solar options

[chloe_s_ranch]

Last summer I had a 240 watt kit(from Solar Blvd.) Installed on our MH. It has two 120 watt panels feeding a 20 amp charge controller. I recently had the two stock 12 volt marine house batteries replaced with four Trojan T-105s since we almost always dry camp or boondock and wanted more amp hours to get us through the shoulder season when we run the heater more(and there is less sunlight.) We also hate running the generator because of the noise. I know a rough rule of thumb is about 1 watt of solar for each amp hour of battery capacity and I now have a 450 amp hour battery bank. So if I have more solar installed here are some options: A--Have another kit from Solar Blvd.installed with its own wiring and another 20 amp charge controller so both kits would work in parallel charging the batteries. They have a 300 watt kit for $500. Or B--get their 120 watt kit and have them swap out the 20 amp charge controller for a Blue Sky sb3000i 30 amp mppt charge controller for about $500 also. I know option B would require heavier gage wiring since all three panels would be wired together feeding a single controller. Or option C--get the 300 watt kit and pay a little more to swap out the 20 amp pwm charge controller for a 40 amp pwm charge controller and wire all four panels into it. Again needing heavier gauge wiring. It seems to me that option A(having two separate kits feeding two separate 20 amp pwm charge controllers) offers the most bang for the buck. What are your thoughts?

[NinerBikes]

BFL13 wrote:
AFAIK the Iota IQ4 goes to 14.8 but that's so the batteries can get to 14.6. Once the batteries reach 14.6, it stays there for 15 minutes and then drops to 14.2. Phooey on that!

I don't know any converter that will do it right in every way. That's why I still use the 13.8v Parallax 7355 as the converter for when on shore power (works great) and use separate chargers for the real battery charging stuff to proper high voltages for my 6s and Trojan 1275s.

For fast charging four 6s I use a 100amp charger that goes to 14.8 and stays there, or I can crank that voltage higher if it is cold out so it should be more like 15.1v Note that 100/440 is only a 22% charging rate and you could safely go higher to a 30% charging rate on the four 6s if you want.

Yes it is a way to get by in the fall/spring when solar is not as good as in summer, to just charge for an hour in the morning with charger and then go solar for the rest of it. Trick is to have :
- a serious charger and gen to run it
- gen hours that let you run it in the morning.

That may let you off the hook for getting more solar, so you end up with too much solar in the summer. I keep going back and forth on this, where I get too much solar for summer and sell some, then buy more for the spring and then wish I hadn't and sell that, then a sale on panels happens I can't resist so I buy more and end up with too much solar again! There is nobody who can help you if you get that affliction. 😞

So, then if I set my adjustable Voltage Charge controller voltage to 15.0V, does that mean my T1275's will get an actual 14.8 volts from my solar panel?

[mena661]

BFL13 wrote:
AFAIK the Iota IQ4 goes to 14.8 but that's so the batteries can get to 14.6.

Yep, that's what it does (I think).

[BFL13]

AFAIK the Iota IQ4 goes to 14.8 but that's so the batteries can get to 14.6. Once the batteries reach 14.6, it stays there for 15 minutes and then drops to 14.2. Phooey on that!

I don't know any converter that will do it right in every way. That's why I still use the 13.8v Parallax 7355 as the converter for when on shore power (works great) and use separate chargers for the real battery charging stuff to proper high voltages for my 6s and Trojan 1275s.

For fast charging four 6s I use a 100amp charger that goes to 14.8 and stays there, or I can crank that voltage higher if it is cold out so it should be more like 15.1v Note that 100/440 is only a 22% charging rate and you could safely go higher to a 30% charging rate on the four 6s if you want.

Yes it is a way to get by in the fall/spring when solar is not as good as in summer, to just charge for an hour in the morning with charger and then go solar for the rest of it. Trick is to have :
- a serious charger and gen to run it
- gen hours that let you run it in the morning.

That may let you off the hook for getting more solar, so you end up with too much solar in the summer. I keep going back and forth on this, where I get too much solar for summer and sell some, then buy more for the spring and then wish I hadn't and sell that, then a sale on panels happens I can't resist so I buy more and end up with too much solar again! There is nobody who can help you if you get that affliction. 😞

[NinerBikes]

chloe's ranch wrote:
Thanks NinerBikes. Last November my informal power analysis showed that the battery dropping lower each morning with 240 watts of solar and I ended up running the generator more than we like. In the summer the 240 watts worked fine for our needs(led TV and led lights.) So adding more solar is more for our use Nov.-Feb.and probably more than we need in the summer. I do like your comment about the advantage of redundancy.

If you want to run the generator less... there are 2 ways to do that.

1. Run the generator first thing in the morning, when the batteries state of charge is lowest, and the charge controller on your motor home is most efficient. Brew coffee with 120V and hair dryer too while your batteries are getting a bulk charge.

2. Since you run Golf Cart batteries, look into an Iota 55 or 60 amp charger that has IQ4 mode, and charges at 14.8 volts for bulk mode, whereas most other brands for off grid use charge at only 14.4, not really what a golf cart battery is spec'd for. Run it for an hour or 1.5 hours, or 2 hours, first thing in the morning, where the generator charger is most efficient in dumping amps into the battery to bring it up to 75, 80, 85% charge. Top off the total charge to as close to 100% as you can get with your solar panel array.

