# solar set up question



## kbrothers (Jul 17, 2014)

Was given 8 75 watt solar panels by family member which I'd like to use for power in a small 16 X 20 cabin Heavy wooded closest feasable panel set up 300 foot Is there any way to make something work here what batteries, controls ,etc. Thanks


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## Peasant (May 18, 2013)

300' will be a challenge but not impossible. Run 120VAC line from inverter to cabin. If you have a 600W inverter, for example, you'd only need #10 wire to limit voltage loss to <3% over 300'.

I'm assuming these 75W panels are 12V, Imp is probably ~4 amps/ea. So 48 amps total for the array. With inefficiencies, a ~370 ah battery bank would be suitable and will give you a nice 10% charge rate. That's a convenient number because that's what L16 batteries are rated. So two L16s wired in series giving you 370ah @ 12V.

I'd probably go with a 60 amp charge controller to give you some wiggle room. Panels can sometimes produce more than their rating. Morningstar makes a nice 60 amp charge controller, either PWM or MPPT depending on your budget. Outback also makes a really nice (and expensive) MPPT controller.


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## kbrothers (Jul 17, 2014)

Thanks Peasant will check out the equipment you suggest and have an old pasture about 100' away Belongs to a farmer neighbor May see if I can work out something to shorten run Would I have to be concerned with battery freezing? Thanks again


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## Peasant (May 18, 2013)

kbrothers said:


> Thanks Peasant will check out the equipment you suggest and have an old pasture about 100' away Belongs to a farmer neighbor May see if I can work out something to shorten run Would I have to be concerned with battery freezing? Thanks again


100' is better than 300', but it can work at 300' depending on your loads. You'll pay more for wire/extension cords, of course.

I run 120' of extension cords from my inverter. My loads are light, though, rarely more than 100W, and usually closer to 20W or less. With 12 ga wire, voltage drop is well under 1%.

What are you hoping to run off these panels?


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## Jim-mi (May 15, 2002)

Connect the panels together to get high voltage and run to the house to a MPPT controller that is made for that. Midnight Solar has the best . . . .tho pricy 
Batteries inverter all at the house.............


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## kbrothers (Jul 17, 2014)

Just plan on running a few lites and some kind of small water pump Maybe six lites and think RV type pump Son is checking out 110 LED? lites for me What do you guys think? Thanks for all input Ken


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## Peasant (May 18, 2013)

My 9.5W Cree lamp draws 0.79 amps @ 12V (not including inverter draw). 

A 370 ah 12V battery bank would run that lamp for 117 hours, assuming batts are drawn down to 75% state of charge. Twice that if run down to 50%.

12V RV water pumps are pretty efficient. I have a larger pump that draws 4.4 amps @ 12V. Let's say you run water for an hour a day. A 370 ah batt bank would run that pump for 21 days if run down to 75%.

Running 5 LED lamps for 12 hrs/day and a 12V water pump for an hour a day would only draw 370 ah batteries down to ~86% per day. Not including inverter draw. Pretty light load.

Problem is that a 12VDC pump needs 12VDC. If you ran line from inverter 300' away, you get 120VAC which you'd have to convert to 12VDC, creating additional inefficiencies. 

Not a huge deal with a light load like this. But you would need a converter. With two L16 batteries I'd use something like an Iota DLS-75, which will pull double duty as a converter and a battery charger that you can use with a generator to charge your batts in poor solar conditions.

Or just do like Jim-mi suggested and wire panels in series, run high voltage line to cabin, and use MPPT controller to step down to 12V.


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## SolarGary (Sep 8, 2005)

Hi,
I think Jim has a good solution -- hook the 8 panels in series. If they are nominal 12 volt panels, the max voltage will be around 18 volts per panel or about 150 volts total. This higher voltage will minimize the wire size you need between the panels and the MPPT charge controller, and, as Jim says it keeps all the sensitive and expensive things in your shop.

