Radiant barrier results


#1

Would anyone care to share their experience with radiant barrier installation? I would like to know how Sense has helped measure the energy savings.


#2

I will comment on radiant barrier here. My results: 40+ degree decreased attic temperature in the Summer months here in SC. Mine is mounted under the rafters and over the knee walls in my attic. It has no effect in the winter but would help in all seasons IF it was on top of the insulation instead of attached to the rafters. It was worth the cost for just the summer decrease. I also added solar attic fans which work well also. I went rabid overkill on energy savings and managed to save over 60% on electric costs. LEDs, efficient pool pump, added insulation, and radiant barrier/solar fans saved me about 50% energy costs. Solar panels save only10% more. Do NOT do Solar, it will take 37years to pay for itself. DO everything else and get a 5 year pay back. IF only my Sense would find my pump, I could comment on efficient pumps, but NO LUCK there.


#3

This was discussed in my neighborhood forum every home is virtually identical. The owner reports 4% total energy savings. This is for the peak cooling months in Florida. The result were not adjusted for temperature days…


#4

My NONSense still cannot find my pool pump. Now 2 years into this. I know it is a drain on my electricity but it is somewhere in “always On”. Wish I could directly tell Sense when I switch it on???


#5

Do you run your pool pump 24/7? Sense hasn’t detected mine but and I run it for long periods of time at a low rpm since it’s variable but Sense hasn’t put this into my always on power calculation.


#6

I have tried running it many ways, low for a while, high for a while, intermittently, always on a low or high. It does not seem to make a difference for the last 2 years. NON-Sense sucks at this. Totally frustrated and have reset it a number of times with even worse results. It even keeps “finding” the same devices. It seems to like “device 1” the most. I also have a “motor 1” that runs for 5 minutes every so often that I cannot tie to anything in the house (???). I wish I had better luck with this. I have 3 bathroom fans that this has not picked up on, a myriad of appliances, many, many fixtures (light), ceiling fans, fans, when I turn things on I can see the results on the graphs but it does not seem to recognize they exit.


#7

I think that solar depends on incentives, net-metering, and other things and I don’t think anyone can make a blanket statement like that. Efficiency is always the first target, and usually the cheaper thing to fix. LED’s are a must with solar, but you can get cheap ones at wal-mart for $2-$5/ea

Take my case for solar for example:
9.52kw peak, with an SE10000A-US Inverter
Average daily generation: ~40kwh
Lifetime production: 5.49MWh (~$1228.02)
Average cost of electricty: $0.20/kwh (MA)
Net metering credit: Full
SRECs: 1 SREC II SREC per 1.2MWh
Total srecs so far: Q1: 2, Q2 (will be 3 on 06/28)

Total system cost (Before incentives):
$32,000
State rebate: $9600 (30%, IBLS)
Federal Tax Credit: $9600 (30%)
MA Tax Credit: $1000
Total system cost after incentives: $11,800
No power bill since feb, power bill before was around $250. I had not built up any credit during the summer, otherwise I likely wouldn’t have had a bill at all.

Estimated SRECs per year (MA SREC II) - 11 @ $200/ea (MIN, will be more) - $2200
$2200 from srecs, and $2400 in utility savings (at underestimated $200/mo) = $4600/yr
11800/4600 = 2.565217 year payoff after incentives.
Not anywhere NEAR 37 years.
Installer estimated 5 year payoff.

This is data taken from my ACTUAL system, not an estimate or sales pitch. Here’s todays data from Sense:


#8

That’s a very specific example. High cost per kw and huge state incentives make solar a no-brainer in your area. As a counter example here in AZ electricity is around 13 cents per kw and the state will chip in a total of 1k tax credit towards the cost. Electricity companies will then add additional fees of $30-$50 to your monthly bill and will buy back any excess electricity for a fraction of what they charge. It’s a shame because we have an ideal location for solar power generation but it is disincentivized on many levels.


#9

Sorry, not a salesman, but a consumer. You either have a very tiny or a very energy efficient house and I definitely envy that. I have a 44 panel 13.5 kW system. In theory it should make 44kWh a day but my average is 34kWh a day. My usage in this 50 yo house was about 100kWh a day or approximately $430 a month. Enter extreme conservation efforts and I was down to about 60kWh a day. This was with extreme effort. Added the solar but only saw an additional 10% savings. I now only use about 50kwh a day. The cost of my system payment is $250 a month for the next 20 years. The installers took about 8 years of life off the roof and I ended up having to replace the roof from leaks they caused (another $9,000 out of pocket). The roof where they did NOT work, did NOT leak. So here we are. My payment to the solar people and the payment to the electric company is higher than my old electric rate. SO where is the upside on solar? Also here in SC solar panels do not increase the values of your home. I cannot require my Neighbors to cut or trim their trees (nor would I want to) and I have had about $6000 of tree work done to increase my solar output. It will only benefit the next owners of this house, if the panels last that long. These panels are Suniva OPT275-60-4-100 on Enlighten micro inverters. Made supposedly in Canada. The cost benefit ratio is heavily slanted to the sellers and installers. Not to the consumers. If you can get all the tax credits and pay cash for the panels and install them yourself it would be worth the sweat equity. Paying payments over 20 years doubles the price of the system and makes it cost prohibitive. Our electric company here whined about it costing them for our solar and added another charge to every customer. So they are chipping away at any cost savings also. The lady down my road was talked into a solar lease. She was told the cost would be $250 a month for the first two years and a “little” increase because of electric rates. They did not tell her IF she used more than her system made, she was responsible for the overage. When her first $2000 bill came due at “true-up” she had a cow. She is 85 and will never break even. They say her house is not good for solar, its all her fault. Its the trees and her house orientation. The trees were there when they installed the panels (2 years ago) and to my knowledge, she has not moved her house (not a mobile home). I am so glad that your solar worked out for you, my experience and calculations say not in many cases. Yours is actually the first I have seen data for. If it is real and you are a real person that is.


