3 Years with Grid Tie

autoxsteve · March 2011

Yesterday marked the 3 year anniversary of 'going live' with my 4kW grid tie system.
Here are the facts:

It has produced 22657 kWh of energy.
Average annually is 7552 kWh per year which equates to an average of 20.7 kWh per day.

@ $0.14 per kWh, I have saved $3172.00 or about 1057.00 per year, just on electricity.

In addition, I have saved about $25.00 per month (300 per year) on my natural gas bill by replacing my gas drier and gas water heater with electric models.

I figure that if I replace my all electric water heater with a hybrid model, I'll get my consumption down below what I am producing and be right where I would like to be.

My current electric bill for the year will be about $350.00...

I'm considering putting one of these hybrid units in this year and get the tax credits on them while they last....

Needless to say, I am pleased.

Seven · March 2011

Re: 3 Years with Grid Tie

It is nice to hear a success story. I hope to someday be able to say the same.

Frxddy · May 2011

Re: 3 Years with Grid Tie

Congrats on the good success! I hope you have many years of trouble free service.

Jburgess · May 2011

Re: 3 Years with Grid Tie

That sound's great. Don't forget you probabably saved sales tax on that amount also.

SkiDoo55 · May 2011

Re: 3 Years with Grid Tie

Sounds Great!! Hope my system is close to that in 3 years. I'm at 5 MWh since 08/2010 as of today. CEC prediction 6.3 MWh per year? Looks like I am ahead of that by a few percentage points. Been a very wet and cloudy winter/spring so far.:grr

Fun point! You need to update your signature line to the current 22.6 MWh

BilljustBill · May 2011

Re: 3 Years with Grid Tie

It is good to see success; I hope my future system will do the same thing!

I see that you have included in your yearly savings what your system offsets in electrical energy by adding an electric water heater and clothes dryer.

What type of inverter do you have?

Have you counted how much you have saved and included the cost of liability insurance your electric company requires? How much do they require and what's your approx. cost?

Do you have your panels/system insured? How much is covered and what does that cost you?

Thanks for the extra details,
Bill

sub3marathonman · June 2011

Re: 3 Years with Grid Tie

autoxsteve wrote: »

Yesterday marked the 3 year anniversary of 'going live' with my 4kW grid tie system.

In addition, I have saved about $25.00 per month (300 per year) on my natural gas bill by replacing my gas drier and gas water heater with electric models.

Needless to say, I am pleased.

I wondered about this, since the off-grid people are always wanting to do just the opposite. And I thought it was almost always cheaper to run a gas water heater than an electric one. And what about an instant hot water setup? With the gas it seems possible to do.

Otherwise, it is great to hear good news.

ggunn · June 2011

Re: 3 Years with Grid Tie

autoxsteve wrote: »

In addition, I have saved about $25.00 per month (300 per year) on my natural gas bill by replacing my gas drier and gas water heater with electric models.

I don't see why this would be a good move unless your PV system produces more than your consumption was before you made the change. The kWh you purchase to run the drier and water heater will more than likely cost you more than the gas did.

If the change converted you from a net exporter to a net importer of kWh, it might make sense because you get either a pittance or nothing for net exporting energy, but otherwise I don't see how it could have been a net savings.

BB. · June 2011

Re: 3 Years with Grid Tie

I have time of use net metering which means I get paid about 3x for summer afternoon generating. I could run an electric drier of peak and save money too--Or I could have installed a smaller array up front.

-Bill

ggunn · June 2011

Re: 3 Years with Grid Tie

BB. wrote: »

I have time of use net metering which means I get paid about 3x for summer afternoon generating. I could run an electric drier of peak and save money too--Or I could have installed a smaller array up front.

-Bill

I am trying to understand how that would work. Are you saying that with running an electric dryer off peak the total of your gas and electric bills would be less than they would be if you ran a gas dryer? I don't see how what you make from peak time of use generation has anything to do with it.

mike95490 · June 2011

Re: 3 Years with Grid Tie

his surplus power is used on site, and not "banked" or sold back to the grid. So it's used to dry laundry with, saving on the gas bill. But those extra panels sure cost a lot of $

BB. · June 2011

Re: 3 Years with Grid Tie

With TOU Net Metering (E-7 PDF), I avoid using power during "Summer" (six month billing period) and most of my solar power goes out to the grid and I am paid, around $0.32 per kWH. At nights and on weekends, I can buy my power back at $0.09 per kWH--So, technically, doing this, my solar array is "3x larger" during that billing period.

