25 kW Solar power project in Iowa.

   / 25 kW Solar power project in Iowa. #1  

Redneck in training

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Location
South Central Iowa
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TYM 330 HST with FEL
I am strongly considering installation of large solar array on our farm in south central Iowa.
Here is what I am planning:
1.) Get a loan. That seems to be harder than I thought. Iowa gives interest free loan for 50% of the project provided that the other half is comes from a bank. Since the bank has to do some kind of reporting they are reluctant to commit.
2.) Figure what it would cost. Solar panels are at all time low cost/W. Got a quote for about $435/250 W DC. Have to add cables from the array to the grid, some enclosures, breakers, lightning arrestors etc.
3.) Decide on the set up. Decided to go with Enphase micro inverters that are DIY friendly because of no dangerous voltages and large currents are involved for most part. It will increase the cost of the hardware about 10% though.
4.) Decide on racking. Industrial racking for ground standing support structure is almost as expensive as the panels. Therefore I decided to build supporting structure out of wood bolted together. Saves about 13K.
5.) I got a ballpark quote for turn key installation by local provider $3.90/W. I think I could do it DIY for about 2.15/W or about 53750k.
6.) I used PV Watts to estimate power generation per year. 33500 kWh/year. We pay 10.9 c/kWh so that is $3651/year or about 300/month. Estimated payment on the loan is about 279/month. That doesn't take into account the federal and state tax rebate yet. I think it is no brainer.

Here are few questions to you guys who have done it or have system installed by somebody else:

1.) What precaution you have taken to prevent corrosion of the panels? I am thinking about plastic or stainless spacers between the wooden racking and the panels and use stainless fasteners as necessary.
2.) What voltage drop you or your installer designed the system for? Considering the distance between the solar array and the power meter and/or transformer I think I need to use much larger wires than necessary for the amps because it is recommended to limit total voltage drop to 2% or less. I think I will pull two 4/0 cables instead one 500 MCM. I will have two banks of panels and each will have its own cable for redundancy.
3.) Is there anything else I am naive about? I would like to hear your opinion before I blow the money.
4.) Could I use corugated 3" drainage pipe as a conduit to pull the cables from the array to the building? Or it is a bad idea and I should use PVC.
 
   / 25 kW Solar power project in Iowa. #2  
My buddy bought all his stuff from this company, you might check out their site and prices. They have knowledgeable staff who can help with the design and selecting components.
You don't mention batteries, I guess this is strictly to sell power back to utility if you don't use it all and you don't need backup. It gets cold where you are so batteries would need to be indoors somewhere. You can use high voltage panels to help a bit with the voltage drop. My friend mounted his first panels on industry mounts, very expensive and relatively difficult to erect and mount. Last time he added a panel he just pounded rebar through railroad ties on the ground and used that to mount the panels. Cost was basically free and it was easier to do the mounting.
 
   / 25 kW Solar power project in Iowa. #3  
Would like to do this as well but I would never see a return on the investment. I just can't justify the expense.
 
   / 25 kW Solar power project in Iowa. #4  
Have you done a sun shine study? November through February is pretty cloudy around here. Half the days are cloudy, one quarter of the days are partly cloudy. That leaves only one sunny day in four. Here is a link to city-data that I like to use.


Indianola, Iowa (IA 50125) profile: population, maps, real estate, averages, homes, statistics, relocation, travel, jobs, hospitals, schools, crime, moving, houses, news, sex offenders


Friends of mine built a window unit for collecting heat from the sun to help heat a small unheated room in their house. That is when we noticed that we don't get much sun in the winter time.
 
   / 25 kW Solar power project in Iowa. #5  
Have you done a sun shine study? November through February is pretty cloudy around here. Half the days are cloudy, one quarter of the days are partly cloudy. That leaves only one sunny day in four. Here is a link to city-data that I like to use.


Indianola, Iowa (IA 50125) profile: population, maps, real estate, averages, homes, statistics, relocation, travel, jobs, hospitals, schools, crime, moving, houses, news, sex offenders


Friends of mine built a window unit for collecting heat from the sun to help heat a small unheated room in their house. That is when we noticed that we don't get much sun in the winter time.

