Which inverter for 12V??

ywhic

Re: Which inverter for 12V??

Sorry.. you guys confused me to.. I didn't know about Voltage drop and heat.. and no one mention 36 VMP for 24v panels.. most panels I have found are hovering at 30 VMP..

MorningStar Pro 30 Amp controller PWM type 12/24 v... forget the MPPT per Photowhit.. the MS 30 PWM manual does not list any max VOC just maximum amperage at 30..

4 of the above mentioned ET Solar 190 watt 24v panels.. into a combiner box..

Voltage Maximum Power 37.20
Current Maximum Power 5.11
Voltage Open Circuit 44.85
Current Short Circuit 5.80

Normal Cell Temp 44.4 +/- 2' C
Temp. Coeff. of Isc (TK Isc) 0.042% C
Temp. Coeff. of Voc (TK Voc) -.0336 % C
Temp. Coeff. of Pmax (TK Pmax) -0.47 %C

and initially just 4 Trojan 105's in series to make a 24v bank.. (to later expand that by another 4 for the a/c during the next summer)..

I'll get a Samlex 24v PST-1000 Watt Sine Inverter.

Can you work with this definate information??

It sound on paper do-able..

Cariboocoot

Re: Which inverter for 12V??

Photowhit obviously caught on to this early. He's a sharp man for sure!

This is good.
24 Volt system with the 220 Amp hour 6 Volt Trojans in series.
The panels described in your last post all connected in parallel (each must have its own fuse) could provide around 20 Amps peak charging current which is about 9% rate. They will certainly exceed the 5% minimum.
The Vmp on the panels at 37.2 is enough to charge a 24 Volt system even with some Voltage sag from heat, just as Photowhit said.
The daily "harvest" will be just over 1.2 kW hours AC on a good day. This is just about the same as the AC Watt hours you can derive from the batteries @ 25% DOD. A good balance.
It may not be ideal for running the A/C, but it's certainly better than any of the 12 Volt configurations we've looked at.
It will be possible to add more battery and panel capacity in the future and have a system that will easily handle your refrigeration needs.

Looks like we have a winner.
Thanks to Photowhit for seeing through the fog I was lost in.

vtmaps

Re: Which inverter for 12V??

ywhic wrote: »

Most have numbers like this Canadian Solar 230 watt panel..

Voltage Maximum Power 29.6
Current Maximum Power 7.78
Voltage Open Circuit 36.8
Current Short Circuit 8.34
<snip>
even though I now understand I can wire all 3 in series and still have the 7.78 Amperage.. (correct?)

the current into the MPPT will be 7.78 amps. The current will be much higher coming out of the MPPT (going to the batteries). The 45 amp rating of the morningstar controller is the current out of the controller. If you do a 12 volt battery system you will be pushing the controller to (or slightly above) its 45 amp limit.

If you really intend to have four 6 volt batteries and a morningstar 45 amp MPPT controller and three canadian solar panels, you should do a 24 volt system. It will be easier on your controller, it will simplify the wiring of your batteries, the three panels in series will be simpler (no combiner box), the wires from panels to controller will be smaller, the battery to inverter wiring and fusing will be smaller, you will be following the best advice you have been given, and you will stop confusing us.

OMG! I was just about to post this and then I saw this:

ywhic wrote: »

Sorry.. you guys confused me to.. I didn't know about Voltage drop and heat.. and no one mention 36 VMP for 24v panels.. most panels I have found are hovering at 30 VMP..

MorningStar Pro 30 Amp controller PWM type 12/24 v... forget the MPPT per Photowhit.. the MS 30 PWM manual does not list any max VOC just maximum amperage at 30..

4 of the above mentioned ET Solar 190 watt 24v panels.. into a combiner box..

Voltage Maximum Power 37.20
Current Maximum Power 5.11
Voltage Open Circuit 44.85
Current Short Circuit 5.80

Normal Cell Temp 44.4 +/- 2' C
Temp. Coeff. of Isc (TK Isc) 0.042% C
Temp. Coeff. of Voc (TK Voc) -.0336 % C
Temp. Coeff. of Pmax (TK Pmax) -0.47 %C

and initially just 4 Trojan 105's in series to make a 24v bank.. (to later expand that by another 4 for the a/c during the next summer)..

I'll get a Samlex 24v PST-1000 Watt Sine Inverter.

Can you work with this definate information??

It sound on paper do-able..

