700 Watt design sanity check

[Monument Mountain Man]

Greetings,

I am new to this, but think I have a good design. I am curious if I missed something or over/under designed something.

I have a Thor Vegas that came “Solar ready”, which gave me a Go Power 10 amp Charge Controller (this one will be removed), with 10 gauge wiring to the rooftop connection ports. Note the 10 gauge wire… I know there are several options for panels, charge controllers… but I thought for my first design I would stick with a single vendor for most items. Hoping that means easy integrations and installation, then trouble shooting…

I am going to use (4) Renogy 175 watt flexible panels. Each panel’s positive connection will have an inline 15 amp fuse at the panel. The cables will then go into the Renogy 4 to 1 Solar Branch Connectors that will connect to the existing roof top connection port with the 10 gauge wire. No issues with this panel design going into 10 gauge wire on the way down to the charge controller, right??

In the rig, the wires will come into the new Renogy’s Rover 60 Amp MPPT Solar Charge Controller, with bluetooth option. The positive outbound side to the battery bank will have a fuse on it, but not sure what size to use. Renogy suggested 75 Amp, which from other posts and my searching, I understand is not a common size. I have found a 70 and 80 on Amazon. Should I just use a 70 here?

The battery bank is (2) Renogy LiFePO4 12-volt 100Ah lithium batteries with self healing functions, with the monitor that connects to the batteries. No shunt required to monitor them.

I am using the Renogy 2000W 12V Pure Sine Wave Inverter. I am using 4AWG cable with a fuse on the positive line. Renogy support suggested a 230 Amp fuse here. I am still looking, but I found 200 and 250. Any suggestions here??

I will do a DC to DC connection in the future, nice review by Will Prowse.

Thanks for any comments on this design.

 

[Rednecktek]

The cables will then go into the Renogy 4 to 1 Solar Branch Connectors that will connect to the existing roof top connection port with the 10 gauge wire. No issues with this panel design going into 10 gauge wire on the way down to the charge controller, right??

If those are the same panels mentioned in another recent thread, IIRC the amperage on each of those is about 9a each. In parallel that would add up to just short of 40a which is 10a higher that 10AWG is rated for. You will probably want to go 2s2p to get the 48v and 10a output from each string which will still let the MPPT have enough voltage to play with AND keep the amperage below the wire limit.

Renogy suggested 75 Amp, which from other posts and my searching, I understand is not a common size. I have found a 70 and 80 on Amazon. Should I just use a 70 here?

Rule of thumb is 125% of the load, so 60a of the controller output * 1.25 = 75a. When in doubt round down and use larger wire. So, 70a fuse/breaker and 6AWG wire according to everyone's favorite chart.

I am using the Renogy 2000W 12V Pure Sine Wave Inverter. I am using 4AWG cable with a fuse on the positive line. Renogy support suggested a 230 Amp fuse here. I am still looking, but I found 200 and 250. Any suggestions here??

2000w * .85 efficiency (rule of thumb) / 12v = 191.6a max draw from the batteries, * 1.25% = 239.6a fuse, so go for a 250a Class-T fuse and at least 2/0 wire according to the chart.

However since those batteries only have a 100a BMS on them, you can't draw more than 200a without the BMS tripping.

 

[Monument Mountain Man]

Rednecktek,

Thanks for the info. I have attached the spec for the 175 Watt panels (Optimum Operating: 8.98A, 19.5 V). I think they are the ones you are thinking of. So being new to the some of the short cuts like "2s2p". Just checking on the panel connections. "2s2p" == I should connect two panels in Series (giving 350 W, 8.98A and 39 V) and a second set in Series and then those two in Parallel to the charge controller (giving 700W, 17.96A, 39V), right?

Sorry, I had a EE prof that made sure I studied Computer Science and not Electrical Engineering LOL...

Regarding the fuse for the inverter. Why do you use T fuses versus ANL? I see they trip faster than ANL.

Gordon

 

[Rednecktek]

Regarding the fuse for the inverter. Why do you use T fuses versus ANL? I see they trip faster than ANL.

When you have a short the LFP batteries are capable of pumping out so much juice that the ANL fuse can just arc right across and keep burning. The Class-T's have a bigger gap when they open to help prevent that.

 

[WYtreasure]

Rednecktek,

Thanks for the info. I have attached the spec for the 175 Watt panels (Optimum Operating: 8.98A, 19.5 V). I think they are the ones you are thinking of. So being new to the some of the short cuts like "2s2p". Just checking on the panel connections. "2s2p" == I should connect two panels in Series (giving 350 W, 8.98A and 39 V) and a second set in Series and then those two in Parallel to the charge controller (giving 700W, 17.96A, 39V), right?

Sorry, I had a EE prof that made sure I studied Computer Science and not Electrical Engineering LOL...

Regarding the fuse for the inverter. Why do you use T fuses versus ANL? I see they trip faster than ANL.

