Solar Power Stations

[Trek]

I'm a big fan of solar and wind power, so I find projects like this fantastic. People working on real energy solutions for the future.

http://news.bbc.co.uk/2/hi/science/nature/6616651.stm

[Texas Proud]

Once they come up with a system I can put on my house in the $5 to $10K range that has a bank of batteries that can power my house lets say 70% of the time (it is hot in Houston... I don't NEED to power the peaks)... I will be buying one...

PS... closer to $5 if you please!!!

[Nords]

Quote:

Originally Posted by Texas Proud Once they come up with a system I can put on my house in the $5 to $10K range that has a bank of batteries that can power my house lets say 70% of the time (it is hot in Houston... I don't NEED to power the peaks)... I will be buying one... PS... closer to $5 if you please!!!

eBay, a lot of patience, some DIY toolwork, and tax credits.

Seriously.

[justin]

Quote:

Originally Posted by Nords eBay, a lot of patience, some DIY toolwork, and tax credits.

You forgot to mention "professional training and experience as a nuclear engineer"!

[Nords]

Quote:

Originally Posted by justin You forgot to mention "professional training and experience as a nuclear engineer"!

It's true that contributes to the attitude of "no fear"-- or at least "blissful ignorance". I spent a lot of my time with mechanics, electricians, & electronics techs. And the Navy did eventually teach me not to ground myself while touching electrical wires.

I'll submit that if you can drill holes in a perfectly leakproof roof and figure out which wire goes to the terminal marked with a "+" then the rest is just details. All the necessary information is free on the Internet. People are selling perfectly sound equipment on eBay for 50 or even 25 cents on the dollar because they have no idea of its value. Spend an afternoon watching a solar crew putting in a roof array and by the end of the day you'll be thinking "That ain't so hard..." Or visit a local college's engineering department and spend some time with their solar geeks. They'll not only show you, they'll be delighted to teach you by letting you help!

But you have to enjoy this stuff. Otherwise it's just a big capital expense with a heckuva long payback that's another decade away from prime time. Kinda like it was in 1997 before anyone had even heard of the Prius...

[SecondCor521]

Hey Nords,

If my electric bill is only $40 a month, does it even make sense to consider a system? Do they scale down well? Because a $5,000 initial capital expense to save $40 per month doesn't seem like a decent payoff.

2Cor521

[Brat]

Here is Nord's favorite solar power generation provider, I think they are on track too: http://www.stirlingenergy.com/solar_overview.htm

[Nords]

Quote:

Originally Posted by SecondCor521 If my electric bill is only $40 a month, does it even make sense to consider a system? Do they scale down well? Because a $5,000 initial capital expense to save $40 per month doesn't seem like a decent payoff.

It's almost always easier to reduce your consumption than to raise your production. A lot cheaper, too.

When your consumption gets to that diminishing returns line, then it's almost always cheaper per KW to build a 3000-watt system than a 1000-watt system. Aside from the electrician's labor, the biggest expense in a photovoltaic system is the DC-AC inverter. We paid $2500 for a brand-new 3 KW inverter (full retail) because of its better design & improved longevity. But with my wisdom of experience I wish I'd spent the extra $1000 for a 6 KW inverter, because someday we're probably going to buy another 3 KW inverter. Of course we're going to drive that expensive electronics with crappy three-generations-old used PV panels.

A $5K outlay at $40/month is a 10.5 year payback, and in the solar business that's darn good! (15-20 years is more common.) In the stock market that $40/month is also a 9.6% dividend. However you may not actually save $40 since most utilities have a minimum monthly charge for staying connected to the grid. (From an engineering perspective it's easier to remain connected to the grid, although it's not always the most cost-wise answer.) We pay HECO $16/month whether or not we use any electricity.

