Installation question.

Old Guy
Old Guy Registered Users Posts: 51 ✭✭
in Solar Beginners Corner #1
Sorry if this has been asked before....

We have a situation where a cabin is surrounded by tall trees (shade) we want to keep.

About 150' from the cabin is a steep hillside that is clear and gets plenty of sun. We only use the cabin on weekends so the batteries have all week to charge.

Would like to install the panels on the hillside. Question is: What would be the best way to do this?

Option 1: Install the controller and batteries with the panels on the hillside and run the power from the batteries back to the cabin.
Option 2: Run the power from the panels back to the cabin and install the controller and batteries near/in the cabin.

If someone would be kind enough to explain which would be a better installation (and why if you have time) it would be appreciated.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Installation question.

    The best way to do it is with the highest Voltage on the longest run. That gives you two options: high Voltage array running to an MPPT controller at the cabin, or array/controller/batteries/inverter on the hillside and 120/240 VAC running back to the cabin.

    In order to determine which is best in this case we need more details as to the system Voltage, panel specs, et cetera.
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  • Old Guy
    Old Guy Registered Users Posts: 51 ✭✭
    #3
    Re: Installation question.

    Thanks Cariboocoot,

    I don't have the specs handy but will get them soon. If it makes a difference, everything in the Cabin is 12v, we don't use a inverter.

    Thanks again!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #4
    Re: Installation question.

    As Marc said, you can do either. It is simply a matter of knowing the actual size of the system (how much power/energy you need) and doing a couple of paper designs to see which works best for you.

    You can get controllers that allow you to send upwards of 400 VDC from the array to the cabin/battery shed--But those "high voltage" MPPT controllers are not cheap.

    Or you can build your power shed at the array and simply send 120 VAC (or even 120/240 VAC split phase power) to your cabin. But that places the battery bank/monitors a 150' walk away--Not always convenient--And if you have bad weather/deep snow, not always a nice walk.

    In general, we need to know the amount of energy you need (Watt*Hours per day, peak Watts, where the cabin is located, nearest major city, etc.) as you need to select components that electrically and cost effectively best meet your needs.

    What you will not want to do is setup "12 volt" panels on the hill and send that low voltage DC to the cabin--The amount of copper you will have to buy/bury is usually cost prohibitive (very thick copper cable for low voltage, low voltage drop, high current).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Installation question.
    Old Guy wrote: »
    Thanks Cariboocoot,

    I don't have the specs handy but will get them soon. If it makes a difference, everything in the Cabin is 12v, we don't use a inverter.

    Thanks again!

    Ouch. 12 VDC only system is going to be a problem because the only high Voltage you could have is array to controller. And then that leads to needing the MPPT controller to down-convert across a large Voltage difference, which reduces efficiency.
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  • Old Guy
    Old Guy Registered Users Posts: 51 ✭✭
    #6
    Re: Installation question.

    I appreciate your help guys.... But you threw some wrenches in my gears. ;)

    I will go out to the cabin tomorrow and make a list of the equipment and get back. I am certain the controller is not MPPT but thats not a big issue. I can purchase one.

    I shall return!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #7
    Re: Installation question.

    You might think about switching to 120 VAC for the cabin... Today's LEDs/CFL's/many appliances are as cheap or cheaper than their 12 VDC counterparts.

    Also, many 12 VDC devices are not really "happy" on a 12 VDC system. They are typically designed to run from ~12.7 to 14.2 volts (car/boat system) and a true deep cycle battery bank will run from 10.5 to 15-16 VDC. And it is not unusual for a 12 VDC appliance to take up smoking when operated over this wide of voltage range.

    An AC inverter can be a cost/energy efficient option--Especially if you have send the power more than a few 10's of feet. A nice/small type of AC inverter is the 300 watt Morningstar 12 VDC TSW unit with "search option" (save energy).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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