Anyone have a solar system on their house/garage?

[Sam1]

We're starting to look for a house and planning on setting up a solar system on it. Looking to do one at a minimum of 5kw (possibly up to a 10kw depending on if we can push it back on the grid in that area) for power and possibly a solar heating system as well.

 

For any of you all that have them, what are the actual benefits you're seeing? One of my friends in Cali said he done a solar water system with the excess fed to a radiator in his garage so he gets free heated water and heat in the garage and said that actual solar power was questionable to do it from an expense standpoint. 

 

Would be interested to hear from someone who actually uses it in TN

[Caster]

A whole solar system? Dude, you have one huge garage!

[peejman]

I've looked into it a bit.  My conclusion is that its only worth doing if you're certain you'll be in the same house for at least 10 years (rough payback period).  Electricity is very cheap here compared to the northeast and especially CA which makes it less financially viable. 

[Sam1]

Caster, there's a lot of options, roof of the house, roof of the garage, ground mounted etc. The output is getting pretty good on them, so they don't need as much room as you would think. There's some past 400watts per panel at barely over an extra sq ft of the normal 250watt ones

Edited January 21, 2013 by Sam1

[Poor_Dog]

I had a system on a cabin/RV that I lived in for two years. Built it myself and when I moved I installed it on my garage and wired a back-feed to the house in case of emergency. Mine was just 1 kw and it was sufficient for what I needed; which was lighting, laptop/internet, television, freezer and such...

 

As far as selling back electricity in Tennessee, the abundance of low cost power makes it close to a 20 year payback or some such, maybe longer. From that aspect I wouldn't recommend it but for a remote location or as an emergency back-up they can't be beat.

 

A 10KW system is going to be expensive, 'specially with the required codes being met...

[Dolomite_supafly]

And in some places, I know knoxville does, limits the amount they buy back. In our area when they announced they would buy back excess so a lot of solar businesses cropped up. And because KUB is only paying so much per year those businesses used up all the funs and cut out the homeowner. I was going to setup solar with the only intention of offsetting my bill but they said all the money allocated buying back energy is already called for.

 

I guess if you set it up to use solar as the primary and grid powder when you need it might be fine.

 

Dolomite

[Sam1]

Agree on the 10kw system, that would only be an option if wherever the house is, pays decent for excess power

[TripleDigitRide]

Caster, there's a lot of options, roof of the house, roof of the garage, ground mounted etc. The output is getting pretty good on them, so they don't need as much room as you would think. There's some past 400watts per panel at barely over an extra sq ft of the normal 250watt ones

I think he was jokingly referring to our solar system, as in our planetary system.

[Sam1]

And in some places, I know knoxville does, limits the amount they buy back. In our area when they announced they would buy back excess so a lot of solar businesses cropped up. And because KUB is only paying so much per year those businesses used up all the funs and cut out the homeowner. I was going to setup solar with the only intention of offsetting my bill but they said all the money allocated buying back energy is already called for.

 

I guess if you set it up to use solar as the primary and grid powder when you need it might be fine.

 

Dolomite

 

Was not aware of this, thanks. Maybe we'll just focus on a system to cut the bill and not even worry about a big system

[MacGyver]

TVA limits consumer buyback to 50kw.  Essentially, they buy everything you produce, and give you a credit.  Systems are getting a lot less expensive, and now with the advent of onboard inverters, they're starting to make a lot more sense for the homeowner.

[Sam1]

I think he was jokingly referring to our solar system, as in our planetary system.

 

Sorry didn't even catch it, have put in over 12 hours in on a 20 page document for school since yesterday on theoretical solutions for problems that do not exist and probably never will... Brain is functioning at about 7% efficiency at the moment

[Poor_Dog]

Good place for DIY's, they have Evergreen factory blemished panels too. Best prices I have found on solar related items and the owner is fantastic to work with. I used their blems, they were very hard to tell from new, matter of fact each box came with a blem and a new panel.

 

http://www.sunelec.com/

[Sam1]

Good place for DIY's, they have Evergreen factory blemished panels too. Best prices I have found on solar related items and the owner is fantastic to work with. I used their blems, they were very hard to tell from new, matter of fact each box came with a blem and a new panel.

 

http://www.sunelec.com/

 

Do you do this for work, or personal?

