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Small Cabin Forum / Off-Grid Living / Solar power surplus
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groingo
Member
# Posted: 26 Sep 2014 15:07
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Well being this past week has been mostly cloudy and raining I am stil showing over a 20 to 60 percent power surplus and it will grow so I am told as it gets colder an the panels put out more juice by up to 15%.

What are you doing when you get a power surplus?

Myself am thinking of a second set of used backup batteries to keep ready to go should something go sideways.

razmichael
Member
# Posted: 26 Sep 2014 15:58
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Quoting: groingo
it gets colder an the panels put out more juice by up to 15%.

Days also get shorter and shorter! Having now had my system up and running for about a year, at first I would think "what a waste" and then started to just enjoy it and worry less and less about the daily consumption. If we need a bit more light - no problem. Need to charge a couple of tool batteries - no problem etc etc. There is still the competitive part of me that wants to squeeze every tiny bit out of the system but lately this have diminished greatly and I just enjoy it - much less time staring at the volt and amp meters etc.

MtnDon
Member
# Posted: 26 Sep 2014 16:02
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Quoting: groingo

What are you doing when you get a power surplus?


I smile happily and get on with the rest of my day.

IMO, any well designed off grid PV system will have energy surpluses. It's necessary to make up for shorter winter days, cloudy days anytime, etc. If you don't have surpluses then either the PV array is undersized or the battery bank is oversized.

If the PV system is capable of putting a charge (in amps) of around 10% of the battery bank capacity in amp-hours) that is good for the battery health.

Surplus power can be more of a PITA to try and harvest than it may be worth. Like those folks who try to use surplus electrical to heat water. OTOH, once the batteries have reached float and the sun is still shining that is a great time to consider some heavier power uses, like pumping water, doing laundry and so on. Ot that can be great if you only need A/C to run during bright summer sun days and not throughout the night.

As long as the batteries are getting the proper absorb time for their design characteristics and as long as the batteries reach float practically every day I feel we should just be happy with that.

fasenuff
Member
# Posted: 27 Sep 2014 09:33
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Things like doing laundry, running power tools, and running a well pump can drain batteries a lot and leave you with little to run through the night. Daylight hours when your batteries are charged is a good time to do those things that use a lot of power. The way I figure it any system that does not produce more juice than needed to charge the batteries is not producing enough. I want my batteries to top off early so when I have to run bigger power hungry items My batteries will still be topped off come sunset so I don't have to ration what I do that evening.

I don't see a surplus I just see power that has not been needed yet! I would rather have power not needed yet as to not have the power at a needed time... I like the idea of heating water with power not being used to charge batteries. Even a little help heating water can save some propane and maybe keep me from having to lug another 30 or 40lb bottle to the cabin...

groingo
Member
# Posted: 27 Sep 2014 10:41
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I do realize that there will be another four hours of daylight lost so am going to pickup some used deep cell batteries and have a second bank as backup and to store any surplus power.

Hot tip for used deep cells, check local golf courses or golf cart dealers, many have maintenance companies contracted or in house, mine replaces all 6 batteries if two are bad so there a lot to choose from and they only charge $15.00 each and are all minimum 225 ah each....check your local areas.

creeky
Member
# Posted: 28 Sep 2014 11:58
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Once my batteries are charged i do laundry. dishes in a dishwasher (electric heated). have a movie afternoon with the big screen and the stereo blasting. stream music.

It's pretty funny. You know. When I first looked at my stats and discovered I'd made and used 240 kilowatts of power but my system could have made 800 kilowatts...

On one hand, who cares. I had electric lights etc. But, on the other, I went out and bought an electric fridge. Goodbye propane fridge at $1.25 in gas every day.

what are you doing for refrigeration?

groingo
Member
# Posted: 28 Sep 2014 16:51
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I use an cold water ice box, change out water and ice twice a week in summer once a week in fall winter only cost a buck a bag for five pounds of ice and it does freeze things or I can just keep cool, depends if food is above or below the ice.
The ice box is basically a cooler within a cooler which is super insulated on the outside.

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