Welcome to our Information and Learning Guide! If you’re new to 12v solar, don’t worry. It’s not magic. Basic systems are pretty simple.
DETAILED instructions with EVERYTHING you need to know to
Install an RV or Off-Grid 12 Volt Solar System that WORKS!
We want you to have a system that actually works well and lasts for years, but here’s the
#1 THING YOU NEED TO KNOW
Ready for the answer? (what most companies don’t want you to know)
Your Off Grid or RV Solar panel system is only as good as the charge controller
It’s the heart of your system and all controllers are far from equal.
Amperage and voltage ratings differ, but more importantly, charging algorithms, protections and advanced features vary greatly between brands. Maybe that’s why there’s a HUGE difference in the warranties!
5 year warranty and 15 year expected life
Besides complete system failure when a controller goes bad, the chronic undercharging of your expensive batteries will cause them to fail and need replacement much sooner. Morningstar is an American company and has had over 2.5 million controllers installed in 112 countries over 25+ years. MANY are still in operation today.
The finest charge controllers in the world are Morningstar MPPT
LEARN MORE HERE 5 REASONS TO USE MPPT (OR NOT)
The following 2 links are experts and provide a massive amount of RV / OFF GRID 12v solar knowledge.
These are the best 2 free learning sources you’ll find and a good place to start
I really like Bob and owe him many thanks for all his knowledge. A retired electrical engineer very compassionate about RV solar, who was off grid by 2003. He is aimed at the “frustrated, technologically challenged and budget minded RV owner who needs basic education about battery supplied electrical power.”
It takes hours to read, he’s long winded, and rants on the state of the RV manufacturing and RV Solar industries but If you read all of it and follow his advice, you will have a great system that works and gets the batteries 100% full so they last longer! Read it more than once, (it’s free, but he welcomes donations!)
Another expert, he wrote a book about RV Solar and has it available for free. His information is a little more complicated, and from the viewpoint of one who can afford to spend more money. It’s well organized and has a LOT of expert advice and instructions with photos
We’ve distilled down and summarized the most important points below
1. NO SHADE
Just shading on one small square on a panel drastically reduces the output of the ENTIRE panel
See those little shadows?
Surprise! Minus 6.4 amps from these two panels! This is 90 % of the output of a full panel.
2. USE BIG ENOUGH WIRE
Voltage loss is the enemy in these systems, and is especially critical from charge controller to battery. Keep wire runs as short as possible, and use the proper cable size. (Don’t waste money on wires bigger than needed for 2% drop on MPPT systems or 5% on PWM systems) Use a wire sizing calculator like this one
3. CHARGE CONTROLLER AS CLOSE AS POSSIBLE TO BATTERIES
Distance under 3′ with large wire. Max wire size accepted: 10 AWG for Sunsaver controllers, 6 AWG for ProStar, and 2-4 AWG for TriStar. Splicing a piece of 10ga onto larger wire is OK and won’t get hot if done properly, or simply clip some of the fine wire strands off larger wire until it fits. This won’t affect anything.
4. USE A REMOTE TEMPERATURE SENSOR
It will send more voltage when batteries are cold so they still get 100% charged. It’ll reduce the voltage when batteries are hot so they don’t overcharge. (A temperature sensor on a controller that is located in a heated area will not see the battery temperature, so it will not work.) The Sunsaver controllers do a good job in cold weather with built in temperature compensation, and the ProStar and TriStar remote temperature sensors are a must. (adding the temp sensor to Prostar controllers requires soldering 2 wires)
5. INSTALL A TRIMETRIC METER & WHOLE SYSTEM MONITOR
Every 12 volt solar system should have a real battery monitor that includes percentage (%) of charge. Not just voltage. This is the only way to ever be confident that your system is really working. learn more
6. CORRECT CHARGE CONTROLLER VOLTAGE SETTINGS ARE CRITICAL FOR CHARGING BATTERIES
*check with the battery manufacturer
If you can get a TriStar controller it has volt set points as high as 14.8 , or Bogart SC2030 can easily be set to any voltage at all. It is even smarter than a Tristar. It will charge better and faster than any other PWM controller. The smaller Morningstar controllers are 14.4 volts with built in temperature sensors, which will get the batteries full, but it takes a little longer. The RV Battery Charging Puzzle
BHA RV Solar kits save you money. Top quality parts that maximize charging and life of your batteries
BATTERY INFO from solarseller.com
Battery System Sizing SIZING YOUR BATTERY SYSTEM
Deep Cycle Battery DEEP CYCLE BATTERY
VRLA (valve regulated lead acid) Battery VRLA BATTERY
Gel Cell Battery GEL CELL BATTERY
AGM (absorbed glass mat) Battery AGM Battery
Flooded Type Deep Cycle Battery FLOODED TYPE BATTERY
Self-Discharge Rate SELF-DISCHARGE RATE
Charge Rate CHARGE RATE
Electrolyte Level ELECTROLYTE LEVEL
Equalization Charging EQUALIZATION CHARGING
State of Charge STATE OF CHARGE
Battery Life BATTERY LIFE
Battery Location BATTERY LOCATION
Used Batteries USED BATTERIES
Battery Safety Battery Safety
How to wire 6v and 12v batteries together in series and / or parallel
Wiring of fuse / breaker devices is covered in detail in this article
“In-line fuses or circuit breakers are important to protect the wiring and components in your system from shorts and other catastrophic failures. Place one on the positive wire within a foot of your battery and another in between the combiner box and the charge controller. The size of the fuse or breaker depends upon the size of wire used in your system. Place no larger than a 30 amp fuse or circuit breaker for 10-AWG wire; no larger than a 48 amp fuse for 8-AWG; no larger than a 74 amp fuse for 6-AWG; and no larger than a 120 amp fuse for 4-AWG wire.”
Fuses for Inverters to battery: Always use the exact factory recommended size fuse stated in the installation instructions
More good info and pics:
From Kelly’s RV Solar Blog – Great blog with lots of interesting info and good photos.
Diagrams From Jack Mayer w/ reading at RV Solar Electric
Typical Wiring Examples below
Typical Wiring Examples above
EASY DIY PLANS
DISCLAIMER : Always make sure that all of your equipment is properly fused and grounded for safety. Also, be sure to read and follow the advice and instructions that come with your equipment. While our projects have actually been constructed and tested under actual operating conditions, we do not guarantee that they will meet all electrical codes in all locales. Nor do we suggest that our advice supercedes the recommendations of a licensed electrician. Hey, we’re just trying to help!