Hours of full sun?

If I placed 2 panels, it would require a 60A Controller (660Pvw/12V= 55A) BUT my batteries can only handle 30A charge based on their Ah & charge rate factors so if I limited the 60A CC output to 30A what would be the performance differences between the single panel at 330PVw VS. 2 -330PVW panels with the 30A limited CC?


Also I assume it probably gets more complicated too over the 24 cycle as I will be starting out day 1 with full batteries, so I only need to serve my daytime draw of (729Wh) BUT day 2 & after I will need to charge the batteries from the previous nights draw of 729Wh/12V = 60.72Ah AND serve my day time needs so the system is charges the batteries full to get it through the next night 6PM - 6AM.

Also I assume it's ok to run a 72 cell grid ties as well as the 60 cell as long as if I run 2 that I run the same exact ones?

Thanks



YES Sun King I've read your stuff and I have your diagrams downloaded but the diagrams you've posted do not answer my questions for my particular set up as I posted previously in this thread. Not everything people want to do will conform to how you think it should be built.

[Sunking]

Did you try reading the STICKIES? Here are a few examples of the proper wiring of an RV system.

[sensij]

Question: If I get more panel wattage than this it woulds just be a waste as it won't charge the batteries any faster based on a 30A max charge rate, it would just be excess capacity I could use for other things BUT based on my usage calculations above I only need 125W of panels to power the fridge so 330W should be more than enough to run my fridge set up and keep the batteries charged ???

Please edit your posts to show the distinction between Wh (energy) and W (power).

Use a Kill-a-watt to verify the fridge's consumption, and build in a fudge factor for seasonal variation. It is worth the $20 it costs.

Use PVwatts to get a better idea of seasonal array production (especially at the expected mounting orientation). Drill into the hourly output results. I'd set the loss at around 10%, and focus on the DC power and energy production. System loss calculations for battery based systems are different than for the grid-tie systems for which PVWatts is designed.

If your consumption is truly 624 Wh, I'd use 0.75 round trip efficiency on the battery, meaning you'd need to be capable of generating 832 Wh of charge daily. Another 10% loss on charge controller efficiency puts you at 924 Wh of generation from a solar panel... probably closer to 200 W of PV required than the 125 W you calculated.

With a 220 Ah battery, you really should try to get at least 18 amps into it routinely. I'd be looking for a deal on a 60 cell grid tie panel in the 250-300 W range, and a 30 A mppt CC. A 2nd panel would be excess capacity for future loads, as you say, but will help get your batteries through absorb into float more regularly, if you have space to mount it.

[Carv]

Duplicate

[Carv]

Ok I've done a little more digging around here and got some more information: fuses are only to protect the wires from burning up due to over load not to protect the electronics per the site many on here have referred to: http://smartgauge.co.uk/sb_fusing.html


With that in mind I think I'm ok fusing the main positive battery cable off the batteries at 150A-175A since the 1/O welding wire I used is rated at 350A (at 50' length & I have a 10' run) (http://www.directwireusa.com/Resourc...IDE%202016.pdf) and my inverter calls for a 200A main line fuse but pulls 125A at max sustained (1500W) and 250A at peak (3000W), and then fusing the MPPT controller at what ever it's rated at before the distribution block.


On the system design side I found a great write up by Sun King:
https://www.solarpaneltalk.com/forum...battery-design

So following this write up:
1) Daily usage in watts: My guess at fridge wattage usage is: 1.1A X 115V = 126.5~130W. I estimate my duty cycle time on the high side to be 5 out of every 15 minutes which gives me 20 minutes per hour of run time. So 20 minutes per hour X 24 hours in a Day equals 8Hrs per day at 130W = 1,040Wh.

2) Fudge factor for battery & line loss = 1.3. So 1,040 X 1.3 = 1,352Wh per day

3) Sun Hour day calculation: Per the solar map where I'll be using the panels in December my factor is 5.0 -5.5

4) determine the size of my array: 1,352/5 = 270W is the min panel needed for fridge only.

5) Determine Voltage used: "0 to 600 watts = 12 Volts or higher" -I'm using 12V

6) Determine Charge controller size 270W / 12V = 22.53A min

7) Determine Max charge Batteries can take: I'm running Centennial Flooded Lead Acid (FLA) 6V (GC2200P http://www.centennialbatteries.com /products_golf.html) in series for 12V at a 20A discharge rating of 214 Amp Hours) AH...so C/8 is my max charge (for safety) so...214/8 = 26.75A max charge rating. If I take it down to C/7 charge/discharge rate it takes me to 30.57A. So I would say my max controller amps I should use for this set up is 30A to keep the batteries happy.

8) Reverse engineer my max usable panel wattage based on battery capacity : 30A x 12V = 360W so...if I get 1 panel at 330W it should generate 27.5A at the charge controller keeping my batteries happy and lasting long plus give me more than I need to keep the fridge running.

Question: If I get more panel wattage than this it woulds just be a waste as it won't charge the batteries any faster based on a 30A max charge rate, it would just be excess capacity I could use for other things BUT based on my usage calculations above I only need 270W of panels to power the fridge so 330W should be enough to run my fridge set up and keep the batteries charged ???

[Wrybread]

It's not at all clear from the Amazon ad, but they don't come with fuses...

