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#189708 - 10/22/09 02:45 PM Solar Power: The Basics AND Business of it.  
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
A thread in the business forum showed an interest in discussing Solar power, so I thought I'd open a thread here.

Just for the sake of good conversation, I'd like to avoid the general 'political' aspects, and concentrate on the 'nuts and bolts' issues.

First, for the mechanics:
If you have a way to tuen sunlight into electricity, you have two ways to use that electricity: you can either be 'on grid' or 'off grid.' For safety reasons, you really can't be both.
"On Grid" means you're tied into the PoCo. You have an inverter and a disconnect switch; in code terms, you have a 'separately derived system.' The inverter is the key element, as this is also the part that prevents the unit from energizing a downed power line. This safety feature is NOT found on the inverters you find at the auto-parts store. Your PoCo meter will slow, or even reverse, as you produce power. Some PoCo's will also want an additional meter on the solar power system.
"Off Grid" means you don't connect to the PoCo at all, and store the power in batteries.

The Business Aspects:
Most 'solar' seems to be installed by plumbing & mechanical contractors. When the 'solar' is for heating water, this is fine. Many of these guys are also installing the photocell packages as well, or there will be local distributors that do this work. Be advised that most of these guys do NOT have the required 'electrical contractors' license. If you look at the fine print of the licensing statutes, you will probably find that an EC license is needed, even if you're just assembling the modules, and letting someone else tie them to the grid. I see a business opportunity here.

"Guerilla Solar"
This is something popular within the solar movement. This is where you have an installation completely without the knowledge of the PoCo, the city, or anyone else. Some of these guys simply have a male plug on a cord, and plug it into the nearest receptacle.

Work Gear for Electricians and the Trades

#189721 - 10/23/09 02:59 AM Re: Solar Power: The Basics AND Business of it. [Re: renosteinke]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,057
I am still not sure why I can't have a hybrid system with a grid tie and batteries. When my batteries are topped off and all my loads satisfied, I will share with FPL. The grid tie will work the same and the inverter is still the same, it is just part of my load would be batteries. The only difference is when the transfer equipment switched me off the grid in a power outage, I would still be producing power after the sun went down. (from my batteries)
Basically it is just a UPS at that point.
Net metering assumes you don't use much power during the day. With an air conditioner going, that is probably not going to be true.

Greg Fretwell

#189730 - 10/23/09 09:57 AM Re: Solar Power: The Basics AND Business of it. [Re: gfretwell]  
Alan Belson  Offline
Joined: Mar 2005
Posts: 1,803
Mayenne N. France
Greg, couldn't you do this anyway? From Reno's description, it seems that the solar generation is cleaned up and synchronised by the inverter and effectively reverses your meter to credit you with your grid input. Your consumption runs the meter the opposite way to enable the PoCo to bill you for net use. So you can store whatever you like in batteries by plugging into any receptacle. That way, the solar array can generate at maximum potential regardless of your battery back-up load and you pick up all the Gummint promotional breaks. Most of the year you will only be trickle charging the batteries for make-up, and in fact the cost of same plus charger plus reinversion to ac will probably be more than a gasoline engine gennie backup over their respective lives.

Wood work but can't!

#189734 - 10/23/09 01:43 PM Re: Solar Power: The Basics AND Business of it. [Re: Alan Belson]  
SteveFehr  Offline
Joined: Mar 2005
Posts: 1,198
Chesapeake, VA
I did the math after Hurricane Isabel left me without power for 8 days a few years back. I could spend tens of thousands of dollars on solar panels and batteries enough to barely power a refrigerator and a couple lights... or drop $250 on a portable gen that power pretty much my entire house, sans heat and hot water.

The batteries needed to power a house overnight is just massive. If you assume even a modest 800W average load, that's a bank of about 72 deep-cycle batteries, at a cost of about $30k, not even counting installation. And those would need replaced every 3-5 years.

It's not even really going to be effective as a UPS because mechanical ATSs are not fast enough to beat the voltage dip when line power is lost. A whole-house UPS is cost prohibitive, but a couple $40 UPS on specific equipment would be fine to power through the transition.

You just can't beat a generator for backup power.

#189736 - 10/23/09 02:32 PM Re: Solar Power: The Basics AND Business of it. [Re: SteveFehr]  
brianl703  Offline
Joined: May 2005
Posts: 166
Manassas, VA
I can get 85 amp-hour, 12V deep cycle batteries for $70 each. One of these is enough to power an 80 watt load for more than 10 hours. 10 of them would cost $700 and power an 800 watt load for more than 10 hours.

#189738 - 10/23/09 03:10 PM Re: Solar Power: The Basics AND Business of it. [Re: SteveFehr]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,057
Generators sound great until you have to feed the monster.
How much fuel can you keep on hand and how hard will it be to find after a hurricane? That was the biggest complaint I heard after Charlie.
I am also not sure where you got the "72 deep cycle batteries" from. A decent battery will store one KWH so 800w should be less than 10 in the summer. I got into a lot of this when I was looking at electric cars. My thinking is one set of batteries might actually do both. Use them in a car day to day and also use them to back up your house power in emergencies. My current plan is basically the same deal except I have that 12v alternator/engine deal I made and a golf cart I have in the garage.

I am really just trying to avoid one more engine that won't start when I need it wink

Greg Fretwell

#189739 - 10/23/09 03:12 PM Re: Solar Power: The Basics AND Business of it. [Re: gfretwell]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,057
Thanks Brian, I guess we were typing the same thing at the same time.

Greg Fretwell

#189742 - 10/23/09 03:26 PM Re: Solar Power: The Basics AND Business of it. [Re: gfretwell]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,057
As an side issue, I kept a watt meter on my tiki bar fridge for 2 months living outside in the Florida summer.
(August September, peak hurricane season)
It is a fairly new Whirlpool side by side with ice and water in the door. It averaged just shy of 2KWH a day. (61.2 days 120KWH)
That would be less than 1KWH after sundown and it would tolerate running half that time at night without seriously affecting the contents. It is clear the fridge is not your big load.
You could keep that going with one big battery and a solar collector that was around 2x the running load. The average load is ~83 watts and some storage would allow you to average that load.
The other critical load for me are the well pumps.

Greg Fretwell

#189744 - 10/23/09 03:32 PM Re: Solar Power: The Basics AND Business of it. [Re: renosteinke]  
wa2ise  Offline
Joined: Nov 2002
Posts: 782
Oradell NJ USA
This is probably one of those gorilla operations:
"Inventor From Minnesota Swears Under Oath He's Not Cheating The Electric Companies He's Simply Generating His Own Power At Will!"
Though the POCO may wonder when you produce more power than you consume over the month. Or they may assume you burned enough power to make the meter almost do a complete turn over (like when your car's odometer rolls over to zero miles). laugh I don't think that is possible (you'd trip the main breaker). But they'd be worried about their linemens' safety, if your system doesn't shut down during an outage.

#189750 - 10/23/09 06:06 PM Re: Solar Power: The Basics AND Business of it. [Re: wa2ise]  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,798
Brick, NJ USA
Just a FYI note, scheduled for tie-in to POCO tommorrow (Sat), but canceled due to weather:

1 solar at 375KW and 1 at 250 + 375 KW
2 structures (roof mtd panels), 3 inverters, 480 volt tie-in at utility. Net meters TBI, owner has metering equip also, POCO and Solar

I'll see if I can get any pics.


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