House as a Marine Electrical System

[JayCall]

This may be a bit bizarre, but I have been reading about the latest in residential solar systems (now primarily leased rather than purchased). Not because we are considering it, we will dump the dirt as soon as possible, but just out of curiousity. It made me think-could a house be designed in the same manner as a boat electrical system? One of hte big issues with residential solar is storage-there is none so local utilities are forced by law to purchase the excess.

Many here have boat systems completely self-sufficient and self-supporting. Carefully calibrate balance between usage and storage (battery) capacity. Can a house be esentially a 12V DC system? With batteries (weight is certainly not an issue on dirt!). Plenty of roof space for panels. An inverter for 120V AC needs? I don't see why it could not be done, there are ore than a few 12V appliances now-for instance a 12/24V DC home refirgerator/freezer thant uses about 1/5 the power of a regular 120V AC of similar size. Most electronics nowadays are converting 120V AC to between 12 and 19V DC anyway. 12V DC llighting is way more efficient.

Heating and hot water, the two most power hungry uses can be natural gas, eliminating electicity altogether.

Seems to me it would not realy take that much for a house to be completely self-sufficient.

Just curious about others thoughts.

[cal40john]

Just one example:
Off-Grid Solar, Wind Power Systems & Off Grid Power System Design

One of the people here on CF has a solar powered house with battery storage.

[I.Grind]

I've stayed in a 12v house. Totally off grid, on an island. Juice supplied mostly by wind, solar added later (basically if you don't have one, you'll have the other). The wind was the real workhorse, in a gale we could waste electricity, otherwise it was mostly conserved for the water pump (from West Marine) because hand pumping water and carrying it to the house sucked. Fridge and stove ran on propane, lights were used sparingly (unless wind was over 25kts). There was a bank of batteries(golf cart, I think) in the basement. Lots of kerosene lamps and candles for back up. Very low tech, nothing fancy, much less luxurious than the average modern cruiser, but totally comfortable and adequate. Hot showers were only available on sunny afternoons when the miles of black plastic pipe on the shed (Okay, oversized outhouse) got warmed up. Took my dad 3 years of vacations to get it so you could flush the toilet. I remember baths there being the ultimate luxury. Everything had to be brought by boat and then a 15 mile hike.

So with LED 's and other recent advantages, I'd say no problem, although for a better all electric kitchen I bet you'd want 48V. It would be better for inverter for AC loads too. I' m no expert, plenty electrical engineers on CF I'll let them take over.....

[Tellie]

Still a bit expensive to run a modern house on solar. 48Volts would be the norm. But it can be done, it's only money. I set up a small home 12V system from boat parts collected over the years after Wilma came through a few years ago. I just grab the panels off the boat and bring them home. It will run a 12V fridge and freezer and a few LEDs, two small fans, and a small circulating pump for the home built solar water heater, all from a small battery bank. But so far I've never needed it. When standard sized panels put out 500 watts and cost $100 each I'll re-visit the whole house plan.

[Sand crab]

Lots and lots of houses are done this way. I know of about a dozen in my county and those are just the ones I know of.
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[gts1544]

JayCall,
Let me play the devil's advocate with no horse in this race! Assuming that your motivation is solely economic, have you considered the following: that most batteries have a useful life of 3 - 7 years (depending on type) before needing costly replacement / that converting energy (albeit free - solar to electrical / mechanical to electrical / 12V DC to 120 V AC) is fraught with inefficiencies requiring expensive equipment up front / the loss of income had that capital been deployed elsewhere, does it really make sense to try to produce your own power on such a small scale? Factor in the whole picture. gts1544

[djmarchand]

Years ago, I attended a display of all solar powered homes on the Mall in Washington. It was an annual competition among universities. It may still be going on for all I know.

All of these houses had huge banks of solar panels that fed a huge bank of batteries with appropriate contollers, chargers and inverters. They were 48 V DC systems which supplied most house loads, but air conditioning was also powered by the battery bank through an inverter. These were supe rinsulated houses, about 800 sq feet and also included solar hot water. Some had passive solar heating elements.

So yes it can be done and if you don't need air conditioning the cost to do a whole house will be under $10,000 and probably under $5,000. But we pay about $2,000/yr to heat and cool an all electric, 2,500 sq ft house here in eastern North Carolina. So it won't be economical.

But that wasn't the question. The question was can it be done and it can.

David

[Stu Jackson]

David's right, and I, too, read about that university competition. As I understand it, it occurs yearly.

Sure, it can be done and there are different ways, just like on a boat, to do it. Some use straight solar and fee back to the grid, off the gird can use batteries, some even add generators for high AC loads.

Hmm, just like a boat.