Solar Power question again

[MarGreen]

Hi. We have an Escape 17B with front and back Zamp ports. We have a 100 watt solar panel and need more power. What would be the best way to add another panel and maximize the power from the panels? During cloudy days or in shade the controller says 12.2-12.4 volts are going in. After a few days of camping, the plug-in gadget in the cigarette lighter looking thing says we have 11.8-12.2 v power. The heater fan in the winter and the water pump for showers seem to draw a lot of power. We like to turn on the inverter to charge my laptop and then turn it off but don't do it if the power looks too low. Thank you very much for any answers!

[Ron in BC]

There'll be lots of opinions on your question.

Mine is the next step would be a 100 watt semi flexible panel used as a portable panel. Lightweight and easy to move and incline to get max power.

Ron

[Ian and Sue]

Are you running a single 12v battery or 2 6v batteries? If it is a single maybe it is time to add more storage.

[MarGreen]

Ron_ Thanks. That's what we have now. Should we buy one and another controller and plug one in each zamp port? Or should we link the two panels together?

[MarGreen]

Thanks, Ian. We have two 6 volt batteries.

[Ron in BC]

Are you using the one that you have as a portable panel and moving it as much as possible out of the shade? If you are then definitely more panel surface area would help improve the output.

It depends on what controller you have now whether you'd need another controller. If the one you have now is minimal then there's lots of inexpensive ones on Amazon and they're capable of handling 2 or 3 panels. You don't need multiple controllers.

Ron

[padlin]

We're all different so you have to decide how you want to handle things.

You can get multiple portable panels and attempt to keep them in the sun when parked in the shade, something I've had limited success with when parked in the shade.

You could get a panel or 2 mounted to the roof, set up your portable when in the shade and move to the sun if you need to.

You can bring along a generator for the times you can't manage with the portable.

You can even go find a campground with power to let the batteries recharge when need be.

Running the furnace sucks a lot of power, you need to supplement your portable solar some way when using more power then it can generate. Roof top panel/s and parking in the sun would be my choice when it's cold.

Might be a good time to consider a power monitor that will keep you better informed of the state of the batteries.

[dfandrews]

As a reference: We have a 17, with a single larger than std. 12V battery (Group 29 - 126 Amp H), and 150 Watt solar on the roof.
Our 12V electric use is furnace fan, MaxxFan on during the day, water pump on only when drawing water (yes, we switch it off when not actively drawing water), small 200W plug-in inverter to charge laptop occasionally, 12V to USB at night to charge phones and 2-way radios, the E-17's LED lights on at night.
The only times we discharged the battery to near 12.0V was w/several days of rain while in a shady camp site, and once when we accidentally left the frig. on 12V instead of propane (after a ferry ride).

We use propane for the frig. at all times, except when restricted by travel on ferries, travel through long tunnels (per posted regulations), and refueling.

[Brian B-P]

Originally Posted by MarGreen

Should we buy one and another controller and plug one in each zamp port? Or should we link the two panels together?

Unless you are using a maximum power-point tracking (MPPT) controller, there is no advantage to separate controllers. All panels (up to the maximum capacity of the controller) can just be wired in parallel to the same input of one controller.

[jxoco]

I think linking the two panels together would make it easy to aim them both at the sun and only have one wire as a tripping hazard.
Your voltages sound low to me.
Maybe it is my misunderstanding of your measurement but I would expect higher than 13 volt numbers when the sun is on the panel and the battery is charging.

Here are the voltages on batteries that have been unplugged from anything and allowed to stabilize for about a half hour;
12.73v 100%
12.62v 90%
12.50v 80%
12.37v 70%
12.24v 60%
12.10v 50%
12.0v 40%
11.8v 30%
11.7v 20%
11.6v 10%
<11.6v 0%

[alanmalk]

Originally Posted by jxoco

...
Your voltages sound low to me.
Maybe it is my misunderstanding of your measurement but I would expect higher than 13 volt numbers when the sun is on the panel and the battery is charging.

Start with the easy & cheap approach first before you spend $$$.
Make sure the batteries are properly full.
Clean the battery posts of any corrosion and inspect the wires.
Borrow a reliable & accurate multimeter and confirm the voltage right at the battery posts matches your trailer voltmeter.
This time of the year it is important that the portable panel(s) are aimed directly at the sun. (I did a test in January and found a flat on-the-ground panel produced 1/3 as much power as a panel aimed directly at the sun.)
Run the fridge on propane and turn off any tank heaters if you don't need them.

All the above - no cost other than time.
Spending money...
Upgrade the wire from your current panel if suspected of being too thin. There are tables of voltage loss verses wire gauge + length. (Length is 2 X the actual wire to account for both the positive and negative wire.) Shorter and fatter wire is always better than thin and long. At least until the wire cost approaches another panel.
Finally, another panel for more power. And a battery upgrade for more storage if warranted by your camping style.