What most people overlook is that the final system price may also include a bunch of federal/state tax credits (as much as 30%-- and that's a credit, not a deduction). Another easy-to-miss number is inflation. Two years ago Oahu electricity cost 16 cents/KWHr and now it's 20.5 cents/KWHr. HECO's already campaigning for another rate hike and I'm sure they'll dream up a bunch of additional fees & charges that don't have to be approved by the PUC.

Speaking of consumption, a house's two biggest energy-suckers are typically the water heater and the refrigerator. Replacing the first with a solar water-heating system (with an electrical backup) can cost as little as $1500 in Hawaii and pay for itself within three years. Your location's numbers may also be that favorable. And if your fridge is more than five years old then it's worth spending the $750-$1000 to replace it with an Energy Star over-under 18-20 cu ft. We bought our Fridgezilla at a stupid price because it only uses 75% as much energy as our six-year-old model.

Of course if you're one of those people who's buying their frosty beverages or their frozen meat all over again every month with the electricity costs of the extra ("beer") fridge or the chest freezer, then you can make a huge improvement by getting rid of them...

[SecondCor521]

Nords,

I think my consumption is already pretty low. Checking my last bill I used 490 kWh. Cost per kWh is about 5.4 cents.

(Note that $40 is my level pay amount.)

You're right, looking at payback and as a dividend yield it's pretty good...if a $5k system can get me $40 per month.

I checked my state tax forms, and I can get a deduction, but not a credit, for a solar electricity device.

I pay $4.46 per month as a flat service charge, so the actual max monthly savings would be $35.54 if I did my head math right.

My water heater is one of those on-demand heater, and it's natural gas, not electric.

Fridge is 2 years old, came with the house. Dunno how energy efficient it is.

I would think my dryer is also a big energy sink, but I don't know how to tell.

No extra beer freezer.

2Cor521

[Brat]

Don't overlook the fact that some electrical utilities buy energy from solar systems, the power feeds back into their lines.

We had solar hot water in our previous home.. it's location wasn't 'sunny' and the house was above the 45 =. The water got so hot that it damaged something inside the water heater (a dip-stick kinda thing), it wasn't designed to handle those temps. I think solar hot water is fantastic but the hot water tank needs to be designed to accommodate it.

[Nords]

Quote:

Originally Posted by SecondCor521 I think my consumption is already pretty low. Checking my last bill I used 490 kWh. Cost per kWh is about 5.4 cents.

Man, we use less power than that (even before going solar) but I'm jealous of that KWHr rate!

It looks like you've done your research. Reading the rest of your comments, you're better than the average American and you can sleep soundly at night on your green accomplishments. You don't need the hassles of going solar unless you think it's as geeky cool elegant an engineering solution as I do. I do this as much for fun as for the money.

If your gas water heater blew out then you might do better with a solar replacement, but you have to check your area's insolation maps. And Brat's right, most of the cost of going solar water is the big heat collectors and the special high-temp design of the water tank. It gets even more complicated if water freezes at your latitude.

The fridge is probably efficient enough that it's not worth the tweaking hassle of finding something better-- unless it breaks. You can measure your fridge's energy consumption by looking up its energy rating for its model or by plugging it into a Kill-A-Watt power meter. I wish I could find a 220v Kill-A-Watt for electric dryers, but I doubt it'd convince my spouse to hang a clothesline. Even worse it might get me permanently appointed to "Laundry Boy", and there's no telling how much I'd have to screw up to get fired.

HECO is pulling their hair out over powering Oahu's beer freezers. Most of them sit in people's hot garages or, even worse, on their sunny lanai. They even used to buy people's second fridges for $25-$35. After all it's not like we can ship in a bunch of extra power from Canada or the TVA...

[SecondCor521]

Water freezes where I live, so I don't think I'll do a solar heater. Besides, I like the tankless.

You actually use less electricity than I do? Wow. About 65% of the time it's just me, and I'm gone from my house the vast majority of that time. The rest of the time it's me and my three kids. I do have an electric oven, which I use to cook with a lot, that may make my numbers go up a bit.

If I did something like this it would be to learn about electricity and to save myself some money. I'm not much of an engineer although that's what my job title says.

