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alano · 06-17-2015, 02:39 PM

Ray,

Yes, you will need to drill a hole in the roof. Use a combiner box on the roof to provide an enclosure to connect the roof mounted panels to the solar pre-wiring. AM Solar sells these boxes and also supplies the wiring you'll need to connect the panels and provide waterproof connectors for the combiner box.

I would recommend that you connect two panels in series and buy the Blue Sky Solar Boost 3024 controller. Get the IPN pro remote too since it's a good battery monitor. By connecting your panels in series using a MPPT controller you'll reduce the losses in the solar pre-wires by half! Any good solar setup requires a battery monitor so you know how different loads deplete your batteries and when you system is fully charged. The Blue Sky controllers are programmable so you'll be able to adjust the settings to be compatible with Lithium cells.

Good luck with your system.

RaymondFitz · 06-17-2015, 03:01 PM

Al,

Thank you very much. That is what I was looking for. I was planning on getting the AM Solar's box. Good advise on the running them in series, I've been reading your posts with rodsterinfl on running in series and I was thinking of doing just that.

Thank you,

Ray

lewster · 06-17-2015, 03:25 PM

Series connections is one way to go...... But be prepared for almost no solar charging if one of the panels is even slightly shaded. This is the primary reason we don't use series canine croons for our installations.

We looked at this issue long and hard a while ago and determined that we got more usable charging from parallel connections.

As always........ YMMV!

Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

alano · 06-17-2015, 03:59 PM

The series/parallel debate continues, but there are many factors that play into it. The panels you choose often come equipped with bypass diodes to mitigate the effects of shading. A fast-acting MPPT controller will always find the optimum operating point for extracting energy from the solar panels. These choices will affect the performance of the system.

From a purely theoretical view, I believe the series/parallel differences to be negligible, even when one considers shading. The more practical viewpoint is that a parallel arrangement is better. There's not a lot of really good parallel data out there that's convincing for us EE's. So for me the opportunity to reuse the existing solar pre-wiring and be able to install the system myself with relative ease won out. Since the MPPT controller and battery monitor cost was in the neighborhood of $500 and the cost of (4) 100 W Renology panels was only $142 each, I could afford a few extra watts to spare if one of more of the panels became full or partially obscured.

switz · 06-17-2015, 04:09 PM

Remember when using the NEC tables for wire size, they are talking AC.

DC looses energy quickly in small wire. Otherwise why is 4-0 okay for five feet but over five feet it needs to be 2-0 wire between the converter and the battery bank? The answer is power loss.

That is why we have AC power to our homes. In the beginning, Edison wanted to run DC power, but the wire sizes were huge for short distances. George Westinghouse came up with AC and the rest is history.

rodsterinfl · 06-17-2015, 07:18 PM

Quote:

Remember when using the NEC tables for wire size, they are talking AC.

The chart I am using has a drop down that you chance to the voltage being used. It has DC and 1 phase AC as the same. Yes, really long distances and lots of watts definitely make a difference. I have large wire for my inverter but the panel on the roof is only 150 watts or 9 amps max. At 15' it is a 2.3% loss in DC with 10AWG wire by the chart.

BTW, my roof run is much shorter than I envisioned. I will get a footage figure soon. It appears to be about 8 feet total to the prewire plus whatever it is to the controller. My panel is wide and the mounts short but will bow in/out. My panel will be touching the roof in the middle. hmm.

Question to anyone familiar with the fridge vent.

Tonight I was trying to figure out how to get my solar cables down it and found a place in the screen at the top I could squeeze them through so I did. When I got down to get the wires there were no wires to be found in the fridge vent. Is there something up there between the screen and the bottom besides the fridge and that arched filler wood piece? I cannot understand why I cannot see anything.

rodsterinfl · 06-21-2015, 11:55 AM

OK, I found out for myself. Yes, there is a problem when just sticking wires through the screen. apparently there is a second screen or something there that blocks anything from getting through. I had to drill through the vent shaft like before to clear it and get the wires down the shaft. It is done. Here are my pics.

rodsterinfl · 06-21-2015, 12:06 PM

BTW, for some interesting reading regarding AC versus DC. Check this out. DC is starting to replace AC primarily due to energy loss that does not impact DC.

Tesla turns in his grave: Is it finally time to switch from AC to DC? | ExtremeTech

rodsterinfl · 06-21-2015, 12:19 PM

Here is another one- I added these SAE2 ports on each side of my battery box to just plug in easily with the portable units:

tsunami · 12-16-2015, 04:34 PM

Having read this entire thread 3 time, I noticed that that the installer ventilated the controller box that was installed in the cabinet. How much heat is generated by the controller? Is this something to be concerned about?

alano · 12-16-2015, 05:05 PM

Solar chargers never operate at 100% efficiency, so for example if your solar charger operates at 96% efficiency and you have 400 W of solar panels, the solar charger will need to dissipate 16 W. Heat is the enemy of electronics so it's always good practice to make sure there's adequate airflow. The Solar Boost 3024 manual calls out, "CAUTION: Mount the unit with heatsink fins oriented vertically to promote cooling and do not enclose in a confined space."