--
Alan

[jxoco]

Originally Posted by alanmalk

Start with the easy & cheap approach first before you spend $$$.
Make sure the batteries are properly full.
Clean the battery posts of any corrosion and inspect the wires.
Borrow a reliable & accurate multimeter and confirm the voltage right at the battery posts matches your trailer voltmeter.
This time of the year it is important that the portable panel(s) are aimed directly at the sun. (I did a test in January and found a flat on-the-ground panel produced 1/3 as much power as a panel aimed directly at the sun.)
Run the fridge on propane and turn off any tank heaters if you don't need them.

All the above - no cost other than time.
Spending money...
Upgrade the wire from your current panel if suspected of being too thin. There are tables of voltage loss verses wire gauge + length. (Length is 2 X the actual wire to account for both the positive and negative wire.) Shorter and fatter wire is always better than thin and long. At least until the wire cost approaches another panel.
Finally, another panel for more power. And a battery upgrade for more storage if warranted by your camping style.

--
Alan

I totally agree with Alan and just a fine point, when you are making sure the batteries are full, use distilled water.
Also it sounds like the solar controller is on the panel and then the wire to the battery. It should be the wire from the panel to the controller which would be beside or as close as possible to the battery.
The panel can easily put out 16 volts and if you lose a volt or two no big deal but the controller puts out a fixed 13.2 and if you lose a volt across the wire to the battery you will be undercharging the battery

[tdf-texas]

Originally Posted by jxoco

I totally agree with Alan and just a fine point, when you are making sure the batteries are full, use distilled water.
Also it sounds like the solar controller is on the panel and then the wire to the battery. It should be the wire from the panel to the controller which would be beside or as close as possible to the battery.
The panel can easily put out 16 volts and if you lose a volt or two no big deal but the controller puts out a fixed 13.2 and if you lose a volt across the wire to the battery you will be undercharging the battery

You may be correct that losing a volt or two from the solar panel is no big deal if you have a PWM solar controller - the controller is going to clamp the incoming voltage to what the battery can take anyway.

But if you have a MPPT solar control, losing panel voltage means losing power that could be charging the battery.

The only reason I can find for using a PWM solar controller is that they are cheap. A MPPT controller outperforms a PWM except for price. Well, you get what you pay for.

[Doug2000]

If all the prior suggestions check out, I would add 2 100 watt portable panels. Make sure they’re aimed at the sun with no obstructions. I read even a very small obstruction on the panel drops efficiency substantially.

Are your batteries good? Always keep your batteries charged, don’t let them go dead. If your upgrading your batteries, look at AGM.

[alanmalk]

Originally Posted by tdf-texas

You may be correct that losing a volt or two from the solar panel is no big deal if you have a PWM solar controller - the controller is going to clamp the incoming voltage to what the battery can take anyway.

But if you have a MPPT solar control, losing panel voltage means losing power that could be charging the battery.

The only reason I can find for using a PWM solar controller is that they are cheap. A MPPT controller outperforms a PWM except for price. Well, you get what you pay for.

Looking into the question of 1 or 2 volts lost between the panel and the controller - due to wire resistance...

The PWM controller does limit the voltage to the battery ("clamps") when needed - which happens when the battery approaches full. Or looking at it from the battery perspective, when the amperage going into the battery drops and the voltage at the terminals rises above (typically) 13.8 to 14.4, then the controller needs to restrict the average voltage to no more than the absorption rate specific to that battery. This is happening at the end of the charge.

What is happening most of the time is that the battery is able to absorb all of the amperage from the (typical) 160 watt panel. Because the amperage is at a maximum that the panel can produce, the voltage is reduced at the panel - typically a bit over the controller output voltage plus the voltage drop. Under this condition - say 2 Volts of drop times 8 Amps, you have lost 16 watts of power to warming up wires. That's 10% of the panel output. If you are not happy with your battery charge at the end of the day then perhaps that 10% is important to you.

Using a MPPT controller will not recover that 10% because it is lost before it reaches the controller.

So, what is MPPT? Simply a DC to DC converter run by a microprocessor. DC to DC conversion takes input voltage A and changes it into output voltage B (up or down or sometimes both as needed), with a high efficiency. The microprocessor adjusts the output "B" voltage as required by the battery state of charge.

The advantage of MPPT is that when excess voltage is available (remember, as the battery becomes full), it can convert that excess into usable power (Amps). But the battery may not be able to accept those extra Amps. Which makes for an interesting question. Is MPPT worth the extra $$$?

Perhaps! They seem to be better designed for the most part, with more intelligent controls to handle more types of batteries (like AGM and Lithium). But the real advantage is when the input is coming from the bigger home-size 250-300 watt panels, or a pair of trailer panels hooked up in series. Now you have a system putting out 28-36 Volts at the same Amps as a smaller panel but double the Volts. A MPPT will take double the Volts and put out double the Amps at a voltage the battery can use. And since voltage loss in the wire is relative to the Amps and not the Volts - there is no need to buy heavier wire for the 300 watt panel - a big savings.

