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Small Cabin Forum / Off-Grid Living / Thoughts???
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rachelsdad
Member
# Posted: 27 Apr 2016 04:23pm
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Based on great reviews from people who had purchased their product I had a company give me their recommendations for my needs.
Please see the email trail...starting from bottom. Some slight redactions

I was pretty specific as to my demand. While they dismissed the mppt controller I am hopeful that the package he recommends made sense...

The names have been changed to protect the ignorant, (me).

Would love to hear some thoughts.

Thank you.


W,

A couple of notes here - MPPT controllers are so much more expensive that it is cheaper to just add another 100 watt panel to a PWM controller when you are at this scale of size (generally below 1.2 KW or so). They typically improve array output by 10-15%, which is not as much as the gain from simply adding another panel.

Since MPPT controllers are required for the larger panels, that would also increase your cost significantly if you went with those (they also cost much more to ship, as they must be shipped via an LTL shipper). The 400 watt kit is definitely your most cost-effective option here, in terms of dollars per generated kilowatt-hour.

Your battery solution sounds fine, our customers seem to really like the 6-volt types.

An 80-foot run would definitely require a "heavy duty" AC cord as I mentioned, properly sized to avoid voltage drop. However, this can be accomplished with 8 awg wire - see the attached screen shot. Please let me know if you have any other questions.

Best,



Thanks Se,

Couple points. From what I have read an MPPT charger sounds like the "better" alternative. Is there merit to that and do you sell them?

Also, I think I'd rather run 2 of your 265 watt panels. If the batteries can handle that much....your thoughts?

My thought was 4x 225 amp hour golf cart 6 volt batteries for power bank..A friend is a wholesaler and I can get them for $100 per...name brand.

What about connections? mounting etc

Also, you're not suggesting an extension cord to run the power 80' are you? I was going to use 4 gauge wire.

bc



m,

For intermittent usage like that, our 400 watt kit should provide enough power for those months. I've attached a production estimate for your reference - you can always add another 100 watt panel if necessary. You would want to pair this with a slightly oversized battery bank, in the 600-700 amp-hour range (for example, four 150 Ah batteries in parallel. I have attached a short guide on battery connections for your reference.

http://www.homedepot.com/p/Grape-Solar-400-Watt-Off-Grid-Solar-Panel-Kit-GS-400-KIT/2 03505963

You would want to put all of this equipment (solar kit plus batteries) in the boat house, and use an heavy duty AC cord for the longer 80-foot run to avoid voltage drop. Please let me know if you have any other questions.

Best,

S-

I want to use it three season, probably May – Sept ...push it a bit to perhaps November but certainly no winter use.

12927 is the zip. Northern Adirondack area.

I figured weekend use mostly, Friday 2:30 pm- Sunday 2:00 p.m. No draw during away hours.

Figure 3 full weeks of staying during height of summer. More than likely less..but hey rather over estimate

I assume 25 lights at 10 watts...(12 Volt LED) overestimating all on for 6 hours per day...but this will never happen.

1 water pump assuming 4 hours per day at 125 watts per hour...(Shurflow 2088)

I'm guessing 2,000 watt hours per day

Issue number 1. House is totally covered with trees, need to mount panels on boat house roof...80' away and run line to house.

Issue number 2. Not sure which way to go 12 volt vs 120. Distance from panels to house may decide for me. I can place panels and batteries in/on boat house.

Would prefer an mppt charger

NorthRick
Member
# Posted: 27 Apr 2016 07:03pm - Edited by: NorthRick
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Couple of thoughts:

1) You do want to convert to 120v AC at the boathouse and run an appropriately sized and rated wire to the cabin. Your amps will be 1/10 that of 12v dc and wire size can be much smaller (and cheaper).

2) If you do that, use 120v AC LED lights, not 12v. They are in every store that sells light bulbs now.

3) "Grid Tie" panels that operate at higher voltage (VOC of 37-40), are 1/2 to 1/3 the cost on a per watt basis as "battery panels" (VOC of 18). The catch, as you are aware, is that you need an MPPT control to properly charge a 12 or 24 volt battery bank if using grid tie panels.

4) I haven't done the math, but sticking with PWM and adding another battery panel, as he is suggesting, may not be cheaper than an MPPT charger with grid tie panels. While MPPT is still more expensive, the difference isn't as great as it use to be and they make smaller MPPT chargers now.

5) Are you really going to run a water pump 4 hours a day? Seems like a lot.

creeky
Member
# Posted: 27 Apr 2016 07:17pm
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Quoting: NorthRick
Couple of thoughts


what he said. epsolar has a nice mppt unit. and the mppt prostar from morningstar is now available. might want to look at those.

rachelsdad
Member
# Posted: 28 Apr 2016 07:52am
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thanks all...do you think the 400 watt system is adequate for my power consumption?


North Rick,

yeah, looks like converting to 120 is the ticket. I do plan on the LED bulbs as well...I use them in a lot of commercial Bldgs I manage.

"Grid tie panels"...do you mean the breaker panel or solar panel? If the latter, could you lead me to a few vendors you trust?

Water pump use...yes, way way way overestimate..better safe than sorry I guess.


Creeky,

Do you have a few recommendations for those Li batteries you recommend?

Thanks again!!

Steve_S
Member
# Posted: 28 Apr 2016 08:18am - Edited by: Steve_S
Reply 


Grid Tie Panels are the higher wattage, higher voltage panels. The typical 12 volt panels max out @ 100 watts and are very pricey at that wattage level (between $1.25 - $2.00 per Watt). Like the Grape Solar 100W @ HomeDepot.COM is $141.00 USD, Here's a good (limited)price comparison chart www.solar-electric.com solarpanels


Best bang for buck is using the Grid Tie panels which can now go as high as 500 watts a panel(just coming out), the most common on the market being between 250-310 watts each panel averaging at 80 cents per watt or lower.

My own system uses
Canadian Solar 260W 60C Poly PV module, CS6P-260P, which cost me $ 214.00 CAD, ea. (in April 2015) Attached is the electrical specs for my panels, hopefully that helps.

With MPPT you can over panel somewhat to keep your production up in lower light conditions and the controller will handle that and step it down for charging your batteries.
CS6P-260P data
CS6P-260P data


rachelsdad
Member
# Posted: 28 Apr 2016 11:47am
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Thanks Steve!!!

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