It is do-able. Personally, I would stick to the MPPT. If you want to add more panels for the a/c next summer you will be pushing or exceeding the limits of the 30 amp PWM.
--vtMaps

Edit: Cariboocoot beat me to it again!

ywhic

Re: Which inverter for 12V??

Thanks for clarifying.. I was going to go 12v then the 24v krept in.. then the MPPT..

All that for $2540 with 4 panels (& shipping), 4 T105 6v batteries (or equivalent), MorningStar Pro 30 PWM controller, Samlex 1000 Sine Inverter 24v, & wiring..

I can find any listed limit on the PWM Controller.. is that because its based soley on AMPS for the model maybe??? or is that 'the way it is'???

Cariboocoot

Re: Which inverter for 12V??

vtmaps wrote: »

It is do-able. Personally, I would stick to the MPPT. If you want to add more panels for the a/c next summer you will be pushing or exceeding the limits of the 30 amp PWM.
--vtMaps

A good idea, vt, but the Tristar 45 MPPT is about $225 more than the Prostar 30 with meter. So he could also just get a second Prostar (if he doubled the panels) and connect the two in parallel. Or maybe change out the whole controller and re-wire the array if he wins the lottery.

There is expandability here.

P.S.: You could have "the duty" all day tomorrow if you like. :P

ywhic

Re: Which inverter for 12V??

vtmaps wrote: »

the current into the MPPT will be 7.78 amps. The current will be much higher coming out of the MPPT (going to the batteries). The 45 amp rating of the morningstar controller is the current out of the controller. If you do a 12 volt battery system you will be pushing the controller to (or slightly above) its 45 amp limit.

If you really intend to have four 6 volt batteries and a morningstar 45 amp MPPT controller and three canadian solar panels, you should do a 24 volt system. It will be easier on your controller, it will simplify the wiring of your batteries, the three panels in series will be simpler (no combiner box), the wires from panels to controller will be smaller, the battery to inverter wiring and fusing will be smaller, you will be following the best advice you have been given, and you will stop confusing us.

OMG! I was just about to post this and then I saw this:



It is do-able. Personally, I would stick to the MPPT. If you want to add more panels for the a/c next summer you will be pushing or exceeding the limits of the 30 amp PWM.
--vtMaps

Edit: Cariboocoot beat me to it again!

vtMaps.. Ok.. so if I stuck with the MPPT 45 (for sake of question).. can I use these same 4 ET Solar Panels..

4 of the ET Solar 190 watt 24v panels.. into 2 parallel and then series them for 90 VOC and 10.22 Amps??

Voltage Maximum Power 37.20
Current Maximum Power 5.11
Voltage Open Circuit 44.85
Current Short Circuit 5.80

Normal Cell Temp 44.4 +/- 2' C
Temp. Coeff. of Isc (TK Isc) 0.042% C
Temp. Coeff. of Voc (TK Voc) -.0336 % C
Temp. Coeff. of Pmax (TK Pmax) -0.47 %C

Then I can do a 24 or 12v bank and retain my original 12v Inverter and RV water pump..

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

I can find any listed limit on the PWM Controller.. is that because its based soley on AMPS for the model maybe??? or is that 'the way it is'???

That's the nature of a PWM controller: they expect the right Vmp in to give the correct charging Voltage and like all controllers the Amp rating is the maximum out. You wouldn't connect a PWM to, say, a 60 Volt array for a 24 Volt system because that extra Voltage would just be wasted.

The main caution is against the "24 Volt" panels that have a Vmp around 30: these are actually designed for GT systems and don't work well on battery systems because of that lower Voltage.

vtmaps

Re: Which inverter for 12V??

ywhic wrote: »

vtMaps.. Ok.. so if I stuck with the MPPT 45 (for sake of question).. can I use these same 4 ET Solar Panels..
<snip>
Then I can do a 24 or 12v bank and retain my original 12v Inverter and RV water pump..

Yes, you can still use those ET panels, but four of them would be over the limit for the MPPT 45 in a 12 volt system. I don't see how you can do both a 12 and 24 volt bank. As Cariboocoot mentioned above, there is some expandability even with the PWM controller.

--vtMaps

ywhic

Re: Which inverter for 12V??

MorningStar Pro 30 Amp controller PWM type 12/24 with meter..

4 of the above mentioned ET Solar 190 watt 24v panels.. into a combiner box..

