Fred Flintstone's posts

Believe what you want to believe, it matters little to me.  But if you're wondering why your wind or solar installation does a crapping job of selling power back to the electric company and/or keeping your battery bank charged, you'll know what the answer is.

There are estimates that solar panels could easily last 50 - 80 years since they only spend a fraction of their day actually working.  In other words, if a panel is rated for a 25 year life, and it only spends 8 hours in a day working, then it stands to reason that the panel should last 75 years.

If properly taken care of, that is.

And for the record, putting water on a hot solar panel is not recommended by any manufacturer and may actually break the panel.  Proper air space behind the panel combined with not mounting them on an overly hot surface (like a dark roof) is the likely definition of 'proper care'.

I know that I've got a 10 year old panel that still puts out well over its 'rated' voltage, (1 panel of a batch of 50), so its not like it is 'unique' or anything.

In this instance Ken Hall is right.  Not only are the underlying numbers of those tables calculated using 120V AC as a reference or baseline, but they also don't take into account the derating of the wire that normally occurs when you use it in places that are exposed to temperature extremes as in DC installations outdoors, particularly in reference to heat.
Those tables are based on wire in an insulated wall.  Not on wire running on a roof or up a tower, etc.

Bigger is better. #6 looks correct.

LOL!  So lacking a valid argument on the subject and confronted with your distortions of HandyBob's article and distortions of my references to it, you resort to namecalling?  WTF?

Is that what happens also when one of the recipients of your purportedly great solar installations dares to question you on what you're doing (or done) and why?  Call them names and become defensive?  LOL!

As long as we're back on the subject of solar, maybe next time you install solar panels in cloudy, hazy, foggy, or otherwise sun obstructed locations you'll use thin film/amorphous panels which are capable of putting out close to their rated wattage even on cloudy days in ambient light instead of the higher priced panels and mppt controllers you love so much.  Ah, but thin film/amorphous panels and standard controllers using thick wire and "training batteries" (for new solar system owners) aren't near the money maker that all of the latest wiz-bang stuff is, eh?

Apparently, you're the exact kind of individual that HandyBob was referring to.  What a surprise.  Thanks for proving HandyBob's point.

False.  For the record, HandyBob clearly states that he believes the majority of players (not just in Quartzsite) in the solar biz (RV or otherwise) are less knowledgeable than they portend to be, and more likely to simply parrot manufacturers dubious claims and figures, and more likely than not to simply push the hardware that will bring them the most revenue. And install it incorrectly or inefficiently.

I simply happen to agree with him.  That isn't "disrespect", its simply a observation of the industry.  Sadly I might add.

No, I said HandyBob /may/ be persona non grata with an article like that.  The article can't be persona non grata because the article isn't a person.

This thread is about RV's so the wiring and battery choices I listed specifically apply to RV's.  (The concepts carry over to other photovoltaic systems however.)

If you read what I posted on controller voltage, you'd see that I specifically stated that 14.8v was what Trojan recommended, and that the proper voltage is what your battery manufacturer recommends, not what your controller manufacturer recommends.

As for mppt, if you read his article, he explains that increasing wire size delivers more volts to the batteries, rather than attempting to 'boost' voltage to the batteries via a costly mppt controller (and subsequent higher voltage array which results in more amperage not more proper charging voltage being delivered by the mppt controller), or by spending even more money for more panels to overcome the inefficiency of an underperforming system.

All in all, HandyBob explodes some popular current PV myths and fads, myths and fads that can be used by unscrupulous salespeople to pad their own wallets and sell people more hardware than they actually need....and have it all work at less than stellar efficiency to boot.

Thanks for the clarification.  I assumed that since your name was 'Robert' that you were the 'Handy Bob' who wrote the article.  No matter, great job linking to it.

So, according to 'Handy Bob's article, those two 135 watt panels should have no problem whatsoever running a moderate-sized RV off-grid.  The key seems to be:
1) Get a controller that can be set to 14.8 volts if needed for wet cell batteries.
2) Locate the controller as close as possible to the battery bank (and not above the RV fridge as is common).
3) Use big wire in your installation.....#6 or #8 ....the bigger the better.
4) Use 2 - 6 volt golf cart batteries wired in series to get 12v in your battery bank, batteries such as the Trojan T105, and follow the battery manufacturer's recommended charging voltage (14.8v for Trojan T105's)
5) Don't ever rely on the RV manufacturer's battery charger as they are underwired and underperforming junk.

There is plenty of other useful information in that article, I simply listed the highlights.  I encourage everyone interested in the subject of PV to read it.

I'm about 1/4 way through your article and I just have to say....good job!  That and....methinks you may end up being persona non grata around these parts (and anywhere else solar power components are sold) LOL!  Unfortunate, but inevitable I suppose.

Thanks, I looked into mppt controllers several years ago.  While they have their uses, they aren't the be-all end-all of PV controllers, and the excessive cost must be weighed against the added benefit.
In this instance, is roughly 4 times the cost for the mppt controller worth it over the non-mppt controller such as the Xantrex C40?  It certainly isn't to me, and you read the original poster stating that he wasn't going to be using the system during the times when an mppt controller would be a benefit, i.e. during the wintertime.  He's using the system during the summertime, so why oversell him what he doesn't really need, particularly when he already told you he's on a budget?

