PV is ideal for cooling. Max power available when you need the
Not very efferent. If you have the sun light and space an absorption system
can work better. A knowledge of thermodynamics can be your friend.
Or evaporative cooling in dry climates.
Will be a time (some say it's here now) when water will be more valuable
than energy. Swamp coolers (evaporative cooling) are typically not much
better then a 20 F delta T which is fine if the ambient temp is not over
100F but a bear if it's 110 F and above. BTDT and have experience with some
that product a 100% RH which is better known as sticky heat.
That isn't true, at least not for all locations. It depends
on exactly what the payment arrangement is from the
actual local utility. Here in NJ for example it does not
matter at all when you use the electricity. The only
thing that matters is how much you generate and how
much you use, not when.
Read the contract VERY carefully.
I questioned one such company that had a tent at a local outdoor event.
They were VERY slippery.
According to them, there are significant corporate benefits not available
The lease allows them to get the benefits you couldn't. The initial
cost is offset by taxpayer-provided energy funds.
The price the lease so that you pay slightly less than the savings
you'd get on electricity. And since electricity cost is rising
exponentially, you'll save even more in future years...
But there's a catch in the fine print.
Your "savings" is calculated based on the electric company buying your
excess power at 5X what they charge you. There's no guarantee on that
5X. Local utilities are backing down from that. If I understand the
there's a lottery of some few people who can get it.
You have to renew it every year. He admitted that their computer
has a finger on the "go" button at midnight the day of the lottery
and they're all gone in milliseconds.
And even if there is a payback period, you don't own anything but the
option to renew the contract at the then-current rate.
Explain to the buyer of your house that there's a long-term lease
that they must pay for those ugly-ass panels on the roof.
I thought I'd follow up with a visit and quote. Guess they lost
I just saw a system that was a combination power and heat source
It was for a large dorm on the north shore of Lake Superior.
The system supplies about 50% of the daily use of total hot water, both
summer and winter.
It's actually set up for winter efficiency, but in the summer, even
though it's not lined up optimally, it still is productive enough to be
Some states (Texas) have a net billing law which makes the process much more
Other states (NC) you can't (effectively) sell the excess back to the
I expect there are states in between as well.
As for me and mine, I'd look at the process favorably but would be very very
careful of the fine print.
Typically you get 100% credit for the power you use because your meter
is not running but that drops of to around half when you are selling
it back to them because you are still paying for all of the fixed
costs, taxes franchise fees etc.
Your rebate is based on the actual KWH and it might not even be 100%
When I had the quote on a 2.3KW system it only made sense to me if I
could get both the 30% federal tax credit and the Florida $4/watt
rebate. That rebate program went broke and I let the deal go.
My <proposed> payback time was about 8 years with all of the rebates.
Without the Florida rebate it was one of those "I would have been 90"
kind of things ... assuming nothing broke or got blown away in a
It dependson the meters. The old style spinning disk meters will run
backwards when power is exported.
The new electronic meters don't.
If the homeowner has a system of generation the power company has a method
of metering in/out which also includes electronic meters. My son has a 10KW
NG/LPG powered emergency gen set and an agreement with the power company to
feed the system.
If the power goes out he also feeds a small amout of power to the neighbors
so there is no one objecting to the small amount of motor 'noise'.
We're building a new home on a decent amount of land that will support wind,
solar and NG generation. A conservative spread sheet gives a pay back of 5
to 7 years with a positive cash flow from day one.
And yes we know what we're doing as we had a cabin in the NC mountains that
has been off grid for ~ 20 years.
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