Any advice on solar electric?

[JohnP]

Nords - as a mechanical engineer I've been following your photovoltaic project with interest. I appreciated your approach and would also have avoided the battery system. It looks like you have made an excellent, professional, system with good expansion potential. Congratulations!

I did hydrothermal in my house 25 years ago after looking into photovoltaic; photovoltaic just doesn't work well in Ohio. Hydrothermal has its own challenges - you must pump many, many gallons of water through a heat pump - basically lots of water flow and little BTUs. I abandoned it after the first winter.

PV has some basic advantages as well as challenges; the sun produces just about 1 watt per square inch maximum when straight overhead; any off angles, atmospheric attenuation, and conversion efficiencies reduces the power you can realize from the system, thus one has big panels that produce power, in your case, 55 watts.

Take care with the wiring and keep your pinkies away; 400VAC will give you a burn and toss you across the room to live another day but 400VDC is a lot less forgiving.

As far as expansion is concerned, I had a friend who had relatively good luck by mounting his solar array on a judiciously aimed A-frame outbuilding. This had the added advantage of keeping the equipment and mountings out of the house. Thus, any leaks, etc did not happen inside his main living space.

Great Job

JohnP

 

[Nords]

Another update

When I first started this project our utility was selling electricity to us for 15 cents/KWHr. Late last year that had crept up to 16 cents. Last month's newsletter was 17.7 cents. This month it's 20.5 cents-- up over 30% in less than 18 months. Welcome to the island of oil dependence!

Even if that 20.5 cents/KWHr cost stays flat for the next eight years, we'll still pay off the system faster than putting our money in a mutual fund paying 6% APY after taxes. Every one-percent increase knocks another month off the payback. Admittedly we're getting that from used equipment, a lot of sweat equity, and a big chunk of tax credits. However even at full retail prices a solar water or PV system will pay itself back by this extremely conservative method within 15 years-- better than 95% of the stock market's dividends.

This morning I installed a spring-check valve in the solar water system's hot-water return leg. It blocks the natural circulation reverse flow that lets the hot water rise back up to the panels when the pump shuts down. Even after just eight hours on a cloudy day we're already up 60 degrees F. I doubt we're going to lose much after sundown, either. Tonight-- after things cool down on the roof-- I'm going to have to shut down one of the two panels.

 

[Nords]

Yet another update.

Freakin' unbelievable.  HECO just sent a human being out to the house to ask why our power consumption has dropped so low.  (At least that's why he said he'd come out here.)  Then he said that he'd noticed the inverter on the side of the house, and instead of sneaking away with his own personal humiliation at answering his question, he rang our doorbell to let me confirm it and add my dose of humiliation. 

I told him it was because of our net metering agreement with our electric company, a group called "HECO", and that if he had used a "telephone" I would have been able to answer his question before he used "our" money to get in his car and drive out here.

He had a photo ID, a clipboard with a record of our previous years' use, and a car with a HECO decal on the door.  After he'd left the HECO customer service call center confirmed that yup, by golly, they have that guy working for them, and they even described his appearance.

Sure glad I don't own the stock.

 

[Brat]

Ah, give the guy a break. His supervisor sent him to your door. There are folks who tap around the meter.

Maybe you should offer the HELCO customer service folks a tour of your set-up...

 

[laurence]

My coworker is taking bids to have a system installed, he's looking at $4.80 a watt(?). I told him you had cut costs by installing it yourself with collected parts. He looked at his carefully manicured hands and said, "yeah, this'll pay back in 15-20 years, that's good for me". What is your cost per watt for the installation, Nords? Am I doing the math right that you are less than $1 a watt?

 

[Nords]

My coworker is taking bids to have a system installed, he's looking at $4.80 a watt(?).  I told him you had cut costs by installing it yourself with collected parts.  He looked at his carefully manicured hands and said, "yeah, this'll pay back in 15-20 years, that's good for me".   What is your cost per watt for the installation, Nords? Am I doing the math right that you are less than $1 a watt?

$4.80/watt is a great retail price around here, where contractors are having trouble getting panels for less than $7/watt and installed systems cost about $10/watt. But CA & PG&E have much more aggressive subsidies than Hawaii.

We still have a few years' tax credits in the future, but when all the credits are taken our installation cost should be about $2.34/watt. 15-20 years' payback is about standard, and hopefully he'll be staying in his house that long because I'm not sure that home buyers are paying extra for PV. Of course PG&E scares a lot of people over there, so maybe there is some home value in PV.

http://early-retirement.org/forums/index.php?topic=7749.msg138978#msg138978
http://early-retirement.org/forums/index.php?topic=975.msg40144#msg40144