Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

Re: solar

Reply #25 – November 05, 2018, 09:16:37 pm

To clarify how I wired the four panels, each set of two panels was wired in series to bring the voltage up to 2x39+78 volts. The two sets (of two) were wired in series by sending two wires each for a total of four wires down to a mini bus right behind the controller. The 78 volts was then sent to the controller via two wires from the mini bus. I could have brought them together on the roof but wanted all the connections where I could get to them easily behind the controller.

So, yes, the four panels are wired in both series and then in parallel. Series doubles the voltage of each set of two panels, parallel double the amps when the two sets are wired that way.

Sorry if I was confusing as it's harder to explain instead of having a diagram for the wiring.

Here are a couple of photos. The MidNite controller is mounted in the top compartment with the small door. The area behind has be lined with Hardibacker. The red bus brings the two positive wires down from the two sets of roof panels. The black bus does the same. Single wires are then run from the buses to the controller (no room to bring four wires into the controller). You can't see the wires but in controller input and output go through sets of circuit breakers. The controller output goes to the connectors with the huge welding cables against the back wall. From there, it goes down to the big electrical bus next to the wet compartment.

A large fusible link is at the electrical bus to protect the coach in case of an accident or short. So, everything is protected, the panels, the controller and the large cables feeding the electrical bus.

The solar CBs are turned on after the controller is turned on. Shutting down, the panels go off first, then the controller CBs. It has arc protection but this sequence is just extra to make sure.

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Re: solar

Reply #26 – November 05, 2018, 09:48:09 pm

Thanks Roger and Chuck. I changed parallel to series in the first post. Give me a gun and I would blow my toes off. Why didn't my proof reader catch the mistake?      Could not figure out why my ears were burning.

Thanks again,

Pierce

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Re: solar

Reply #27 – November 05, 2018, 10:35:07 pm

i have a magnum pt-100 charge controller that I bought early this year just to not repeat the undersized controller  posts here when adding panels,  the pt100 is capable of the 240 volts and 100ADC. Scaleable times 4. 

I  note the now demonstrated  expertise about Powerwalls that I had not seen before today here.

Using non inverted rv panels would need a charge controller then to the rest of the conventional system,

Inverted Residential 240 volt panels seem to go direct to the Powerwall and it seems its internal systems control the charging automatically,  plug and play hopefully.

My guru buddy liked the idea right away as almost every coach he works on  is somewhat underpowered. 

Seems a lot easier to run from the Powerwall to the main breakers to use its output.

Then into the already correct system.

Would have 1400 amp hours total useable.  And no voltage drop until the last 375 amp hours,

6  61 x 41  panels should fit our roof just fine.  Close to 2k watts output. 

When my guru buddy and were the bluebird salesman in 1989 the birds had enough battery and enough inverters that the entire breaker panel was connected.

Roof airs would both operate off of batteries.  Not for long obviously but they did work.



 


 

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Re: solar

Reply #28 – November 06, 2018, 01:07:40 am

Quite likely the Tesla is not designed to be in a moving vehicle.  That being said I saw  a picture of an early version one mounted on the rear vertical wall of a coach, 

On the other side if I put in our house there is a large rebate from the PUC

Hmmmm.  Remount the unit?  Naw that's cheating.  Sort of.

Unit requires fairly specific leveling.

We will see.  No hurry for me.  I have a good system now. 

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Re: solar

Reply #29 – November 07, 2018, 03:26:13 pm

Just some notes:

1. Sunpower makes their panels in China, Mexico and the Phillipines and has gotten a tarrif exemption.

2. I predict that Sunpower will survive and do not believe the article about shorting the stock. The stock is low because people don't relize that Sunpower is the "Betamax" of solar panels: superior technology but it's higher price puts it at a disadvantage. Laypersons do not know that these panels are far superior in terms of lower temperature coefficient, lower lifecycle degradation and much better warranty. See the following comparison table of Sunpower to a typical cheap Chinese Winaico panel:

Sunpower is far superior in all four key parameters:

COMPARISON, WINAICO VS SUNPOWER
KEY PARAMETER                           WINAICO       SUNPOWER  DELTA (% Better)
Efficiency, %                              18.6            22.7        18%
Product Warranty, Years                       12            25              100%
Power Temperature Coefficient %/oC                    –.43            -.29              73%
Degradation per year after 5th year, % power              .7            .4         63%

3. Not much engineering would have to be done to integrate into a Foretravel. I am running my rig from a true 230 VAC source from my home. That's two 115VAC legs with a neutral. A transfer switch could be designed to engage the solar charger, which would convert the 220VAC from the panels to the correct charge voltage.

4. They are safe. The newer solar panels, including the Sunpower X22-370 panels require no ground because they are all internally grounded and isolated, and UL approved.

5. I believe that microinverters are the future because each panel is isolated, so shading and panel failures will mitigate typical solar panel confounding issues. If one panel fails or is shaded, it will not affect the others.

I'd be happy to engineer a system for an intrepid Foretraveler and share my experience.

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Re: solar

Reply #30 – November 07, 2018, 05:28:14 pm

Perfect. Thanks Tim. I am far from rich.  At the same time I am not a "price buyer."  If someone says "it's less money" I Normally I ask why?  I personally buy the "best."  Long term satisfaction is better in my experience. 

You help offer is appreciated.  Will my magnum pt-100 work and/or  is it needed?

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