Telling people to buy more expensive hardware than they really need was the downfall of the solar movement in the 1970's.  I see that we haven't really learned much in the intervening 30 years, and it doesn't comfort me that things will necessarily go any better this time around.

That's the reason why 12v panels typically put out 18v-24v at peak output.

A 24v array would be putting out upwards of 30v at peak output.

Again, that seems like an awful lot of wasted output to have a controller reduce it to 14v for a 12v battery bank.  Unless, of course, you're hooking up a dump load from the controller into a water heater or air heater.

And while we're on the subject....why spend 4 times the amount of money for a Xantrex C40 on a charge controller (Blue Sky SB3024iL) that is supposedly able to maximize voltage (MPPT) if you're just going to dump a bunch of excess voltage into the controller with a 24v array anyways?

It doesn't make sense....dollars or otherwise.

Exactly what would be the reason for essentially wasting half of the output of your 24v array by allowing the controller to reduce the output to 12v?

It's one thing if you're stuck with used inexpensive 72v direct-to-grid panels and looking to use them to charge an off-grid 48v battery bank for example (which they were never intended for).  Then the loss may be deemed acceptable due to the cheap per watt cost of the panels.
But it's another thing entirely to intentionally waste your new panel's output by not correctly designing your system for the correct voltage of your battery bank.

Remove my 'membership' please.

2 12v panels wired in series will give you 24v output.  3 panels wired in series is 36v, and 4 panels wired in series is 48v.

2 12v panels wired in parallel is 12v output.  3 panels wired in parallel is 12v output, and 4 panels wired parallel is still only 12v.  The difference is the amperage increases the more panels you wire in parallel.

Thanks for the clarification.  Correct, its a single panel of the thin film variety, a BP/Solarex Millennia as you state.

Huh?  "Cold temp derating" would mean that 72v panels would be putting out less than their normal rated voltage, not more.  For instance, I've got a 40watt 72v panel that puts out upwards of 90v on a nice sunny day.  So to use that panel to charge a 48v battery bank I would simply need to pair it with a charge controller that was rated to handle the max voltage (90v+) that the panel was capable of putting out.  Sure, there's some 'loss' reducing from 72v to a 48v battery bank, but the good news is that even if the panels are extremely dirty they'd still be putting out more than the 48v necessary to charge the battery bank.  As an example, I can partially shade the panel and it still puts out between 50v-60v, perfect for a 48v battery bank.

12v is generally for short runs, small setups, low total wattage, and/or the direct running of 12v devices.  Once you start looking at running a household on PV, it becomes more prudent to step up to 24v or 48v for the panels and battery bank, and then bump the output to regular 120v/240v through the inverter and use normal (albeit 'energy star' or energy miserly) devices and wiring throughout the house.

As for 96v.... why?  Even if you have 72v panels it is no problem to simply bump them down to charge a 48v battery bank via the controller.  Not much PV equipment is made for 96v setups....as 48v is about the upper limit for most off-the-shelf PV equipment.

Find an old 50 gal electric water heater ('tall' variety) and recondition it by stripping off the jacket and insulation, sanding/wire brushing off rust, replacing the anode and fittings, rinsing out the insides, paint with black paint, and build a ICS or batch heater out of it.  There are tons of plans available for free on the internet.

There are no rebates that I am aware of on these 'poor boy' passive solar systems, but the cost is only several hundred dollars total, and you recycle/reuse what is usually a perfectly good tank.  (Most old water heaters are replaced not because the tank is bad, but because the anode is gone or the heating elements have failed.)

I just designed, built, and installed a 40 gallon batch heater about 10 days ago.  Our regular propane water heater was burning through money 24/7/365, to the tune of $1200+ last year.  Since hooking up the batch heater (which 'preheats' for the old propane heater, which is relegated to 'backup' and storage now) the propane heater barely comes on at all now.  Woohoo!

Total cost for the batch heater and plumbing to hook it all up...less than $300.  Break even cost will be in 3 months [actually it was immediate, since it costs $300+ to fill the propane company's 120 gal (rental) tank at approx $3.50 per gal for propane, and bought my own 23 gal propane tank instead ($124)].

But that pales in comparison to the cost of converting the skeptical wife over to the benefits of going renewable.  Priceless.

I should do a website.  Anybody interested?

It depends on the specific system setup whether or not you need a vacuum break.

On a truly 'closed loop' system you would most definitely want a vacuum break installed or the water wouldn't ever 'drain back' due to the vacuum created by bleeding air out of the system when the system is initially pressurized.

On an open loop system, or a system that drained back into a non-pressurized collecting tank where the input end of the tube was not submerged there would be no need for a vacuum break in the system, since as soon as the pump stopped, gravity would drain the liquid back into the collecting tank through the submerged 'output' end and air would be drawn into the line through the non-submerged 'input' end.