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Small Cabin Forum / Cabin Construction / On grid but isolated solar system possible?
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KinAlberta
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# Posted: 24 Aug 2019 00:36 - Edited by: KinAlberta
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Would this make any sense? Stay on grid but reduce your utility consumption by using solar to some limited extent but NOT interconnecting the two systems.

Are there cases of people staying on grid but wiring in a separate non-connected solar system for say; lights and TV, but not the furnace, fridge, etc.

There’s certainly got to be people powering outbuilding via solar when running a power line is cost prohibitive or some other factor ales a stand alone system the best solution.

However could a dual system within one’s cabin save any money or trouble?


Maybe avoid or reduce the cost of the inverter, run DC lighting?

But loose the opportunity to sell back into the grid. (Why aren’t farmers putting big arrays in their barns and selling loads of power into the grid?)

Steve_S
Member
# Posted: 24 Aug 2019 07:49
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You can configure it that way if wanted. The tech exists for any form of connections, it all boils down to complexity & cost of course.

For example, my inverter is a Samlex 4024 and has 2 AC Input lines, one for the grid power in with it's own ATS and one for the generator line. Victron, Outback and other's also have such models with similar capabilities.

For some, it may be a very good alternative as they can start smaller on solar system and build up over time while transitioning off the grid. Or to use the Grid as a backup power source in case their batteries need a charge.

Brettny
Member
# Posted: 24 Aug 2019 08:25
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Farmers arnt putting big arays up because you buy at retail and sell back at wholesale. So theres little to no gain by making more power than you can use. Here the monthly fees to be connected is the killer, but cutting that cord is a big gamble with 4hrs of peak solar per day.

If your going to have an inverter to run your TV theres not really much gain in going to DC lights. Your just adding another complexity to the system. I saw a few solar videos where people had XX volts DC lighting and they said they could only get that bulb from china and it cost way way more than a 120v AC bulb. They also said they wish they just ran 120v everywhere for everything.

12v DC is really only standard in RV stuff. 24v DC stuff can be found but this is the highest DC voltage i would try to run any DC appliances off of becids a inverter. 36/48v DC is just not that common for anything but solar and golf cart stuff.

darz5150
Member
# Posted: 24 Aug 2019 09:38
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Kinalberta
Everything in your post describes our set up.
We have ac or 12 volt power in all rooms. Also have transfer switch for generator, for extended power outages.
We have a $25 meter charge. Last electric bill was $72.
That was running 2 window air conditioners also.
The lowest I ever paid for actual electricity was .76 cents per day.
So your idea is doable, and can save you money. As well as having peace of mind during power outages.

creeky
Member
# Posted: 24 Aug 2019 09:58
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You can do this by putting in a separate load center and wiring the "off grid" solar into the new lc.

Then put your mission critical loads on the new load center. So fridge, a/c, lights.

It is quite a bit cheaper to just grid tie with battery now. Essentially does the same thing. Starting next year we should see some pretty good grid tie with battery options.

ICC
Member
# Posted: 24 Aug 2019 14:38
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Doesn"t make a lot of sense to me to have both the grid and some solar that is completely separate. If I wasn't actually using all that the solar made I would feel like I was shortchanging myself.

Grid tie with some battery if you want to be able to actually store some power onsite.

If you grid tie your hardware must be approved by the power co.

I would check with the poco and find out what plans they support before doing much planning.

Brettny
Member
# Posted: 24 Aug 2019 15:12
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And you should really do the number to see if its going to save you any money. I wouldnt think it will.

Atlincabin
Member
# Posted: 24 Aug 2019 17:34
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But could be useful if you have regular power shortages. I would stick with 120V, though and not mess with 12V. Back in the 80s our house was wired for 120V but the inverters then were not particularly reliable, so I was also set up with 12V bulbs that could be put into regular sockets (and I could switch the entire house system to 12V - I was not connected to the grid at all). Occasionally, I used those bulbs. But nowadays, inverters are so much more reliable I wouldn't go back.

creeky
Member
# Posted: 25 Aug 2019 11:05
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And I'll disagree with Brettny. Solar is so cheap now. Reliable. Your payback is 3 to 8 years.
Given that you'll get 25. That's a lot of years of free power.

Brettny
Member
# Posted: 25 Aug 2019 20:41
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Creeky i think your missing that im saying that solar with batterys when you have grid power available is a loosing situation.

With any solar system you need to figure out the useable solar hours per day. In my area thats about 4hrs average. I cant make power cheap enough at WH when the power company buys it at MW.

darz5150
Member
# Posted: 25 Aug 2019 21:44 - Edited by: darz5150
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Brettny. The last time you lost power, did you get out your power bill and think what a good deal it is?
Since I have multiple power sources, I don't have to go without Power.

Brettny
Member
# Posted: 27 Aug 2019 09:05
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The last time i was with out power was actualy about 3 weeks ago. I did not think i needed $2000 in batterys plus pannels. I went out and burned 3gal of diesel and slept well.

I actualy alreaty own two 235w pannels and havnt done anything with them due to such little ammount of sun we get and the cost of batterys.

ICC
Member
# Posted: 27 Aug 2019 15:11
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Generators are useful at times, but have maintenance needs. Plus a generator does one no good at all if you are absent and the generator does not have an autostart system.

I was in CA for 10 days with a local friend. There was a power failure that lasted more than a day here when we were gone. My fridge and freezer kept on running off the stand alone solar system. My friend had enough of a melt down that the ice tray was a solid block of melted and refrozen former ice cubes. He tossed some food as he was not sure how safe the frozen fish would be.

Another friend, in another location, uses a battery backup that maintains its charge by being connected to grid power. His fridge is wired to keep running off the battery/inverter when the grid goes down. His furnace is also on the aux system to keep the heat on enough to prevent frozen pipes in winter. He has not gone solar because he has a small place and never uses more than 300 kWh a month.

We're all somewhat remote and have outages any time of the year from wind blown trees falling on lines. We're sort of on the wrong end of the fixit list much of the time. That's one reason I did 100% solar without any grid tie when I built this new place a few years ago.

creeky
Member
# Posted: 27 Aug 2019 22:29
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Here in Ontario you can pay for your solar system by charging your batteries at night and using battery power during the day.

No solar required.

Of course. If you have solar as well. Gets even cheaper.

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