[ClintK]

I'm buying some land soon, and rather than run utility lines out to it I'm looking into a full Solar Power solution. Initially my family will be moving into a fairly small house on the land.

I haven't called yet, but these guys seem to have the best prices:
http://partsonsale.com/cabins2intermediatetemp.html
Either their 1600W or 2400W system.

I want to be able to power all standard household items (energy efficient where possible): refrigerator, microwave, lights, TV, computers, etc. (And of course my electric car!) Hot water heater, stove, and clothes dryer will probably have to be gas.

Ideally I'd like to have an expandable system where as we increase usage I can add additional panels / inverters. Also, a backup gas generator for when we really need extra power.

Any suggestions? Is there a company you've worked with that has been pretty good? Thanks!

[dimitri]

I found this company to be very price competitive, but haven't bought anything from them yet.

http://sunelec.com/

Hope this helps.

IMHO, cost of solar setup largely depends on your skills and desire to do most of the work yourself. If you are capable of calculating system size and config and can assemble and install yourself, you can save lots of money by finding deals on Ebay, collecting components from different sources and then put it all together. Its especially easy for off grid system since you don't deal with utility hookup.

You can go as crazy as getting individual PV cells on Ebay for $1 per Watt, but you have to actually assemble them in panels yourself, solder them and mount them together. Lots of fun labor, but less $$$ to spend.

[ClintK]

Originally Posted by dimitri

I found this company to be very price competitive, but haven't bought anything from them yet.

http://sunelec.com/

Their prices seem pretty good.

I'm trying to figure out how to make a system that I can expand on as I go. It seems like the inverter would be the most difficult in that regard, and I should probably purchase the maximum power inverter at the beginning to tie into my distribution panel. Adding additional solar panels / chargers / batteries would be very simple after that. Does that sound right?

[ClintK]

Well so far I've found 3000W/6000W inverters for $200. Once you get above that wattage the prices skyrocket! I wonder if it will just be more economical to wire multiple inverters into a single distribution panel. Pricing for solar electricity makes no sense.

Latest hunt also found 200W panels on ebay for $496, but I still need a charge controller.

Components wise (right now) I'm thinking:
3000W Continuous Inverter(s) ($200 each)
Walmart MAXX29 Batteries ($80 each)
200 Watt Solar Panel ($496 each)
Solar Charger (?)
Wiring/Fuses (a couple hundred)
Distribution Panel (?)
Gas Generator + 12V Charger (Maybe $200?)
Mounting (?)
What else?

[dimitri]

Be careful with multiple inverters. To parallel multiple inverters they must be daisy chained to sync the AC phase. Only some models have this feature, and I doubt that $200 model has it. It has to be advertised on a spec sheet. Basically one unit becomes master and it sends a sync signal to all slaves so they all produce syncronized sine wave.

I agree, pricing on PV stuff is crazy, you really have to do your homework

Also, I think more expensive inverters have battery charge control integrated, so you don't have to buy separate battery charge controller, you just connect battery to battery terminals, PV to PV terminals and AC output to your house.

Please note, I haven't done any of this yet, just learning and planning.

[Amberwolf]

You could always just use one inverter per circuit (or room), rather than having them all physically wired together.

[Sunking]

Clint I do not know if you are still reading along or not, but I design/build a lot of solar PV systems both off and on grid. Frankly it is not feasible possible to do what you stated in your first post.You could not possible afford it or the upkeep after with a battery system.

Let me run through a quick design making some assumptions on your energy usage and location. I will assume you use 1500 Kwh per mnth and live in say Wichta KS.

Since this is an off-grid system you have to design for worst case. For this I will assume winter, where the days are the shortest so your solar insolation is 2.2 Sun Hours.

First step is to figure daily usage and account for system losses. 1500 Kwh/month = 50 Kwh per day. Solar battery systems are 66% efficient so your solar panel system needs to generate 50 Kwh / .66 = 75 Kwh per day. Note this figure as it is used to determine solar panel size and battery capacity.

To figure out the solar panel wattage is simple Take the adjusted number and divide by the Sun Hour Day Solar Panel wattage = 75 Kwh / 2.2 hours = 34 Kw or 34,000 watt.