[Poor_Dog]

Personal, I started researching/buying it back in '04. More as a SIP type of thing, trying to prepare. I only used one 180 watt panel at the time. Got divorced in '06 and bought myself a cabin down on the Harpeth river and set the whole system up. I told you wrong earlier, it was 1.4 KW system (8 x 180w). I lived in the cabin and a small camper using the system. The camper could run on it infinitely as it was 12vdc or 120vac, I usually ran on the AC side. That system could very easily run my freezer and all the lights I needed, laptop and satellite internet (Hughes Net). My power requirements were minimal. I kept a generator handy if I needed a boost which was rare.

 

It's important to remember that if you have a 1.5 kilowatt system, at max you are only going to have 65% of that to actually use and that is relying on excellent sunlight. Some of the newer systems may do a little better but not by much.

 

Just to put it in perspective, the average home will use near 40-50kw/day, BUT you can make it work for way less, by arranging your life style around it... Living that way sure makes a fellow appreciate the amount of work a watt can do!

[vontar]

I keep looking at solar but batteries seem to be the tipping point.  I figure batteries will last 2/4 years (based on nothing other then knowing batteries go bad) and will have to be replaced.  So the entire battery cost is going to cycle ever few years even if the panels hold up perfectly.

 

I just find it hard to invest it it where I have my home electric bill down to around 50 a month on average.  Except when I run the AC heavy in the summer.

Edited January 22, 2013 by vontar

[Romad7]

Hmm, this has me thinking. The batteries would be great for when the power goes out here...

[Poor_Dog]

Batteries can be a large expense unless you do some shopping. A typical deep cycle battery would be sucked dry and ruined in short order. I used recycled UPS batteries from the phone company, over 100 lbs each. 2 year old, 10 year life, for 35-60 bucks. I've also bought them by the pallet at $15-20 per battery. You have to be careful about deep cycling them, usually never go below 12.0vdc, I tried to keep mine at 12.1vdc or above, 13.1 or so is fully charged, 11.0 is dead, below that is real damage to the plates. Operating, mine would generally hold 12.4 to 12.6 until they started to run down, then they dropped rather quickly.

 

Charging is important too, your charger will need to float the batteries at 13.4-5, over charge them at times, shut the system down if need be, so on and so on. There's allot that goes in to it, read and research before anybody takes a shot at it. I couldn't get in to all of it without writing a book, you can get seriously injured by hooking up some batteries to an inverter and plugging in the house...

[vontar]

Poor Dog

 

You have to tell me where to get these 2 year old 10 year life batteries at such a nice price.  Something like that might put me back in the game.

[Sam1]

We're working with someone now and are waiting on an estimate to come back comparing the PV vs. water system.  The company was saying that PV's will pay back pretty quickly, but the more he talked about a water system, the more desirable it got. The new solar water systems can heat water to 160 degrees easily, and for safety, it only heats the water in the tank to 120, so there is a lot of excess.

 

He said they can install a coil in the HVAC unit so we can pull excess off there in the the central unit, they can do the normal fin radiators, or floor heating. The one that takes the cake though, is he has installed "heated towel racks" that are plumbed into the system. Obviously these are not for us because we want some functionality, caring about the difference between a warm towel and a room temperature towel should be left to spas and lottery winners... But it does look legit, and they even manufacture "heated shower curtain rods" lol

 

http://www.mysoncomfort.com/TowelWarmers/European

 

http://www.mysoncomfort.com/TowelWarmers/ShowerRails

 

^ for if you ever have extra money and have bought everything else known to man  :rofl:

[BillP]

I installed a system with battery backup.  That was a mistake because it cuts efficency too much. 

At the same time we installed a 8400 watt system on my brother's house, which faces the ideal 180 degrees.  Even this winter, with sun low, he is getting about $30.00 a month more than what his water and electic bill is.  Up to 50 KWH per day in the winter.  His system uses the Enphase microconverter.  It is a great system with a pretty quick payback.  He will pay no utility bill for the next 10 years plus get a check for about $1300 at the end of each year from the local utility.   

We both installed our system while the TVA contract pays a $.12 premium plus the retail price of electricity. EPB Chattanooga is paying me $0.214 per KWH for what my system produces.  TVA has now reduced that to a $.09 premium in addition to the retail price.  Go to TVA.gov and read the (rather long) rules for the deal.  Limited to 10 KW system on a home currently.

TVA will pay you (through local utility) $1000 upon completion of your system, then you can subtract 30% of the full cost of the system from your income tax.   Not worth doing unless you do it by the rules to qualify for these paybacks.  

[enfield]

As in, "Doesn't make financial sense to do unless you get your neighbors to help pay for it".

[peejman]

I installed a system with battery backup.  That was a mistake because it cuts efficency too much. 