Here's the fuses:

https://www.amazon.com/Blue-Sea-Systems-5190-Terminal/dp/B0017SJOH4

Could also get the single fuse model:

https://www.amazon.com/dp/B0019ZBTV4

> And can they be reset on site without replacing parts?

No, you'd need to replace a fuse. But it shouldn't ever blow, it's just there for an emergency short.

[Carv]

Saw those, I just enlarged the picture and one says 200A and one 40A, is this what their rated, listing says nothing I could find.

And can they be reset on site without replacing parts?

Thanks

[SunEagle]

These are handy and connect directly to the battery terminal:

https://www.amazon.com/gp/product/B002INJXO6

Those are great battery terminal fuse blocks.

[Wrybread]

These are handy and connect directly to the battery terminal:

https://www.amazon.com/gp/product/B002INJXO6

[SunEagle]

C.S. is customer service

Thanks for the links wrybread

my inverter calls for a 200A breaker on the DC positive lead so if I breaker each piece of equipment I assume I should breaker the inverter with the 200A it calls for? If I do it this way how many amps should I breaker the batteries with?

i was thinking something like this that I can reset on site without having to replace a fuse if I'm in the middle of no where.

https://www.amazon.com/Lumision-Wate...h+manual+reset

Or this for 100A
https://www.amazon.com/dp/B00139FQSS...=A6AY1HFZHO49U

I have one of those circuit breakers but I also have a 30amp in-line fuse to protect the wire. I only use the CB as a "switch" to disconnect my CC from my battery system.

[Mike90250]

The resetable circuit breakers (watch the label, get the one with the Test button on them, or termed SWITCHABLE) are a very good idea,
Look at the Ampicity chart for the cable needed to safely carry 200A, that's what you have to use on a wire protected by a 200 A device, (i think 3/O or 4/O is required)
Other wires, need to have a protection device, sized to protect the gauge wire you are using.

The MorningStar TS MPPT 60 & 45 have a settable Max Amps limit - i've seen it in the menus.

Fridge 1,1A @ 120VAC = 132watts @ 12V = 11Amps DC plus 20% for inverter losses, So you are looking at 13.2amps, at maybe a 40% duty cycle, 9.6 hours of runtime and total of 1,520 watt hours in a day

Most MPPT controllers DO NOT have any disconnects built in, you need to supply that all externally. I used a 6 position breaker box to build my combiner, and also mounted my breakers for controller in it.

[Carv]

Too late tonight to do another round of Q/A

But what is "Q) I spoke to a C.S. rep at go power " ?? CS computer science ? Corporate Supervisor ? Contract Sales ?

I have a 24V inverter with internal GFI, and it's grounded to a Rod. Along with battery - & charge controller - & PV - , it all works.

C.S. is customer service

Thanks for the links wrybread

my inverter calls for a 200A breaker on the DC positive lead so if I breaker each piece of equipment I assume I should breaker the inverter with the 200A it calls for? If I do it this way how many amps should I breaker the batteries with?

i was thinking something like this that I can reset on site without having to replace a fuse if I'm in the middle of no where.

https://www.amazon.com/Lumision-Wate...h+manual+reset

Or this for 100A
https://www.amazon.com/dp/B00139FQSS...=A6AY1HFZHO49U

[Wrybread]

You really should put a fuse on your batteries. But that's ok, it's all easy and cheap. This is a great option:

https://www.amazon.com/gp/product/B002INJXO6

If you need to add an internal fuse box, I'm a big fan of these:

https://www.amazon.com/gp/product/B001HC0QXG

Or if you don't need that many circuits:

https://www.amazon.com/gp/product/B001445O5W

As far as your desire to power your fridge without impacting the batteries, I had the the same project in mind and wound up homebrewing something, but I didn't completely disconnect the batteries, I just turn on my fridge when the batteries are fully charged and there's enough power coming from the panels so it's in effect the same thing. But there's a few off-the-shelf products that have the ability to power an external load once the batteries are fully charged such as (I think) the Victon BlueSolar models:

https://www.amazon.com/dp/B011KHV1RM

Note that I haven't had any direct experience with those, and I'm not positive about that model, but I know some of their previous models had the ability. I'm pretty impressed with the programmability of their charge controllers in general, and the fact that they sell a bluetooth adaptor that lets you monitor the panels on a smartphone is a very good sign in my opinion. It looks like the Amazon seller at that link is answering questions that people post to the "ask a question" section of the Amazon listing so you might see if you can get a direct answer from him.

[Mike90250]

Too late tonight to do another round of Q/A

But what is "Q) I spoke to a C.S. rep at go power " ?? CS computer science ? Corporate Supervisor ? Contract Sales ?

I have a 24V inverter with internal GFI, and it's grounded to a Rod. Along with battery - & charge controller - & PV - , it all works Something is odd.

You CANNOT (ok, should not) leave out any of the mentioned circuit protection devices. You have to pay, to safely play in the solar/battery game. Talk to someone who's had a electrical fire.

[Wrybread]

I have a feeling 720 watts of panels is overkill, I bet 600 watts (two 600 w panels) is just fine. Personally I'd go with a 40 amp charge controller since they get more expensive quickly as the capacity goes up.

I recently built a system to the specs you're describing and posted the equipment list here, which might be useful:

https://www.solarpaneltalk.com/forum...e-advice/page2

Go down a few posts from that link.