With 8*75 = 600 watts, the current will be about 600 watts/150 volts = 4 amps.
With #12 wire, the voltage drop would be around 4 volts, which should be fine.

The only expensive part would be the MPPT controller.

Gary


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## kbrothers (Jul 17, 2014)

Thanks Gary and all Having shoulder problems at present time Hope to get back to it ASAP


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## wy_white_wolf (Oct 14, 2004)

Just a note that you need to use panel VOC and calculate in for cold temps when figuring string voltage. That puts 8 - 12V panels in the 200 to 250V range. Midnight solar does offer a controller that can handle that or change the array to 2 strings of 4 panels. That would drop you to 100 to 125V and most quality MPPTs can handle that.

WWW


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## Nimrod (Jun 8, 2010)

SolarGary said:


> Hi,
> I think Jim has a good solution -- hook the 8 panels in series. If they are nominal 12 volt panels, the max voltage will be around 18 volts per panel or about 150 volts total. This higher voltage will minimize the wire size you need between the panels and the MPPT charge controller, and, as Jim says it keeps all the sensitive and expensive things in your shop.
> 
> With 8*75 = 600 watts, the current will be about 600 watts/150 volts = 4 amps.
> ...


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## Jim-mi (May 15, 2002)

You are missing the magic of todays super electronic circuits in a MPPT' controller to change high voltage/low current DC into lower voltage higher current DC.....

I know 'boB the guy who spent years developing the Mid-Nightsolar MPPT controller . . yes he is a electronic wizard.......


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## wy_white_wolf (Oct 14, 2004)

Nimrod said:


> SolarGary said:
> 
> 
> > Hi,
> ...


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## kbrothers (Jul 17, 2014)

OK got the MPPT charge cotroller ordered today a Morningstar TS-MPPT-60amp Next on list is batteries Would it be better to use 4 instead of 2 and would the panels charge them Thanks Ken in Pa


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## Peasant (May 18, 2013)

kbrothers said:


> OK got the MPPT charge cotroller ordered today a Morningstar TS-MPPT-60amp Next on list is batteries Would it be better to use 4 instead of 2 and would the panels charge them Thanks Ken in Pa


I looked at my first post and saw I got the amp output of the array wrong. It's likely close to 32 amps if these are 12V panels.

32 amps @ 10% charge rate = 320 Ah of battery

Whether to use 2 or 4 batteries depends on what batteries you're talking about. 

Need some basic numbers. Imp and Vmp of panels, Amp hours of batteries, and expected load in Watt hours. Otherwise can only make random guesses.


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## kbrothers (Jul 17, 2014)

Peasant, sorry for slow response Batteries are 2 Crown deep cycle golf cart model # CR-205 6 volt and A.H, rating 205(20hr) and 170(5hr) the charge controller is Morningstar TS-MPPT-60 8 panels/Shell Solar 75 Watts;600v max open,open cir volts 21.7 rated volts 17, short cir current 4.8A and rated cur. 4.4A series fuse 15 amp Thanks ken Any help appreciated Have a great day


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## SophysMom (Mar 31, 2015)

I am so grateful to people, who find time and share their experience with others. It helps us to avoid many mistakes and save money. I realized that that best decision for me is to apply to Solar Panels Company and ask them for help. There are some things that should be done by specialists. However, there are some people, who can cope with this task better than anyone else. All is all, it is pleasant to know that more and more families choose alternative sources.


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## wy_white_wolf (Oct 14, 2004)

SophysMom said:


> I am so grateful to people, who find time and share their experience with others. It helps us to avoid many mistakes and save money. I realized that that best decision for me is to apply to Solar Panels Company and ask them for help. There are some things that should be done by specialists. However, there are some people, who can cope with this task better than anyone else. All is all, it is pleasant to know that more and more families choose alternative sources.


SCAM link. You'd be asking to get screwed if you applied to them.

WWW


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