Without solar GT--I would be paying flat rate of around $0.12 to $0.29 per kWH (this is tiered pricing, and PG&E is lowering the tiers--I used to be able to "fit" in the baseline tier... Now I may get hit with some tier 2 chargers which can be as high as $0.40 per kWH at this moment (Flat Rate Residential PDF).

If I was to tie this with a Heat Pump Water heater--it would be interesting to see if I could actually save substantial money. Right now, I get around $300-$360 per year in "lost" net metered banked money--By now, I thought I would have had some sort of Electric Vehicle (installed system over 5 years ago).

You can play with this Fuel Cost Calculator and see what works out for you... If I assume 200% efficiency with hot water heat pump and $0.09 per kWH vs $1.20 or so per Therm for natural gas... The calculator shows that electric would be about 15% or so cheaper than electricity.

Add that my solar "cost me" around $0.17 per kWH and I get back $0.32 per kWH payments during summer afternoons--I would be "making money" in some sense of the term.

Would I invest my 401k in such a system--probably not.

-Bill

solar_dave · June 2011

Re: 3 Years with Grid Tie

Yeah it sure is nice to have net metering that allows for dollars instead of Kwh. My Utility does TOU with on peak ~$0.179 in summer and off peak ~$0.058. BUT the on peak credit is in Kwh and can only be used to offset on peak usage.

At the end of the year they settle up any excess Kwh @ $0.0659 on peak and $0.05963 off peak and credit your account that amount. The down side is you push into the grid mostly on peak watts and they sell them to your neighbor for at least ~$0.179 in summer and as high as ~$0.24445 depending on TOU rate plan the customer has, also if the customer has contracted for Green Power generation then add another $0.004 to those rates. You are offsetting high dollar rates but on any excess they make a killing on it.

autoxsteve · June 2011

Re: 3 Years with Grid Tie

ggunn wrote: »

I don't see why this would be a good move unless your PV system produces more than your consumption was before you made the change. The kWh you purchase to run the drier and water heater will more than likely cost you more than the gas did.

If the change converted you from a net exporter to a net importer of kWh, it might make sense because you get either a pittance or nothing for net exporting energy, but otherwise I don't see how it could have been a net savings.

That is exactly why I did this. At the time I pulled the trigger on the electric water heater (and earlier with the drier), SCE was not paying back people who created an electric surplus (and I did - in 2008 my house could be seen from space station during the Christmas season due to all of the lights to burn up the surplus).
They now pay but it's still not worth it.

I did this as the drier I had was dying and needed a replacement anyhow, and I did a pre-emptive replacement on the water heater to avoid coming home to a river running down my driveway when the original one burst while at work.

I am seriously considering the hybrid unit and may pull the trigger on it later this year - I just don't know which to buy. GE or Rheem.....

My gas bill last month was one therm for a total of about 7 bucks.....

solar_dave · June 2011

Re: 3 Years with Grid Tie

autoxsteve wrote: »

My gas bill last month was one therm for a total of about 7 bucks.....

Jeez nice bill, If I use 0 therms I still have to pay almost $17. I used 4 therms this month and can't figure out where it is going but for a few pennies per therm I am not chasing it too hard.

drees · June 2011

Re: 3 Years with Grid Tie

autoxsteve wrote: »

I am seriously considering the hybrid unit and may pull the trigger on it later this year - I just don't know which to buy. GE or Rheem.....

Since you just got a new water heater - why not get one of the retrofit heat-pump units? Might be cheaper than a GE/Rheem.

autoxsteve wrote: »

My gas bill last month was one therm for a total of about 7 bucks.....

Luckily my hot-water usage is low enough that the bill is typically only $7/mo w/a gas water heater.

autoxsteve · June 2011

Re: 3 Years with Grid Tie

drees wrote: »

Since you just got a new water heater - why not get one of the retrofit heat-pump units? Might be cheaper than a GE/Rheem.

Luckily my hot-water usage is low enough that the bill is typically only $7/mo w/a gas water heater.

Enlighten me - I am oblivious to the retrofit heat pump units you refer to.....

drees · June 2011

Re: 3 Years with Grid Tie

autoxsteve wrote: »

Enlighten me - I am oblivious to the retrofit heat pump units you refer to.....

http://www.nyle.com/water-heating/geyser-r/

Edit: Here's another:
http://www.airgenerate.com/retrofit.php

autoxsteve · June 2011

Re: 3 Years with Grid Tie

Drees,

Thanks for the info! The Nyle unit is much too large bt the AirTap unit looks promising. It wil fit on top of my existing water heater - I am going to discuss in detail with them n maybe purchase tomorrow...

