off to on grid

10 Posts
Feb 4, 2009 01:36 pm
off to on grid

Hi,
It seems that a person starting out should build an off grid system and then keep adding more panels until there is enough kwatts to make it worth while to tie into the grid.
What do you suggents?
 
578 Posts
Feb 4, 2009 02:01 pm
Re: off to on grid

I dont think that is the case.  like all renewable energy it depends on the demand or load and the specific resources available (sun and budget). 

i am not sure why it is worth while to spend money and inefficiencies on batteries when the ultimate goal is grid tie.  figure out what the goal is.  If it is fun with a small off grid system, then great, but that should not be confused with the grid tie system goal as just about all of the components will not transfer over.

i would suggest knowing your energy usage first.  second i would set a goal for potential energy usage and possible energy production.  third implement the plan for conservation and efficiency.  fourth, site analysis for renewables.  fifth renewable energy system design, purchase, installation.

if the goal is ultimately grid tie, then i see no reason to bother with setting up a small off grid system first.  dont get me wrong, small off grid systems when installed safely are lots of fun, and a great learning experience.  that learning experience does not necessarily have anything to do with the goal of the grid tie system.  you can get into a grid tie system for less than $5k.


my question to the forum is what is "worth while" to tie to the grid?  for me the mere completion of the project no matter the wattage is walking the talk and setting the example for friends and neighbors.  any code compliant safe system to me is worth while.  what do you think?


thanks for writing in.

james
altE staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
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351 Posts
Feb 4, 2009 03:10 pm
Re: off to on grid

James:

I agree with most of what you said. The one item that could use clarification is "then i see no reason to bother with setting up a small off grid system first."  That holds true for people in net metering states or utility areas with easy interconnect requirements.

But for people that do not, some of the utility requirements are onerous, and it takes a certain size system to justify the tie. If you are getting 5 cents for mid-day generation and paying 10 cents for power at night, do you even want to think about grid tie ?  Or, I remember one utility in the south, where even though they "offer net metering",  they insist on two separate meters and charge you $18 a month (IIRC) to read the second meter.

So, with family budget limitations, building the off grid system over time, and then making a call down stream whether you convert to grid tie or not, makes some sense. Hopefully the rules change during that time and make the decision easier.

For those that live in net metering areas with easy interconnect rules (and good incentive rebates), it is a no brainer. A grid tie inverter and a single panel will do it.

Ken
 
15 Posts
Feb 4, 2009 09:57 pm
Re: off to on grid

Having batteries to back up your heating system and a few essentials can be very handy.
Regards,
Dennis
 
578 Posts
Feb 5, 2009 11:08 am
Re: off to on grid

Hi,
It seems that a person starting out should build an off grid system and then keep adding more panels until there is enough kwatts to make it worth while to tie into the grid.
What do you suggents?

to be clearer, i have no beef with batteries or off grid systems.  the parts i was responding to were in the quote above.  that is, the concept that if the end purpose is grid tie anyway, that a person SHOULD start by building an off grid system until it meets some "worthwhile" threshold.

I do not subscribe to that concept.  obviously batteries have their place and if the load/need/want requires a battery based solution, then great. 

i do not think however that it is a linear progression from off grid to grid tie (operating under the assumption that distributed generation policy in your area makes grid tie possible).  if a grid tied system is the ultimate goal, there is not a need due to technology or cost to require pieces from an off-grid setup for a ramping up period. 

whether that small scale grid tie system (for roughly the same investment as the off grid equipment)  is meaningful or worthwhile  is in the eye of the beholder.

with higher voltage modules and approved listed inverters with low voltage windows, the cost of the minimum grid tie system is decreasing relative to the past.

good discussion

james
altE staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
 
9 Posts
Feb 6, 2009 11:01 am
Re: off to on grid

My 2 cents worth,
     I got into this with the motive of getting off the grid.
At first investigation I was told to call the power company and ask about net metering. My power company ask me to explain what net metering was, I did explain. They said very snubbally No. Like I was stupid for even asking, I told them to get ready cause it is coming. Then I was advise to check codes for my solar water heater. Code department told me that they have never been asked that question, and did not know. Poof I was done with them.
 I now have solar water heater, 430 watts pv, and a 800 watt windmill. All bought out of state. Drove to pick up panels and collector. Got 1500 watt pure-sine inverter, 2 charge controllers, 1 Windmill by shopping around on-line. I would not reccomend doing it this way. Codes and all. But I like a challenge and adventure. I am shooting for maybe 10 years to be totally off grid and its not looking good. But who knows, Gotta have hope. And just maybe. Alt-e store has been very Helpful and one of the best suppliers I have dealt with. Good luck As we trudge the road to happy destiny.
 