#10

@jackfurr,
Agree that conservation and efficiency offer the best price/performance solution. And you can even get rebates from the power company here in addition to the savings. But in high-cost markets with tiered rates, solar panels are a strong option as well.

My example for NorCal:
I use about the same amount of power as you do now, 60KW/month, after doing similar efficiency changes, though I have 3 EVs plus a plugin hybrid. I “bought” a SolarCity prepaid power purchase agreement in 2012, that was installed in Dec. 2012, before we owned the EVs so dynamics have changed over the years. They did a great job installing (no roof damage) 220W Kyocera panels and took care of every aspect from permitting, through closing with utility company.

Specs on the system / PPA contract:
System rating: 4.62kW
Total upfront cost of 20 year PPA: $15,500
Cost per kWh: $0.1057 - all prepaid for 20 years
Estimated First Year Annual Production: 7,689 kilowatt hours (kWh)
Estimated Initial Term Total Production: 146,687 kilowatt hours (kWh)
Estimated First Year Monthly Payments: $0.00
Price per kWh Annual Increase: 0.0%

My system produces just slightly less than the contract per year so I get reimbursed tens of dollars per year.
Hard to figure out exact savings because you have to calculate cost without solar - in a 3-4 tiered pricing system, that means using very complex spreadsheet, or better.

I originally was on the basic tiered net metering (NEMS) pricing and calculated about $2,000 savings per year.
I moved to a time of use (TOU) NEMS rate schedule about a year ago, and moved 95% of the EV charging to nighttime and now see about $6,000 savings. (true-up payment dropped from $5K/yer to $1k/yr)

At a blended $2K to $6K savings per year, I see a 5-6 year breakeven point. So I’ll be celebrating free energy at the end of this year.


#11

I am indeed a real person :slight_smile: and that is real data.

Something about your solar setup feels off to me, my system is 34 Trina 280w solar panels, 9.52kw peak, 1 string of 10, and 2 strings of 12. It uses solaredge optimizers and a solaredge inverter (Benefits of microinverters, costs of string inverter. Optimizers to mppt at the panel, but the DC to AC conversion is done at the inverter)

Could your setup be the issue?

Also, 100kwh a day? How in holy h*** are you using that much? Our lighting is efficient (All Phillips hue), but we have 7 people, an electric stove, central heat pump, and an electric dryer. A really bad day is 50kwh.

I designed my solar system, but had it installed by APEX solar power. I can’t say if something is wrong with yours, but those numbers are way off. Shading maybe? I’d look into why it’s not producing like it should.

Also, I’m not saying solar is right for everyone. Mine is a pretty extreme example, yours seems pretty extreme in the other direction. Just that it’s not a fair blanket statement for everyone.


#12

Here’s a bad day for us, really bad solar generation (Thunderstorms all day) and really high usage (I love the new goals feature btw)


#13

I am not sure, that is one reason I bought the (NON)Sense to try and find out where the electricity was going. Unfortunately, I get nearly nothing on that either. I am sure the pool pump is sucking power. Four adults live here and the other three never met a light they did not like to leave on. 2500 sq ft house built in the 70s with 2 heat pumps, pool pump, oven, stove, washer/dryer, frig, freezer, ceiling fans, in SC where the humidity stays at 70+%. I have changed the inefficient windows, changed heat pumps, increased insulation, added solar fans, NEST thermostats, and gone LED but am still leaking electrons somewhere:) Most of the panels put out less than 1/2 kW a day and we have many cloudy days. About 34kWs a day out of these 44 panels. This was an old plantation before it was a subdivision and monster oak trees and magnolia trees abound in my yard and neighbors. Solar was a poor choice for this area. I do have a group of 4 panels that actually put out >1kW a day so it is possible for these panels to produce, just not here. But my calculations still say that if all my panels put out the same the output would not justify their cost of around $1000 per panel. Electricity costs about 13.4 cents per kW. At that rate it will take 28.62 years to generate the equivalent electricity (not taking into account the interest for the panels if not paid up front) which is where I got the approximate 37 years. In my case, closer to 50years, if they can produce that long. Fuzzy math and cloudy logic by the installer along with guarantees that they did not stand behind got me into this and I want to keep others from making this type of mistake. So glad it worked for you.

plaguethenet

    June 5

jackfurr:
Yours is actually the first I have seen data for. If it is real and you are a real person that is.

