Adding plug in panels to existing Sportsmobile solar system

RCR

The new Sportsmobile installed solar setups use 115w Zamp panels and a controller that is supposed to accommodate 30 amps. They also install a plug to add additional portable array.  I am new at this! Can I add any wattage portable array to system? Can I use a portable kit that is complete, with its own controller?

BB.

I guess this is the company's system:

https://sportsmobile.com/solar-panels/

Realistically, they overestimate solar production by almost a factor of 2x... Plus they get some basic electrical units wrong (talking about X amps per hour & Amp/Hr, and using "amps" and "Amp/Hr" instead of "Amp*Hours" were needed)...

I don't know anything about their panels or solar charge controller (quality). But--You really need to start with the basics first.

What are your energy needs and where will you be using the system/dry camping. There are a few places on earth where you will get near 8 hours of "useful" solar energy per day for any more than a couple months a year (summer). For example, say you are in the central valley around Sacramento California, panels mounted flat to roof:
http://www.solarelectricityhandbook.com/solar-irradiance.html

Sacramento
Average Solar Insolation figures

Measured in kWh/m2/day onto a horizontal surface:

Jan	Feb	Mar	Apr	May	Jun
2.18	3.09	4.65	6.08	7.21	7.93
Jul	Aug	Sep	Oct	Nov	Dec
7.79	7.02	5.64	4.12	2.63	1.99

As you can see, if you assumed 8 hours of sun per day, but need power in the winter--The system would be 1/4 the size needed... 

Also, there are losses/derating factors in solar power systems... If you start with the "marketing specifications" for your solar panels and hours of sun per day, you will, on average, get around 52% to 61% of "marketing numbers" worth of energy.

For the most part, people over estimate the amount of energy they will harvest. Say you have 2x 140 Watt solar panels on your RV. And that you have a minimum of 4 hours of sun per day for October (8 months out of the year for Sacramento):

• 280 Watts solar array * 0.61 * 1/12 volt battery bank * 4 hours of sun per day = 57AH per day @ 12 volts DC energy
• 280 Watts solar array * 0.52 * 4 hours of sun per day = 582 Watt*Hours of energy

And you would have a battery bank that supported ~57 AH per day @ 12 volts (4x daily load):

• 57 AH * 2 days of storage * 1/0.50 maximum discharge = 228 AH @ 12 volts
• 2x 6 volt @ ~220 AH "golf cart" batteries in series = 12 volts @ ~220 AH

Would this work for you? I have no idea. Just a starting point for discussion.

So:

• Estimate your loads (Amp*Hours@12 Volts or Watt*Hours per day) by season
• DC or AC or mixed power needs?
• Design the battery bank, typically 2-4x your daily loads.
• Design the solar array to provide 5% to 13%+ rate of charge for battery bank (10%+ for full time off grid)
• Design the solar array to support your loads (WH per day, where you will be parked, seasons system will be used)
• Design backup genset system (if needed)

Once you have done a few paper designs and know what you need... Now you can go shopping for hardware that will support those needs (from turnkey vendors, or piece parts--Your choice).

-Bill

RCR

Thanks Bill. You're a star. That's their stock marketing, but it's pretty current.
The system will be used in Baja, when I'll be primarily off-grid. Otherwise, I expect to have shore power, a 2000E inverter generator or vehicle alternator charge assist.
I will be running a refrigerator and charging phones. Some LED lights. I really don't know what else. So, coming up with loads is a long shot.
Sportsmobile only puts in one battery. I've asked them to leave room for a second, if I need it. I realize I'll install new batteries to keep them equal. I have asked for a plug to be installed, which would allow me to add additional, portable panels to the system.
My question is, if the two Sportsmobile panels are 115w ea, must I use 115w (2) portable panels or can I use a an portable array of 2, say, 100w panels?
I appreciate your help. I'm sorry that I'm not informed. I have more money than brains (and not that much money).

BB.

Will this be a propane or electric refrigerator?

A 1,000 WH per day system can keep you pretty happy with LED lights, laptop computer, cell phone, and RV DC water pump.

As a refrigerator (electric with compressor), and you are getting close to a 3,300 WH per day system. Not small.

 

Bill

mcgivor

My question is, if the two Sportsmobile panels are 115w ea, must I use 115w (2) portable panels or can I use a an portable array of 2, say, 100w panels?

The controller is PWM, this will allow parallel panels of any wattage as long as the voltage is the same, however as the controller is limited to 30A the maximum total  wattage would be limited to ~430W, so 2 100W modules added would be a good fit.

BB.

You have to check the manual, but roughly, the maximum array wattage for a 30 amp controller would be:

• 30 amps * 18 Volts Vmp = 540 Watts...

However, the manual may derate a bit for various reasons.

Any mixture of panels with Vmp ~ 17.5 to 18.5 volts and less than 430 Watts would work. If you have three or more panels in parallel, you are supposed to put a series protection fuse (or circuit breaker) in each parallel connection to reduce the chances of fire if one of the panels gets shorted out (you check the fuse rating in the solar panel specifications).

-Bill

RCR

Thank you for the information!