Voltage Maximum Power 37.20
Current Maximum Power 5.11
Voltage Open Circuit 44.85
Current Short Circuit 5.80

Normal Cell Temp 44.4 +/- 2' C
Temp. Coeff. of Isc (TK Isc) 0.042% C
Temp. Coeff. of Voc (TK Voc) -.0336 % C
Temp. Coeff. of Pmax (TK Pmax) -0.47 %C

and initially just 4 Trojan 105's in series to make a 24v bank.. (to later expand that by another 4 for the a/c during the next summer)..

I'll get a Samlex 24v PST-1000 Watt Sine Inverter.

It will be possible to add more battery and panel capacity in the future and have a system that will easily handle your refrigeration needs.

Thanks for the help again folks.. I don't think $2500 on a good starter system is a bad place to be..

I'll figured also I can add 1 more 190 watt panel the array (total of 5) and max it out at at 25.55 Amp (or 29 with IMP)..

This would be a raw 950 Watt PV setup.. 613.2/5 panels (5.11 max *24v) and 5 Hours = 3066 max.. which when I double my batteries to 440ah of 24v should work out pretty good to maybe get my Air Conditioner idea working for 1-2 hours..

Cariboocoot

Re: Which inverter for 12V??

Albert, I have to say you keep calculating the Watt hours from the panels wrong.

950 Watts of panel * hours of good sun (usually 4, in your case 5) * system efficiency (usually 52%) = AC Watt hours.
That's 950 * 5 * 0.52 = 2470 Watt hours AC you can expect, not 3066.

That conversion from DC panel Watts to AC output Watts is a killer, but with battery based systems it can't be helped.

Just don't want you expecting more power than you're likely to get. That is a very common and disappointing mistake.

ywhic

Re: Which inverter for 12V??

Cariboocoot wrote: »

Albert, I have to say you keep calculating the Watt hours from the panels wrong.

950 Watts of panel * hours of good sun (usually 4, in your case 5) * system efficiency (usually 52%) = AC Watt hours.
That's 950 * 5 * 0.52 = 2470 Watt hours AC you can expect, not 3066.

That conversion from DC panel Watts to AC output Watts is a killer, but with battery based systems it can't be helped.

Just don't want you expecting more power than you're likely to get. That is a very common and disappointing mistake.

Someone on here had said on here its CMP (Amps) * 24v (or 12v pending on system) * 5 hours daylight.. thats where I am getting the numbers from..

The 2470watts into the newer proposed 440ah 24v battery bank.. what would be my DOD rate %??

and if I left the 2470watts into the original 220ah 24v batter bank..???

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

Someone on here had said on here its CMP (Amps) * 24v (or 12v pending on system) * 5 hours daylight.. thats where I am getting the numbers from..

The 2470watts into the newer proposed 440ah 24v battery bank.. what would be my DOD rate %??

and if I left the 2470watts into the original 220ah 24v batter bank..???

Eek! Now you're confusing Watts with Watt hours. Watts are a rate (Volts * Amps), Watt hours are a total amount (Watts * time).
2470 is the usable AC Watt hours you can expect from a 950 Watt array in 5 hours of good sun.

The other calculation would be the Watt hours you can get from a given size battery bank, and that looks like this:

Amp hours * depth of discharge (usually 25%) = usable Amp hours * system Voltage = DC Watt hours * inverter efficiency = AC Watt hours.

For a 440 Amp hour 24 Volt bank that would be: 440 * 0.25 = 110 * 24 = 2640 * 0.90 (usually) = 2376 AC Watt hours.

See how nicely that number works with the expected array output? You always want the array "harvest" to be larger; it ensures the batteries can be fully recharged.

One of these days I've got to write all these formuli down somewhere on this forum so people can study them.

Another thing; if you're thinking of starting with four of those panels now and adding a fifth later, wire for five panels now. It is so much easier than having to change the wiring out to accommodate another 5 Amps later!

ywhic

Re: Which inverter for 12V??

Thanks.. pending my $ and my timeline..

I may do just 2 of the 190 watt panels first.. wire the combiner for 5-6.. (in case I need to adjust my panels that I buy).. I will keep them within resonable voltage and amperage.. which I here is like 1 amp..

And buy the 4 T105's (or the NAPA 8146 / T125 of 240ah)..

1st purchase will be the Morningstar Pro 30.. (seems like I keep coming back to this in all my scenerios)

BB.

Re: Which inverter for 12V??

