Mostly new to solar and seeking advice

[Sixfold]

Hey everybody!

I was seeking some good resources on off-grid solar power and ran across this forum a few days ago. Been devouring posts ever since.

I have some experience with solar as I helped a friend install his 6kw microinverter grid tied system, but that's about it.

Here is my situation. I recently purchased 20 acres about an hours drive south of St Louis, Missouri. It was mostly wooded completely unimproved acreage. I have since added a driveway and a well. I had them install a 120v 12amp well pump. I am in the process of designing the house that will be built, hopefully, starting this spring. Looking at a 2000sq/ft house for a family of 4. I wanted to do ICF construction to keep my heating and cooling costs down but I am having difficulty locating anyone capable of building with ICF in my area (Lots say they know how, but when I ask how many houses they have done, zero is the answer I always get). I have some passive solar ideas and will most likely be supplementing electric heat with wood. Electric water, dryer, dishwasher. LP stove. Gravity septic. No sump.

Anyways on to the electricity problem. $11k is what it will cost me to tie into the grid (I am nowhere near any power lines). Also there is inherent value, to me, in not being dependent on the grid electricity. Enough so that $1/kwh or more is acceptable to me. I recognize the associated costs can be high and I'm trying to pin down more accurate numbers for a completely off-grid system.

I estimate my consumption will be 30-35kw/day. I know this is on the higher side of things, but I anticipate alot of powertool usage and some welding (120v @ 30amp, right now but I may need a bigger welder soon). This can however be arranged so it coincides with sunny days. I also plan to incorporate some thermal mass principals into the house, thereby allowing me to heat and cool more during sunny days.

I plan to add some wind power in the future and possibly some microhydro.

As for our sunniness:
My friends 6kw system produced 875kwhs in June, 1006kwhs in July, 878kwhs in August, and 831kwhs in September (he is less than 10 minutes from me). His panels are not an ideal angle or direction since they are just aligned with his roof, but lets use his numbers for average sun.


So initially I thought that I would focus on a panel heavy system since my primary consumption is during the day. But then I realized that this could cause my batteries to charge too fast during periods of high sun and low load. So I'm back to square 1 and thought I would pose the question to the forum.

What would the ideal complete system (panels, batteries, chargers, inverters, generator, ect) be if you could start from scratch? Including designing the house to accommodate (wiring, roof pitch/angle, ect).


Oh also a side question. I recently obtained my Amateur Radio Tech license and was wondering which pieces of equipment are going to interfere with my signals?

Thanks for your time,
Sixfold

[inetdog]

Hello Sixfold and welcome to Solar Panel Talk!

To avoid overcharging your batteries when the available panel power would produce more current than the batteries could handle when in bulk mode, all you have to do it use a Charge Controlller (CC) which either has a low enough maximum output or can be throttled back to a lower maximum current setting.

If you are going to be charging your batteries and supplying heavy loads at the same time, you really need a CC which can produce a higher output current than your batteries can take, but which uses a shunt wired into the battery circuit. This allows the CC to regulate its output based on the current going to the batteries while continuing to supply as much or more current to your loads. The load current is seen by the CC but is not seen by the shunt in series with the - leg of the battery bank.

The panels themselves will not generate any EMI, but may well radiate EMI generated by the CC, so filtering on the DC wiring entering the CC may be helpful if you have problems.
The inverter may also generate EMI, and you may need to install filters on its DC input and AC output leads.

There are quite a few members who have their Amateur license who will be happy to share their experiences with you.
If you do not get a reply here, you may want to start a new thread in another topic with that specific question.

[fun2drive]

Solar System

Besides consideration of what solar power you need I would seriously consider a good generator that will help keep you powered until you self sufficient. Gas or diesel since you don't have other fuel choices would be a good idea. I have both actually a couple in Florida (hurricanes) and a large unit in Ohio that runs my entire home to include AC. There will be a number of times you will not have the power you need given your climate thus this provides the help you need when batteries are not charged or a number of cloudy days in a row. Don't go cheap on a generator get one that is at least 120% of what you need. If you can get by with 6KW panel array a good 8KW generator will work fine.
My diesel generator is small but never bogs down like gas units do of the same size. Diesel generators cost more too. A good gas generator of the same size (8KW) will have the right plugs to run into your home wiring with a small transfer panel. Your welder is what 240VAC? You can run it with this type of generator but welders play havoc with voltage regulators on cheap generators so again one that has a good voltage and frequency capability will help.