In full agreement with you here. Remember yrs back when solar was first being talked about. Local electrical Co built a demo unit, back when it was just solar hot water, no PV panels, first month's report was the setup produces the equivalent of $11 of energy. Think electric price back then was something like $.04kWh. The project dropped from the news shortly.

In the original post I saw no mention of maintenance costs and it certainly isn't free. Lets not forget the possibility of damage to the setup from natural or human caused events over the life of the components. The cost difference between current electric rate and paying off a loan being ~$21/mo is a long way from being a no-brainer for me. If this makes good economic sense, why isn't the power company doing it?

Lots more to think about than what info given. Since the setup appears to not track the sun's movement, power output is going to vary with time of day and time of year. One needs to know that info before making any cost comparisons IMO.
 
   / 25 kW Solar power project in Iowa.
  • Thread Starter
#6  
I got connection agreement from the coop while ago. They will "bank" the excess summer generation and apply it toward the winter deficit. Then once per year I can either cash the excess at wholesale price or pay if there is a deficit. Based on data collected and averaged over past years Iowa is above average in solar energy potential. There is an on line calculator that will estimate yearly production based on location. NREL PVWatts Viewer
I am still trying to learn more about the systems. So far, based on information on Internet ( if you can trust everything what is there) the systems are quite trouble free and perform at least as estimated. I need to learn more about the technical aspects of the systems but I think it is quite easy doable by DIY.
Tracking system could provide about 30% more power generation but since it would increase cost and complexity it is cheaper to add more panels. Tracking system makes sense much farther north where they have very long summer days.
Regarding to financials: If the energy production makes as much money as the loan payment it will cost me virtually nothing or very little to install the system. Then the tax rebate is cash in my hand.
I would like to hear from somebody who has done it.
 
   / 25 kW Solar power project in Iowa. #7  
... There is an on line calculator that will estimate yearly production based on location. NREL PVWatts Viewer...
Went to the site ... loaded my zip ... sent to calculator ... got the results ...

What do the results mean?? Is this based on one collector? What size?
 
   / 25 kW Solar power project in Iowa. #8  
Let see if I understand your post, you want to spend $53,750.00 on a system that will save you $21.00 a month on electric??????
A system that has a limited life span and degrades over time.
30 years ago I took a class taught by a published solar instructor. I learned that it is very expensive up front! And works best for water heating. For power generation it is better than nothing at all but can't compete with the grid.
 
   / 25 kW Solar power project in Iowa.
  • Thread Starter
#9  
Went to the site ... loaded my zip ... sent to calculator ... got the results ...

What do the results mean?? Is this based on one collector? What size?

1.) First you select your location.
2.) Send it to PV Watts calculator.
3.) Enter how big system you want to install.
4.) Edit DC to AC derate factor. Most new systems are better than 0.77. 0.77 is worst scenario.
5.) Edit cost per kWh if different than default value
6.) Calculate.
The calculator spits out how much energy the system will produce at given location each month, year etc. Some location have also hourly data available.

Then you determine how much the system will cost and from that you calculate the payback.
 
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   / 25 kW Solar power project in Iowa.
  • Thread Starter
#10  
Let see if I understand your post, you want to spend $53,750.00 on a system that will save you $21.00 a month on electric??????
A system that has a limited life span and degrades over time.
30 years ago I took a class taught by a published solar instructor. I learned that it is very expensive up front! And works best for water heating. For power generation it is better than nothing at all but can't compete with the grid.
If my assumption is correct and I borrow 50K at about 2.5% interest (remember that half of the loan is interest free, the other half is at 5%) and pay $279/month while the system produces about $300 in energy. That way my household expenses will be $21 less/month. In addition to it I will get 30% federal and up to $3000 Iowa tax rebates. That is about 20K cash in my hand. I think that is great return on investment. Another thing is that the cost remains constant for the life of the loan while cost of energy is very likely to go up.
At current cost/W solar is very competitive with the grid especially when you DIY.
 
 
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