Cheezmo
Posts: 359
Joined: Tue Feb 28, 2012 3:18 pm
Delivery Date: 29 Mar 2012
Leaf Number: 9084
Location: Plano, TX

Help me make a hard solar decision

Wed Aug 01, 2012 8:30 pm

I am on the verge of installing a 6Kw solar array on my roof. I currently pay a very low rate (we are in an energy choice area of texas) of about 7.1c/Kwh. I was sold the system based on the concept of net metering, such that none of the solar power we generated would be wasted as the "meter would spin backwards" and we would only be charged by our power company for the net power used per the meter at the end of the month.

After HOA approval, lease company approval, months of paperwork, etc., the solar installer informs me that there is an issue with the power company I have as they will not offer "interconnection". Well that leads to actually looking at the detailed info from Oncor, who it turns out uses in-flow/out-flow metering.

Only a few of the REPs (Retail Electric Providers) buy back outflows, and of course their base rates are significantly higher than what I"m paying now, over 9c/Kwh and probably over 10c for the plans that will actually buy back.

Our usage the last few months has been 3700Kwh to 4700Kwh.

So now of course the installer says we are very unlikely to generate much in outflows anyway so it shouldn't matter.

But I'm really hesitant to go into this blind knowing that some amount of the solar we generate is going to be given away. The ROI on this system wasn't great to start out with (12-15 years on a 20 year lease) so there isn't much room for getting less value out of it.

Given my usage is it fair to say I should not worry about outflows? Or does the lack of net metering and the current great rate I'm paying blow this deal.

I'm thinking I should check the meter during the afternoon when the A/C is cycled off, none of our EV's are charging and if it is over 6Kw anyway, maybe he is right. Our smart meter was just installed so there is no online data to go by.

Thoughts?
Steve Martin
White 2014 BMW i3 - Aerovironment EVSE
White Diamond Tricoat [2012 Volt - Blink EVSE
Black 2014 Volt - Blink EVSE
6kW Solar array

User avatar
RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Help me make a hard solar decision

Thu Aug 02, 2012 2:20 pm

Cheezmo wrote:Our usage the last few months has been 3700Kwh to 4700Kwh.
I'm going to assume that you mean you use that much *per month*. If I misunderstand, please correct me.
Cheezmo wrote:So now of course the installer says we are very unlikely to generate much in outflows anyway so it shouldn't matter.
Of course your installer is not providing an unbiased opinion on this subject. He has a strong financial interest in favor of you doing this.

In any case, even if you don't produce ANY outflows, your base rate has gone up by 40%, so it's a bad deal. If you are thinking of sticking with your current energy provider, then it sounds like you will simply be giving them energy when you produce more than you consume. This will happen OFTEN, whenever your air conditioner cycles off during the day in the summer and much of the fall and wintertime. Or it could be even worse: your provider might use a meter which CHARGES you for ALL energy which flows through the meter in either direction. That's what my electricity provider did until I could get a new meter. You can see in the link in my signature that I had to turn off the system between February and July of 2011 because I couldn't afford to run the system.
Cheezmo wrote:But I'm really hesitant to go into this blind knowing that some amount of the solar we generate is going to be given away. The ROI on this system wasn't great to start out with (12-15 years on a 20 year lease) so there isn't much room for getting less value out of it.
I don't think this makes sense for you. Does Texas not have a net-metering law?
Cheezmo wrote:Given my usage is it fair to say I should not worry about outflows? Or does the lack of net metering and the current great rate I'm paying blow this deal.
I think it blows the deal. You cannot control when the system produces electricity and you have limited control of when your loads consume electricty, so you are likely to give away a significant amount of electricity in this deal.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

Cheezmo
Posts: 359
Joined: Tue Feb 28, 2012 3:18 pm
Delivery Date: 29 Mar 2012
Leaf Number: 9084
Location: Plano, TX

Re: Help me make a hard solar decision

Thu Aug 02, 2012 3:00 pm

I appreciate the feedback. I am going to go ahead with it. The biggest reason probably is that I have invested so much effort in the planning and everything and I just really want to. The other thing is to make sure that the sub panel upgrades I need for adding car chargers will be what the solar system needs. Doing both of those at once seems to make sense.

We have smart meters with Oncor that support in flow and out flow metering (if the smart meter they just put in doesn't, it will be replaced but I am pretty sure it does). Even if our current really cheap energy provider does no buy back out flows, it is a fairly new thing around here and I imagine more companies will over time. Once I can measure how much I'm generating and using, I'll be able to tailor future energy choices to my usage and car charging practices. With 3 EV's working things out so that one is charging during the peak sun hours most days is probably workable. I can also make sure the pool runs the polaris with the pump at the higher speed during those hours.

