My Solar Panel Power Project

[Rob-D]

Pete,
Nice set up and great documentation! A couple of things some folks might not know. First, panels are rated for 20 or 25 years but in truth they put out useable power for two to three times that. It does drop but not more than 10 to 20 percent. The point is you still keep getting a benefit and there are 50 year old panel still putting out power.

The tracking debate is an interesting one. I want to build a tracker for my panels but right now I'm happy to have them supplying power. I like panels on the ground even in my northern location. You get to site them exactly south, they're easy to clean the snow off and when it comes time for a new roof you're not dealing with panel removal.

Right now I'm running only eight 175 watt panels 48 volts into two Outback 3648 inverters. One runs everything and the other kicks in when it's needed. I'm on a coop grid here, incentives are low so I'm not intertie. I have Rolls batts coming off and MX60 with another one dedicated for my homemade windmills and probably another for my microhydro power that I'm also developing. I want the microhydro to help with the heat in the winter so things will be on a dump load with blowers after the batts reach 100% charge.

Great to see people putting systems together and as fuel prices rise payback time drops.

I just saw in one of my trade magazines that a company has just developed a see through glass solar panel. Also, there's a lot of design work going into high efficiency power circuits and chips. Thanks to the MOSFET we're all getting 95+ % efficiency in our pure sine inverters today. I remember 25 years ago a 1500 watt mod sine inverter cost 5k and was the size of a large suitcase. Things have sure changed, my Outbacks are a thing of beauty!

Rob

 

[eepete]

I wish I could still edit the post, that must time out after some amount of time. Was also kicked by pasting in the descriptions, the single quote kicks in some sort of font change under the "right" (really wrong) circumstances.

OK on the life. in 50 years I'll be at zero percent output with slight fertilizer residual value :laughing:. The typical longer life you mention does suggest that roof mount systems might collide with roof replacement down the road. I have a metal roof, so nothing is going up on that (it has a 50 year life in theory). I do plan on covering the wires as they run between the panels with black nylon spiral wrap so that the wires will last as long as the aluminum, glass, and silicon. That will probably be a change every 10 years based on other places I've done that (such as the indoor thermostat wire that the HVAC guy used outside at the old house).

The Fronious inverter has 3 stages that can be kicked in, so the efficiency is across the entire operating range. High power, high voltage P channel MOSFETs sure do help. I'd love to take the skin off and look, but don't want to risk wrecking the inverter or warranty. I got the 10KW inverter so I could take the DC array up to 10 KW if I wanted to. Will probably be limited by if I can get the same size panels or not. If not, I'll have to take it all apart and intermix the "new" panels into the existing strings. But that's a problem for another day after the financial dust has settled and I have a better feel for performance.

Your system sounds great, too bad the incentives aren't there for grid tie. Batteries definitely up the cost a bit.

Pete

 

[Rob-D]

Your system sounds great, too bad the incentives aren't there for grid tie. Batteries definitely up the cost a bit.

Pete

The up side is that I own it. We get power failures here throughout the winter and that's when it shines. Also I'm planning on an electric car that will charge from my system. I'm not jumping into the first phase of electrics coming out now. My hats off to those folks who get the ball rolling but the second generation will be much better and cheaper.

The nice thing about the Outback system is that I can hook anything I want to it from my own windmills to microhydro, all I have to do is tie in another Mx60 charge controller.
What I'm doing now is working to get my power usage down as much as possible. I'm starting to go to laptops for almost everything now even running my small CNC lathes. My range is gas and I have oil hot water which sips fuel although I want to go to on demand hot water.

The other thing I built into the house was radiant floor heat that runs my boiler at 110 degrees. I'll be tying electric elements into it that run off my stream to reduce my oil consumption. Land is power!

Rob

 

[saltman]

Wow, what a system. I Have an off grid 1,700 square foot home with 9- 215 watt panels and make twice as much power than I will ever need.

Why so many panels? What are you running there a 10 ton AC unit?

Your like the Jay Leno of home owners with all those panels.

My system can make all the power I need here in Southern CA in about 3- hours of full sun. I just finished it in May but anticipate the winter will be the same since I will not be running my ceiling fans.

You obviously have a handle on Solar and I appears yours is about buy back where mine is just about making power for myself.

Everyone has their objectives, but I think if people get their electrical use in order first and then look at what they really need to run an efficient home then Solar would be much more appealing.

No way would the power company here buy back very much power. They only encourage solar because they are forced to but they do it in a discouraging way if that makes any sense. They are all about making big money and selling power not trying to use alternative energy.

Having said that I run everything a normal house would have, Full size Kenmore Fridge, 52 inch flat screen, LG Washer and Dryer, just no AC.

Great System!

