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.

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, 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.

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.

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.

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

Thanks Brian, I guess we were typing the same thing at the same time.

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.

This is probably one of those gorilla operations: http://www.power4home.com/index.php?hop=taa200
"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). 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.

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.

Hotline, what did that whole set up cost?

"You can build your ow for less than $200!"

That's the sort of shyster we have to learn to deal with. The only thing 'less than $200' on that site is the set of literature he wants to sell you for $49.95, but claims a 'value' of $109.95. I'm pretty sure that you could buy those books, let them sit on the table, and not generate a watt of energy. Actually making electricity will cost you more.

Gorilla? He sure wants to make a monkey out of you!

$200 sounds like a rudimentary solar hot water system. He probably has you buying a couple rolls of black irrigation pipe, some plumbing parts and a little pump.
It might actually work if you live where water doesn't freeze.
In my shopping I have found PV collectors for around $3 a watt which is half what they were a few years ago.
(Japanese brand, probably made in China)
An off grid inverter is some hundreds of dollars, depending on size. I didn't see a grid tie inverter but I really wasn't looking since you need to buy a certified "system" to do that and there is significant cost to simply getting your product certified. I also think that in a rapidly developing world, the certified system might be obsolete by the time it gets through the process. That is probably good if you are a consumer but does not encourage innovation.

Any of you install oany of these solar panels yet? What Manuf is the best? What is cost for household? 3200 sq ft two people. Total cost including all required materials and install?

This is only a small piece of info needed for a system. All honestly this info is about is important as the color of the house you would like to power with solar. You need to know what you are powering, for how long, Solar conditions at the site, panel configuration, mounting, etc. Then you have to dive into local code and ordinaces... Must go and catch a flight

When you look at the people who get a significant amount of their power from their PV solar the first thing you see is they lowered their usage significantly before they started (better insulation, tighter house, CFL lamps and a whole regimen of energy saving practices) and that might have been where they should have stopped if saving money was their goal.
You really need more than simply saving money to justify this kind of project.

I was using C&D's runtime charts for UPS12-400MR which are high quality deep-cycle AGM batteries used in industrial UPS systems, but cost $300-400 a pop. And unfortunately forgot to divide by 6 electrochemical cells per jar even though I know better, doh! (72 cells = 12 jars.) Serves me right for trying to do the math in my head. I was assuming 12 hours of run-time. Call it 12 batteries, and chop my numbers by a factor of 6. In winter months in northern lattitudes, night lasts a lot longer than day, and you would need larger solar panels and additional batteries to compensate. And that's of course not considering any type of electric heat. You'd need an entire neighborhood worth of roofs to get enough solar power to heat a home in New England in the winter.

Cheapest I'm seeing 85Ah AGM batteries online is about $150. You DO get what you pay for- I clicked a link for one of the cheaper ones, which claims 85Ah on the title, but then in the fine print says you only get 36 minutes run-time at 75 Amps. In this case, the 10 hour run time is slow enough we probably would get close to 85Ah from it, but that sort of deep cycling is very hard on batteries, and there's no word as to the # of cycles. I *know* the $300 C&D above will perform as advertised, and will do so for several hundred deep cycles before performance degrades to 80%.

You just can't beat a generator for this type of backup power, though- even if you have to keep a couple cans of fuel on hand. For the price of just one battery, you could buy an awful lot of gasoline. AND you can do it on rainy days as well as sunny. What happens, for instance, to your 12 hour battery bank during a blizzard that knocks out power lines, coats your panels in a foot of snow, and is accompanied by clouds that blot out the sun for 2 or 3 days? At roughly 1 battery per hour of 800W load, that adds up.

"Snow?" I have heard of this thing.
Cold stuff that falls from the sky, right?

Around here a blizzard is a cup of ice cream at the Dairy Queen.

My outage is most likely going to be in August so temperature and lack of sunlight is not my problem. I do have a problem with feeding the monster. How much fuel do you need to have around? If you don't want to go start the generator every time you want water you need to run it all day but the overall usage is really pretty small.
That is why I think batteries may do the trick.

Alan:

I'm not the EC, but the inspector....

One job is $ 377K, other is $ 251.7K from the app's, which is public information.

Not to say that the 'costs' are accurate, but that's what is on the apps.

One is 2970 panels, other is 2069 panels.

With an average $300 a month electric bill the big one pays back in 105 years but the small system will only take 70 years

Of course that assumes nothing ever breaks and you have a zero maintenance bill. I hope you have a 70 year roof!

gfretwell,

outbackpower.com They have grid interactive inverters which are fed by 48V battery arrays, which then are charged of course by the PV system. Trace/Xantrex has just come out with some grid interactive ones as well now, but I'm kinda partial to Outback myself. Their reputation for their inverters producing VERY clean power especially for motors/refrigerators is well known when running off grid.

However I will say, when pricing these systems for a few customers, unless they REALLY want that instant UPS style transfer, its hard to beat a backup generator. Not many people want to deal with maintaining the batteries monthly, and replacing them years down the line. They like the idea of having a maintenance free PV system, especially since it is part of their house. And you are gonna have a hard time running your A/C off the inverters in a power outage. With a standby generator, at about a third the cost of a battery/grid interactive system, at least you will be able to run all your loads. And if you dedicate a 250gallon propane tank to it, you could go a pretty long time in a natural disaster.

I install solar in the South California, so if I can be of any help.

Greg:
FYI, both jobs are for a climate controlled warehouse operation, both bldgs are >75% refrigerated.

A "$300 electric bill might cover a few hours"

Thanks, That is good to know about the 48vDC system. It fits right in with my golf cart scenario. I am really only looking for enough battery backup to keep a fridge going and run my well pumps. Anything else is just bonus stuff.

If I can keep my pool blue the A/C is not really that big a deal. I am looking at a dedicated system that just runs the pool pump. Do you deal with them? It is a DC pump connected pretty much directly to a collector array.
Dollar for dollar that looks like the biggest money saver for me. Unfortunately Florida does not seem to think that is worth a rebate, in spite of the fact that about 20% of all residential electric usage here is the pool pump if you have a pool.

Most of my solar is northern and I am also partial to Outback. On paper they look great and I have yet to experience trouble with them.

To add though, the Outback can accept voltage input well above the nominal and seems to efficeintly down convert the voltage without much power loss. This is extremely helpful when dealing with voltage drop.

We go for a similar type system with water systems for Grundfos solar pumps which can accept up to 300 VDC and can run by 120 or 240 VAC from a generator.

I am beginning to sound like a salesman, but I have also worked with hybrid systems using both solar and generator with batteries. Atkinson Electronics offers generator start control modules for three wire start small generators. This works great for alot of our sites where there is no public utility.