Posted by Derek Broughton on December 23, 2005, 9:41 pm
Jeff Thies wrote:
Nice try, but you also have a monthly bill from your utility - whether you
use any power or not - which you didn't bother to include.
My nominal 800W of panels cost $200 (In Canadian dollars) and generate in
excess of an average 2.4kWh daily. The utility charges about $0/month +
$.10/kWh. I use all that 2.4kWh, so I would use that if I was
grid-connected too (of course, if I didn't have to turn on a generator to
use more, we know I _would_ use more than the 2.4kWh). My monthly utility
bill, then would be about $0 + (30 * 2.4 * $.10) = $7.20, and my payback
is clearly well under 100 months.
Thanks for making me do this. I did it because I didn't want to pay $5,000
dollars for a grid connection and didn't really care about the payback.
Yeah, add those prices in and I'm up to 16 years for payback - still without
figuring in the high connection cost for a grid system.
Yes, if you have a grid connection, solar is an expensive proposition (I
wouldn't need the batteries, but I _would_ have the minimum monthly bill -
perhaps some areas have _real_ net billing, but here you only get net
kilowatt-hours - so we're back to the vicinity of your numbers), but if you
don't have a grid connection it can pay off. I've never recommended PV or
wind for people with grid connections. As for having, at the end of the
amortization, "ancient and inefficient" equipment, I'll actually have
ancient _fully paid off_ and still valuable panels. They won't be
generating their nominal rates, but they'll be doing pretty well. The
batteries should still be pretty good, and they have significant value as
scrap - should be able to trade them in. All this may be offset by having
to buy another inverter - I don't know how long that will last.
You bet. We only use CFs and LEDs (just the Christmas lights) for lighting,
and laptop computers. The next TV will be an LCD.
Passive solar heating is, quite literally, free if built into your home from
the start. It takes no extra cost to design it into your home.
Posted by Jeff Thies on December 24, 2005, 10:35 pm
Derek Broughton wrote:
Not here, not for electricity but for natural gas and most recently
water. I can see how that is an incentive!!!
I've also come to appreciate how much lower my cost of electricity is
than most other places.
Posted by Derek Broughton on December 25, 2005, 1:28 am
Jeff Thies wrote:
Well, then, that's called "subsidy". A utility _should_ be charging a base
monthly rate, because there's a cost associated with the infrastructure to
deliver the commodity to you, whether or not you make much use of it.
Posted by Andrew Burgess on December 25, 2005, 6:01 pm
You think your batteries will outlast your inverter?
I always thought batteries were the big consumable in off grid PV.
My UPS batteries (apples to oranges but still lead-acid) don't last anywhere
near that long and they seem to have an easier life than yours.
Posted by Derek Broughton on December 26, 2005, 12:17 am
Andrew Burgess wrote:
please include attributions so we know who you're talking to - if I don't
see my name, I'm not likely to realize it's me:-)
Not so much "think" they'll outlast the inverter, as not know what the
likely lifespan of the inverter is. The warranty on my Outback inverter is
way less than the warranty on my Surette batteries. I _expect_ 20 years
from the batteries, and more than that from my pv panels
I really think my windmill is the big consumable :-) I guess it depends how
many more hurricanes it goes through.
Why would you think so? My batteries are _never_ allowed to discharge very
far. UPS batteries can pretty well fully discharge. I don't know what the
charging circuits on UPS's are like, but they can hardly be kinder to the
batteries than the charging systems on my Outback (for generator charging)
and Trace (for charging from the PV).