Solar panel battery charge

I can go almost indefinitely with my two 6v charged by 150w of solar, rain or shine. I'm usually parked where I get the least direct sun as possible. We typically watch a movie or two at night in addition to the regular lights, pump, fridge. Maybe I'm a miser.

pianotuna wrote:
Hi webwringler,

Going MPPT is similar to any other decision made about a solar system.

If you want every last watt and have no more room on the roof, MPPT may get you there. If you don't then a good quality PWM controller with adjustable voltage set points and a battery temperature sensor, may be a better choice.

Handy is/was a Morningstar fan and the controller he loved was twice the price of the Xantrex c-35.

So his advice needs to be taken with a LARGE grain of salt, for it is not terribly useful. You need to be quite knowledgeable about what to accept from him and what is chaff. So it is no place for a beginner.

In 2005 going MPPT with 200 watts of solar was a no brainer because cost per watt for panels was $5.50. That is why I have MPPT with 256 watts.

webwrangler wrote:
But he does debunk the belief that you need an MPPT controller for 250 watts in an RV.

Fair enough.

One of the advantages to MPPT is using low cost 24v panels.
And please do not compare a low-end $25 PWM controller to a full featured MPPT.

I have 300 watts on my roof. 2x 140watt panels, and a 20 watt panel. They are located front, mid, and rear of the roof. This allows me to get some sunlight on at least one of the bigger panels in most areas where i camp. On the island here where i live there are many tall trees or high mountains and having full sun such as an open field does not really happen. This way I usually can get ~150watts of charging for 5hrs or so, sometimes even more if im in a bit more sunny spot. My power usage is considered very light, my solar panel wattage would be way overkill but i factored in only 1/2 of it ever working at one time. I am extremely happy with solar and so is my friend who i helped install his system. Neither of us ever use a generator during spring/summer even on 10+ day trips. Our families are outdoor campers, there is no tv watching/indoor shenanigans eating power up other then a radio, sensors, fridge and charging kids electric quad batteries. I also have 2 6v batteries (trojan)

Hi webwringler,

Going MPPT is similar to any other decision made about a solar system.

If you want every last watt and have no more room on the roof, MPPT may get you there. If you don't then a good quality PWM controller with adjustable voltage set points and a battery temperature sensor, may be a better choice.

Handy is/was a Morningstar fan and the controller he loved was twice the price of the Xantrex c-35.

So his advice needs to be taken with a LARGE grain of salt, for it is not terribly useful. You need to be quite knowledgeable about what to accept from him and what is chaff. So it is no place for a beginner.

In 2005 going MPPT with 200 watts of solar was a no brainer because cost per watt for panels was $5.50. That is why I have MPPT with 256 watts.

webwrangler wrote:
But he does debunk the belief that you need an MPPT controller for 250 watts in an RV.

About 100 watts per battery. More for heavy use, less for misers.
But then with heavy use you may need more batteries.

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pianotuna wrote:
Handy's information is, at best, dated. It is not a site for a beginner.

Hooterville wrote:
To really understand solar for rv's Google handybobsolar and read his words of advise. I followed his advise for a reasonably priced system that actually works.

But he does debunk the belief that you need an MPPT controller for 250 watts in an RV.

2oldman said it: a couple hundred should do it. I have 170, due to starting out too small and adding on. I wish I had 200 or 250. In the spring, summer or fall in a sunny location, I can go indefinitely. In February in the Olympic rain forest, I'm good for about a week. YMMV depending on your power use. I use the water pump, lights (have put LEDs in the most-used fixtures), satellite radio, phone charging and in February, occasionally the furnace. The furnace fan will run your batteries down fast.

One 240W panel, two deep cycle 6V batteries and a 600W inverter. I also use a smaller inverter in the bedroom. Works great.

A four month trip to Canada and back w/o the generator and this summer five weeks with no hookups or generator.

Laptops, lamps, television, etc.

Handy's information is, at best, dated. It is not a site for a beginner.

Hooterville wrote:
To really understand solar for rv's Google handybobsolar and read his words of advise. I followed his advise for a reasonably priced system that actually works.