I'lll post a seperate thread if I pull the trigger...

SolarLurker · July 2011

Re: 3 Years with Grid Tie

My dads water heater died and we replaced it with the GE unit. It is a really nice unit, I plan to get one for our house, we use natural gas on demand now, so I will keep the unit and place the heat pump in line, set it too heat pump only mode, natural gas as backup.

I am going to move my freezer from the garage to the basement, I figure the cooling and dehumidification of the heat pump should help the freezer run a little more efficient. Not to mention that the basement utility room is nearly 20 degrees cooler than the garage.

BB. · July 2011

Re: 3 Years with Grid Tie

Watch the temperature in the basement... From what I recall, much below ~55F, the heat pump water heaters are not that efficient (and would normally begin to use the backup resistance heater).

-Bill

solarvic · July 2011

Re: 3 Years with Grid Tie

BB. wrote: »

Watch the temperature in the basement... From what I recall, much below ~55F, the heat pump water heaters are not that efficient (and would normally begin to use the backup resistance heater.

=BB Bill I won,t dispute your information but I understood if you set it on energy saver mode that the heating elements won,t come on. It just runs longer and the fans run faster.
I did notice when the ambient air temp is lower that the fans run faster. On average I get about 2 quarts of water when it is humid. In the winter I didn,t hardly get any water from the dehumidifier part of water heater. I have mine in my utility room next to kitchen which helps to cool my kitchen area. Planing small battery system and think the charge controler, inverter heat will complement the waterheater and the waterheater might help to cool the inverters ect. Solar lurker, Maybe you could enclose the freezer heat output to waterheater and use the cooled air to help the freezer be more efficient. Since you have installed a Geospring you know there is lots of cool air comes from the waterheater. I read somewhere once that the waterheater,s cool air is about 3,000 BTU. Since I have free gas from my gaswell I put a small NG spaceheater in the utility room. Since my oct 2010 install of the GEO I used about 335 KWH. :Dsolarvic:D

BB. · July 2011

Re: 3 Years with Grid Tie

Vic,

Not a problem...

As I understand, at lower temperatures they become less efficient. And if they get too cold, they ice up and (some/all?) have defrost heaters to remove the ice.

-Bill

solarvic · July 2011

Re: 3 Years with Grid Tie

BB. wrote: »

Vic,

Not a problem...

As I understand, at lower temperatures they become less efficient. And if they get too cold, they ice up and (some/all?) have defrost heaters to remove the ice.

-Bill

Bill I hope it doesn,t get cold enough in my homes living area for that to happen. In Pa we do get fairly cold. The record for my area is -26 f. That I use when planning my highest voltage for a string of Solar panels. The last few years my weather station limit has been -15f and the highest 96f. -15f was this past winter.
:Dsolarvic:D

CAOkie · November 2011

Re: 3 Years with Grid Tie

Can I ask what your usage was prior to going solar? I am about to install a system on my house. I am with PGE and will utilize the E7 TOU plan. My usage is pretty high with a two story house and a family of 8 so my system size is big. I am sized for about 95% of my annual usage. This is just a PVWatts vs usage calculation. I am still struggling with how the TOU changes things. I dont mind being a little over, in fact i have room for another 1KW on the roof, since i may add electric vehicle etc. It seems that currently with the E7 TOU structure there is no downside to overproducing. Do you see it that way? Also, the CSI will not allow sizing greater than previous annual usage, at least they wont pay you for it.

Side note: trying to find a thread about "continuous ground" discussion, can anyone direct me?

Thanks

BB. · November 2011

Re: 3 Years with Grid Tie

CAOkie,

Do you already have GT Solar?

My system is also with PG&E on E7 plan. My usage is probably around 200-300 kWH per month (natural gas so all heating/cooking is non-electric, other than a microwave and toaster oven).

If you are installing a new GT Solar system, I think you have to use E6 which is much less solar friendly (peak and partial peak extend well into darkness).

The tiered billing and peak/off-peak makes it difficult to determine the bill (there was a time 6+ years ago where peak and off peak tiered kWH levels were not pooled and you could get into higher rates eventhough you had more than enough total kWH generated to stay in the lower tier pricing).

-Bill

CAOkie · November 2011

Re: 3 Years with Grid Tie

No i dont have GT already. You are saying i cannot get onto the E7? Great. This is exactly why i am struggling with the size. Are you positive about that? I will have to call PGE today.