Regarding ICF I am planning to build an ICF 7000 sq ft house in 2 months and have studied a lot of manufactures, talked and seen the products out there. If you have average mechanical skills and time you would be better off doing the blocks yourself assuming you can get a concrete pump truck and concrete trucks to your place. There is nothing magical about doing the blocks especially on a one story home that is square. Most blocks (Nudrua, Fox Blocks, Arixx, etc) all come with plastic channels to lay your rebar into. Bracing is key as well as a level foundation that will carry the weight. I suggest you head over to Greenbuildingtalk and you can educate yourself on ICF. There you can find experts on ICF and also recommendations. If my house was smaller and not 2 stories I would do the ICF myself but it is too big a DIY project for a house of the size I am building. Also there are other options for energy efficiency like SIPs which are not hard to install and are hard to beat. I need concrete because of hurricanes but if I had other options SIP or SCIP would make sense. Again a lot of discussion on SIPs too at the site I mentioned.

Hope this helps some sounds like a fun project given you have a clean slate to do what makes sense for you...

[inetdog]

Don't go cheap on a generator get one that is at least 120% of what you need. If you can get by with 6KW panel array a good 8KW generator will work fine.

That advice makes sense when you will be running the generator primarily to bulk charge batteries and support some major loads at the same time.
But if the generator will be running at half capacity or less it will be relatively inefficient and expensive to operate, the more so the more oversized it is.
And a diesel operated at less than 50% is vulnerable to "wet stacking" and premature failure of the engine.

If you are only looking to provide emergency power for a couple of days and have lots of fuel stored, then oversizing the generator is not as significant a disadvantage.

[mapmaker]

$11k is what it will cost me to tie into the grid (I am nowhere near any power lines). Also there is inherent value, to me, in not being dependent on the grid electricity. Enough so that $1/kwh or more is acceptable to me. I recognize the associated costs can be high and I'm trying to pin down more accurate numbers for a completely off-grid system.

I estimate my consumption will be 30-35kw/day.

Welcome to the forum,

I think you mean your consumption will be 35 kwh/day. And you're willing to pay $1/kwh. That's $12,775 dollars a year. Every year. Assuming you can build a system that costs you only $1/kwh. Not only do you have a high daily load, you have very high (welding) peak loads... that will cost you.

Unless you have more money than brains, I think your decision is a no brainer... Connect to the grid. Put in a grid-tie system. Get a generator.

--mapmaker

[SunEagle]

Welcome to the forum,

I think you mean your consumption will be 35 kwh/day. And you're willing to pay $1/kwh. That's $12,775 dollars a year. Every year. Assuming you can build a system that costs you only $1/kwh. Not only do you have a high daily load, you have very high (welding) peak loads... that will cost you.

Unless you have more money than brains, I think your decision is a no brainer... Connect to the grid. Put in a grid-tie system. Get a generator.

--mapmaker

mapmaker

Nice short and sweet analysis. I agree with your reasoning.

[Sixfold]

Thanks for all the great advice!

Unless you have more money than brains, I think your decision is a no brainer... Connect to the grid. Put in a grid-tie system. Get a generator.

Well one would hope the former isn't true. =) From a purely economical standpoint your are more than correct. But to me, energy independence is worth much more in piece of mind. Tell me, Do you pay extra money each month to insure your house against disaster? Why not insure your electricity (and in my case water) against disaster? I'm just taking a more physical approach than contractual.

The United States' 3 power grids are susceptible to several types of failure. Current back order for most large transformers is 3years, and that is with no problems occurring. There have been attempts recently to disrupt the power grid. I depend on myself for everything else, why not my power? Even if at some point its only on sunny days.