Reliant is one of the companies that does buy back and they have a plan that is free from midnight to 6 AM. If that could be combined with a plan that buys back overproduction during the sun hours, I could see managing to come out ahead even if the base price is higher than what I'm paying now. Charge the cars at night for free, sell them some electricity in the afternoons. I'm willing to gamble on what may become available in the future.

So, I will look at it as a science experiment without an expected return, but doing some good for the world and teaching my kids a lot about energy usage in the process. Can't be a bad thing.
Steve Martin
White 2014 BMW i3 - Aerovironment EVSE
White Diamond Tricoat [2012 Volt - Blink EVSE
Black 2014 Volt - Blink EVSE
6kW Solar array

DesertDenizen
Posts: 399
Joined: Sun Aug 28, 2011 9:23 am
Delivery Date: 11 Sep 2014
Leaf Number: 314507
Location: Tucson

Re: Help me make a hard solar decision

Thu Aug 02, 2012 3:25 pm

Good for you Cheezmo. I installed 9 years ago, and with all the number crunching aspects it is easy to overlook the visceral impact it can have. At least on me. Seeing the sun hit the panels and my meter spinning backwards I still smile, all these years later. Even more so now that it powers my Leaf.
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.

User avatar
Boomer23
Posts: 3550
Joined: Sun May 23, 2010 9:57 pm
Delivery Date: 30 Mar 2011
Location: Orange County, CA

Re: Help me make a hard solar decision

Thu Aug 02, 2012 3:33 pm

DesertDenizen wrote:Good for you Cheezmo. I installed 9 years ago, and with all the number crunching aspects it is easy to overlook the visceral impact it can have. At least on me. Seeing the sun hit the panels and my meter spinning backwards I still smile, all these years later. Even more so now that it powers my Leaf.
+1

We put in a 5.2 kW system five years ago. That led to our being more aware of our energy use, which led to our conserving energy more, which led to our producing a 20% excess to our needs, which led to our seriously considering an EV. Now, with net metering combined with TOU rates for EV charging, we're paying nothing for all of our power use including EV charging, and by offsetting our driving fuel costs, we're paying off the solar investment faster. A very satisfying outcome.
2018 Tesla Model 3 Long Range RWD
2017 Chevy Bolt EV Premier Kinetic Blue
Blog: http://drivingelectric.blogspot.com" onclick="window.open(this.href);return false;

User avatar
RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Help me make a hard solar decision

Thu Aug 02, 2012 3:44 pm

Cheezmo wrote:I appreciate the feedback. I am going to go ahead with it. The biggest reason probably is that I have invested so much effort in the planning and everything and I just really want to.
Cheezmo wrote:So, I will look at it as a science experiment without an expected return, but doing some good for the world and teaching my kids a lot about energy usage in the process. Can't be a bad thing.
Those sound like good reasons to me! Frankly, the laws which we were counting on paying for our system over five years were changed with no grandfather clause, so our payback may now be 20 years, but we are still very glad we put in the system. Keep in mind that you are locking in a fixed price for electricity for the life of the system. If you install a reliable system which lasts, you will likely save money as well as the environment over that time. For reference, I noticed the other day that we paid $0.065/kWh for electricity back in 2006, but today we pay $0.105/kWh. I sure wish my salary would go up that rapidly!
Cheezmo wrote:The other thing is to make sure that the sub panel upgrades I need for adding car chargers will be what the solar system needs. Doing both of those at once seems to make sense.
We did *exactly* the same thing here, and I will share some information on this topic which you may find useful:

My subpanel for the 9.87-kW PV array is just inside the house right next to the garage, so the intention was to also use it for electricity for the garage and for EV charging. Connecting this panel to the main panel required a wire run about 100 feet long. I oversized and installed 2-2-2-4 wire for this panel, even though I only installed a 60-A breaker in the main panel to reduce voltage drops, thus maximizing PV efficiency.

But even though the wiring was oversized, I still ended up with a situation where there is sometimes an overvoltage condition at the PV subpanel. Why is that? Partly because we sometimes get an overvoltage condition from our electricity supplier (even without any PV generation), but even when they are within specifications, they are close to the top end and the PV produces current flow which increases the voltage within our main panel and even further increases it in the subpanel. I estimate the highest we might see is 254V at the subpanel, but that is outside of the specified range for most products, including the EVSEUpgrade. The LEAF does not give a voltage range, but I would hate to have a claim for a failed charger denied due to overvoltage.

Anyway, this may not apply to your situation at all since your power is probably near the 240V nominal value for North American power. It is also not likely that you will have any equipment fail (except perhaps incandescent lamps) even if you have an overvoltage condition. But the bottom line here is that I recommend that if your subpanel is far from your main panel like mine is that you oversize the wire to that panel quite a bit to minimize voltage drops (from the EVs charging) and voltage rises (from PV production). They definitely will occur at different times sometimes.