I think in my HOA clotheslines are effectively outlawed because people think they look trashy. Oh well.

2Cor521

[Khan]

That reminds me: it's time to put the clothes line back out. (I have the umbrella style).

20 month running average: 230 KWH/month.

[Texas Proud]

The problem here in Houston is the air conditioner... I have a 5 ton unit and it can suck some energy... during the summer it is not unusual to use 1600 to 2000 KWH... the price is 'going down' to 12 to 14 cents per KWH...

Do you have batteries Nord I would think that for heavy load items such as air and if you have it electric heat you would 'like' them.. but don't know if they would be cost effective... just use your utility connection..

I have gas heat and gas tankless water heater... cheap to use...

[Nords]

Quote:

Originally Posted by Texas Proud The problem here in Houston is the air conditioner... I have a 5 ton unit and it can suck some energy... during the summer it is not unusual to use 1600 to 2000 KWH... the price is 'going down' to 12 to 14 cents per KWH... Do you have batteries Nord I would think that for heavy load items such as air and if you have it electric heat you would 'like' them.. but don't know if they would be cost effective... just use your utility connection..

No heat here, and only a half-dozen ceiling fans for cooling.

I spent a career with submarine lead-acid batteries and the last thing I wanted to do in ER was to take care of a bunch of my own. We have a PV array to make money, not for reliable power generation.

Grid-tied PV gives us HECO's rock-solid 240-volt AC bus voltage with wiggles noticed only by the computer's UPS. When the fridge or the vacuum or the dryer start up there's no voltage transient and no adverse effects on anything else in the house. (In the bad old days of 1970s-80s solar, people used to avoid 40-volt bus transients by using fridges powered by propane and with smaller canister vacuums instead of power-hungry roller-brush self-propelled vacuums.) Our grid-tie inverter is cheaper than a battery-charging version and we don't need the added expense of a charge controller or a battery bank. I also don't have to monitor water levels, specific gravities, or other battery-related issues. Of course the grid-tie inverter has to sense HECO's grid voltage before it'll power up, so if HECO goes down then we're out of business like everyone else on the street.

Otherwise on the average sunny day our array generates 10-12 KWHr of electricity. It varies about 25% from June to December and even keeps going during rainstorms. We use between 300-400 KWHr/month so we're making just slightly less than we use. (I still have to mount the 325 watts of panels I bought in January, which will bring our total power generation to 11-13 KWHR/day but which will also be pushing a 3000-watt inverter to about 3350 watts.) The excess power we make during the day is dumped into the grid (analog meters spin backwards) and HECO credits our account at their retail rate (the same rate we pay for the electricity we consume). At dusk the inverter shuts down (until there's enough morning light & array voltage to start it up again) and we take our power from HECO's grid. If we make more power than we consume, HECO's digital meter keeps the credit on our books for up to a year.

It's totally autonomous. I don't have to look at it or tweak anything, and I only clean the panel glass once or twice a year (mainly pollen & bee poop). Never had a problem, although we & HECO were offline for about eight hours during last October's quake.

Our pictures are at:
http://s11.photobucket.com/albums/a1...ltaic%20array/
http://s11.photobucket.com/albums/a1...y%20expansion/ and
http://s11.photobucket.com/albums/a1...Solar%20water/

Now if I could just find the square footage for another 6-8 KW of panels to support a plug-in Prius...

[TromboneAl]

There was an entertaining NOVA on solar power recently on PBS. They showed a thermal solar plant that was built during the 70s fuel shortage. The reported problem with those is that they have to be built in a large space, such as a a desert, and that there are losses involved in transporting the electricity. Would have been nice if they quantified it.

The other news was the quest of Germany to get 20% of their energy from renewable sources by 2020. So there are big subsidies for solar panels, and that's driving a lot of production.

