Thoughts on 400w Renogy Solar kit

[YGoHom]

I’m looking for some thoughts or opinions before I make a purchase.
From my reading, this kit seems to be pretty good, no? Mono panels and MPPT 40 amp controller with BT. This is the best price I’ve seen for the kit, whether on Renogy’s website or Amazon.

https://www.ebay.com/itm/283906206901

I have 230 amp hours in two 6v batteries, and a 1000w inverter that runs the residential fridge and tv’s. I also have a 4K Onan not-so-quiet generator.
I’m just looking to run the generator less when not “plugged in.”

Thanks,
Robb

[DavidM]

I think you can do as well and have a better controller if you buy individual components. Renogy panels are fine, but I would get a Victron controller like this one: https://www.amazon.com/SmartSolar-MP...s%2C190&sr=8-4

David

[gurroz]

I run Renogy Solar and Renogy Lithium and have no complaints. Victron makes good stuff as well, I use the Victron 712 battery monitor.

[AJMike]

I do not know about the quality of the Renogy solar panels or their solar controller but I have not had a good experience with their support concerning my Renogy 40 amp DC-DC charger and you might want to check into what support you would get.

The issue with the 40 amp charger started 6 months ago, shortly after I bought it. I reported issues with it and kept getting put off and put off, and once being ignored in my emails for 2 months until I managed to upgrade my request to someone else. Even now, about a month after they received the charger to fix under warranty apparently no one has even looked at it.

They also have a phone support line, but you need to get on that line immediately after they open. When I called about 5 minutes after the line opened I was told I was something like number 50 in line, and when I called back later in the day I was told I was something like number 120 in line.

My experience with their equipment is that if it works, it works well and is well worth the price but if it needs repair work you may be out of luck. In the end I solved my problem by buying the Viltron 30 amp DC-DC charger, but perhaps you will have more luck than I.

[powercat_ras]

It appears to be a reasonable price and quality. Renogy has a support center in USA/Canada so if you have any issues you can get support. The parts supplied will require that you connect all 4 panels in series. This is most efficient when none of the panels are shaded. If you park in partial shade a lot you may want to get additional parts to wire panels in parallel. The controller can handle it either way.

[creativepart]

I have some Renogy panels and they've been good. But I bought a Victron Smart Solar controller.

My controller is 100/30 as in 100 volts and 30 amps. That's fine for 400 watts of panels but you wouldn't want to go too much higher. I think ~500w is the max for 30 amps.

[YGoHom]

Thanks for the feedback. I'm going with your suggestions and piecing a kit together, and mounting in parallel.

4 Renogy 100w mono panels, Victron 100/30 MPPT controller with bluetooth, mounting feet, 6 branch connectors, 20' harness 10AWG, wire assembly tool, and a cap for running wires through the roof = $740. I'll have to add a fuse and some final wiring.

[rarebear.nm]

You'll getting to a better solution now, some good advice above. This will likely achieve what you'll looking for.

Sun angle and shade can work against you in many cases.

I did a custom design for use in Alaska and north of the Arctic circle. In four years our solar has provided 100% of our 12 volt power. The converters were turned off when the solar went active and have not been on since.

[DavidM]

I had always thought that solar controllers were rated at maximum amps that they can handle. 400 watts of solar panels could produce 400/12=33 amps DC when charging a fully discharged battery, maybe a little less due to efficiency losses.

So I went to Victron's site which gives a nice calculator that selects the appropriate controller and gives expected output at a selected geographical location. It recommends the Smart or Blue Solar MPPT 100/30. So it looks like you made the right choice as I would otherwise would have said 100/50.

Here is a link to the site: https://www.victronenergy.com/mppt-calculator

BTW it shows beween 13 and 19+ kWhr each day depending on the time of year for your Oceanside, Ca location presumably for fixed, horizontally mounted panels.

David

David

[YGoHom]

I had the same thought about the 30 amp vs. 40 amp controller.

New questions...
Being wired in parallel, should the controller be closer to the panels or to the batteries? As I understand it, the wire needs to be thicker than if wired in series. The kits all seem to use up to 30’ of 10awg. I’ve got a ton of 8 awg I can use, if it would be better, for the controller to the batteries.


I really appreciate all your guidance here!

[powercat_ras]

If you use your own cable you will want to be beware of UV rays causing the cable insulation to fail if the cable insulation was not designed for outdoor use in sun. Most cable sold for power amp installs is not UV protected. Also beware the cheaper power cable is not pure copper but is aluminum. The UV sunlight caused insulation failure can ber mitigated by putting the cables in split wire loom tubing.

10 awg can handle up to 30 amps safely. Your maximum worst case current for 400 watts of panels will be 26 amps but in the real world for non-tilted panels you'll rarely see more than 20 amps due to less than optimal sun angle on the panels. I suggest you run standard 10 awg solar cables separate from each panel to a roof top junction box.

