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Old 03-25-2020, 07:19 PM
hardcalibres hardcalibres is offline
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Originally Posted by Aerindel View Post
Quiet isn't that big of a deal as I don't have anyone else who lives close enough to hear. Mostly its just ME who doesn't want to listen to a generator run.

The alternative is a gas powered alternator. A 'generator' except instead of a generator to make AC, an alternator to make DC. Run for a few hours as needed to charge the batteries.

Perhaps even gasifier fed, which I did get working many years ago as a test but never messed with again as at the time it just wasn't a priority.

Or just going without power, which was always plan A when I built this place, but things would certainly be better if I had something to charge devices, headlamps, etc with.


That is a good point.

Here is another question.

Is it better to place the panel where it gets some light all day, or good light, for a couple of hours?

In my case, south, or west orientation respectively.

Not an ideal solar day in any case:

I would go with good light for as many hours as you can get it.

As I think I have mentioned before, I don't hard mount my panels. Like you, they are a supplementary or emergency source of power. I ground mount mine and then move them through the day to track the sun and stay out of the shade.

This works well for an emergency and if the grid was out long term, ground mount would be easier to hide.

We had a planned power outage a couple of days ago. I set up two 200W panels, an MPPT controller, two 100Ah batteries and two inverters to run our big domestic fridge/freezers for the day. That system did that job well for about 9 hours (although the batteries had discharged deep into their capacity by the end of the day). When the power came back on, I put the batteries on mains chargers overnight.

If the mains power was never coming back, I would decommission the domestic fridges and use 12V freezers I have instead.
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Old 03-25-2020, 07:48 PM
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Yeah, I am trying to avoid the roof mount obviously.

There is a reason solar kills more people per MW that Nuclear.
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Old 03-27-2020, 12:55 AM
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Aerindel,

What panel are you using? 12V rated?.. or 24V rated?

What is the make and model of your controller? We need to know what the controller's maximum input voltage is. If true MPPT, then it's not the best choice for 12V rated panels charging a 12V rated storage bank. With most MPPT controllers, it's best to use at least two 12V panels connected in series for 24V controller input to charge12V storage batteries.

Also... What is distance between the controller and batteries? And what gauge is the cables?
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Old 03-27-2020, 01:03 AM
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Aerindel,

What panel are you using? 12V rated?.. or 24V rated?

What is the make and model of your controller? We need to know what the controller's maximum input voltage is. If true MPPT, then it's not the best choice for 12V rated panels charging a 12V rated storage bank. With most MPPT controllers, it's best to use at least two 12V panels connected in series for 24V controller input to charge12V storage batteries.

Also... What is distance between the controller and batteries? And what gauge is the cables?
Welcome to the boards!

Yes, two panels in series does help to keep the panel input volts to the MPPT, above the charge voltage for the battery and reduce losses in the wiring from the panels to the controller.

When I was keeping the fridges going, I was running the two 200W panels in series.

My controller is rated up to 50V input.
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Old 03-27-2020, 01:18 AM
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12volt panel.

50volt input on the charge controller.

10 gauge wire, 20 feet to the panels, 10 feet from the charge controller to the batteries.

So are you saying when I get my second panel I should wire it in series instead of parallel?
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Old 03-27-2020, 01:34 AM
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Quote:
Originally Posted by Aerindel View Post
12volt panel.

50volt input on the charge controller.

10 gauge wire, 20 feet to the panels, 10 feet from the charge controller to the batteries.

So are you saying when I get my second panel I should wire it in series instead of parallel?
It may help when the panels have poor light input.

Good thing is, with that controller, you can try both parallel and series to see which works best.
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Old 03-27-2020, 01:53 AM
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Quote:
Originally Posted by Aerindel View Post
12volt panel.

50volt input on the charge controller.

10 gauge wire, 20 feet to the panels, 10 feet from the charge controller to the batteries.

So are you saying when I get my second panel I should wire it in series instead of parallel?
Yes,... assuming the output voltage from the panels is safely below the controller's maximum input voltage (check the owners manual). The panels will produce their highest output voltage during cold conditions w/bright, direct sunlight, (while unloaded - ie: not connected).

Because of the lower 12-13.7 charge voltage between the controller and the storage, I would recommend at least 8ga ( or double-up your 10ga if you have extra.

Do you have a DMM?

Last edited by HPV; 03-27-2020 at 03:23 AM.. Reason: corrected wording
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Old 03-27-2020, 02:28 AM
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My current system on my RV has...

Six 100W PVs (5 in series, 1 parallel). Bright sunlight I typically see 112-115V @ approx. 5-6A to my controller. I have 4 more 100W PVs waiting to be install (all to be added in parallel to boost amps).

Victron 150-35 (150V - 35A) MPPT controller
Victron Phoenix 48-1200 (48V - 1200W) 120VAC sinewave inverter
Four deep cycle 12V FLA batteries connected in series (48V nominal system).