At the same time we installed a 8400 watt system on my brother's house, which faces the ideal 180 degrees.  Even this winter, with sun low, he is getting about $30.00 a month more than what his water and electic bill is.  Up to 50 KWH per day in the winter.  His system uses the Enphase microconverter.  It is a great system with a pretty quick payback.  He will pay no utility bill for the next 10 years plus get a check for about $1300 at the end of each year from the local utility.   

We both installed our system while the TVA contract pays a $.12 premium plus the retail price of electricity. EPB Chattanooga is paying me $0.214 per KWH for what my system produces.  TVA has now reduced that to a $.09 premium in addition to the retail price.  Go to TVA.gov and read the (rather long) rules for the deal.  Limited to 10 KW system on a home currently.

TVA will pay you (through local utility) $1000 upon completion of your system, then you can subtract 30% of the full cost of the system from your income tax.   Not worth doing unless you do it by the rules to qualify for these paybacks.  

 

 

Care to say how much the 8400W system cost?  Or what the payback period is?

[BillP]

The 8400 watt system cost about $20,000 for a DIY install.  Brother is a PE, and EE with 35 years work in electrical distribution.  He did hire roofers to do mounts on the roof. 

From the $20,000 investment, he got a grant of $1000 from TVA and a 30% ($6000) refund from the IRS, for a net cost of $13,000. ABSOLUTELY, you can not get a payback on these systems without sucking on the government teet!    Solar power can not sustain without subsidy, paid by government and other electric rate payers. 

The system is producing at the rate of $2950 per year, with the $0.12 per kwh premium that TVA distributors payed on contracts made last year.  Now it is $0.09 premium. 

So, about a 4 1/2 year payback, counting no interest.  The TVA program includes the premium for only 10 years, then you get only credit at the normal retail rate.  But the system should produce for about 30 years. 

His sytem is highly efficient, using the Enphase microinverter.  95% of the power produced by his 36 panels flows out to the electric system. 

My system has batteries, so if the electricity goes off, I continue to have power.  But payback on my system, unless you put value on that backup power, is basicly, never.  Batteries cut the efficiency too much, and they won't live over about 5 years before replacement. 

More later.

[peejman]

The 8400 watt system cost about $20,000 for a DIY install.  Brother is a PE, and EE with 35 years work in electrical distribution.  He did hire roofers to do mounts on the roof. 

From the $20,000 investment, he got a grant of $1000 from TVA and a 30% ($6000) refund from the IRS, for a net cost of $13,000. ABSOLUTELY, you can not get a payback on these systems without sucking on the government teet!    Solar power can not sustain without subsidy, paid by government and other electric rate payers. 

The system is producing at the rate of $2950 per year, with the $0.12 per kwh premium that TVA distributors payed on contracts made last year.  Now it is $0.09 premium. 

So, about a 4 1/2 year payback, counting no interest.  The TVA program includes the premium for only 10 years, then you get only credit at the normal retail rate.  But the system should produce for about 30 years. 

His sytem is highly efficient, using the Enphase microinverter.  95% of the power produced by his 36 panels flows out to the electric system. 

My system has batteries, so if the electricity goes off, I continue to have power.  But payback on my system, unless you put value on that backup power, is basicly, never.  Batteries cut the efficiency too much, and they won't live over about 5 years before replacement. 

More later.

 

 

Thanks much.  I'm the nerdy engineer type too, hence my curiosity.

[BillP]

You can take a look at what my brother's system is producing right now at:

https://enlighten.enphaseenergy.com/public/systems/x9pB113233

It includes a photo of his roof.  We installed this system last fall and it has produced 4.2 MWH so far, during the worst solor months of the year. 

 

If you would like to calculate what a system would produce at your house, go to:

www.nrel.gov/rredc/pvwatts/

I suggest you use "Version 1" of the calculator.  You input your possible system design and  location.  It will give you what you will produce pretty accurately, if you put in the correct percent efficiency.  It defaults to 77%, but a well installed Enphase microinverter system, on  a 5/12 roof, facing south, will give about a 95% efficiency. My battery backup system is about 67% efficient.   For "nerdy engineer types" this calculator is fun.  For electricity value, put in what you pay per watt, plus $.09, as that is what you will be paid if in the TVA area.  We get the $.12 premium over the rate as our contracts were signed last year.  So currently $.214 for me.

 

We installed the Sharp 240 watt panels made in Memphis, but I don't think Sharp produces them there anymore. 

 

If you have more questions, let me know as I have paid dearly for my practical solar power education!  Had to skip some gun purchases I really wanted to make because money was tied up in solar.