You can run 8 awg in split wire loom tubing from the junction box to your Charge Controller (CC). Put a 30 amp breaker with manual disconnect button near the charge controller in the positive cable.

You can also run 8 awg from the CC to your batteries. Put a 40 amp breaker in the positive of that run.

The manual disconnect in the solar is advised so you can disconnect the solar from the CC in the event you need to disconnect the batteries from the CC.

Finally I like to connect the metal frames of the solar panels to chassis ground with a ground wire, but in your case where the panels are 20 volts open circuit and wired in parallel this is not critical for safety like it is in a higher voltage solar system.

[YGoHom]

Excellent. Thank you. Btw, the 8 awg cable is quality wire leftover from wiring a 50 amp breaker for a welder in my garage. But as you mentioned, not UV resistant, so I’ll use it in covered areas - not on the roof.
Now to figure out where to put the controller. My shorty Intent 26m doesn’t have much free space. The smart controller seems like it can be tucked away, say behind a panel under the galley, just above the battery compartment? Since it’s controlled thru the app.
The battery compartment isn’t sealed, but is very open to the elements and moisture.

[DavidM]

Some considerations about wiring your panels and batteries to the controller:

How are you going to wire these panels: series, series parallel or parallel only. Series panels reduce the current in the wire but increase the voltage. A 100 watt 12V nominal panel operates at about 17V Vmp but can hit 21 V if the batteries are completely full. So 4 wired in series produces as much as 84 volts, which is a safety problem. As I have said before at the least tape over your final connections to the controller so wandering hands can't touch it.

I think series parallel wiring for 4 panels is a better choice and keeps the voltages to a relatively safe 42V. And 8 gauge wire will be fine for that voltage/current. You need to keep the voltage drop down to about a half a volt.

The wire from the controller to the batteries needs to be bigger if it has any distance to go. Say for a 10' run you need #4 to carry 30A and keep the voltage drop down to less than 0.2V which is my rule of thumb. You could use two parallel circuits of your 8 gauge and keep it below 0.2 V as well.

You can use SJOOW cable that you can buy at home stores for the rooftop sun exposed wire. Put a junction box right at the point where it goes through the roof to splice your 8 gauge to the UV protected SJOOW or similar cable. Another way is with 8 gauge MC4 pre made cable and connectors to the panels.

David

[creativepart]

Originally Posted by YGoHom

Now to figure out where to put the controller.

In my Adventurer the battery bank is in a basement compartment mid-coach on the driver's side. The Solar Charge Controller is mounted to a wall in a basement compartment mid-coach on the passenger side. So, the wire run from one side to the other is about 6 feet. Super short and easy to deal with.

[YGoHom]

Based on what I’ve read about shade, this seems to be the way to configure it. We camp all over, so conditions will always be different then at home. But, shade will always be a potential factor.

I’m an idiot with this stuff, so I’m open to any guidance!

[DavidM]

That diagram shows all panels wired in parallel. Yes it is less susceptible to shading which will affect all panels wired in series if one is shaded. But how much shade do you get on top of your coach? I suppose trees could cause shade to come and go throughout the day and parallel wiring would be best for that situation.

But that last parallel run to the controller will see the full amperage so keep it short.

David

[YGoHom]

Yes, that’s why I though it might be best to have the controller closer to the panels, with 10 awg, then run heavy gauge wire and fuse/disconnect to the batteries. Is it necessary to run heavier gauge from the controller to the batteries? All the manufacturers kits seem to only use 10 gauge.

[DavidM]

Reread my post #13 about wire sizing.

David

[YGoHom]

I went back to post 13 and some other really good diagrams/tutorials which backed it up. It seems the off the shelf kits are a bit undersized.
I have a plan and parts have been purchased.
Now to research how to mount the panels in a way that will allow easy replacement without removing the mount from the roof.

Thank you all for your guidance.

-Robb

[JLUSoCal]

Robb,

I have 2 180 watt panels in series and they are not enough for running my small fridge on anything but a good sunny day. I have a Rich Solar 40 amp MPPT controller that has capacity for another panel bringing me up to 540 watts and that should be enough I think for doing most of what I want on decent sunny days. It's true about angles and shade, just never going to be optimum without tilting and that's a hassle. We have generators that need to be exercised so running for a bit helps. I do have Lithium so I can pull all the power they generate.

All that said, peicing together series parallel connection is likely your best best. If you want to get clever and it makes sense, wire next to your inverter to use it's connection back to the battery.

Victron controllers are the best but I'm ok with my MPPT controller and Bluetooth module. It gives me the basics and I find after a while I don't watch the numbers.

I'm going to deduct on this year's taxes as well, motorhome counts as a second home. Now if I could just get that last panel on sale...

David