Enjoy your new system!
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

dhanson865
Moderator
Posts: 1496
Joined: Wed May 25, 2011 7:12 am
Leaf Number: 16156
Location: Tennessee

Re: Help me make a hard solar decision

Thu Aug 02, 2012 6:23 pm

Consider getting a smaller total system with racks on the roof left empty for additional panels and add them later when you are sure you will get paid for your excess electricity. You can't go too small without changing the inverter choice so ask for a quote on a system that is a panel or two smaller and see what the numbers look like. Let them know your target (I'd shoot for no more production than the least you use in a spring/fall month)

Also 4000kwh per month is huge, I'm using about one third of that on average and as little as 700-800 in a month in spring/fall when the weather is just right. That's for a two story house around 2100 sq ft. My worst case scenario is closer to 2000 in a month but that takes record cold

You may want to look into your roof/insulation before putting the panels up.

Is Plano in area 2, 3, or 4 on this map?

http://www.energystar.gov/index.cfm?c=h ... tion_table" onclick="window.open(this.href);return false;

Energy Star roofing material (reflective), reflective barrier under the roof (http://en.wikipedia.org/wiki/Radiant_ba ... and_Attics" onclick="window.open(this.href);return false;), and as much insulation as you can stuff in the attic could reduce the AC load a ton (figuratively), I don't know how many tons it would reduce it AC wise.

I don't live in a desert so I have 40+' tall trees providing some shade, but then I don't have energy star roofing yet. My roof tiles are grayish black asphalt shingles the cheapest they made I'm sure.

I'm waiting for the roof to need replacing to upgrade to better roofing but I put in tons of insulation in the attic a couple of years ago. I'm probably between R40 and R50 in my attic. I'll probably do white or very near white (light gray or light brown more on price than my preference for color) roofing when I redo the roof.

If you are using many tons of AC it'd pay for itself in very little time to look into upgrading the insulation and/or roofing. And it's always cheaper to replace roofing / work on the roof before you put panels up.
Blue 2012 Leaf 195/65/15 tires, 15" Rims
Silver 2012 Leaf 16" stock wheels
http://www.mynissanleaf.com/wiki/index. ... acity_Loss
(efficiency 3.x KW vs 6.x KW)
please join Truedelta.com and input your repairs.

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Bellevue (Seattle), WA

Re: Help me make a hard solar decision

Thu Aug 02, 2012 6:55 pm

Cheezmo wrote:I appreciate the feedback. I am going to go ahead with it. The biggest reason probably is that I have invested so much effort in the planning and everything and I just really want to.
Congrats! It's too bad your pay back is so long already. Your relatively cheap power is certainly causing that time frame to go out, and who knows how long that will last.

I don't think it's been specifically mentioned but if I were you I would get some good electricity metering in place. That way you'll be able to monitor your generation and use in real time and be alerted when you are generating a significant amount over. If you find that you are giving away a lot some home automation would be good if there are things you could turn on/off. Before I had my new meter installed a friend setup an application that monitored the PV output and when it got above a certain point it would tell my LEAF to start charging.

Obviously keep pressure on your current provider in hopes they'll come around.

Having good data on your generation and consumption will obviously allow you to do sophisticated analysis of if changing providers would make sense.

Did your installer provide you with estimated monthly generation expectations? It would be interesting to compare those with your past bills. That at least gives you some idea if you'll be close. Just based on the numbers you gave us 4000kWH a month averaged over the entire month is 5.5kW. Your system will probably put out a peak of that. So that just leaves the question how low is your day time usage.

BTW: I would highly recommend making sure your break even math is conservative. It would not be fun to find out it was too optimistic so you end up extending your break even to begin with and then add this problem and then you are really not in a great place.

Is 4,000kWH a lot for your area? Seems like it's pretty common for people to spend a few hundred a month in the summer in hot climates but I have no idea :)

Keep us updated on your progress and how your experiment turns out.

Cheezmo
Posts: 359
Joined: Tue Feb 28, 2012 3:18 pm
Delivery Date: 29 Mar 2012
Leaf Number: 9084
Location: Plano, TX

Re: Help me make a hard solar decision

Thu Aug 02, 2012 7:00 pm

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 :-)
Steve Martin
White 2014 BMW i3 - Aerovironment EVSE
White Diamond Tricoat [2012 Volt - Blink EVSE
Black 2014 Volt - Blink EVSE
6kW Solar array

ILETRIC
Posts: 740
Joined: Sun Dec 19, 2010 9:36 pm
Delivery Date: 04 Jun 2011
Location: Marin County

Re: Help me make a hard solar decision

Thu Aug 02, 2012 7:03 pm

Instead of panels look at the DOW Powerhouse Solar Shingles. Much nicer than panels and cheaper too.
------------------------------------------------
1st bar lost at 38,700 miles/22 months
2nd bar lost at 45,750 miles/27 months

Traded-in on 10-19-2014 at 56,150 miles
-------------> for Kia Soul EV+ <-------------

Return to “Solar”