I am indeed a real person :slight_smile: and that is real data.

Something about your solar setup feels off to me, my system is 34 Trina 280w solar panels, 9.52kw peak, 1 string of 10, and 2 strings of 12. It uses solaredge optimizers and a solaredge inverter (Benefits of microinverters, costs of string inverter. Optimizers to mppt at the panel, but the DC to AC conversion is done at the inverter)

Could your setup be the issue?

Also, 100kwh a day? How in holy h*** are you using that much? Our lighting is efficient (All Phillips hue), but we have 7 people, an electric stove, central heat pump, and an electric dryer. A really bad day is 50kwh.

I designed my solar system, but had it installed by APEX solar power. I can’t say if something is wrong with yours, but those numbers are way off. Shading maybe? I’d look into why it’s not producing like it should.

Also, I’m not saying solar is right for everyone. Mine is a pretty extreme example, yours seems pretty extreme in the other direction. Just that it’s not a fair blanket statement for everyone.


#14

I’m sorry your experience didn’t work.
I use the meter to troubleshoot by flipping breakers, and my brother in law has a pool, the pump is a huge consumer. I just find it shocking 100kwh, that is so much energy. Is there any advice I could give to help? Would how I use it help you troubleshoot your usage? I don’t want to sound condescending either, I’m sure you’ve done what you could, I just wish there was a way to help you figure out that usage. I can’t even imagine, even with electric rates that low, that’s like $14-ish/day. Over here it’d be like $23.


#15

Sorry for your bad experience. I am certainly not saying that there are many many others like you that would suffer the same. I am saying however that there are also many many more who are loving the solar experience. The question should be then how to aide folks like you in the future.

I love electric EVERYTHING. I drive an electric car, have an electric chainsaw, hedge trimmer, blower, weed eater, whole house dehumidifier, geothermal heat pump, electric stove, electric dryer and the list goes on. I am looking to replace my lawn mower in a few years with an electric one, and when electric trucks become a reality, I will have one of those too. When I added up my “always on” thanks to Sense, I have over 30 electric items. With the help of the Sense goals, I have my “always on” under 75 watts with NO personal sacrifice. My house is of average size of 2700 square feet. I live in an average climate in North Carolina but near the South Carolina border so not too far from your conditions.

Now interestingly, I get ALL of this done with a Solar array half the size of yours at 6 kW array. Keep in mind, that counts about 8,000 electric miles driven annually. My house is not 50 years old but is 20. Sounds like, for starters, you have a really crappy house as energy efficiency goes. A solar array can’t fix that for you. The Sense monitor can help you find your problems and react to them. As for trees, any reasonable solar installer starts with a device that shows you exactly how much trees will affect your annual output. It is a brilliant device that only takes a few minutes to setup and read the data. Curious if you are running micro inverters such as Enphase or optimizers like SolarEdge? They are a MUST if you have tree blockage. The point being, this is not a solar design problem, rather a bad installation if you don’t. Combine that with the online PVWATTs calculator and you will have no surprises on the output of your solar array. No surprises. Simply input your address and PVWATTs will let you know how much energy you will produce on a month-by-month report.

While I am genuinely sorry for your bad experience, for cases like yours impact the move to solar. At the same time, I think your energy would be better served learning from the mistakes. The device to determine solar blockage from trees is less than $300. Your panels look to be outputting half of what they should. You either don’t have micrinverters or optinizers and/or you have tremendous shading. With out them, the entire array suffers when one panel is shaded. Step one is to get to the bottom of your problem instead of declaring solar as a sham. As for your inefficient use of energy, let the Sense monitor aide you and get busy making the changes.


#16

The one positive of taking delivery of a solar system as power purchase agreement instead of a system purchase, is that the installer/operator is incentivized to make the system as efficient as possible, instead of going for the maximum the roof can accommodate. My system utilizes only 1/3 of the possible usable roof area, but I get much more per panel out of the 22 panels I have, than a 60 panel plan drawn up in one of the other proposals. I get paid back when my system does not deliver to specs…


#17

Yeah, I mean, I think buying was right for me, but as I stated, I designed my own and told them what I wanted rather than allowing them to design. Buying can raise the value of a house, while leases and ppas generally decrease value, or have no impact. I think everyone’s situation is different, and in his case I think he’s right about his installer being shifty. They should have, and sounds like they didn’t, warn him of any potential shading issues. Or they designed a traditional string based system, rather than microinverters or optimizers, which would cause any shading to affect the whole string instead of a single panel.


#18

That pvwatt site is shockingly accurate. I’m impressed. I put in my system parameters and address, it’s also spitting out estimates my installer used for warranty. Cool. Thanks for sharing that.