Gordon

I was going to say welcome to the party MM&M, but now it's Gordon.

Take a look at the reviews on the renogy equipment. Someone has been slipping in the QA department.

Class-T fuses are faster. If you have the room and the money they are the way to go.

Use a fuse - and wear safety glasses... This could have been very bad.

If she did not have that fuse, this would have been a lot worse... Definitely worth the cost of the Class T fuse.

diysolarforum.com

 

[MisterSandals]

I am using the Renogy 2000W 12V Pure Sine Wave Inverter. I am using 4AWG cable with a fuse on the positive line. Renogy support suggested a 230 Amp fuse here. I am still looking, but I found 200 and 250. Any suggestions here??

Assuming inverter has 10V cutoff voltage:
2000W / 10V / .85 efficiency x 1.25 headroom = 294A fuse

My handy reference chart goes to 200A and it starts at 2/0 awg, i would imaging 4/0 for 300A but just guessing. 4awg is wildly undersized.

 

[mikefitz]

I strongly advised you to rethink you chosen supplier of parts. Renogy brand products are made by third parties and their support is not the best. Byfar on all forums associated with solar and van conversions, it seems the brand that has most issues is Renogy.

Flexible solar panels, unless you pay top$$$$$, degrade quickly and rarely last beyond 2 years.

You will be spending time and money on your system, do yourself a favour and consider alternatives.

For example Battleborn or Victron batteries, rigid framed panels from known manufacturer, like LG or Canadian Solar, charge controlers and inverters from Victron or Xantrex. These are just a few examples there are other quality products available.

One item not discussed in your post is a shunt based battery monitor. These are extremely useful in managing your battery power.

Mike

 

[12VoltInstalls]

Flexible solar panels, unless you pay top$$$$$, degrade quickly and rarely last beyond 2 years.

And even then…

 

[mitchofcanada]

Flat sticky solar panels heatsink the sun into your RV. basically cooking you and making your ac work even more.
Panels with an air gap are better and panels will output more power as they can run cooler with air flowing under them.

My goto is strut panel with 1-2 inches of airgap under it then you can uprade, move panels etc at any time. And say stick out back of trailer 6inches or so. fold outs. flip outs, etc.

STC @25C is what your panel will make. Temperature goes up, less power is made.
Temp goes down, More power is made (hence if you use solar in winter you need to plan system for say -30c and potential higher voltages.

 

[Monument Mountain Man]

Flat sticky solar panels heatsink the sun into your RV. basically cooking you and making your ac work even more.
Panels with an air gap are better and panels will output more power as they can run cooler with air flowing under them.

I understand, I did not want to stick it on my rig either and was concerned about the heat issue as well. I am using the method that Brian used on his rig. (RV with Tito DIY;

) So I am raising the panel above the surface, not as much as hard panels, but I don't want to put holes in my roof and wanted a low profile for the road. My trips are into Canada, Yukon and Alaska. So that helps a little.

 

[mitchofcanada]

I would go with rails and solid Panels. Upgradeable and easily removable. you already have items sticking up that high so the flat part is not that important. Any RV roof work will be a pain in the ass with stickies.
Maybe fill voids with stickies to their own MMPT?

Also if you are REALLY boondocking ALOT, and have panels on rails you can tilt them if you really want to.
Rails on Standoffs with Rivet Nuts makes for a very clean install and you can use the rails as cable channel.

I highly doubt you will see any performance difference on flat vs traditional panels. If traveling alot and far a wind deflector spoiler may help.

 

[Kcdaniels]

I would go with rails and solid Panels. Upgradeable and easily removable. you already have items sticking up that high so the flat part is not that important. Any RV roof work will be a pain in the ass with stickies.
Maybe fill voids with stickies to their own MMPT?

Also if you are REALLY boondocking ALOT, and have panels on rails you can tilt them if you really want to.
Rails on Standoffs with Rivet Nuts makes for a very clean install and you can use the rails as cable channel.

I highly doubt you will see any performance difference on flat vs traditional panels. If traveling alot and far a wind deflector spoiler may help.

I really shocked by his numbers.... Would have thought it just the opposite ? Thanks for posting....

 

[eXodus]

(4) Renogy 175 watt flexible panels.

Sorry, most flexible panels are not worth anything. They are good for a year or two then they die.
I've made the mistake twice and wasted the money. I wouldn't use them when I would get them for free.

Just get glass panels. They are good forever.

Otherwise the Plan itself looks decent.

Sorry, I had a EE prof that made sure I studied Computer Science and not Electrical Engineering LOL...

Very normal, EE has a 50-60% rate of people starting and switching to other majors/ quitting.

I mean the responsibility a EE has is probably one of the biggest of any engineer. EE work on the biggest machines human kind has developed - the PowerGrid. You do some wrong calculation and a whole country could be sitting in the dark. That major should be hard.
In CS you just push an update to the app when you messed up.