Solar That Really Works

[John Hilley]

Originally Posted by Dunner

I don't usually buy from places that say "Call for Pricing". They more often than not, have high pressure sales people that try to talk you into more than what you need.

I have good luck buying from Solar Electric Power Systems For On & Off Grid

Their pricing is on their WEB site.

[Dunner]

I edited my post. I was talking about some of their charge controllers.

Charge Controllers

[Dunner]

I have two 48 Watt Siemens Solar panels wired in parallel and to the house batteries. They are rated at 3.35A, 19.8 open circuit volts. On a good day, I get ~6 amps and I forget what the open circuit volts are. Do I need a Charge Controller? Which kind will work best for me?

I run my 2000 Watt Yamaha in the morning to replenish the batteries and let the array help keep them up during the day.

[chapdog]

Had the pleasure of meeting Bob, his lovely bride and puppy dog. Bob truly does know his stuff. And he cares... about people, the environment and the bigger picture.

He helped guide us through everything we needed.
Bob is a quality, quirky, and genuine guy. He only will help you if you if meet his rigorous screening criteria. And he was quite insistent I helped as much as I could through the whole installation mostly to educate me on how it all works.

Plus we now have a system capable of boondocking without running that infernal generator.
And that wasn't easy. Our rig is a power hog with a 3 amp phantom load, and we run microwave and even a media system with surround sound, 32" TV and hi-def DVR. Obviously conservation is critical.
FYI, we have 585 total watts in 3 panels, a Morningstar MMPP controller and Tristar meter. Total cost right at 2k.

Yes we may not get all our money back for sometime but to us the ability too hang out for extended periods in remote areas is worth it alone.

Really glad we had a chance to get to Bob and his family.

[Hamshog]

Originally Posted by chapdog

Had the pleasure of meeting Bob, his lovely bride and puppy dog. Bob truly does know his stuff. And he cares... about people, the environment and the bigger picture.

He helped guide us through everything we needed.
Bob is a quality, quirky, and genuine guy. He only will help you if you if meet his rigorous screening criteria. And he was quite insistent I helped as much as I could through the whole installation mostly to educate me on how it all works.

Plus we now have a system capable of boondocking without running that infernal generator.
And that wasn't easy. Our rig is a power hog with a 3 amp phantom load, and we run microwave and even a media system with surround sound, 32" TV and hi-def DVR. Obviously conservation is critical.
FYI, we have 585 total watts in 3 panels, a Morningstar MMPP controller and Tristar meter. Total cost right at 2k.

Yes we may not get all our money back for sometime but to us the ability too hang out for extended periods in remote areas is worth it alone.

Really glad we had a chance to get to Bob and his family.

Hey Dave,

So you have 6/6 volt batteries, or ??????? Inquizative minds want to know!!!!

Regards, Hamshog

[Midniteoyl]

Also, how long can you boondock?

[Wanderman]

Hey All,
Forgot about this thread! When I was researching the design and install of my own Solar charging system, this gave me a good head start! HandyBob's info was invaluable, but I did stray a bit from that. Still, everything is doing exactly what it's supposed to. I am a little heavy on Solar panel watts and low on storage amps, but that's simply a matter of time and space to fix. I wrote all about it in a 6(!) part article for the RV Newseltter. It's online at:

WanderMan: A Better Solar Charging Mouse Trap.PART 1

Maybe some of it would be helpful for anyone considering an solar install. It's not the END ALL, but it should give you some useful info in plain english.

If I can help, let me know.

Rich "The Wanderman"

[chapdog]

Originally Posted by Hamshog

Hey Dave,

So you have 6/6 volt batteries, or ??????? Inquizative minds want to know!!!!

Regards, Hamshog

Sorry, left out that critical piece of info. I have 4/6 volt Golf Cart batteries with 440/220 available amp hours.
Regarding how long we can be out it depends on how much of a purist you might be. Without the dreaded generator and water aside our power will last indefinitely (even this time of year) only as long as 1) we are careful with use and 2) we have continuing sunny days.

