Need WA State electrical contractor/off grid advice

[solv3nt]

Solar panels in a string can have voltages up to 600V allowed by the NEC. The panels are wired in series. The panels then have a home run to the inverter, and most inverters will allow for 2 or 3 strings max, depends on the size of the inverter. The inverter then outputs a 120VAC, 240VAC or 208V signal. Typically, these systems are typically tied to the utility side of the panel, which will protect your panel from drawing too much power.

My experience is in $30 million luxury yachts, and solar design, so I know that there is a 120VAC/240VAC battery charger that is capable of charging battery banks. The one side that I'm unsure of, is the 12VDC to 120VAC inverter, IE, I'm not sure if they make ones large enough to power a house.

Personally, I'm concerned about resale, so I wouldn't wire a house for 12VDC only. Maybe the solution would be to run parallel wiring to each location, one for 120VAC and one for 12VDC. Since it will be new construction, design in two main panels, one 12VDC and one 120VAC. The main 120VAC can feed a battery bank, which in turn feeds the 12VDC panel.

 

[Blitzkrieg]

OK, that makes sense.. my plan was to have on grid power through a rectifier into a 12VDC system for the lights, 12VDC outlets, etc, so grid is available, but to slowly wean us off the grid system on the 12CDC side of the rectifier

But if I have to I can run double wiring. That was my initial plan but then this current idea came to me. All comments welcome

 

[solv3nt]

solvent, I got all of that except the 110 and an inverter at each piece

You're right, my idea wouldn't address that very well.

 

[Redcap]

OK, that makes sense.. my plan was to have on grid power through a rectifier into a 12VDC system for the lights, 12VDC outlets, etc, so grid is available, but to slowly wean us off the grid system on the 12CDC side of the rectifier

But if I have to I can run double wiring. That was my initial plan but then this current idea came to me. All comments welcome

Personally, I'd run doubled (and separated) wiring.

 

[solv3nt]

You're right, my idea wouldn't address that very well.

Since you're planning on still being connected to the grid, then you can connect your alternative production on the line side of the main breaker, which will allow for more alternative energy production. Keep in mind that the Utility may limit the amount of energy produced in a year if you are still connected to the grid.

Also, since you're still connected to the grid, if you aren't using a lot of power in the day, other than the battery chargers, then the majority of your energy will flow back onto the grid.

 

[Blitzkrieg]

Personally, I'd run doubled (and separated) wiring.

Problem then is I also would have to have separate lights that run on 12VDC @ extra cost. 12VDC cannot power 110 VAC items directly

 

[Blitzkrieg]

Since you're planning on still being connected to the grid, then you can connect your alternative production on the line side of the main breaker, which will allow for more alternative energy production. Keep in mind that the Utility may limit the amount of energy produced in a year if you are still connected to the grid.

Also, since you're still connected to the grid, if you aren't using a lot of power in the day, other than the battery chargers, then the majority of your energy will flow back onto the grid.

Another possibility.. I noted earlier in the thread that Mason Cty PUD will not pay for any extra power over the monthly bill.. quite backwards, IMO

But I do want a battery bank, I don't see how that merges with a line side off grid feed into the grid?

 

[solv3nt]

Problem then is I also would have to have separate lights that run on 12VDC @ extra cost. 12VDC cannot power 110 VAC items directly

One other option, would be to size all of your wiring for 12V voltage drop. #12 Romex is 600V rated AC/DC, same as #10 and #8. The problems arise when you try to land a #8 on a #14 terminal. The solution would be to have a small run of #14 and a really big wire nut. Upsizing the wire will cost more, but it is necessary to run 12VDC later.

 

[solv3nt]

Another possibility.. I noted earlier in the thread that Mason Cty PUD will not pay for any extra power over the monthly bill.. quite backwards, IMO

But I do want a battery bank, I don't see how that merges with a line side off grid feed into the grid?