 

[Inland NW]

I used to live in Southern California. I put 30 PV panels on my roof at an intial cost of around 45K. The company that installed them projected my ROI at 10 years. I got a refund from the utility (SCE distributed the refund) of 11k making my out of pocket 34k. You can spend more for an "islanded" system that can run without your intertie to the utility but I did not choose this option due to increased cost and ROI. There is a switch in the inverter that senses a hot line, if that switch does not sense a hot line (power outage) the inverter cannot send the converted DC to your AC panel. This is a safety feature to protect line workers (no back feed). My experience was that the real hot days were not the best for generating power because the PV panels lose efficiency in the heat. February was the best month for generating on PV panels due to relative low ambient temps and sunny days. Shortly before I sold my home and moved to Spokane Washington, California changed the net metering laws and I would have started making money for the excess I generated, but did not use. Charges were.12/KWH(Tier 1) to .28/KWH(Tier 5) in Ca when I left. I liked knowing that I was a little more self sufficient and felt less guilty when running my AC during the dog days of Summer. Now I am in Spokane Washington and my home is served by a Rural Cooperative. Due to the lower cost of electricity and no incentives, PV solar panels are not even a consideration. Reading this thread sure made me miss my PV panels.

 

[BillG_in_TX]

Inland,

How much value do you think you recovered on that installation when you sold your house?

 

[Inland NW]

I would say that the solar panels were a definite selling feature for my house. My realtor seemed to think we could get more for the house due to the PV solar panels. I ended up getting within 10k of my asking price, but it is all a matter of opinion if I made my money back or not. I did manage to make money on my house which I first purchased in 1999 and sold in 2010. Then you start adding up all the improvements you made to the home and you start to realize maybe you didn't make as much as you thought you did. Long story short I came to Spokane and put down a large down payment on my home here. I have 10 acres of treed land, no neighbors in site(from my house), and it only takes about 25 minutes to get to work. So far I think I have made a good move. If I had to sit down and crunch the numbers maybe I didn't make my money back, but my quality of life has improved dramatically.

 

[Inland NW]

Maybe I went off on a tangent in previous post. You asked how much value I recovered.... I had the PV solar panels installed in the Summer of 2008 and sold my house in April 2010. In roughly 2 years I did not pay for electricity, but never received any credit for the excess I generated. If my ROI was 10 years as the company predicted then I should have received $3,400/yr in value in those two years. I am not sure that I would have paid that much for electricity in two years, but the way prices were going on electricity in California it probably would have been close.

 

[eepete]

Why so many panels? What are you running there a 10 ton AC unit?

Having said that I run everything a normal house would have, Full size Kenmore Fridge, 52 inch flat screen, LG Washer and Dryer, just no AC.

It's all about the HVAC. The weather extremes in San Diego vs. North Carolina is the difference. We're having a record number of days over 90 this year. You're close on the tonnage, I have a 5 ton and two 3 tons. But they all run at half speed and are all geothermal. They account for about 60 percent of our power usage. From May to September, the geothermal units make all the hot water we need when we're cooling. They help al little bit the rest of the time, mostly they can maintain temperature once it's been reached using the electric heaters in the hot water heaters. The hot water heaters run the most during the spring and fall when there is little HVAC activity. But this is all the stuff I want to monitor and look at.

The inverter is a 10KW, so if I wanted to add 12 more panels I could max it out. But that would cost about $10K to do that, so I'll wait until I have more data on how it's all working.

Pete

 

[BillG_in_TX]

I think if people get their electrical use in order first and then look at what they really need to run an efficient home then Solar would be much more appealing.

Saltman,

I agree with your premise, and I know from reading his posts that Pete is on board, too, but not everyone can live in beautiful SoCal and not need heating and AC to survive. My parents grew up in Beaumont TX without AC, but they both said they don't know how they did it.

We bought our 1970's era 3500 sf home in early 2007, and the previous owners had averaged 3100 kWh per month in the year before we bought the house. That actually killed the deal for me, despite my wife's love affair with the house, and we backed out of the contract during the inspection period. However, the sellers came back with some cash for energy upgrades and lowered the asking price, and we finally did close on the property. We're very happy in the house now, although bringing a 35 year old house up to today's energy efficient standards is nearly impossible.

We immediately replaced one of the HVAC systems that was original to the house, added six inches of insulation, and did a few more things to make the house "tighter". We also replaced an old water heater with a new tankless electric model. Our first year in the house, we averaged 1630 kWh per month - a reduction of 47%. The second year, we replaced 24 single pane windows with Energy Star rated windows and reduced our electricity usage to 1380 kWh per month. At the beginning of our third year, we added the solar PV system and that has reduced our monthly average to a net 900 kWh.

That may be as low as we can go, realistically. Some months our net demand has been as low as 250 kWh, but in the summertime, the AC and the pool pump kicks it up to about 1800 kWh. I can live with that, especially considering the alternative when it's 105 outside (and that's NOT a "dry" heat). Congratulations to both you and Pete on your design efficiencies.