Feb 6, 2009 08:20 pm
Re: off to on grid

A grape is to a raisin what a ______ is to a prune?

Below is a few places that can give you more information to juggle around.
 Basically though, the cost of a PV system to power a conventional house as if it were "off grid" would cost as much as a life time of electric bills. Its a general rule of thumb that "off grid" is best left to those that want to build a remote home but to have grid power means spending $10k to $20k or more for miles of wire and poles.

Think about it this way. Take your electric bills for one year and add them all up. Multiply that by how long you expect live and pay for your electricity. Thats about how much money you might need to go off grid at your current home that is on grid. Unless of course your already 90 something. Part of the reason for this is battery bank replacements.

Another way to look at it. A 10kw PV array might cost as much as $50k if you can get dealer prices and, after any state incentives and, if you do the work your self. If your in an area that does not "net meter" Then you might be getting "payed" the averted cost for your electricity. What it cost the power company to make it or a city to buy it. Lets say your only getting payed $0.024 cents per kWh. A 10kw PV system might make a 40 kWh a day averaged out over a year. Thats $0.96 cents a day or $350.00 dollars a year. That means this system will have payed for itself in the year 2152 if it was installed today.

After all is said and done. What do you want to do Mr. Butterfield?
It all depends on that and uhh, how deep your pocketbook is. Know what I mean?
In the meantime read up. Knowledge is power!

http://www.dsireusa.org/index.cfm?EE=0&RE=1
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/
http://www.homepower.com/home/
http://www.solarelectricpower.org/
http://www.cleanerandgreener.org/resources/pollutioncalculator.htm
http://photovoltaics.sandia.gov/
http://www.wholesalesolar.com/bulk-solar-panels-by-the-pallet.html
http://www.aeesolar.com/
http://www.corrosion-doctors.org/Biographies/OhmBio.htm
This is just the tip of an iceburg.
 
2 Posts
Feb 8, 2009 02:39 am
Re: off to on grid

Actually not a great idea.  Grid tie panels are different.  You really need to make the decision right up front.  For example if you want to run 12v DC stuff like lights and fans and small appliances, and have some inverters for AC stuff, you'll be buying panels that put out 17-18v to charge 12v batteries.  On the other hand, if you want to do grid tie you'll be buying panels that put out 23v or so. 

I found this out when I got all excited about 200watt panels I wanted for my 12v system.  If the watts are that high, they are probably for grid-tie systems.  The biggest I could find (and I'd love to hear from an Alt-E person if this has changed) is 125-130watts for a 12v system. 

I've wrestled with this same question and have concluded that if you want to do grid tie, just plan on taking out a big loan and do it all at once.  Make sure you do your math carefully on how long your payback will be in relation to utility savings. 

If you want to grow a small system into a bigger one like I do, you can do it a few bucks at a time.  I'm attacking my ranch in modules and don't feel a need to even have the whole place on one single unified system.  I will stay on the grid, but I don't want my system grid-tied cuz our grid power goes down 3-4x a year. 

You can buy more panels as you can afford them, but if you're growing a battery bank try to complete it in a few months so you don't end up with batteries of different ages.  Also, a huge charge controller like a Xantrex c-60 is not that much more than smaller 30 amp controller, so start with the biggest charge controller you can imagine ever needing. 

As your system grows beyond that, you can have entirely different charge controllers and battery banks to do different duties in the home. 

That's my perspective on the piece-meal plan.  If you want a unified solar system that runs everything, get a loan and hire someone smart.

SS
 
 
351 Posts
Feb 8, 2009 11:00 am
Re: off to on grid

Steven

You need to learn about MPPT controllers.
http://howto.altenergystore.com/Library-Articles/Solar-Electric-Power-or-PV-Systems/Solar-Charge-Controllers/How-MPPT-Charge-Controllers-Work/a13/
http://howto.altenergystore.com/Sizing-MPPT-Charge-Controllers/a61/
That is how you can make use of the larger/higher voltage panels on a 12vdc system.

Ken

 
 
10 Posts
Feb 9, 2009 01:01 am
off to on grid with Enphase Micro-Inverter

Well,
I am glad I was able to spark a little conversation.