Being a bit obsessive about power loss, I would probably go for MPPT myself in my next Escape. But for now I will just adjust my portable, keep the wires short and my connections clean - all for free.

--
Alan

[tdf-texas]

Originally Posted by alanmalk

Looking into the question of 1 or 2 volts lost between the panel and the controller - due to wire resistance...
--
Alan

There's more it as to why a MPPT controller is more efficient than a PWM. Here goes the technical stuff I was trying to avoid.

At a solar panel's maximum voltage, it will produce no current. At a solar panel's maximum current, it will produce no voltage. Power is the product of voltage and current and we want a PV panel to operate at the point on the IV curve where it will produce its maximum power. This operating point is called the maximum power point (MPP) and is the area where solar systems operate for maximum efficiency.

All solar panels have a MPP where they produce the most power. This MPP is affected by both temperature and shading as well as the amount of solar radiation that hits the panel.

A PWM (Pulse Width Modulation) solar controller regulates the average value of voltage (and current) fed to the battery by turning the switch between solar panel and battery on and off at a fast rate. The longer the switch is on compared to the off periods, the higher the total power supplied to the battery. A PWM solar controller controls the battery charge on a linear line that rarely matches the MPP of the solar panel. (see chart below)

A MPPT (Maximum Power Point Tracking) solar controller forces the solar panel(s) to operate at their MPP in any light condition. A MPPT controller is able to balance voltage and current by increasing one, current for instance, and decreasing the other (voltage) to force the solar panel to operate at it's MPP at all times.

Maximum Power Point Tracking is why a MPPT solar controller will almost always be more efficient than a PWM controller. The only time a PWM can approach the efficiency of a MPPT is where the solar panels are operating at a reduced level that happens to match it's MPP. Since this doesn't occur often, MPPT controllers usually produce more power for the given conditions than PWM controllers.

https://www.solarlightsmanufacturer....ge-controller/

So back to my earlier comment. Why would anyone want to use a PWM solar controller other than a cheap price. A PWM controller is not as efficient as a MPPT controller so on a day to day instance, all the solar power available will not be utilized using a PWM controller. Only a MPPT controller operates the solar panel(s) at their MPP and produces the most power available.

[Berndad]

Thanks!
A very nice summary of why I am looking at MPPT, now which do you recommend?
I have a Go Power system installed by ETI with 2 roof mounted 190 watt (an unexpected upgrade!) panels their standard 30 amp pwm module with a nice display and the ability to remote control the 1500 watt Go Power inverter(seldom used, but nice to have when needed). My battery monitor is a Victron 712 and I was planning on getting their 100/30 smart solar MPPT, but would lose the remote ability to switch the inverter on and off. Go Power now has a cool new MPPT 40 amp for substantially more money (https://thesolarstore.com/go-power-4...te-p-2777.html) and the remote allows some monitor functions and remote operation of the inverter, but does not appear to have configurable charging profiles and lacks a dedicated Lithium profile.

I also have a Zamp port installed by ETI with a 100 watt renogy panel wired to the PWM controller in an unknown configuration. leading to my second question; does anyone know how the Zamp port is wired, I hope parallel, but do not know for sure?
Still running the dual 6 volt lead acids provided by Escape on our 2019 19.

[Vermilye]

You can purchase a remote for the GoPower Inverter -the simple on/off or one that has more information in a display.

I like the ability of the Victron 100/30 to provide data & allow programming on my phone (like the 721 battery monitor). The combination of the Victron & remote for the inverter will also be less expensive than the GoPower MPPT controller.

If you switch to lithium in the future, rather than needing to purchase a new controller, all you need to do is reprogram the Victron.

[tdf-texas]

Originally Posted by Vermilye

You can purchase a remote for the GoPower Inverter -the simple on/off or one that has more information in a display.

I like the ability of the Victron 100/30 to provide data & allow programming on my phone (like the 721 battery monitor). The combination of the Victron & remote for the inverter will also be less expensive than the GoPower MPPT controller.

If you switch to lithium in the future, rather than needing to purchase a new controller, all you need to do is reprogram the Victron.

I have the Victron 100/30 as well and am very pleased with it.

Bernard, Jon spends more time boondocking than anyone I know. If he is pleased with the Victron, you can be assured that it will be a good choice.

[Berndad]

Originally Posted by Vermilye

You can purchase a remote for the GoPower Inverter -the simple on/off or one that has more information in a display.

I like the ability of the Victron 100/30 to provide data & allow programming on my phone (like the 721 battery monitor). The combination of the Victron & remote for the inverter will also be less expensive than the GoPower MPPT controller.

If you switch to lithium in the future, rather than needing to purchase a new controller, all you need to do is reprogram the Victron.

Is the 100/30 enough for the 480 watts of power the panels are rated for?
I believe it is if the Zamp is wired in parallel?
Thanks for the rapid response!