Plus I am going to have alot of fun learning and building my system.

But if the generator will be running at half capacity or less it will be relatively inefficient and expensive to operate, the more so the more oversized it is.
And a diesel operated at less than 50% is vulnerable to "wet stacking" and premature failure of the engine.

I didn't know this! So many static sizing requirements based on a very fluid load. =/

If you are going to be charging your batteries and supplying heavy loads at the same time, you really need a CC which can produce a higher output current than your batteries can take, but which uses a shunt wired into the battery circuit.

I didnt know this existed =) Definite area of interest I'll be looking into.






So lets throw some numbers out now that I have a better understanding of my options.

First of all lets drop my kwhs down to 25kwh/day. I'll just fire up the genny to run the welder or any other similar large tools.
Second lets assume I can find a use for any energy that is surplus over my full batteries and current load. (I'll pump water up the hill, or use it for heat, or whatever)

~10kw worth of panels. Its large. I know. 2.5 hours of sun and I have roughly what I need for the day (losses here an there).

12kw diesel genny. So just quickly looking at Ebay a good 12kw Honda Diesel genny will cost me around $5-7k. That should last me a good long time. And hopefully I can repair any problems myself.

Batteries! 48v ~1000ah. This is the area where I am least sure about sizing. 48vx1000ah = 48kwh So that would be enough for roughly 2 days worth of power with no sun. But its best to discharge < 50% so its roughly 1 days worth of electricity? so say 2000ah and we are getting into a serious amount of batteries and cost =) What would the typical battery bank size be for a house needing 25kwh/day say for 2 days with no sun?

MPPT CC. One that keeps the batteries from charging too fast.

Inverter. Closer to pure sine the better. Better to have 1 large inverter or a couple smaller ones?

If you have average mechanical skills and time you would be better off doing the blocks yourself assuming you can get a concrete pump truck and concrete trucks to your place.

Im doing a 2 story and don't really have the time to do it myself. I have read some horror stories about the concrete not being poured properly and getting a weakened structure. I have also looked at SIPs as a possible option. I'll check out that site. Thanks for the info!



I am getting tons of great information from you guys. Thank you for all of your responses.

-Sixfold

[SunEagle]

Thanks for all the great advice!



Well one would hope the former isn't true. =) From a purely economical standpoint your are more than correct. But to me, energy independence is worth much more in piece of mind. Tell me, Do you pay extra money each month to insure your house against disaster? Why not insure your electricity (and in my case water) against disaster? I'm just taking a more physical approach than contractual.

The United States' 3 power grids are susceptible to several types of failure. Current back order for most large transformers is 3years, and that is with no problems occurring. There have been attempts recently to disrupt the power grid. I depend on myself for everything else, why not my power? Even if at some point its only on sunny days.

Plus I am going to have alot of fun learning and building my system.




I didn't know this! So many static sizing requirements based on a very fluid load. =/




I didnt know this existed =) Definite area of interest I'll be looking into.






So lets throw some numbers out now that I have a better understanding of my options.

First of all lets drop my kwhs down to 25kwh/day. I'll just fire up the genny to run the welder or any other similar large tools.
Second lets assume I can find a use for any energy that is surplus over my full batteries and current load. (I'll pump water up the hill, or use it for heat, or whatever)

~10kw worth of panels. Its large. I know. 2.5 hours of sun and I have roughly what I need for the day (losses here an there).

12kw diesel genny. So just quickly looking at Ebay a good 12kw Honda Diesel genny will cost me around $5-7k. That should last me a good long time. And hopefully I can repair any problems myself.

Batteries! 48v ~1000ah. This is the area where I am least sure about sizing. 48vx1000ah = 48kwh So that would be enough for roughly 2 days worth of power with no sun. But its best to discharge < 50% so its roughly 1 days worth of electricity? so say 2000ah and we are getting into a serious amount of batteries and cost =) What would the typical battery bank size be for a house needing 25kwh/day say for 2 days with no sun?

MPPT CC. One that keeps the batteries from charging too fast.