[Brat]

There is a major research facility in the north end of the Napa Valley. Noticed it as we were driving from OR to SF along 101 in February. DD (who works for a VC on Sand Hill Road) said that she expects major developments in the next couple years - told DH to hold off adding a solar system to her home remodel.

Mt. View home owners are repesting proposals from solar contractors for whole neighborhoods.

[Nords]

Quote:

Originally Posted by TromboneAl The other news was the quest of Germany to get 20% of their energy from renewable sources by 2020. So there are big subsidies for solar panels, and that's driving a lot of production.

I love capitalism.

A couple years ago all the solar contractors were complaining about "Those $%&^ Germans" driving up all the prices. Meanwhile some solar stocks like Evergreen and Sunpower were rising triple-digit percentages or more, and solar silicon was a hugely expensive commodity. I made almost as much profit from Evergreen as I've made from our PV array.

By now the demand has worked its way through the system and businesses are starting to respond to the profit opportunities. Laboratories are reporting huge increases in conversion efficiency or the uses of alternative materials. Manufacturers have all ramped up production (both of the raw materials and the finished products) and unit costs have dropped way down. Businesses & homeowners are responding to the tax incentives (and the lower costs) by driving up the demand and further raising the output.

And a lot of people with old systems are ditching them for upgrades. Those old systems are almost fully depreciated and widely viewed as 1967 VW Beetles. But like the Bugs, there are still parts available and they still have plenty of mileage left for DIYs. In the last couple years what I used to pay $4/watt for now costs $3 watt and even less.

So if you're thinking about a PV system but not an early adopter or a DIY, start talking to contractors and keep an eye on the prices. Contractors are usually hugely busy in Oct-Dec (the end of the tax year) but languishing in Jan-Mar. Govt tax incentives & utility subsidies may expire or be replaced by new ones. In a year or two the supply will inevitably exceed the demand and pricing will drop even further, at which point you'll be able to scoop up a bargain system with cheap installation.

And lemme know if you come across a good used Xantrex 3G inverter...

[SecondCor521]

Nords,

OK, I'm procrastinating on an MBA term paper doing a DCF analysis of a PV system.

Basically, where is a good place to start learning how to design a system?

What inflation rate in energy costs do you assume?

If I assume an average use of 20 kWh per day, how do I figure out what size of system to install? Do I need to worry about peak usage or just average usage?

Should a beginner like me try to cover just part of my electric usage, about all of my electric usage, or more than my electric usage (assuming my electric company buys back any excess power and lets my meter run backwards)?

How do I decide if I want battery cells or not?

What are the main cost components of a system? I have down PV cells, mounting hardware, wiring, inverter, and connection stuff (whatever it takes to connect the PV system into my house system), and tools (if I need to buy any special tools to install -- I have the basic screwdrivers, drills, circular saw, etc.). Batteries if applicable, also.

How do I figure out how much electricity I can generate from my PV cells? My roof is a standard pitch (I think they call it 6/12 pitch?) roof with composite shingles. The main ridgelines of my roof runs essentially north/south over the main house and east west over the garage, so I could probably use the east facing side of the main roof as well as the south facing side of the garage roof and west facing side of the main roof if my HOA allows PV cells facing the street. I assume I have to do some calculations with number of days of sun and latitude.

I have a bachelor's degree in computer science but I didn't do that well at electricity stuff when I took physics. I can follow basic math, though.

2Cor5t21

[SecondCor521]

Nords,

Never mind. I found books that appear to answer all the questions I had plus more.

Where do you find cheap panels, though? A quick google found me a 161.5 watt panel for $850. That's new, of course, but it makes the system really expensive. I did a quick calculation and it looks like it would take a 28 panel system to meet my energy needs at 5.4 peak sun hours, 80% battery efficiency (I think I could take that factor out if I did a grid-tie system like you), and 90% inverter efficiency, assuming 16.86 kWh / day usage. That system is $24K just for the panels, which is obviously way too high.

I think unless I find cheaper panels or move to a sunnier area this may be a non-starter.

2Cor521