[SGVLUG] Off-topic - grid tie home guerrilla solar systems

[Robert Leyva]

As I have been researching more and more:

there are "grid tie" systems that do not require batteries. You simply
produce power from your panels, put that into the grid-tie inverter, and
it outputs AC synchronized to the utility into your home.

If you simply want to reduce your overall power usage from the utility,
this system requires no batteries. Of course the power reduction is only
during the day with good sunlight, but I am a pragmatist, and that's just
fine for me.

And since almost all power failures are during the day, I will be doing my
part to reduce my load on the grid during those times.

It doesn't require batteries, it simply pumps power right into the grid.

As for how long the systems will last, that is an open question for me at
this point. If my system lasts 10yrs, and costs about $1k then I would
have been happy to pay what approximates to under $10/month for 10yrs for
my hypothetical 100W grid-tie system.

My first purchase, and the heart of the system, will be the grid-tie
inverter. It will have it's input requirements of voltage and current that
will then drive what panels I get.

At this point the only inverter I have found for a small output power
(most are for 2kw or so, way to big for my budget/desire) is about $300.
It requires between 24v and 50v DC from the panels. It bothers me that I
have found only one model in my power range, as I want to be a good
consumer and do some price/feature comparasons. So I will keep researching
until I find a few more to compare.

I am seeing many grid-tie inverters on the market lately, too. It seems a
nice way to get started without going tie-die T-shirt, wheat grass eating,
and chanting kum-bah-yah all over the place.

> On Fri, Feb 23, 2007 at 08:07:00AM -0800, Don Gibbs wrote:
>> While the group entertains this off-topic thread ...
>>
>> I've wondered about the long-term benefit of PV (photovoltaic)
>> systems.  I've done a some searching but have not seen any decent
>> analysis evaluating the overall energy efficiency  of such systems.
>> For instance, for a non-steerable, residential system capable of
>> delivering 1kW peak (noon, mid-summer, surface normal to sun) in the
>> LA area and tied to the neighborhood utility, how much total energy
>> was required to build and install it and how much total energy will
>> it deliver over a ten year period?  I suspect the payback is pretty
>> good.  But my gut judgements have proven wrong before.
>
> If it costs less for electricity this way, then it likely will use
> less energy.  All energy (including labor energy) get added to costs
> so this is about the best criteria we have for estimating energy
> content.  I've read that PV will cost more for electricity so if
> that's the case then it's a loser.  Another unknown is how long the PV
> installation will last.  You also need to include the cost of
> batteries.  The cost method of estimation of energy content has been
> widely used for decades.
>
> Here's an important paper on PV economics from profs. at the Naval
> Postgraduate School at Monterey, CA.  They seem to agree with me and
> conversely.
> http://www.nps.navy.mil/drmi/WorkingPapers/DRMI%20Working%20Paper%2006-02.pdf
>
> 			David Lawyer
>


-- 
"Knowledge is Power" -- Francis Bacon

Robert Leyva
mrflash818 at geophile.net