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New Solar

April 20, 2020, 09:59:23 pm

We are considering some solar panels for the roof. Not looking to be self sufficient, just want some solar help to charge the batteries.  We have 3 of the Lifeline 8D AGM batteries and a Magnum 2000 inverter.
Was really looking for a system to add some power back every day after using some LED lights and a few hours of TV, maybe even a short use of the microwave or hair dryer.
Any suggestions ? Again, just a fairly small system for a little power help. If we're boondocking for several days, I have no problem running the generator every few days to get a full charge.

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Re: New Solar

Reply #1 – April 20, 2020, 10:06:14 pm

6-800 watts, you will consume more amps than you think. Hair dryer, microwave, electric coffee pot will get into batteries quick.

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Reply #2 – April 20, 2020, 10:11:08 pm

How about without any of the "heavy users", just LED lights and some TV, do you think 400 watts would be enough ?

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Reply #3 – April 20, 2020, 10:51:57 pm

Easy answer:  Write down how much solar you "think" you will need, then double it.  Triple it, if you have the space on the roof.

Better answer:  Calculate exactly what the devices you want to support will use, then educate yourself on what size system will do the job.

How Much Solar Do I Need On My RV?

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Reply #4 – April 20, 2020, 11:04:23 pm

Forget the hair dryer, cut the hair short so it dries on its own. We have same batteries and 900 watts solar. Batteries have there own panel for engine. We have no problems living off the hook ups for many days and this is with a residential fridge. Hardly ever use the genset.
In 10 yrs we have put about 50 hours on it.
JohnH
We do not watch the tv much and our computers are used just for necessary use not streaming etc contrary to  others. We travel mostly in sunny times as where we live summer is great here along with scenery.

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Reply #5 – April 20, 2020, 11:36:40 pm

Pretty easy to put 1200-1500 watts on the roof of a 36' especially if you use some of the newer 66 cell panels.  They are the same width of the 72 cell panels just shorter.

More is better with AGM batteries, the top end of the charge process is the hardest.  More watts helps. 

900 watts on the roof will replace a couple hour of generator hours per day.  Less in the winter, more in the summer.

A typical user without a residential refrigerator will use about 2000 watts per day.  That is about 160 amp hrs.  That is about 4 hrs of generator time per day to keep up, maybe more. 

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Reply #6 – April 21, 2020, 12:54:36 am

Four of the new shorter panels would be perfect unless  you have a residential fridge. We have a 50 inch TV with a smaller in the bedroom. We use the microwave and latte maker in the morning and never start the generator unless for AC. Batteries are full before noon each day. Almost all LEDs.

We only have about 435 Ah worth of AGM house batteries but they are still going strong after 11 years. The greater number amp hours you have means less percentage of discharge each day means longer battery life.

I use a lighter plug to lighter plug cord to keep the engine batteries up here at the house or if camping for more than a day. We shut off the inverter at night.

A 300 solar panel will not come close to 300 watts. Even if you tilt the panels, they won't be perpendicular to the sun for more than a few minutes each day. Temperature of the panels will usually be higher than the rated test temperature which drops the output. The panels are rated at 25°C so if the panel is 50°C, it will produce 10% less. (0.4% x (50°C -25°C) = 0.4% x 25°C = 10% ......or 0.4% per °C above 25°C.

Buy a good MPPT controller. Make sure the voltage to the controller won't go over the controller's maximum on a cold morning. We have 72 volts going down to the controller but it can be quite a bit higher than that even before the sun comes up. No watts but higher voltage. The reason we didn't go all series when wiring as it would have gone over the controller's 150 volt maximum on a freezing morning.

Pierce

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Reply #7 – April 21, 2020, 08:31:35 am

I have 400 watts solar along with 300 amps Battleborn batteries.  Last summer on our trip to Alaska we never ran the generator and dry camped up to 10 days at a time.  Now Alaska is somewhat unusual that even with the low sun angle there are more daylight hours so you actually get more charge each day.
We normally use 120 amphours/day.  Start the day with the big inverter on to make coffee, run the microwave a couple minutes to warm our cups, a small 12V fan running all night, led lights as needed, Aquahot on diesel in the morning and again in night to take the chill off and for hot showers (with a temperature gauge to know when I need to run the Aquahot).  Don't run the heater at night.  TV has a separate 400 watt inverter to watch for a few hours each night, 12 volt chargers for the laptops and phones.  I do have a Dometic fridge.
In February we spent a few days in Quartzite and had rain and cloudy days so weren't getting back up to 100% each day.  Even so we never ran the generator.  Lead acid or AGM, Gel batteries might be a bit different and take longer each day to reach full charge.
One piece of advice is to plan for additional panels when mounting and when buying your solar controller in case you want to add more later.

