How Much Solar?

[3TV]

I'm getting a new truck camper and plan on adding a 170 watt solar panel on the roof, which got me to thinking, why not add another 170 watt panel, or two more panels? Is there an advantage to having 340 watts, or 510 watts, or am I wasting my time and money. The camper will actually have a cover on it when stored, so solar panels wont be used when stored, and it will be plugged in to a battery tender. But when in use, would the extra panel allow me to use items like the DC TV, and still keep up with battery charge by using the solar panels? What do you people think?

[MEXICOWANDERER]

Still waiting to see the first

I wish I had bought less

Post

[CincyGus]

From what I have learned about solar, The main benefit of having additional panels is for those days you are not getting full sun or only getting sun for part of the day.

Say you have a day where the morning was cloudy and you were getting zero to minimal output from the panels. Then during the afternoon, you get about 3-4 hours of bright sun giving you near maximum output from your panels. Obviously if you have a third (all equally rated panels) panel vs. two, you are going to recover about 50% more AH's than you would with just the two. So it's a matter of better recoverability in less than ideal conditions.

On good sunny days, you may recover to near full on your batteries and have "overkill" solar. So it's a case of how much recoverability do you want and how much do you hate running the genny. If that aggravates you, add the extra panel. If it's not a big deal to run the genny on cloudy days if you need to, save the hundred and change to spend on something else.

[3TV]

I like what was said earlier about one panel per battery. The truck camper will come with dual batteries, and I have asked for the biggest that will fit in the space allowed. So two panels sounds like a good idea.

[Joel_T]

We have two 160w panels feeding two 6v 260a batteries. With just a fair amount of sun we have no problems recovering around 40 or 50a a day. Hit and miss sun and we might get a week before needing to use our 2200w westinghouse to recharge although we'd probably run it sooner. No sun and we can go 3 days before a charge is necessary. Just our example...a lot of variables to consider.

[jplante4]

Moved from General RVing

[fitznj]

Summer and winter will place differing demands on the solar/batteries;
14 hours of sunlight in summer and 10 of cloud in winter;
Light electric demand in summer and heavy usage in winter;

I have 200W and 2 Walmart batteries which work great in summer but I need
generator boost in winter; I keep the solar plugged in during storage and
keeps the batteries topped up till the next camping trip.

As others have said - you can never have enough solar panels.....

[Lwiddis]

“you can choose to run things like the water pump (showers or dishwashing) or watch TV, while the sun is high.”

Good point, bpounds. I shower, recharge phone, iPad and tire air pump etc. too.

[bpounds]

Yeah, you didn't tell us how much battery capacity you have.

But I'm so far very happy with 400w handling 230ah of battery.

I'm not sure there is overkill as far as panel size. Unless you consider spending a nickel more than necessary as overkill.

Consider this...the best way to charge your battery is to not discharge it to begin with. So with a lot of panel capacity, you can choose to run things like the water pump (showers or dishwashing) or watch TV, while the sun is high. Use that excess panel output instead of battery supply.

We did the same thing with our generator. Try to do water pump things while it was running, and at the time we had to run it to watch TV anyway. We have carried those habits over to our solar life.

[garyhaupt]

I have 250 and 3 12v Deep Cycle and have never ever run out of power. I don't have a microwave or TV. Lights are the normal ones and I don't let the furnace run all night. I's go for one more panel. There is an overkill..you aren't there quite yet.


Gary Haupt

[doc_brown]

I have 400W and 6 batteries. Boondock for a week at a time, assuming full sun I let the inverter/auto gen start dance take over. I have a residential fridge, all lights changed to LED as well as the tv’s. Gen typically goes on once early morning or if I need AC’s. Be sure to get an appropriate controller and gauge wire based upon your distances.

[time2roll]

100 to 200 watts per battery should be fine. Two panels is probably good unless you have a crazy usage pattern. Many get by on less. Less than ideal conditions may still have you wanting more. Find your middle.

[2oldman]

Forum members solar
Solar basics
Why solar? 2016

[donn0128]

Where are you going to put all the batteries?
Solar is useless unless you have the storage capacity to support it.

[Lwiddis]

The number of solar watts is usually determined by battery amp hours...one to one for us southern US RVers. If living in Colorado I’d go more...1.25 or 1.5 watts per AH. And, yes, the goal is not to need the generator except for AC. The key is to wire for more than you anticipate needing so that adding a panel is easy. When my TT is at rest the solar panels are too. I use a 25 watt panel and weather proof WindyNation controller to keep the batteries charged. Start with an energy use survey. That determines necessary battery AHs and that determines solar watts.