Grid Tying

[Brian Graham]

Jim Baber said,The biggest problem I have with my solar PV (grid
tied) is when the grid is down, so is my solar.
<<

I can't say I know much about the setup of these systems, but is this normal?? Do all Grid-Tied systems go AWOL without the grid? If so, when I use PV it certainly won't be tied.

 

[Steve Spence]

If you have no battery bank, then yes, without grid, your grid-tie
system is useless.

Steve Spence
Dir., Green Trust
http://www.green-trust.org

Contributing Editor
http://www.off-grid.net
http://www.rebelwolf.com/essn.html

 

[Brian Graham]

Steve Spence<[email protected]> March 31, 2005 12:17:14 pm >>>
If you have no battery bank, then yes, without grid, your grid-tie
system is useless.
<<<<

I didn't note the lack of batteries in the original post, but that would certainly explain it.

Now the only thing I don't understand is the lack of batteries.. ;-)

 

[Steve Spence]

Typically, a grid tie system dumps power onto the grid, there is no
local battery storage. Grid down, lights out. Put in a battery bank, now
you have an off-grid system with grid sell back ......

Steve Spence
Dir., Green Trust
http://www.green-trust.org

Contributing Editor
http://www.off-grid.net
http://www.rebelwolf.com/essn.html

 

[Windsun]

Then it will cost you 50% more and have 25% less efficiency.

 

[Brian Graham]

Steve Spence<[email protected]> March 31, 2005 2:07:56 pm >>>
Typically, a grid tie system dumps power onto the grid, there is no
local battery storage. Grid down, lights out. Put in a battery bank, now
you have an off-grid system with grid sell back ......

Seems like an expensive way to lower the Hydro bill. I'd rather work towards eliminating it.

Even if you can't go off-grid completely, you could certainly keep certain circuits up & running when Hydro's out. And isn't that usually the whole point of the matter??

 

[Brian Graham]

Windsun<[email protected]> March 31, 2005 2:23:52 pm >>>
Then it will cost you 50% more and have 25% less efficiency.
<<

But you'll have 100% more efficiency when the Hydro is out.

 

[Brian Graham]

The biggest problem I have with my solar PV (grid
tied) is when the grid is down, so is my solar.

I can't say I know much about the setup of these systems, but is this normal?? Do all Grid-Tied systems go AWOL without the grid? If so, when I use PV it certainly won't be tied.

Jim's Reply to Brian:
without the grid being up. First, the equipment that is NOT grid tied,
is not acceptable for any inclusion as any part of the California rebate
plan, so you would have to pay for it separately by yourself.<<<



Rebate?? In Canada I'm not aware of any government assistance. It sure would be nice! From what I've heard, the rebates in the US are quite substantial.


rebates is a state administered fund that all privately owned utility
customers pay into as a percentage fee per kWh used on their bills. <<<


Don't get me wrong, selling back surplus to further reduce your bills is not bad. But having a solar setup which goes down with the grid...

batteries and charge controllers for the batteries are more expensive
than just the grid tied inverters anyway. <<<


Personally I'd rather not be connected. What's to stop the gov from mandating how much of your supply you have to sell back to them - I mean if they're in a real crunch.. And you could then be left without sufficient power for your own needs.

some specialized knowledge. <<<


Absolutely. But all that takes is a bit of reading and planning. Nothing insurmountable.

Again, to clarify, my initial query was to indicate my confusion with the statement that your solar went out when the grid does. I was wondering if that was always the case with the grid-tie setup. And the answer is no - its the result of a cost-benefit analysis. Best bang for the buck, and all that. Fair enough.

 

[Windsun]

And how often does that happen?

-------------------------------------------------------------------------------

 

[John P. Bengi]

Typically, a grid tie system dumps power onto the grid, there is no
local battery storage. Grid down, lights out. Put in a battery bank, now
you have an off-grid system with grid sell back ......

Seems like an expensive way to lower the Hydro bill. I'd rather work towards eliminating it.

Even if you can't go off-grid completely, you could certainly keep certain

circuits up & running when Hydro's out. And isn't that usually the whole
point of the matter??

In most places it is too expensive to go off the grid. You will probably
never compete with grid prices.

My payback for my small system is about 70-85 years not considering the
money I spent not making interest. It's mostly a fascinating hobby.

 

[John P. Bengi]

normal?? Do all Grid-Tied systems go AWOL without the grid? If so, when I
use PV it certainly won't be tied.

Jim's Reply to Brian:
without the grid being up. First, the equipment that is NOT grid tied,
is not acceptable for any inclusion as any part of the California rebate
plan, so you would have to pay for it separately by yourself.<<<



Rebate?? In Canada I'm not aware of any government assistance. It sure

would be nice! From what I've heard, the rebates in the US are quite
substantial.

funds to pay the
rebates is a state administered fund that all privately owned utility
customers pay into as a percentage fee per kWh used on their bills. <<<


Don't get me wrong, selling back surplus to further reduce your bills is

not bad. But having a solar setup which goes down with the grid...

batteries and charge controllers for the batteries are more expensive
than just the grid tied inverters anyway. <<<


Personally I'd rather not be connected. What's to stop the gov from

mandating how much of your supply you have to sell back to them - I mean if
they're in a real crunch.. And you could then be left without sufficient
power for your own needs.

important. and does require
some specialized knowledge. <<<


Absolutely. But all that takes is a bit of reading and planning. Nothing insurmountable.