Now for the batteries on a solar system you never want to discharge more than 20% in any given day to maximise battery life and carry you through a cloudy day or two. Forget the 50% rule for EV because if you get more then one cloudy day, you go dark for at least two days after recharging or have an on-site generator to recover. So to figure battery size take the adjusted daily Kwh usage of 75 Kwh, multiply by 5 and that gives you 75 Kwh x 5 = 375 Kwh storage capacity. Now to find the amp hours divide by the nominal system voltage, So lets say 96 volts since that is about the highest you can run with charge controllers on the market. So at 96 nvolts you will need 375 Kwh / 96 volts = 3900 AH

Ok so the cost of just the solar panels and batteries are:

Solar Panels = $4.00 per watt = $136,000
Batteries FLA = $120 per Kwh = $45,000
Total = $181,000

That is only just for the solar panels and batteries dropped shipped and does not include inverters, charge controllers, materials, and labor. The real total would exceed $250,000.

Now for the bad news, the batteries have to be replaced in 5 to 7 years and require about 1000/ft2 structure to house them. All this expense for rougly $5 per day electricity or $150 per month from your electric company. How long do you figure you will get your payback. Your great-great-great grandchildren will never see a return.

[Woodsmith]

It might also be worth having a look at The Centre for Alternative Technology. They have been off grid since the 70's and only recently joind the grid to feed their excess energy back rather then storing it all summer to last out the winter.
They have PV, wind and hydro on site and use solar hot water too.

They also have a variety of book on the subject and know what works and what doesn't over the last 40 years of direct experience.

[Dave Koller]

Ok - my system is grid tied at my Health Food Store... I do about 2/3 's of my power with solar and wind - in a very far North Region of the US... I have coolers running 24/7 AND my system is small compared to what you are doing ! BUT I have trackers (35 to 40 % more) and wind that blows 130 feet in the air - atop a hill - and blows all night and when the sun stops shining!! I run Led lighting and any other thing I can to CONSERVE power - keyword here is CONSERVE - people who live OFF-GRID know what conserve REALLY means ..
NO electric irons, stoves, hairdryers, toasters - well you get the idea.. WE have at least 10 families in our area (snow, 40 below and LONG winters!) off grid! Again I am not talking yuppie here! They live fine - just different. They do things with wood or yes even gas.. But they do it different. Lifestye is the big issue here. I wont get into KW's - IT IS NOT ABOUT HOW MANY YOU USE - IT IS ABOUT HOW MANY YOU SAVE...

Before anything figure out what adjustments you want to make in your Lifestyle and go from there....

[ClintK]

Originally Posted by Sunking

Let me run through a quick design making some assumptions on your energy usage and location. I will assume you use 1500 Kwh per mnth and live in say Wichta KS.

Since this is an off-grid system you have to design for worst case. For this I will assume winter, where the days are the shortest so your solar insolation is 2.2 Sun Hours.

Please check my calculations...
1500 KWh per month / 30 = 50 KWh per day
50 KWh per day / 24 hours = 2000 Watts continuously?

I just checked my January electric bill.. 420 kWh without conserving at all. Summertime it's up to 1500 kWh, but that's Phoenix!

To clarify a few assumptions...
We're moving to San Marcos, Texas (30 N). People there have heard of this white powder that falls from the sky, but they've never seen it!

For initially getting on the land, we're looking at building a small efficiency style barn house (600-800 sqft). Basically one big room but the bed will be in a loft. Exterior walls will be heavily insulated, CFLs for lights, and other equipment energy efficient or propane.

Per day (excluding car):
Lights: 18 Watts * 6 * 6 Hours: 650 WHr
TV: 200 Watts * 8 Hours (yeah, I know): 1600 WHr
Computers: 250 Watts * 12 Hours: 3000 WHr
Refrigerator: 100 Watts * 24 Hours: 2400 WHr
Various 24/hr items: 40 Watts * 24 Hours: 960 WHr
Total: 8610 WHr
http://michaelbluejay.com/electricity/howmuch.html
I'm ordering a Kill-A-Watt gauge right now to know for sure!

Say I get 3 hours of usable sunshine a day, minus losses, I need 3000 Watts of solar panels?

Summertime will need AC, but I'll have more usable sunshine hours.
Opinions?


Side note: I just found in one of my old links a contender for inverter:
http://www.wildnaturesolutions.com/sinewave.html
1500 Watt, 48V, Pure Sine Wave, $469 or
3000 Watt, 24V, Pure Sine Wave, $849