3. Increase the efficiency of your solar panels by getting a trailer hitch mount that you can aim your panels directly at the sun 2 or 3x during the day to increase the panels intake efficiency to closer to max amps capability. Do a search of BFL13 for solar panel amperage yield. Do a search on rjsfishing for trailer hitch solar panel mounts.

You can probably pick up 40-50% in the winter time by doing this.

4. Buy a quieter generator.

[chloe_s_ranch]

Smketter I should have mentioned the MH is in indoor storage when not in use so no solar then.

[BFL13]

smkettner wrote:
I would not want 14.5 volts on my battery for two hours every day when not in use.

This is where the Morningstar (and others) can be programmed to charge differently depending on the start voltage each day. While in use you may want four+ hours at 14.2/14.8 and not in use just 15 minutes.

Storage is different from camping for sure. Adjustable voltage is good so you can also set to a Float like 13.4 when in storage and crank it back up to 14.8 for camping.

It also depends on the charging profile of the controller as to what it does once it hits the 14.5. Some have a timer that holds it there for say two hours. Some stay there till it gets dark which could be another six hours. Some stop charging right away and let the battery voltage fall to 13.x (low set point) and then start charging again till it reaches the high set point again. I think most solar float chargers do that up and down thing.

[chloe_s_ranch]

Thanks NinerBikes. Last November my informal power analysis showed that the battery dropping lower each morning with 240 watts of solar and I ended up running the generator more than we like. In the summer the 240 watts worked fine for our needs(led TV and led lights.) So adding more solar is more for our use Nov.-Feb.and probably more than we need in the summer. I do like your comment about the advantage of redundancy.

[time2roll]

I would not want 14.5 volts on my battery for two hours every day when not in use.

This is where the Morningstar (and others) can be programmed to charge differently depending on the start voltage each day. While in use you may want four+ hours at 14.2/14.8 and not in use just 15 minutes.

[NinerBikes]

BFL13 wrote:
Many/most controllers do not have an adjustable high set point and they top out at 14.3 or whatever. I don't know what the Phocos does.

Trojan 105s want 14.8 so it might be a consideration to make the second controller an adjustable one. They cost more of course.

You can buy an adjustable voltage PWM in 10-15 or 20 amps on ebay all day long, for under $20... will go from 14.4 +- .9 V

You need to read the instructions and program it in "b2" mode, with a "+4" for an entry for it to charge at 14.4 +.4 V = 14.8V for your GC-2 batteries.

http://www.ebay.com/itm/24V-Solar-Panel-battery-charge-controller-20A-amp-12V-Solar-PV-system-Black/151181596678?_trksid=p2047675.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D18845%26meid%3D4515165716874710266%26pid%3D100005%26prg%3D8532%26rk%3D3%26rkt%3D5%26sd%3D141178180469%26

http://www.ebay.com/itm/Upgrade-version-20A-Solar-Charge-Controller-Regulator-12V-24V-auto-switch-480W-/271327078984?tfrom=350856561025&tpos=top&ttype=coupon&talgo=undefined

[BFL13]

chloe's ranch wrote:
I checked online and the Phocos factory boost set point is 14.5 for two hours. I did not see that you could change that setting.

14.5 is not bad. You can work with that ok. Since solar does not often fully recharge the batts anyway, maybe getting to 97% SOC on a good day, you have to do some sort of overcharge every month or so to get the batts to 100% anyway. So it doesn't matter if you only get to 14.5 instead of 14.8----as long as you do your monthly 100% overcharge.

You can do that by going "panel direct" on solar (by-passing the controller) or with a charger on shore power that can get into the 15s.

That's what I have been doing with my 6s that want 15v to be truly full and my solar controller only went to 14.6 The batts are fine.
I use a VEC1093DBD at home to do their 100% SOC overcharge using the Equalize feature of that charger.

[NinerBikes]

I would go for redundancy and two 20 amp controllers. In the event one of them fails, you still have power generation from the other unit, and at least 50% of your total watts available charging the batteries, plus the generator for emergency days or cloudy days to top off your batteries.

You really need to do a power analysis and see how much you are using, in amps, in a typical average day. Then throw in some cold days when you are running a lot of fan time burning the propane to stay warm. That fan sucks a lot of amps down when you are running it. 4 golf cart batteries, when new run to 50% state of charge (SOC) will allow you to draw off 220 Amp hours or a bit more, safely. You should be able to get close to 14 or 15 amps per 240 watt panel, ideally, if you were aiming panels at the sun, for 5 or 6 hours in winter... but it sounds like your's are roof mounted, so you get quite a bit less yield, in the winter. Which is when you run the heater the most.

14 amps x 5 hours is 70 amp hours... buy another 240 watts, and you double that to 140 amp hours. That is roof top, un aimed. By the time spring rolls around and the days get a little longer, you'll get more daily.

Before you do anything, you need to calculate your usage, worst case scenario, to see what you need to make up.

[chloe_s_ranch]

The $500 price was for the Blue Sky mppt controller and the 120 watt kit all included.

[chloe_s_ranch]

smkettner wrote:
$500 seems high for a 30a MPPT. Highly rated Rogue 30a is $375, Morningstar 60a is ~$550. I can assure you the Morningstar is topline.

[time2roll]

If staying with PWM the second 20a s/b fine.
Although 45a Morningstar PWM probably has way more features for just a bit more $$.

[chloe_s_ranch]

I checked online and the Phocos factory boost set point is 14.5 for two hours. I did not see that you could change that setting.