Anyway, please shed some light on sizing a GT system in CA with PGE as my provider. I would love to hear from people who are dealing with actual data and bills, etc. Would you go bigger or smaller now that you have a couple years of time to look at the data?

I should have my permit this week and i have 3 quotes for equipment. I am nearly at the point of no return!

Thanks

BB. · November 2011

Re: 3 Years with Grid Tie

I over-sized my system ~6 years ago expecting an electric vehicle... Now, lots of extra power (~$300+ lost credit every year) and no electric car yet.

Mine is a 3.5kW (3kW rated) system south of San Francisco and generates enough for my home with 4 people.

It is really a difficult call... Because there is so much difference in power pricing (from $0.09 to ~$0.52 per kWH) depending on when you use it and how much you use.

If you have a "smart meter", I wonder if you can get the hourly data and work out the cost of power on E7/E6 vs the size of your GT system.

It is nice getting a $6 per month electric bill--But we never used that much anyway ($30-$45 per month on the old E1 flat rate residential plan).

You really need to look at when you use power (AC? Cooking? Water Heating?) and see where it puts you in the rate plans.

GT system costs have certainly plummeted in the last few years (just my panels where ~$5.50 per watt before hardware/installation costs--but we did get a $2.50 per watt rebate from State of California/PG&E).

I would suggest a serious round of conservation first. Usually that is a better place to "invest" your money first (insulation, more insulation, energy star appliances, changing from desktop to laptop computers, turning off DVRs and computers when not used, etc.).

Being pressed to make decisions like this puts you in a difficult situation.

-Bill

CAOkie · November 2011

Re: 3 Years with Grid Tie

Thanks Bill,

I have fretted about this for a while. My bills are around $300/mnth. This in part because we live under a magnifying glass (Bakersfield), where the summer months are pretty brutal. I have installed attic fans, solar shades, and solar screens which have helped. I will be adding more insulation before next summer and my 20 year old appliances should start to die soon and will be replaced. My real conservation will come when my 6 kids move out

.

Solar City and Sun Run both offered a size of ~7kw. My design is for ~9kw. They both said i actually wasnt too bad on my annual usage but i am not sure i believe that, maybe in relative terms i guess with the 8 people.

I will be installing this system myself so my after rebate cost is around $1.75/watt. If i am generating to much and/or improve on conservation i could cross over from gas to electric on some things as mentioned in this thread. And we can always be a little more comfortable in August!

I guess i am still mostly comfortable with my size. Thanks for your input Bill.

Can i ask here why every circuit in my house and its associated ground utilizes wire nuts, buss bars, metal screws, etc. but the same power coming from my roof must have a single unspliced ground wire? Am i missing something here? The logic just does not hold for me. What i have noticed is that this "continuous" designation is used often but its real definition is vague. Continuous does not necessarily mean unspliced to me. Strictly speaking continuous means uninterupted or stopped. A splice does not interupt or stop this pathway to ground. Does the NEC specifically forbid splices in PV systems because they do not forbid them anywhere else in my house. But i am just a dumb ME. Maybe this makes perfect sense to the EE's and electricians out there.

Scott

Cariboocoot · November 2011

Re: 3 Years with Grid Tie

Actually the third line in the "power coming from your roof" is a neutral line, not a ground. In the main panel box it will bond to the ground bus bar. From there it goes to the Earth grounding rod(s). That is the line they want to be continuous (at least where I am). Why? Because the more connections there are the greater the possibility of failure and that is the safety line for all the grounds in the house. Basically the rules are trying to minimize the risks.

CAOkie · November 2011

Re: 3 Years with Grid Tie

Even the nuetral has connections, in the case of microinverters, at the Jbox, the subpanel, the disconnect, and the main. But I see your point, this wire is critical to have a good path.

I am talking specifically about the bare equipment ground that often is implied must be "continuous". This i dont get. Dont misunderstand less connections is generally always better but one or two at the roof would make installation much easier given that the racks, modules, and inverters can be sufficiently bonded together using WEEB, etc. I can then tie the rails together on the end and run that to a rod. Anyway, just trying to save myself a couple bucks and a little time without violating a code that may or may not exist. It has just been dificult to get the true story on this subject. I realy think it is that word continuous that is confused with unspliced. Thanks Cariboocoot, its good to bounce things around and get different angles on stuff.

Scott

3 Years with Grid Tie

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