when the power goes out at home,

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michael shore asked Aug 28, '19

when the power goes out at home,

I wish to send the solar power from my grid tied roof panel to the batteries in my RV solar system. The roof panels produce approx 30V each. The roof panels are connected in series to make 300volts that feeds the grid tied inverter.

When the grid goes down I would like to use a transfer switch to send the roof power to my RV which holds presently 360AH of batteries.

I am guessing (but will calculate later), that depending on wire size, the 100 feet from rooftop to RV will provide sufficient voltage drop to safely add the rooftop panels to the RV panels.

The panels would need to go automatically from series to parallel wiring .

Can I apply those 30v panels into my RV system? Where would I make the connection?Can they simply be connected as are the RV panels at the roof top combiner box?

What is the maximum current my RV is likely to ask of these additional panels? That current draw will help me determine the needed wire size..

battery charging

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ceriw answered · Aug 29, 2019 at 01:21 AM

Getting the panels to automatically change from series to parallel wired would be tricky and is likely to give you issues.

What MPPT/solar controller were you thinking of using?

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Modifications Space

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Answer 1 · 2019-08-29T20:12:33Z

michael shore answered · Aug 29, 2019 at 08:12 PM

I agree the reconfiguration will be a chore. With the power down think of all the free time I will have! If this concept has enough merit, I plan is to install manual switches at the combiner box for the roof panels. Ten toggle switches and I am good to go.

The MPPT question is where I begin to get in over my head. The RV has a Victron MPPT 100/50 wrangling 6, 90watt panels. I have no idea how this device works or what it rules are. I am curious.

In order to get 240VAC out of the RV, I will have add a second inverter/charger. This will be programed so the phases are "split" and the two inverters working together can produce the higher voltage.

The goal of joining the roof panels to the RV's panel is to improve charging times. In this part of Oregon even fairly distant forrest fires can send sky darkening smoke.

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