Inverter. Closer to pure sine the better. Better to have 1 large inverter or a couple smaller ones?







Im doing a 2 story and don't really have the time to do it myself. I have read some horror stories about the concrete not being poured properly and getting a weakened structure. I have also looked at SIPs as a possible option. I'll check out that site. Thanks for the info!



I am getting tons of great information from you guys. Thank you for all of your responses.

-Sixfold

I understand your desire to more self reliant including power generation. There are a few people in this Forum that have been living off grid for years. You may want to contact a few to learn the ins and outs of what it takes to build and maintain a solar battery system.

Two people come to mind. ChrisOlson has been off grid for about 14 years and lives in Northern Wisconsin. And Mike90250 has been off grid in Northern Cal for a few years. Contact them and learn what they built and spent as well as what it takes to maintain a large off grid system.

[J.P.M.]

I understand your desire to more self reliant including power generation. There are a few people in this Forum that have been living off grid for years. You may want to contact a few to learn the ins and outs of what it takes to build and maintain a solar battery system.

Two people come to mind. ChrisOlson has been off grid for about 14 years and lives in Northern Wisconsin. And Mike90250 has been off grid in Northern Cal for a few years. Contact them and learn what they built and spent as well as what it takes to maintain a large off grid system.

+1. You will probably get things peddlers and dreamers won't or can't (respectively) tell you. Besides, it seems as though Chris and Mike likely don't have any skin in the game or any need to impress, or bluster.

[inetdog]

... I didnt know this existed =) Definite area of interest I'll be looking into. ....

You might want to start by looking at the Midnite Solar site for information on their "Whizbang Jr." remote shunt data transmission system and the ways that it can be integrated into their systems.
They have a well managed user forum that can help you with ideas on that too: http://midniteforum.com/index.php
And, of course, you can search for information on that topic in older threads here.
Two helpful search phrases would be "whizbang" and "end amps"

[mapmaker]

Unless you have more money than brains, I think your decision is a no brainer... Connect to the grid. Put in a grid-tie system. Get a generator.

Well one would hope the former isn't true. =)

What's wrong with having more money than brains? I aspire to it

--mapmaker

[inetdog]

What's wrong with having more money than brains? I aspire to it

--mapmaker

As long as you achieve that state by increasing your money rather than decreasing your brains.

[Sunking]

Anyways on to the electricity problem. $11k is what it will cost me to tie into the grid (I am nowhere near any power lines).......I estimate my consumption will be 30-35kw/day.

Pay for the POCO to run lines, it is a heck of a bargain. To get you 30 Kwh a day in your area you are looking at 12,000 watt panel system, 3 mppt charge controllers, and 9000 pound $30,000 battery you get to replace every 5 years. Initially with all the hardware, EPA permits for the batteries, and misc equipment you are looking at $60 to $70,000 all paid up front in cash. Then in 5 years replace a $30,000 battery at even higher replacement cost.

Even if the batteries never failed at your current 12 cents per Kwh it would take you roughly 35 years before you broke even even paying the POCO $11K up front. Invest that same money and in 35 years after you are dead your kids are multi-millionaires and wont be left with a toxic waste dump no one would buy.

EDIT NOTE: With that much battery is going to require spill containment, add another $10K or add on another addition to your house. Your solar system will cost as much as the house or more. Forgot th egenny as it will need to be a 12 to 15 Kva unit with 550 gallon LPG tank, you are looking a $100K easy.

[russ]

As long as you achieve that state by increasing your money rather than decreasing your brains.

Darn! So that is where I went wrong!

[Sixfold]

you are looking a $100K easy.

Hrm. That's a bit out of my budget.

9000 pound $30,000 battery

What does this look like? Got a link?



Thanks you have given me some things to consider. I may have to reduce my daily load or find some other options.

Is there a way to set up a system where the batteries are missing or minimal, you pull power from the panels when they are producing but the grid when you need the extra? BUT not a true grid tied system where I back feed onto the grid? (That requires a 7 year contract here with some details I don't like, so would never agree too)