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Reply #8 – April 21, 2020, 09:40:38 am

Last year, I boon-docked almost exclusively, and the only time I had to run the generator was on the coast in Washington State as it rained almost everyday for two weeks.  We don't use the microwave much, but we do use laptops a lot and my wife likes to use the electric kettle to make hot tea.  I have 400 amp hours of Lithium batteries, and I had at that time 640 watts of flexible panels that I have since changed out to 1000 watts of rigid panels this past February.  So to answer your question, 400 watts of solar with occasional generator topping up will work if it is warm and you use the generator to run the microwave, it won't in the cold because the propane furnace blower uses a lot of 12 volt energy.  Of course more is better, but that depends on how much you boon-dock.  If you do so only occasionally, it may not be worth the money to put more panels.  However, if you boon-dock more than a couple weeks, it is worth it for the golden silence in my opinion.  I would suggest you put the 400 watts of solar up that you want, but over size your solar controller and wiring so that if you like the resulting silence from not using the generator as much, you can add more solar in the future without having to replace those components.

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Reply #9 – April 21, 2020, 09:55:15 am

If adding solar the first thing you should always do is an energy audit. That way you know approximately how much you use on a daily basis. Once you know how much you're using then you can size your bank accordingly. If you're just trying to run a few lights and maybe add a little few amps into the batteries one small solar panel 200 watts or so might do it for you. If you want to have enough solar to run your electrical needs for several days of boondocking then of course you're going to need a lot more than that. It's already been said if you do decide to do this put in the infrastructure to power your entire coach and start with one or two panels. You may find that you really like the idea of not having to run the generator. So that would mean putting in a good sized solar controller as well as the right size wiring and fusing. The fusing of course you can change out as you expand. But you don't want to have to change out the wiring.one thing to be really careful of when putting solar panels on the roof is to make sure you leave room enough for you to get around. Several of my panels were put in by a previous owner that causes a trip hazard for sure. At one point I plan to remove them all send the roof down seal and repaint and when I put the panels back on will be in slightly different areas. I also have the ability to tilt my panels in the winter. This will make them much more efficient when the sun is lower down on the horizon. But I doubt if I'd ever do it if it means possibly falling off the roof !

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Reply #10 – April 21, 2020, 01:53:33 pm

Our installers moto was " too much is just right" and I believe it.  After installing 1200 watts of solar and 720 amp hrs of lithium I'm finding we leave more lights on and run stuff longer and more often than we used to.      So for that reason I don't put much stock in the energy audit that people recommend.    We're not wastfull people in general, I just now don't have to run around behind the DW turning things off a split second after she is done with it.

  So I recommend doing as much as you can afford,, very much doubt you'll regret it and wish you had less. After all these coaches were built with a little bit of excess in mind ( thank goodness ).

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Reply #11 – April 21, 2020, 03:41:05 pm

We dry camped a lot From 2007 to 2017, got by with three 50 watt panels for 150 watts on the two Monaco Sigs, ran the gen for A/C, and if no A/C ran the gen every other day for a couple hours to charge up batteries to approx 80-85%, I did not have Victron  712, now I concider that a must.  I am running similar AGMs and inverter/charger to yours.

Since that worked so well, went with a new "huge" system for the FT.  That was two new LG 280 watt panels for 560 watts, more than triple my old system. That was good for one year.  Added two more LG 335 panels bring total wired up to 1187 watts.  Soon thereafter I came across SunPower used panels 305 watt each for $100 each, so an additional 610 watts, now 1797 watts.

I can still get on the roof easily and move around safely.  I especially like the two Victron smart bluetooth solar controllers (150/85 and 150/50 run in parallel) for ease of settings and cell phone application.  My original Morningstar 40 amp solar controler is on the two SunPower panels.  Invest in good solar controllers, I would recommend Victron with the smart feature.

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Reply #12 – April 21, 2020, 04:03:18 pm

Here is a list of MPPT controllers with recommendations and reviews. We have the Midnite Classic 150 (96 amps). We purchased it 11 years ago. Best Solar Charge Controllers in 2020 [Reviews, Pricing & Specs] | Wholesale...  Undoubtedly all good. I liked the made in the U.S. model for factory tech help and quick turn around if needed. They were very helpful when I called for advise. Discounts available for all models. I purchased ours at Northern New Mexico Wind and Sun for about $520 with free delivery, no tax.

Pierce

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Reply #13 – April 21, 2020, 05:57:52 pm

Magnum makes a Power Trace 100 solar controller.  Plus they have a web connection wireless unit so the entire system can be accessed anywhere there is web service.  A auto gen start can be added. 

Future system adds could integrate the roof airs and heaters into the auto start with either  board changes or the auto starts included temp sensor  and a 10 button controller to allow auto gen start to be temp controlled or the batteries state of charge.

You already have the Magnum inverter. 

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