A key piece to our independence was also installing a gas stub and brick propane heater. Didn't realize what a drain the fan part of our furnace was on our power.

It is indeed freeing to be able to be on our own while giving up very little of the luxuries.

[Dave Wilburn]

I am in the researching mode for an eventual solar system (about 400 watts I think) and have read all the articles and websites talked about in this thread.

The commonality I see over and over again, is that people don't correctly design their system to account for minimum voltage loss. This is due to the continual use of too small a wire (as Bob and others point out). The reason I think that happens is because people get wrapped around the axle over voltage drops using 12 volt voltage drop charts.

It occurs to me that the one thing I don't see mentioned anywhere is that those charts are modeled on a normal 12 volt ciruit consisting of a battery, conductors and a load. Then they are told to keep losses under 3%.

Its here that it seems to me is where people desiging underwired sytems are going wrong...and that is that we aren't designing a simple circuit, we are designing a charging circuit. I.e, we are pushing current into a battery that already has its own potential voltage (say 12 volts to keep it simple). If we are are charging at, say, 14.5 volts, the net difference pushing the current into the battery is only 2.5 volts! Now run a voltage drop calculator, but instead of telling it we are using 12 volts, input 2.5 volts and see what the voltage drop percentage is.

Here's an example a perfectly acceptable sized conductor for a given circuit: A 10 AWG wire, carrying 20 amps a distance of 10 feet at 14.5 volts experiances a drop of 2.76%, or .4 volts. Its doesn't seem like much only losing 2.76 percent to resistance in the wire. Pretty standard stuff.

But in charging, we need to subtract the voltage the battery already produces. So, 14.5 volts charging, minus 12 volts (nominal the battery already produces), leaves a voltage potential of 2.5 volts. Now if we rerun our voltage drop calculator using 2.5 volts and the same length of wire and the same 20 amps, we still lose .4 volts, but we have now lost 16% to to the resistance of the wire. Now it becomes easy to see why the systems Bob sees and describes are losing up to 50% of the potential charging from their panels.

[Shadowcatche]

Good point. However one consideration, I have high voltage panels and a Morninstar MPPT converter that has 10" of 10ga to the shunt and about 8" of 4ga cable from the shunt to the battery.

[John Hilley]

Originally Posted by Shadowcatche

Good point. However one consideration, I have high voltage panels and a Morninstar MPPT converter that has 10" of 10ga to the shunt and about 8" of 4ga cable from the shunt to the battery.

But how long is the cable from the panels to the controller, that is where the voltage drop is.

[Dave Wilburn]

Originally Posted by Shadowcatche

Good point. However one consideration, I have high voltage panels and a Morninstar MPPT converter that has 10" of 10ga to the shunt and about 8" of 4ga cable from the shunt to the battery.

You lost me. Is the shut on the + side in your system and why would you have one size wire to the shunt and another coming out?

[Shadowcatche]

The shunt and Vectron meter measure all of the current going in an out of the battery from and to every source therefore needs to be heavier. When you have 50+ volts coming out of a panel voltage drop is not a real concern between it and the controller.
The trailer was in Challenger door getting the galley hatch repaired and their over head lights were exciting the panel to put out 13.6 V, not enough to do anything with but shows how a high voltage panel can take less light and make it usable, (Battery was already at 100% SOC).

[jimbo16720]

Originally Posted by SpursMVP

Thanks for the great tip.

Okay so now we're waiting for all the parts to come in. Got a pair of 200 watt Evergreen panels from Sunelectric at a great price (less than $1000 with shippping). Also decided to go with flat mounts and I will get the breaker box and combiner box from Lowes/Home Depot.

Love the idea of using jumper cable wiring for the cables....man you guys (and this forum) are awesome.

You could have got panels from solarblvd.com for less than 1/2 of that with shipping.