If you eventually go above the 400-800 watt range--You probably will want to look at a MPPT controller anyway to reduce the amount of copper wire from your array... Voltage drop and the cost of wire/fuses/electrical equipment (high current/low voltage installations) just tends to naturally drive people to higher voltage battery banks/solar arrays with MPPT based (higher voltage) charge controllers.

It is very difficult to "cost effectively" grow a PV system.

-Bill

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

I may do just 2 of the 190 watt panels first.. wire the combiner for 5-6.. (in case I need to adjust my panels that I buy).. I will keep them within resonable voltage and amperage.. which I here is like 1 amp..

I'm hoping "1 amp" is a typo.
Most panels will produce 5 to 8 Amps each. When you connect them in parallel the current goes up. So the wiring from the combiner to the controller needs to be able to handle the current for all panels and keep the Voltage drop low over the distance.

Since you're planning on a PWM controller with a 30 Amp current limit, wiring for the full 30 Amps (in and out) to begin with is a good idea. I don't know (or remember if told) the length of your wire run, but 10 AWG is certainly a minimum here. You'd get about 2.5% V-drop in 10 feet @ 30 Amps. If it's 15 feet, go wit 8 AWG. Easier to put the big wire in now than to have to change it out later.

That is one of the other advantages of MPPT: the ability to run higher power arrays over longer distance by using higher Voltage instead of greater current. If the distances are relatively short and the current manageable the advantage is smaller.

ywhic

Re: Which inverter for 12V??

Cariboocoot wrote: »

I'm hoping "1 amp" is a typo.
Most panels will produce 5 to 8 Amps each. When you connect them in parallel the current goes up. So the wiring from the combiner to the controller needs to be able to handle the current for all panels and keep the Voltage drop low over the distance.

Since you're planning on a PWM controller with a 30 Amp current limit, wiring for the full 30 Amps (in and out) to begin with is a good idea. I don't know (or remember if told) the length of your wire run, but 10 AWG is certainly a minimum here. You'd get about 2.5% V-drop in 10 feet @ 30 Amps. If it's 15 feet, go wit 8 AWG. Easier to put the big wire in now than to have to change it out later.

That is one of the other advantages of MPPT: the ability to run higher power arrays over longer distance by using higher Voltage instead of greater current. If the distances are relatively short and the current manageable the advantage is smaller.

Going with 10AWG to the combiner box.. then 8AWG about 15' is the plan..

I meant the spread between different 24v panles if I buy say 2 or 4 now and that 1 panel later.. I may get stuck with different voltages and amperages.. I'll try to keep them with-in 1 amp (output) of one another.. (again what I heard on here)..

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

Going with 10AWG to the combiner box.. then 8AWG about 15' is the plan..

I meant the spread between different 24v panles if I buy say 2 or 4 now and that 1 panel later.. I may get stuck with different voltages and amperages.. I'll try to keep them with-in 1 amp (output) of one another.. (again what I heard on here)..

That wiring plan should work.

Usually similar Wattage & Voltage panels aren't so far apart in current that it matters for parallel connections. Where it does matter:

1). Very different Watt panels like 68W added to 135W. Even though the Vmp on the two might be the same, the 135 might put out 7.6 Amps which could overwhelm the 68 (which might produce 3.8 Amps) if the latter shorted.

2). Serial panel connections where the current will be limited by the lowest panel rating and too much difference could fry a "small" panel in normal operation (as with the above two panels which if placed in series would force 7.6 Amps through the 'circuit' of the 68 Watt panel that is only designed to handle about 4 Amps Isc).

silvertop

Re: Which inverter for 12V??

I would also add a Tri-Metric battery meter to keep track of battery percentage full and amps in amps out:cool:.......

ywhic

Re: Which inverter for 12V??

Maybe I should get the Xantrex C35 with meter..?? works to $165.. and the Morningstar Pro 30 with meter is same..

and I'd get 5 more amps flexibility and no 'clipping'.. and be a little safer.

ywhic

Re: Which inverter for 12V??

I just saw a YT video on the C35.. the side sticker said Max Open Circuit PV Input DC..

C35 55VDC
C40 125VDC
C60 55VDC

After discussing MPPT to ad nauseum and the VOC max thing.

Does this mean only 2 24v panels can be put into the controller?? that would make no sense as the rating is 35 amps..

Or does this mean like max VOC per panel is 55?? and then go by the amperage added up??

ywhic

Re: Which inverter for 12V??