My original goal and my long term goal has changed since I have joined the ranks of solar power users.
Because I am in an old apartment in Houston I have huge electric bills. The apt. complex has no interest in putting in an efficient a/c unit. I spend $315 for 2kw/h per month for a 1000 sq. feet.  Doller per sq. foot I am getting really ripped off.  At first I just wanted to drive my own window a/c unit with a solar panel hidden on my back porch since a window unit couldn't be any worse then the a/c unit that I have from the apt complex.

But since then I have started to look at buying my first home.  It will need to be a run down foreclosure needing help. 

My thoughts based on what everyone here has said are now to skip the batteries at the apartment and go to a small grid tie system and some how bundle it into a renovation of the foreclosure.  This might be possible with the Enphase Micro-Inverter which I am told can be used to start a "small" grid system and grow with more panels over time.

I think a good goal would be 1.5 kw/h per month for a 1500 square foot home with 50/50 grid and tie in electric.

Maybe the question should be put out to the community is not how many panels or on/off grid system but how many kw is need per square foot of living space.

More thoughts please.

Tony
 
220 Posts
Feb 9, 2009 03:03 am
Re: off to on grid


 hi tony,

now..i mean this in the kindest way. but, it's hard to understand the power units you are trying to use.

 i think using this as a key.
"I spend $315 for 2kw/h per month for a 1000 sq. feet."

 you mean 1440kwh's for the month? an average of 48kwh's a day? or aprox 22 cents per kwh.

interesting product, those enphase inverters. looks like a good solution but is still up and coming. looks like there are some connection issues with certain utility providers requiring separate meters and of course an associated fee to go with it. also not sure if it's possible to opt out of the monitoring service that the company has. i'm gonna keeping watching this one.

"I think a good goal would be 1.5 kw/h per month for a 1500 square foot home with 50/50 grid and tie in electric."

so if i'm reading right that 1.5kw/h is 36kwh's per day?
using a daily average of 4 hours of full rated sun we need an array of 9kw. conservation can go a long way at reducing that daily demand and when we look at the system cost, it can be a motivaitor as well.

"Maybe the question should be put out to the community is not how many panels or on/off grid system but how many kw is need per square foot of living space."

i think about this one alot. my grandparents lived most of their lives with 0kwh's and right now there are billions of folks living without any power what so ever. so the "kw needed per square foot" would have to be on a case by case basis.

some good info here about power.
http://howto.altenergystore.com/The-Basics/Electricity-Basics/a18/

best regards. dave
 
10 Posts
Feb 9, 2009 09:15 am
Re: off to on grid

Thanks,
Update to my units:
2040 KWh May to Oct.
1080 Kwh Nov to Apr.

1016 Sq. foot apt.

14.6 cents/KW on a 1 year contract which ends in August.

Shopping for a home $60 square foot not more than 1500 sq/ft. to remodel/renovate which would include the solar system upgrades.
 
578 Posts
Feb 9, 2009 11:00 am
Re: off to on grid

howdy,

if i had a nickel for "how much pv for x square footage of living space",  i might have a new vw.  it is not that it is an unreasonable question, it is just that there is no straight answer.  the amount of electricity usage generally is not that tightly correlated with size of living space.  your apartment is a prime example.  in 800sq feet, i never went above 350kwh/month (with an old frig) because i had gas heat and no a/c.

the issue is not the space, it is the energy usage.  you mentioned your high kwh usage for a small apartment.  the issue is not the space itself, but the loads within it, likely lead by the air conditioner.

to give you an idea, the mean electric usage is roughly 900kwh per household.  during your warm months you are using about double that.  if you do get a house, even though i love pv, i would suggest making the first $5k (that could be used for a pv array) on a set of hardcore efficient appliances, and or insulation and windows.

here are the main determining factors used for determining grid tie systems

1. budget - pv equipment is still pretty expensive

2. loads or % of loads - most folks dont get near 100%

3. space available for pv modules

here is the grid tie calculator link.  as of right now, it assumes a central high voltage dc to ac inverter.

http://store.altenergystore.com/calculators/on_grid_calculator/

cheers,

james
altE staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
 
10 Posts
Feb 9, 2009 11:30 am
Re: off to on grid

Right about the first $5000 of improvements.
Looking at a 203K FHA Loan which will allow for upgrades.

Most homes in Houston have single pan windows and min. insulation.

A local radio home improvement show said that a tankless water heater is so over priced that it would take 15 years for a standard payback.

A friend has a SolCool DC a/c system with 4 dedicated panels.

Almost need a check list.
- a/c
- hot water
- windows
- insulation/radiant barriers
- fridge/freezor
- entertainment/computer/lights

So, to the community, best suggestions for $5000 in home improvements before buying a PV system.

 

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