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.

Did you change the tape?

I don't know what you mean...

K&N reusable air filters
 

I took the plunge and bought two, infinitely reusable K&N home air filters. The cost was something like $130 but we'll worth it, IMo. They should pay for themselves in about 3 years. They're very heavy and seem well-made. No cardboard here.

The filter efficiency rating is 11, which is at the high end of the residential range. It's almost hospital-grade. The picture shows a comparison of the new K&N against the crappy Tru-Blu I was using before. It's pretty obvious which one will filter better.

Awesome! Glad to hear it seems like a good product off right off. Hope to hear more good reports. I'd love to hear how easy they are to clean, how often they need to be replaced, etc.

"crappy Tru-Blu"

Not sure why you say that. They are decent filters and they don't cost much, 2 for $3, when on sale. They do a good job of protecting the A-coil from getting gunked up without adding additional static pressure(resistance to air flow) when changed out fairly often.

I second that opinion. The main filter in a central HVAC system is not meant to be a HEPA filter. They're there to keep the bugs and lint off of the heat exchangers and to cause as little pressure drop as practical. One of the worst things you can do to destroy performance is to put in a filtrete filter in the spot that the factory one came out of. They drop way more pressure than they should and starve the air handler. Everything wears out faster when it runs 30 to 60 percent longer cycles to satisfy the comfort load.

If you feel the need to have super clean air, buy a HEPA filter and use it. That being said, I hope the super hotrod air filter works out for you. I sure hope it doesn't stress out the central HVAC system. I'm sure those things cost a pretty penny when they go south.

I can attest to that fact. I put the largest filter/grill assembly I could find in the return air duct at my mom's house. I figured twice the area would allow me to use the best Filtrete on the shelf.

It created so much pressure drop the 18" round, heavy gage steel return air duct collapsed. And that was on a 1.5 ton unit. I doubt if four times the original filter surface area would have been enough.

I had a feeling that would be Jeff's opinion. There's an interesting chart here to look up exactly what your filter stops. I'm not convinced TruBlu was even catching most dog hair.

https://www.serviceexperts.com/indoo...our-air-filter

I just looked it up, it's a FPR 5 / MERV 7 filter. Not sure how you think a pleated filter isn't going to catch dog hair. Here's a link showing it's MERV 7. I get these on sale from a different home improvement store at 2 for $3.

https://www.homedepot.com/p/True-Blu...6201/100352750

The fiberglass kind is worse. And even cheaper than 2/$3, I think

It has been a long time since I've posted. The family has grown by one and we moved once, downsizing from 1950 sf to 1450 sf. Being smaller and two story, I figured utility bills would drop. But, they actually went the other way. Previously we were topping out around $100/mo in electricity. Now it's not unusual to see $150/mo. I think the problem is that the smaller house is about 10 years older and just not built as well.

I haven't done a ton of efficiency upgrades in the new place. Here's what I can think of:

- heavy drapes
- seal some gaps with foam
- foam in the wall outlets
- Google Nest, upstairs and downstairs

I got the Nests on eBay. Coming from eBay and with a city incentive, they were basically free.

We are also driving less and biking more. Wife picked up a bike trailer in Craigslist recently and that has been great. I bet we drive less than 10k miles combined this past year

I mentioned the reusable AC filters previously. I brought them with me to the new house, but the AC filter size is smaller here. So I carefully chopped and resized the filters. That was kind of fun. I still recommend these filters. They are heavy and well built, very easy to clean. One $13 bottle of cleaner should be enough to last us about 4 years, I figure.

My only caution on the reusable filters is not to use them in overhead applications since they are heavy and could fall on somebody.

The real reason I'm excited to write is that we're moving again soon. Rather than sell the previous houses, we're starting to build up a little collection of rentals. Given the home price surge in Austin recently, let's just say we're doing well.

The new place has a bigger yard (0.21 acres). We are planning a gazebo surrounded by garden in the back. Overall it should be much more energy efficient and bigger (1750 sf).

The new place is being built by Lennar. An interesting aspect is, a solar roof is mandatory. It's called the Lennar "Solar Community" if you would like to Google the program. I think it's cool to see capitalism at work, making PV mandatory to generate a profit. Because that's what this is all about-- I'm not naive enough to think the builder is doing it for green credentials.

I know it would be cheaper to get solar via third party installer, but, again, I'm happy to support this "mandatory" solar program.