Thursday, April 17, 2014

Net metering

First an update on our solar.  We remain pleased with system performance.  Overall we think we use more than we generate, especially this past winter.  We have also had electric fencing on and the new garage has increased our demand.  We have kept all the data but not analyzed it to know for sure.  One panel went down, it took us months to figure it out and then months more to get it replaced.  Joe Sheffield of Alternative Energy Concepts has left that company but was gracious to help us with the warranty repair.

We have been using the system for just over 4 years.  We remain with a buy all sell all arrangement.  Our local utility sells us everything we use at the full retail rate.  We have a second meter that the utility purchases electricity we produce at the wholesale rate.  The info we get from the utility indicates that we pay them a fee each month for the second meter.  My wife keeps track of the system generation data and every three months submits the info to NC Greenpower, selling them our renewable energy credits (REC).  The reimbursement rate for our current contract is 15 cents per kwh.  With one year left to go on this contract we are looking at what the future holds for us.

NC Greenpower still purchases RECs but only for 6 cents per kwh.  This would basically eliminate a lot of incentive for new solar installations.  It also changes the payback to us on our current system to perhaps being equal.  A local installer suggested to me that the local utility sells electric at 13 cents per kwh, buys generated power at 7 cents per kwh.  As solar PV generators we have to keep track of the data, submit to NC Greenpower (or another broker in the future), wait for the check to come, and pay for an extra meter each month.  This will be extra frustration and expense on our part with no additional benefit.

There is a solution to this issue that is available in most of the United States.  This solution is called net metering.  One single meter is used to keep track of net energy usage.  If extra power is generated it is credited with the local utility each month.  After a year of use any excess credit is lost, though in some areas different things happen such as the generator getting paid either the wholesale, the retail, or some other rate based upon incentives.  RECs can be kept by either the utility or the generator.

My local utility does not currently offer net metering.  I would like to begin net metering next year.

In 2005 the Attorney General ( I think this is of my local state) in a brief filed with the North Carolina Utilities Commission (NCUC) supported the adoption of net metering.    NCUC has the following info about their position regarding net metering:

There is a summary of the above available at the following link:

The United States Department of Energy has a publication called Solar Powering Your Community:  A Guide for Local Governments  (click for this document to open in a new window)

On page 89 of this document is the following:  

They then follow up with the following:

Today I am going to go to my local utilities board meeting to request they start net metering.  My local utility is guided by the local city council so I anticipate going to the city council meeting tonight to also ask for their assistance.

If you are a solar advocate in my area, please contact those you know on the boards of the utility and city council to ask for net metering.  Thank you for your assistance.

4/27/14 update:  NC Greenpower said they do not renew contracts at any rate.
Another company said they would not purchase my RECs.
GUC says they will do a rate study that might get net metering started.
GUC already has rates to buy and sell electric so it seems they could just make the decision to net meter?

Friday, April 9, 2010

Financial update

1. We are starting to see credit on our utility bill. The one that arrived today credits us 21.06

2. We have received our federal tax refund and therefore have 30% of our expense back already.

Friday, February 5, 2010

Utility Company data

I am going to try and paste images of an email I got from the local electric company that details energy generated. Click for larger if you wish.

Tuesday, January 19, 2010


Hi guys,
Congratulations on your startup. Interesting monitoring site with neat data presentation.
What do you estimate the annual kwh production of this array ?? Take care

We asked for a system that would produce what we were currently using. We forwarded utility records to our installer and he told us this was the size system we would need. I went back in the blog to look at records and for the previous year we used 7984 kwh, 665/month, or 21.87 per day on average. So that is what we expect to produce over the course of the year.

We expect more light in the summer but the panels will be less efficient due to warmer temperatures. So as time goes on we hope to see increased production just at lower numbers. Our panels are 215 watt rated, so that would be the maximum number we could see on the monitoring site. For efficiency sake, if we see 188, that means that panel is converting 87% of maximum. We also expect we are using more energy with the garage addition.

The reason we went with this size system rather than the breakeven point that a smaller system offered was we wanted to be able to convert to net metering without any subsidy like payout down the road and still make all we need. With selling the renewable energy credits we will make an extra seven cents per kwh, not sure how long this will stay around.

Monday, January 18, 2010

Usage vs production

My off the cuff calculations suggest that over 10 days we averaged just over 20kwh production per day. Our most recent utility bill suggests we used 33 kwh per day. Hmm!

Thursday, January 14, 2010


sounds interesting...I have so many questions. cost to install and maintain, durability and life after install, how many days can you go without sunlight. does it store energy for a rainy day...hahahaha

Cost to install: Both my father and I found systems to be about 7K per kwh, ours is a 5.16 kwh system. It gets a little cheaper as you get larger. If this industry grows hopefully prices will come down.

Maintain: I do not know yet but do not expect to spend anything unless a panel goes bad. I recall them being tested for good 25 year life or better. With my system I have more parts, but they are smaller and if something goes bad the replacement should be cheaper (this refers to my microinverters compared to my fathers). The system I have does have a $2 per panel per year fee for the internet interface, so $48 per year to have the enphase link work.

Without sunlight? No problem as we have two meters. We still pay local utility normally, sell ours through the other meter. In the end, we should make money at this, my rough estimate is 10% return each year.

Electrical storage? We did not install a battery backup system. This would allow us to live off grid but would add five thousand to the system cost and require more maintence.

A note on system cost: NC offers 35% tax rebate on system costs, maximum is $10,500. Federal government offers 30% tax credit, no limit. So while we had to get a bank note to pay for this up front, we will only be responsible for about 35% of the system costs. With the payments for energy generated, most systems will pay for themselves in 5-10 years.

See link at topleft for my father sharing his solar experiences

Wednesday, January 13, 2010


From a friend:
Congratulations on the successful solar project. It was a good reminder to check in on your blog. That new site is cool, too.

I meant to ask a few questions earlier but I'll ask now.

1. What sort of bracket holds the panels on and is it just nailed screwed through the shingles into the roof with some patch or rubber seal around the hole?

2. In 20, 30, 50 years when the roof needs replacing, do the panels come down for that and then go back up? Does the installer do that or the roofer or Joe's nephew?

3. Does having solar panels on the southern roof affect the passive solar qualities of the building (does it make a building hotter or colder and would it depend on the type and color of roof)?

Congratulations again.

1. Our brackets are roof mounted prior to the shingles. It lifts the panels off about 6 inches. The distance should help with cooling airflow in the summer, a good thing since panels run more efficient when cooler.

2. The panels and racking material come off the roof for roof work. Likely extends a reroofing job by a week or so. Hopefully a solar company does this.

3. Solar panels should make the building cooler as they are the object that receives the heat. The shingles beneath them should be in the shade and cooler. As a side note, we went with light colored shingles to enhance the new building looking like our house and also to keep the panels cooler.