Again, to clarify, my initial query was to indicate my confusion with the

statement that your solar went out when the grid does. I was wondering if
that was always the case with the grid-tie setup. And the answer is no - its
the result of a cost-benefit analysis. Best bang for the buck, and all that.
Fair enough.
Just get a decent inverter. Some have "backed up" power breakers and also
grid "backfeed" breakers facilties. You choose the circuit in your house you
want on 24/7 and the ones that are totally grid dependant. when you are not
using enough from your secure circuits you back feed your service for credit
on your grid bill.

 

[Steve Spence]

The only breaker an inverter has is to protect it from overload. You
have to install and wire distribution panels, or pay someone to do it
for you.

Back feeding the grid involves a lot more than just an inverter, it
usually involves contracts, permits, and safety disconnects. Few
inverters are designed or approved for grid tie use.

Our inverter powers everything in the house, with the exception of the
washer, dryer, and well pump. Those are on a gen only circuit. WE opted
not to go grid-tie, as the powerlines would have to be extended 1 mile
at a cost of $15k or so. We really don't have any excess solar, and gen
output is not allowed on the grid.

Steve Spence
Dir., Green Trust
http://www.green-trust.org

Contributing Editor
http://www.off-grid.net
http://www.rebelwolf.com/essn.html

 

[Steve Spence]

30 days per winter or so ;-)

Depends on drunks and ice.


Steve Spence
Dir., Green Trust
http://www.green-trust.org

Contributing Editor
http://www.off-grid.net
http://www.rebelwolf.com/essn.html

 

[Brian Graham]

How often does it have to? Do you not have fire insurance?

And how often does that happen?

-------------------------------------------------------------------------------

 

[Windsun]

If it is worth anywhere from 5 to 10 thousand dollars to you, losing 25% or
so of your total solar output from inneficiencies, and increasing overall
system costs, longterm costs, and maintenance - then sure you are welcome to
put all the battery based grid tie type systems you want to in.

Losing power for a few hours is hardly the equivalent of your house burning
down.

 

[[email protected]]

Then it will cost you 50% more and have 25% less efficiency.

How so?

My battery bank isn't really sucking any significant energy. It stays
topped off 99.9% of the time. It only kicks in (and incurs some
efficiency loss) when the grid goes down. Oh, okay, and when I do an
equalization cycle every 6 months.

 

[Windsun]

1. Batteries cost money. Batteries have to be replaced. Over 20 years life
of the system the batteries would probably end up costing you more than the
solar panels.
2. Direct grid tie inverters are more efficient than the grid tie with
battery inverters in feeding max power from the panels to the grid. And you
also have the additional losses of going from panels to charge controller to
batteries then to grid AC. From what we have seen in installed systems the
total loss with batteries is 15 to 25% more than a straight grid tie.
3. The average power outage in the US for all causes averages less than 6
hours per year.

So, it is your choice. We sell batteries also.

 

[John P. Bengi]

Some have to be more than that average of 6 hours per year. Each case / zone
has it's own problems with it own "better" solutions. I think this applies
in any field of endevour.

Installers will tend to gravitate toward the best solution for their
individual politics, climate and regulations. Essentially becoem "experts"
for their area. These "experts" opinions may not be very compatible online
where geographical boundaries do not exist sometimes.

Have a great one. (we gettin'a snow blizzard today)

 

[John P. Bengi]

In my location, as I stated, the payback time is 70-85 years without
considering the interest on the monetary investment I am not getting.

BTW: You just contradicted yourself very badly. You stated it wasn't
location dependant and then stated it would have cost you $7500 to get the
lines and poles installed because of your location.

Are many of the people in this dyslexic and cannot comprehend simple
sentences of their own or anybody else?

 

[[email protected]]

1. Batteries cost money. Batteries have to be replaced. Over 20 years life
of the system the batteries would probably end up costing you more than the
solar panels.

You are overstating the case by A LOT.

I have two dozen T-105 batteries. They cost around $60 apiece,
including any recycling fee -- that's an investment of under $1,500.

I've had 'em for 4 years. I run an equalization cycle every 6 months.
Takes me about an hour of my time, now that I've found the auto-fill
bottle thingie (most automotive parts stores have 'em). I'm not seeing
any signs of degradation. I figure they'll last me 10 years, so I'll
have to put in another $1,500, maybe $2,000 if recycling costs go up,
before the whole system needs to be replaced.

I have 32 Kyocera panels. Those puppies cost around $500 apiece.
That's $16,000 worth.

I probably paid an extra $3,500 (including the batteries, charge
controllers, and an inverter/charger/grid-tie-capable system) to have
that battery bank, perhaps $5,500 over the life cycle of this system.
For my goals, that was a relatively small cost in order to be able to
run independent of the grid, if I have to or want to.

2. Direct grid tie inverters are more efficient than the grid tie with
battery inverters in feeding max power from the panels to the grid. And you
also have the additional losses of going from panels to charge controller to
batteries then to grid AC.

The charge controllers generally don't have anything to do in my system.
While the grid is up, they're out of the picture entirely. Excess
power is dumped onto the grid.

They only have something to do if the grid is down while the sun is up.

From what we have seen in installed systems the
total loss with batteries is 15 to 25% more than a straight grid tie.
3. The average power outage in the US for all causes averages less than 6
hours per year.

Well, I'd be very surprised if those numbers applied to my system. I've
got a 3kw system that supplies me with over 14 kwH per day, averaged
over the course of a year. The panels are not on trackers, and they're
not even at optimum elevation or azimuth.