Let's say that you're still connected to the grid, have a battery bank, and use solar as your main source of alternative generation. Your batteries are now charged, so all of the power produced will go towards a fridge, heater, etc, but the remaining power will flow back to the grid. If you aren't using it, it's going to the grid.

 

[Blitzkrieg]

So you suggest just using an inverter that is powered by the battery bank to the grid side? Then why the extra size load side wire? Confused, here

 

[solv3nt]

So you suggest just using an inverter that is powered by the battery bank to the grid side? Then why the extra size load side wire? Confused, here

Sorry, I've had multiple thought strings going on. Wire the house as though it is 12VDC, which will require significant upsizing of the conductors to offset the voltage drop.

Here's the issue, if you want to use the existing wiring in your house AND convert it to DC, you will either need a second DC panel or convert your main 120VAC panel to DC, which will require severing the connection to the grid.

 

[Blitzkrieg]

Gotcha.. this is a new ICF home we are getting ready to build. Planning on either propane or AC power to fridge, freezers, range, etc and the backup diesel generator if we lose grid power. I just want to power the lights, fans and 12VDC outlets from the battery bank. Excess power to go back to the grid via an inverter so hopefully no electric bill

 

[solv3nt]

I'm not sure how Washington works with energy credits, but Oregon doesn't allow for individuals to be paid for their energy production, which is what it sounds like for you. In this case, prior to the PUD authorizing a connection, they will want to ensure that you size your alternative energy source to be net zero for the year. For example, they'll take at least a years worth of electric bills, and total the Kw-hours, and allow a size that will net zero for the year. You may be positive or negative for a given month, but the total usage per year needs to match up.

Since you are planning on staying connected to the grid, might I suggest that you not use 12VDC items and a battery bank, but instead use low power lighting? CFL's use around 10W, which is 1/6th of a 60W bulb. Also, electricity is cheap, you're paying approximately $0.10 per kilowatt-hour. A 60W bulb uses 60/1000th of a kw-hour, approximately $0.006 per hour.

 

[Gunwheeler]

Seems like you are trying to give your self a headache for no reason. As explained earlier I have a 5.2kw solar system. I chose to be Grid Tie. I could of just as easily not gone that route and instead installed a battery bank capable of supplying for my needs. There would of been an inverter/rectifier and all wiring existing in the home would still be used at 120/240. Your choice at that point would be if you want to be grid connected you could be or if your choice is to not be all would still be good. The inverter/rectifier works with utility, solar, hydro, wind, generator, nuke, whatever means you provide it with.

Also mentioned earlier was my power bill. I am still connected to the grid. By state statue I receive $0.15 for every kw I produce ( $1220 to $1800 a yr) whether I use it or not. If I do not use the KW it goes to the grid where I still own (banked) it and may use it at a later date when I need it. It cost me $6.80 a month to remain connected to the grid (minimum monthly charge). The solar system cost $30k but after rebates came in at just over $15k. Consider the monthly savings and the $.015 per KW return and I have a 7 year max payback. The system has a 35 year life expectancy. I am not sure the rebate still exist, but if not I would expect to see installation cost drop greatly.

There is a lot to consider when you build a home. This is just one aspect. Also you should be thinking of solar orientation (solar heating does work in Western Washington), extra insulation, windows, hot water floors and such. A solar home does not need to look such (as did early projects)

 

[kickstart my heart]

Sounds interesting but also an expensive pain in the butt way of going about it. For the price of the batteries, I would think you could buy a really really good generator, a large storage tank for fuel, and a lot of fuel to fill it. You should also look into solar. Some of my clients in Western WA are generating more power with their solar than their home consumes. Also, check out the zero energy house they built at Clover Park Tech in Tacoma Zero Energy House | Clover Park Technical College. Might give you some great ideas. The company I work for manufactured the metal roofing panels on it, so I got to go to the open house. Very impressive build for a college class.