So why such a system on an RV? So I can run both my 700W microwave and my 1300w induction cooktop (separately) without seriously draining my storage. Cooking 40 minutes on either during mid-day lunch, storage top-off recovery time takes less than the time I spend eating it. And I used zero propane. Once I install the remaining 4 PV's, I should be able to cook (sunny midday) and use little or no juice from my batteries.
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Old 03-27-2020, 04:58 AM
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Hi Aerindel.
Don't give up. Your second 100W panel will make a difference.

Quote:
Originally Posted by Aerindel View Post
Is it better to place the panel where it gets some light all day, or good light, for a couple of hours?
The second option. Direct sunlight. Clouds cut the power production drastically.
A quick search gives figures of only 25% power output on cloudy days and 10% under heavy cloud. Looking at the picture you posted I suspect you aren't getting much power production because of the cloud. But any shade will also cut the power output a lot.

Also make sure the sunlight is falling perpendicular on the panel. This is why some people set their panels up to track the sun. I use mine when camping and move them manually three times. Once to face towards the morning sun. Then mid morning they get placed facing towards the sun (N in Australia, S in the northern hemisphere). Because the sun is fairly high in the sky during summer at my latitude I lay the panels nearly flat for this phase (perpendicular to the sunlight). Then in the late afternoon I face them toward the setting sun. This gives the most sunlight on the most panel surface which is what gives best power production. You could always make up a simple turntable to make spinning the panels easier.
If you fix the panels in place, eg roof mount, face them towards the sun and fix them where they will get the most direct sunlight. Cut down a couple of trees if you need to.
There are charts already available which will tell you which angle to fix them at for the best overall power output for your latitude.

If a corner or part of the panel is shaded while the rest is in the sun this can also cut power production. Some panel types handle this better than others.

I would recommend having another way of charging the battery. A generator is one way but with a bit of extra wiring you could recharge them from your vehicle's alternator. They put out a lot of power and your vehicle doesn't use very much fuel while idling. It's another option.
But I've always wanted a gasifier, so if you do set one up, please start a thread about how you did it so we can all learn.

LED lights and chargers for your electronics don't use much power. Large electronics like TVs and anything mechanical, like a water pump, sucks a lot of power out of batteries.

The thing I liked about using solar was it really taught me to look at how much power I use. Just like you are now. Good fun.
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Old 03-27-2020, 05:07 AM
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Quote:
Originally Posted by HPV View Post
Do you have a DMM?
Digital Multi-meter? Yes, a couple.

Voltage should be fine, panels are listed as 21.6 open voltage, so two in series is still below the 50 volt input max my charge controller lists.

I think the voltage has been a problem. Looking into my manual, it claims the charge controller charges at 14.6 volts in 'boost' mode to top off the batteries once 'bulk' charging at 13.8 is done but my actual solar output is usually no higher than 13.5 because of clouds, trees etc and my batteries won't seem to charge above about 12.4 on the panels. (Although they are at 13.00 now after putting them on my trickle charger for a couple of days)

Although if I understand this correctly, another panel, even in parallel, will should still raise my voltage somewhat since now I will have twice as many amps going into the batteries and they shouldn't draw down the voltage as much.

Either way, I should hopefully get the second panel in a day or two...if I can. My state goes into shelter in place tomorrow night and I'm not sure if the feed store where I get packages counts as an essential service. I already have extra wires and connectors to set them up either way.

Quote:
The second option. Direct sunlight. Clouds cut the power production drastically.
A quick search gives figures of only 25% power output on cloudy days and 10% under heavy cloud. Looking at the picture you posted I suspect you aren't getting much power production because of the cloud. But any shade will also cut the power output a lot.
In that particular picture there is 1/2 of snow on the panel too

But yes, I have many things working against solar here. Many cloudy days. Sun very low on the horizon some times of year, and trees. Some trees I can cut down but in some directions there are so many at such an angle I would have to clear acres.

All this is why I'm never going to try and run my whole house, I will be happy if I can just get something going to allow me to charge USB devices and power tool batteries and use for house lights etc, during normal non-SHTF outages.

If feasible, I would eventually like to use it to run my water pumps, which shouldn't be too big of a deal as they are little on demand RV style pumps that only need to run for maybe half an hour total each day.
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Old 03-27-2020, 07:04 AM
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Quote:
Originally Posted by Aerindel View Post
....and my batteries won't seem to charge above about 12.4 on the panels. (Although they are at 13.00 now after putting them on my trickle charger for a couple of days)
The smaller the system,.. the more efficient it must be.

Yes, the cloudy conditions are undoubtedly inhibiting the system, so I would strongly encourage series connected panels so the MPPT can best do the job it was designed to do. 43.2V looks good.

https://www.google.com/search?client...w=1093&bih=521

Try to avoid scrimping on wiring. Even though the 10ga between the controller and battery is more than adequate to handle 30+ amps, and you are feeding it 5A, larger cabling will further help to reduce the losses. Or... simply moving the controller closer to the battery produces the same effect.
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