Just called MorningStar.. the tech support said the Max VOC for the Pro 30 PWM controller is 50..

It will go into over current load mode and shut down he said..

The Xantrex C35 is 55 max VOC.. may be a better option down to -20' F...

I love variables... (not)..

Cariboocoot

Re: Which inverter for 12V??

Those Voltage ratings for the Xantrex controllers are the Voc. In parallel panel connections neither the Voc or the Vmp changes; only current goes up.

The C35 can be used with either 12 or 24 Volt systems. It can't be used on a 48 Volt system (obviously the 55V limit is too low for a 48 Volt system). The input limit is set so that it can accommodate "standard 24 Volt" panels which may have a Voc up to 45, not including cold temp increases. The worst case you would see with that is probably the 1.3 factor used up here in the frozen wastelands of Canada. That would be 45 * 1.3 = 58.5, which would shut it down. The panels you pick should have some temperature coefficient rating which will tell you the amount of Voltage change per degree from which you can calculate your likely Voc max.

Nobody ever said any of this stuff is easy. If they did, they were lying.

ywhic

Re: Which inverter for 12V??

Cariboocoot wrote: »

Those Voltage ratings for the Xantrex controllers are the Voc. In parallel panel connections neither the Voc or the Vmp changes; only current goes up.

The C35 can be used with either 12 or 24 Volt systems. It can't be used on a 48 Volt system (obviously the 55V limit is too low for a 48 Volt system). The input limit is set so that it can accommodate "standard 24 Volt" panels which may have a Voc up to 45, not including cold temp increases. The worst case you would see with that is probably the 1.3 factor used up here in the frozen wastelands of Canada. That would be 45 * 1.3 = 58.5, which would shut it down. The panels you pick should have some temperature coefficient rating which will tell you the amount of Voltage change per degree from which you can calculate your likely Voc max.

Nobody ever said any of this stuff is easy. If they did, they were lying.

But obviously.. 4 x 24v panels (37.2 VMP) at 5.11 CMP into a combiner box (aka parallel) would total 20.44 amps..

So the 44.XX VOC (per panel) and the 37.2 VMP (per panel) would be constant minus the weather.. and does not multiply.. correct??

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

But obviously.. 4 x 24v panels (37.2 VMP) at 5.11 CMP into a combiner box (aka parallel) would total 20.44 amps..

So the 44.XX VOC (per panel) and the 37.2 VMP (per panel) would be constant minus the weather.. and does not multiply.. correct??

Yes. You've got it. PWM controller: Imp of panels in parallel adds up, Voltages remain the same.

Remember that's a current potential; you won't necessarily ever see 20.44 Amps going into the batteries. The more charged they are, the less current they'll take.

ywhic

Re: Which inverter for 12V??

I just realized that since I am running 10AWG at the panels anyway I could just get a longer run and bring into my cabin then into an indoor rated panel for combining them.. would save me from buying the 8 AWG and easily get the 5.11 - 6 amps thru the 10 AWG wiring for more distance vs. trying to get 8 AWG to run the 20' length I think I would need..

I would get a 1.03% drop using 10 AWG for 20' or 2.26% using 8 AWG for all 21 Amps (if combined outside).. (of 24 VDC) going the same distance..

I was going to buy 4 x 15' foot wires with MC4 and cut them to 8 1/2' for $20 each.. then into an outdoor rated panel.. then 8AWG to the cabin and controller... but I can buy 4 x 30' foot wires for $30 each and cut them and get 15' runs for +/-...

The reason this posting got prompted into my brain was the fact the panels are 30" wide more or less and 61" high.. and that 36" lead on the back is sucked up by that.. The difference for the 30' over the 15' length is $40 total.. the indoor box is $20 cheaper.. and the 8 AWG would have cost me $41.. so overall I still saved $20.. and the combiner panel will be indoors for easier viewing and action if needed.

So much thought going into this..

ETA/Update and change again..

I need I think 4 of the 30' 10AWG with MC4 anyway to be safe with lengths $120.. but I did find some 6/2 AWG wire for $2/foot so figure 30 foot for $60.. and the bare 3R outdoor rated 6 circuit box is $36.. .

I'll be mounting the 3R 6 circuit combiner panel on a central 4"x4" post about 3' off the ground and about 9' from the PV panel fence 'posts' which have 3' of wire on them.. I can do 2 PV posts facing my morning-midday sunlight and 2 PV posts facing midday-afternoon sunlight.. I found the sun path & tragectory using the suntracker website..

