Here's a link to the more precise cash flow calculator. It says 14 years to pay off.

https://www.calculator.net/payback-p...steadycashflow

Some small work... Planting a juniper that will eventually grow to 4' dia x 20' tall, to shade our AC in this blistering Texas heat.http://i67.tinypic.com/2kjz1c.jpg

Not as hot as this part of tx. You have something green on top of the dirt. I have straw covered with piles of leaves from the dying trees. We have a cold front coming tonight, only supposed to be 95 tomorrow but as you know in tx you always add at least 5 to the forecast temp for real world temps instead of chamber of commerce numbers.

Annual maintenance
 

This was the first time I've really looked around the attic. There's a big, fluffy pile of insulation through most of the attic, but a plywood walkway near the AC ducts. I think there's spray foam under the plywood. Would it be wise to cut some easily-removable sheets of insulation and lay them down on top of the plywood? It seems like a gaping thermal hole in comparison to the giant stack of blown-in insulation.

https://preview.ibb.co/g8bZ7z/attic.jpg

The Tesla solar installation is scheduled for October. I think my next project will be more shade trees in the back yard because the poor grass is scorched. We are considering the very tall, thin juniper.

Thats a common install for most of the south. The issue is you need access to the unit. If you don't mind moving that insulation for the tech go for it.

I have seen some units in these energystar rated houses where they cover the whole unit in sprayfoam. Basically makes it unserviciable.


Also that hanging ductwork is a common method lately and a very bad habit for HVAC installers to get into. They hang the ducts up high and the higher they are the hotter they are. I forget the temp difference per foot from top to bottom in an attic but its a huge difference. Its much better to have them buried deep in insulation. Very very few parts of the country and houses will ever have an issue with condensation on the ducts. If a house does have that issue burying the ducts usually remedies this anyway.

The Tesla solar panels are alive! ABB inverter and 3.66 kW of Hanwha Q-cells.

https://preview.ibb.co/emZBz9/inverter.jpg

https://preview.ibb.co/gH2ye9/panels.jpg

I was originally bummed out to see we got Hanwha Q-cells instead of Panasonic modules. I thought they were cheap Chinese modules. But they're actually South Korean and the quality seems pretty good, based on annual degradation rates, efficiency, and low-light performance. I would say they're maybe third in quality after Sunpower and Panasonic.

It's been rainy the past few days, so our peak production so far has only been about 2 kW.

My small step today was putting some insulation over the attic stairs. This is the $40 Amazon kit I got. Very easy to install.

https://www.amazon.com/gp/aw/d/B07N6...mob_b_pd_title

Apparently the attic stairs can lower your attic's effective R-rating by 20% or so.

https://www.energyvanguard.com/blog/...lding-Envelope

I'm curious to know what your utility bills are now. You've been making tweaks here and there for a few years now, what have the numbers been doing.

@elhigh thanks. I don't track the numbers too closely but our electric this month was $33. Last year it was $72. Some of the differences are a 3.66kW solar system, more computers running at home, and small insulation tweaks. So it's hard to declare success or failure with so many factors involved.

The bill includes a ~$15 monthly fee we can't avoid, so electric usage was actually ~$18.

Found a new little trick to keep us cool at night. Our bedroom ceiling fan is in the center of the room. It blew on our feet. We now sleep upside-down so our upper bodies are under the air stream.