 

[Blitzkrieg]

I'm not sure how Washington works with energy credits, but Oregon doesn't allow for individuals to be paid for their energy production, which is what it sounds like for you. In this case, prior to the PUD authorizing a connection, they will want to ensure that you size your alternative energy source to be net zero for the year. For example, they'll take at least a years worth of electric bills, and total the Kw-hours, and allow a size that will net zero for the year. You may be positive or negative for a given month, but the total usage per year needs to match up.

Since you are planning on staying connected to the grid, might I suggest that you not use 12VDC items and a battery bank, but instead use low power lighting? CFL's use around 10W, which is 1/6th of a 60W bulb. Also, electricity is cheap, you're paying approximately $0.10 per kilowatt-hour. A 60W bulb uses 60/1000th of a kw-hour, approximately $0.006 per hour.

I should have stated right out that we are preppers and want an off grid system just in case, also as backup for inevitable grid failures. Having been off line for 14 days once right in Olympia, we do not trust the grid. We will have exclusively LED lighting and I hoped to make the 12VDC off grid powering up later, easy

In real time the heat for the home will be a log burner and one small upstairs stove. The site sits in the middle of 40 acres of very heavy timber we own. Sure we will have to install conventional heat, but we won't use it

 

[Blitzkrieg]

Sounds interesting but also an expensive pain in the butt way of going about it. For the price of the batteries, I would think you could buy a really really good generator, a large storage tank for fuel, and a lot of fuel to fill it. You should also look into solar. Some of my clients in Western WA are generating more power with their solar than their home consumes. Also, check out the zero energy house they built at Clover Park Tech in Tacoma Zero Energy House | Clover Park Technical College. Might give you some great ideas. The company I work for manufactured the metal roofing panels on it, so I got to go to the open house. Very impressive build for a college class.

We will have solar, wind and maybe hydro.. trouble is if you don't have battery bank and any of your currently powering off grid systems fails and the grid is down you may have no power. Having a battery bank allows 10 + ways of keeping it charged, even a workout treadmill can help charge it

Cost to start it up isn't the issue, it's self reliance and eventual long term savings. Also since we will gradually add off grid items with cash, we will not be in debt for them

 

[sailorfej]

Did you work at Christensens?

Hi Solvent, I crewed on several private yachts and a few tall ships, usually as an engineer. I also worked at Westerly Marine down in California. These days I do IT, but I am hoping to go back to building boats when I "retire".

 

[Father of four]

I worked in maintenance at a yacht club for a while. I meet a few Christensens but only saw their products in magazines. They sure do make'em big. I really did like working at that yacht club and would have stayed if it wasn't for some of the class A people. They can be hard to stomach after a while. I probably should have stayed there though.(Grow thicker skin.) Live and learn I guess.

 

[Stomper]

One other option, would be to size all of your wiring for 12V voltage drop. #12 Romex is 600V rated AC/DC, same as #10 and #8. The problems arise when you try to land a #8 on a #14 terminal. The solution would be to have a small run of #14 and a really big wire nut. Upsizing the wire will cost more, but it is necessary to run 12VDC later.

The reason why Tesla's AC power won over Edison's DC power as the standard for powering the grid was (mainly) due to a whole lot less power loss in its transmission through conductors.


Another thing to consider is a (proper) circuit is designed/sized to run @ 80% of it's rated ampacity.

Generall amp ratings (for AC anyway)

14AWG = 15A
12AWG = 20A
10AWG = 30A
08AWG = 40A

Etc, etc.

Then you deduct 20% for a continuous load rating.


Electricity travels on the outside of the conductor, and stranded wire has more outside surface than the same gauge solid wire, resulting in slightly more ampacity.

I'd have to dig out my NEC sizing tables to get more specific, but do yourself a favor and at least hire an electrical engineer to properly layout and design what you're looking for.

I think what you are wanting to do is cool as hell, but we're talking about fire/life/safety, and electricity in any amount (AC or DC) is NOT your friend when it decides to "jump the shark". Believe me, it'll save you money and potential heartache in the long-run.