EddieO · 12-16-2015, 07:07 PM

Quote:

Tesla turns in his grave: Is it finally time to switch from AC to DC? | ExtremeTech[/url]

Tesla is fine with all this. He always stated DC had its place.

eheffa · 12-16-2015, 10:17 PM

Quote:

Originally Posted by tsunami

Having read this entire thread 3 time, I noticed that that the installer ventilated the controller box that was installed in the cabinet. How much heat is generated by the controller? Is this something to be concerned about?

Hi,

I ventilated the box on spec thinking that it should have some ability to dissipate any heat. The front surface plate of the controller does get warm to the touch when operating under higher loads but never to temperatures that concerned me. The enclosing box is slightly warm on occasion but again of no real significance.

The unit is still working flawlessly.

-evan

KJRitchie · 01-07-2016, 12:26 PM

What are the advantages of 24v panels vs 12v panels?

I have a Zamp 200 watt portable system. I'm guessing they are 12v panels. If I wanted to install 200 watts on the trailer I'm guessing I'd have to find 12v panels. What I'd like to do is put 200w on the trailer and then using a combiner box in the trailer be able to connect my portable panel to the trailer panels then run to an appropriate controller (the portable panel's controller is removed). Looking at AMSolar they seem to sell only 24v panels. Can I just get any 100w Monocrystalline panel to run with my Zamp.

This way I can charge the batteries while towing, charge the batteries if the trailer is in the shade or get 400watts (22 amps) charging in a full sun campsite.

Kelvin

alano · 01-07-2016, 01:16 PM

Most of the panels for RV use, including the Zamp portable panels, contain 36 photovoltaic (PV) cells. Since each cell produces approximately 0.6 V, a 36-cell panel will produce approximately 21.6 V open-circuit and less when producing real power from the panel. Even though the manufacturers refer to the panel as 12 V, if you check the specifications you'll find that they operate at maximum efficiency around 18 V or so.

Of course you realize with your planned configuration that you won't be able to use your Zamp solar controller, since the included controller won't support 400 W. If you want to parallel panels, i.e., mount 200 W on the roof and keep another 200 W as a portable option, I would recommend that you purchase the same panels as your portable panels from Zamp so that all your panels are balanced, meaning that when exposed to direct sunlight each is operating at the same current and voltage. It gets very complicated to connect panels from different manufacturers and doing so would likely degrade the efficiency of your system.

The BlueSky Solar Boost 3024iL MPPT controller will easily handle your configuration and also give you an optional battery monitor, which IMHO is essential for caring for and understanding your system. With this system you have the option of connecting all four panels in parallel, or you can configure your system in a series/parallel arrangement which will double the voltage and cut the current in half. I would suggest this configuration since you'll be able to reuse your existing solar pre-wiring without incurring much loss.

AM Solar is a good resource for the solar controller, wire, combiner box, etc. You'll need to procure identical panels from Zamp. Many folks can help with the details. Just ask.

KJRitchie · 01-07-2016, 01:42 PM

When the solar panels on the roof are actively charging the batteries while towing does the charge circuit from the tow vehicle interfere with the solar? It would be nice to have both so when towing at night you still get some charging.

Thanks.

Kelvin

alano · 01-07-2016, 02:15 PM

It's a rather complicated relationship. Your solar charger will likely be a 3-stage battery charger with temperature compensation. This is ideal for your flooded or AGM batteries. However the TV alternator doesn't sense the voltage of the AS batteries so although you can allow the TV to charge the batteries in the AS it's not ideal. You won't blow anything up, but in the right conditions you may overcharge your AS batteries if you drive frequently which may lead to some degradation of your AS batteries. Many folks simply pull the fuse to interrupt the power going to the TV when they have a solar installation.

KJRitchie · 01-07-2016, 02:20 PM

Would the Blue Sky Solar Boost 3000i be a better solution for me. It seems to have more monitor functions than the IPN remote.

Kelvin

BoldAdventure · 01-07-2016, 02:53 PM

Quote:

Originally Posted by KJRitchie

When the solar panels on the roof are actively charging the batteries while towing does the charge circuit from the tow vehicle interfere with the solar? It would be nice to have both so when towing at night you still get some charging.

Thanks.

Kelvin

I just put an on/off switch on my line. So I can use it when I want. My truck sends a steady 7 amps back. You can easily measure yours to determine how much power is sent. And turn it on/off when you want so you don't fry the batteries.

Quote:

Originally Posted by KJRitchie

Would the Blue Sky Solar Boost 3000i be a better solution for me. It seems to have more monitor functions than the IPN remote.

Kelvin

No, the IPN Remote has more functions, as it's a remote display.

----

So many folks going against the grain lately, using other panels and batteries. Not buying all the marketing hype huh?

alano · 01-07-2016, 02:58 PM

The 3000i might also be suitable, but in either case if you want to monitor your AS battery and know the state of your battery (percent battery depletion for example), you'll still need the IPN Remote Pro and shunt. The 3000i can tell you how many Amp-Hours was produced by the solar controller but it's doesn't know what other loads are on your batteries so it can't tell you the depletion level. The only way to know this reliably is to measure the current coming out of the batteries.