Then I will go up to 22' from the outdoor combiner 'pole' to the cabin.. then use 5' of it from the controller to the battery bank.. then 3' of it from the battery (with 100 amp fuse/breaker) back up to the 1000w (24v) inverter...

I don't like spending $180 on wire.. but do it once I guess comes into play and using 6 AWG is the correct gauge for the 21 amps and the distance.. and I'd like to space my panels out on 4 separate fence posts in my yard..

silvertop

Re: Which inverter for 12V??

The c-35 with a meter is just Amps harvested, the Tri- Metric ( and Im sure there are other brands just as good ) is one of the most usefull tools to follow your batteries, similar to a gas guage in a car. Without something to monitor your batteries you're shooting in the dark. Voltage can give you some insight but the batteries need to at rest to be accurate, and you dont want to pull out your hydrometer every day......8)

vtmaps

Re: Which inverter for 12V??

silvertop wrote: »

the Tri- Metric ( and I'm sure there are other brands just as good ) is one of the most useful tools to follow your batteries, similar to a gas gauge in a car.

I agree that it is a most useful tool, but it is NOT like the gas gauge in the car. The gas gauge actually does measure the amount of gas in the tank.

The trimetric (and other battery monitors) is more like the car's odometer. When your gas gauge is broken, you use the odometer to estimate the amount of gas in the car. The odometer estimate becomes very inaccurate if you do partial fill ups at the gas pump. In order to be use the odometer to estimate your gas tank, you must completely fill up your gas tank. So it is with a battery monitor... it resets to 100% when the batteries are fully charged, and it becomes increasingly inaccurate when you have several days of partial charging.

--vtMaps

ywhic

Re: Which inverter for 12V??

Cariboocoot wrote: »

Eek! Now you're confusing Watts with Watt hours. Watts are a rate (Volts * Amps), Watt hours are a total amount (Watts * time).
2470 is the usable AC Watt hours you can expect from a 950 Watt array in 5 hours of good sun.

The other calculation would be the Watt hours you can get from a given size battery bank, and that looks like this:

Amp hours * depth of discharge (usually 25%) = usable Amp hours * system Voltage = DC Watt hours * inverter efficiency = AC Watt hours.

For a 440 Amp hour 24 Volt bank that would be: 440 * 0.25 = 110 * 24 = 2640 * 0.90 (usually) = 2376 AC Watt hours.

See how nicely that number works with the expected array output? You always want the array "harvest" to be larger; it ensures the batteries can be fully recharged.

So if I get a rate panel set running of 12v panels (2 in series then parallel the 3 sets) and 780 watts (130*6) with a 52% = 405.6/hour * 5hours = 2028 usable max..

and my battery bank starts with 220 ah.. 220 * .25 = 55 * 24 = 1320 * .90 (usually) = 1188 watt hours..

My 'system' would be almost in permanent float during the day.. I would NEED that 440ah bank so the panels have something to do basically @ 2376 watt hours..

Cariboocoot

Re: Which inverter for 12V??

Not checking your numbers just now but ...
That is one of the big problems with off-grid systems; there isn't always a place for the power to go. You plan for average consumption, and on many days the battery is full while the sun is shining and there's nothing to do with the potential power the panels could produce.
It's better than not having enough when there is need of it, however.

vtmaps

Re: Which inverter for 12V??

Cariboocoot wrote: »

That is one of the big problems with off-grid systems; there isn't always a place for the power to go. You plan for average consumption, and on many days the battery is full while the sun is shining and there's nothing to do with the potential power the panels could produce.

Albert, Its time for you to pick up your next hobby: Load Shifting! Its all about using that Potential Power on the sunny afternoons. I try to do laundry, grind grain, pump water, vacuum, etc on sunny afternoons when my batteries are full. My clothes dryer works much better on sunny afternoons, but that's not load shifting because all I have is a clothes line.

BTW, you've probably noticed that many experts recommend running your generator in the morning (if you have to run it to get your batteries fully charged). I that case you load shift to when the generator is running. Turn off the generator when you are in absorb and let the panels take over the final stages of absorb and float. My array cannot give me a full charge on an overcast day, but it can provide enough power for the last hour of absorb. Much less expensive than running the generator another hour for only 200 watts output.

--vtMaps