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Author Topic: Which Solar Kit For You Recommend  (Read 978 times)

thompkinz

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Which Solar Kit For You Recommend
« on: October 19, 2016, 12:55:20 AM »
Hey there folks! I know there's a lot of posts about how much solar to use but I've tried to narrow my usage down to the items I'll need to help find a better answer. I'm trying to find a kit that has every thing I need for simplicitys sake. So here's the items and wattage I'll be using and approximate usage times. So let me know if you see any issues. I know the printer uses a ton of power but since it's going to be a part of our mobile business, it can't really be substituted.

Lights for few hours 20 watt 4 hours
Brother hl3140 660 watt 2 hours max
2 Laptops 20 watts 2 hours
Iphone charger 5 wattage 3 hours
Fridge 500 all day.


Kevin Means

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Re: Which Solar Kit For You Recommend
« Reply #1 on: October 19, 2016, 02:40:02 AM »
Hi thompkinz... I wish answering your question were as easy as totaling the power consumption of the devices you listed, and recommending a suitably sized array, but it's just not that simple. For example, a solar array that just meets your power needs on a sunny winter day in Southern Arizona, won't cut it in Northern Washington - even on a sunny day (not even close.) The sun is much higher in the sky at lower latitudes, and that makes a big difference in how much power solar panels can generate.

Then there's the average amount of sunlight that different parts of the country get at different times of the year due to cloud cover. In the winter, there's a huge difference between Phoenix's average cloud cover and Seattle's. And remember, your appliances don't run on solar power, they run off your house-batteries when you're boondocking, and your converter when you're plugged into shore-power. Solar is just an alternate method of recharging your house-batteries. Little or no sunshine means little or no charging.

Depending on when and where you plan to camp, and for how long, you might find that it's a lot easier, cheaper and more reliable to just add more house-batteries. Solar power is a great boondocking aid, but it's easy to invest a lot of money in it and be disappointed with the results. Let us know a bit more about your camping plans and we'll try to help.

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

VallAndMo

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  • Vall and Mo, a married couple getting ready for FT
Re: Which Solar Kit For You Recommend
« Reply #2 on: October 19, 2016, 05:40:41 AM »
Hi thompkinz, Kev,

I'm also planning my future RV's solar setup, so I will be watching this topic attentively. I've read up a lot on solar and I think I have some understanding of how it all works, but as they say, there's no substitute for experience...

That said, I think I can contribute a little with some things I do have some experience with:

Hey there folks! I know there's a lot of posts about how much solar to use but I've tried to narrow my usage down to the items I'll need to help find a better answer. I'm trying to find a kit that has every thing I need for simplicitys sake. So here's the items and wattage I'll be using and approximate usage times. So let me know if you see any issues. I know the printer uses a ton of power but since it's going to be a part of our mobile business, it can't really be substituted.

Lights for few hours 20 watt 4 hours
Brother hl3140 660 watt 2 hours max
2 Laptops 20 watts 2 hours
Iphone charger 5 wattage 3 hours
Fridge 500 all day.

Please excuse me, thompkinz, but some of your numbers seem a bit off: the laser printer can use 500W, but in my experience (with HP LaserJets) this only happens when its fusor turns on. Will it be on during the entire 2h?

Ditto for the fridge: only when the compressor kicks in will it consume 500W. Unless you leave its door open, the compressor should be off most of the time.

On the other hand, 20W for a laptop seems a bit too low, unless it's a very flimsy one (like a chromebook). In my experience, even a modest laptop consumes something more like 50W.

My experience with those numbers come from having recently completed my own energy audit: I got one of these:
P3 P4400 Kill A Watt Electricity Usage Monitor and plugged it between each of my appliances and its wall socket, then returned 24h later to read its Wh measurement and put it in a spreadsheet. That gave me solid, real numbers to work with.

I recommend you do the same, a solar setup costs a lot of money and it can be much more expensive to "save" on the initial audit and end up getting a less than ideal setup.

Cheers,
--
   Vall.

thompkinz

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Re: Which Solar Kit For You Recommend
« Reply #3 on: October 19, 2016, 11:25:58 PM »
Thanks for the replies guys. I really appreciate it.

I know the area and available sunlight will help determine the needed solar power but I'm really not sure how to define that because  this is all in preparation for full timing and I'll be traveling back and forth across every state while resting  in Tennessee and Alaska. I'm just curious what you guys would recommend for yourself if you were using this much power. But perhaps I should worth more about the battery bank instead of the solar panels.

Vall,
Im not certain on those numbers. It's just what I've pulled from the item specifications. But perhaps that's just stating the maximum output? I think I'll eventually invest in an output monitor like yours so I can precisely track how much each item uses.

Kevin Means

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Re: Which Solar Kit For You Recommend
« Reply #4 on: October 20, 2016, 04:35:21 PM »
There's a general guideline that's talked about on some RV websites, that recommends 100 watts of solar power for every 100 amp hours (AH) of battery capacity. So, if your house-batteries had a total capacity of 400 AHs, you'd need to install enough solar panels to generate 400 watts of power.

In practice, I haven't found that to be very realistic - at least not for our goal, which is to replenish all the battery power we typically consume in a 24 hour period, without having to run the generator. On a sunny day in the southern U.S. that guideline will get you close, as long as you're willing to reposition your solar panels throughout the day so they're always facing the sun, but if they're flat-mounted (like ours used to be) you're probably not going to get a full charge - and the panels will become even less effective the farther north you are.

We determined (through measuring, trial and error) that we needed 900 watts of solar, an 800 AH capacity battery-bank and an almost totally sunny day for our (then) flat-mounted panels to generate enough power for us to achieve our goal. Our panels now tilt, which enables them to generate about 35% more power (on a sunny day) and that's really helped a lot.

If your goal is to replenish all the power you typically consume in 24 hours, here's my recommendation: Accurately determine your RV's power consumption over a 24 hour period; Install enough battery capacity to get you through that 24 hour period without drawing your batteries down below the 60% mark (70% would be better); Install enough solar panels to generate 15 to 20% more power than you typically consume in that 24 hour period. Pay close attention to wire diameters, shading, controller type and controller install-location. It all makes a difference.

If your array starts getting much bigger than 300 watts (ballpark) or if you envision expanding it, you're going to need an MPPT controller and I'd strongly recommend installing a good battery monitor, like the Trimetric RV 2030. Of course, if your goal is to replenish only part of what you consume with solar power, you'll have to determine what that is, and re-size accordingly.  You can see how this this can quickly get expensive, and why it's just not as simple as calculating consumption. I hope this helps. Let us know if you have any questions.

Kev
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

 

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