dhanson865
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Re: Help me make a hard solar decision

Thu Aug 02, 2012 8:08 pm

Cheezmo wrote:Area 3
The house is 4500 square feet wide open 2 story entry. A beast to air condition, but we have Nest thermostats that are helping.
We replaced our roof about 6 years ago and I passed on the radiant barrier because OTA HD was a big deal for me then and it would block the antenna. Since I don't care about that any more, I should look at doing something in the attic. Torn between insulation or a radiant barrier (or both). Of course reducing our A/C load during peak sun hours would actually be counterproductive at this point :-)
Keep in mind much of the thermal load from the roof/attic radiates into the house from sundown until sometime in the middle of the night.

You have 3 periods in relation between the AC and Solar PV.

1. Your solar panels generate power in the morning when the AC load is minimal

2. Your solar panels generate power in the mid day and after noon while the AC load is high

3. Your solar panels don't generate in the evening when the AC load is still high.

To me period 3 is when my house is the hottest and that is where you either pay up front for insulation or as you go for the electricity to cool the house while it's still very hot out but dark.

Now 3 can be negated by opening up the house to outside air once the outside temp drops but humidity and allergens are enough of a reason for most to call that a no go. If it works for you vents, fans, windows, sliding glass doors with screens, etcetera can vent the house after dark.

7c/kwh is cheaper than just about anywhere in the US but even then I'd be seriously looking at reducing my AC load considering the sheer amout of heat you deal with.
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QueenBee
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Re: Help me make a hard solar decision

Thu Aug 02, 2012 9:31 pm

ILETRIC wrote:Instead of panels look at the DOW Powerhouse Solar Shingles. Much nicer than panels and cheaper too.
Could you provide a real quote that shows they are cheaper and considering he just replaced the roof you can't include the cost savings from that.

Cheezmo
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Re: Help me make a hard solar decision

Fri Aug 03, 2012 8:54 am

Been doing some research on the plans that buy back outflows in our area, and it is pretty interesting. Here is some napkin math I did...


TXU purchases outflows at 7.5c/kWh, unlimited.

So, napkin math.

Say we typically use 3000 kWh, right now paying 7.1c that comes to $213/month.


So our solar is supposed to generate about 750kwh/month. Let say we have 200kWh in outflows and the other 550 is usage reduction. Then we make sure all car charging occurs at night, lets say that moves 500kWh to "free" (3 cars, based on our typical miles/kWh and mile/day I think that is close)

So, current plan, 2450kWh/month @ 7.1c new bill is $174/month. 200kWh of outflows "wasted".

Reliant's free nights plan is 12c/kWh, but free from 10pm to 6am.

So we use 1950 @ 12c, sell them 200 @ 7.5. End bill... $219/month, and there is perhaps other reduction for electricity used at night. To do better we would work on minimizing usage during solar production hours to generate more outflows and use as much as possible over night (pre cool the house for free!).

Not quite there, but it will be interesting to see what our real out flow numbers are and what plans can be combined in the future.

This will be fun!
Steve Martin
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Cheezmo
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Re: Help me make a hard solar decision

Wed Nov 07, 2012 2:19 pm

Well, the day is here, the panels are actually going up!
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Steve Martin
White 2014 BMW i3 - Aerovironment EVSE
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Black 2014 Volt - Blink EVSE
6kW Solar array

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RegGuheert
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Re: Help me make a hard solar decision

Wed Nov 07, 2012 2:28 pm

Cheezmo wrote:Well, the day is here, the panels are actually going up!
Congratulations! That's exciting!
RegGuheert
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ksnogas2112
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Re: Help me make a hard solar decision

Wed Nov 07, 2012 3:09 pm

Looking sharp!
Jealous

Tom
Tom in KS
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Cheezmo
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Re: Help me make a hard solar decision

Tue Nov 27, 2012 12:37 pm

Went live at sunset last night. It was generating enough to almost turn on the inverter.

Well it is sunshine today, and generating 4.9kW as I write this. A long journey, exciting day.
Steve Martin
White 2014 BMW i3 - Aerovironment EVSE
White Diamond Tricoat [2012 Volt - Blink EVSE
Black 2014 Volt - Blink EVSE
6kW Solar array

DesertDenizen
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Re: Help me make a hard solar decision

Tue Nov 27, 2012 1:19 pm

Well, since we are posting pics....

Image
Fully charged by photo voltaic system.
Nov 9 2014 got my 2015 lease, SL. My third Leaf. Tucson AZ. 5,500 miles, 5.2 long term m/kwh. Let us see if the 'lizard' battery does better than my 2011, which lost a capacity bar at 6,771 miles.

Hedge74
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Re: Help me make a hard solar decision

Wed Nov 28, 2012 10:18 pm

Cheezmo wrote:Well, the day is here, the panels are actually going up!


I see in the picture that there are Some Windows right below the solar panel. I have a 3330 sq ft House in Fort worth and put up some solar screens on 10 of the windows 5 facing south and five facing east or west. The electric usage difference from previous years was "OVER 9000" kwh less. Actually it was closer to 12,000 I just wanted to put a DBZ refrence.


You may want to try that to lower your A/C usage. I plan on doing the other 12 windows this spring. I Did all the work myself, but I strained my hand putting in the the gasket that holds the screen in place.

Hedge

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