Solar Install Question

Red Wing · 10-16-2020, 01:11 PM

I am planning to install a solar system on my popup.
Here is the concern.
There is only one wire from the converter to the battery. This wire provides a DC feed to the converter and also acts as the battery charging source when connected to shore power when the voltage of the battery drops.
My concern is that when the solar system is installed the DC supply to the converter will be from the load side of the solar controller. The solar controller supplies the battery bank as an isolated system and passes the DC from the battery bank to the load side of the solar controller.
My concern is if I am connected to shore power and the solar system is ON will there be a conflict between the converter charging system and the solar controller charging the batteries? Also if the solar system is OFF will the solar controller supply the DC power from the battery bank thru to the load side side of the controller which feeds the converter/DC distribution panel?
Has anyone here had these concerns when installing a solar system?

Any input would be appreciated.

JimD · 10-16-2020, 01:29 PM

I have solar and love it. Just upgraded from 200 watts to 400 watts.

You will have 2 wires coming from your panels to your controller. You then have 2 wires coming from the controller that you connect to the battery. I recommend connecting them directly to the battery and ignore what is going on with the converter wiring. DO NOT USE THE LOAD CONNECTIONS ON THE CONTROLLER!

The purpose of solar is to charge your battery. It does not conflict with the converter when connected to shore power. I have both connected at times and there has never been a problem. My controller has bluetooth which is used to watch what is happening with the solar. Funny thing I noticed is that it still sends out a charge sometimes even though the controller is doing it too.

Red Wing · 10-16-2020, 06:59 PM

Thanks for the feedback
Why would you not use the load connections on the solar controller?
If they are not used will that effect the total operation of the solar controller?

JimD · 10-16-2020, 07:27 PM

I have no idea what the load output would be useful for in an RV since everything is tied into the 12 volt battery system. It may be useful for other applications such as a fan in an enclosed area or whatever. In an RV you are all set up already for everything so adding solar is just to charge the batteries. Maybe someone will chime in with a use for the load output.

I have attached a picture from my controller manual that mentions the load output.

When I upgraded my unit to 400 watts I did a test. I fabricated a load tester where I could switch in increasing loads to see what my output was. My first test was just to connect the panel array directly into my load tester and measure the available current while watching the voltage. I then hooked it into the load terminals and tried increasing loads.

The load current pretty much matched what the panels were capable of. As far as battery charging is concerned, it appears that I can get close to the max amount available for load output. If I had something connected to the load terminals that would lower my available charge for my batteries.

Hope it makes sense. I recommend you download the manual for the controller you will be using. Good info there.

I am an electronic nerd and love this stuff. Gauges and gadgets, happy days!

Red Wing · 10-17-2020, 06:43 AM

Thanks. This is most helpful I will pay closer attention to my controller manual. What make of controller do you have? Mine is a Victron 100/30. As I proceed with the installation I will start posting a how to post of the project. Maybe this will be helpful to folks on the forum. Please feel free to input suggestions. They are most welcome. I am sure your experience and knowledge will be much appreciated by all of us working with solar for our RV's.

Red Wing · 10-17-2020, 06:51 AM

Your load tester sounds interesting. Post a picture if you are so inclined. It might be useful.

JimD · 10-17-2020, 04:13 PM

I have a Renogy 30 amp Rover which is MPPT. I upgraded from a PWM type to MPPT which is suppose to be more efficient. It does seem to work much better.

Here is a link to my solar testing: https://www.jaycoowners.com/forums/f...nel-78794.html

The solar panel manufacture told me how to test a panel. Very easy! Document attached.

Red Wing · 10-17-2020, 07:08 PM

Thanks. I may build one of these. Also the testing paper is helpful.
BTW I noticed we both live in the Inland Empire. Maybe after this COVID 29 has passed we will meet each other. I like bells and whistles and have added so items that might not actually be required for a functioning system. Keep up the good work and thanks for sharing.

Red Wing · 10-24-2020, 08:07 AM

My problem has been solved. My MPPT controller does not have a load output so I will not have a concern when wiring it into the system. There will be no converter charging circuit tied thru the controller to worry about. If I am connected to shore power or a generator I can simply turn off the solar charging system. My system will monitor the total DC current usage thru the shunt and communicate that to the controller when it is in use. Answers always come when you really read the equipment manuals, spec sheets, etc and then apply some good logical reasoning to the problem.
Thanks to all for the input. It helps in the analysis when looking for a solution. As is always said "Another pair of eyes always helps".

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