Supply for 60 amp shore power connection

mcgivor · March 2017

Regarding refrigerators, just because it's small, dose not mean it is efficient. Insulating, may even impair performance, some use the outer skin as the condenser, so if there is no visible condenser, pipe and fins on the unit, chances are it uses the body to dissapate the heat. Always remember, a refrigerator dose not make cold air, it transfers heat, in this case from within to the outside, just something to consider, but for now it's best to focus on load requirements.

Lumisol · March 2017

BB. said:

I am not sure I understand running the fridge at 80 Watts for 3 hours per day... If you convert a chest freezer to a refrigerator--Yes, you can get down towards that level of power usage (but they still take 100-120 Watts to run the AC compressor, and have the higher starting VA ratings).

http://forum.solar-electric.com/discussion/42/chest-freezer-as-a-chest-refrigerator

-Bill

in 2 hours of on time, it actually only cycles for ~15 minutes (two 7 minute cycles) so in a 24 hour period it would be about 3 hours of on time. At night with cooler temps it will actually run less than that, but I opted for the heavier day time run cycle as it gives a bit more cushion. Keep in mind the room temps will be in the 60's in the daytime and the 50's at night.

Lumisol · March 2017

Using 1717. as a needed daily wh usage, I found a calculator that says

* Number of Solar Panels (80-100 watt) =4
* Number of Batteries (12v @ 105 AH) =9

Refrigerator watts =80

WattHours =480

Television watts =40

WattHours =160

MicroWave watts =750

WattHours =247.5

House lights watts =50

WattHours =150

Cooling system =80

WattHours =480

Misc items watts =50

WattHours =200

Summary of WattHours required

Total daily WattHours required = 1717.5

WattHours required for 3 days = 5152.5

Battery capacity (50% discharge) = 10305

Battery Bank size in AmpHours

12 Volt 858,	24 Volt 429,	48 Volt 214

It says that using 285 watt panels, I'd need 2 apx, so 2 in reality. 9x 105 ah 12volt batteries, 225 ah batteries with 214ah bank needed at 48 volts and I'll be using 8 6volt and I'll have 225 ah at 48 volts.

Does this sound about right?

(edited to add cooling power)

Lumisol · March 2017

mcgivor said:

Regarding refrigerators, just because it's small, dose not mean it is efficient. Insulating, may even impair performance, some use the outer skin as the condenser, so if there is no visible condenser, pipe and fins on the unit, chances are it uses the body to dissapate the heat. Always remember, a refrigerator dose not make cold air, it transfers heat, in this case from within to the outside, just something to consider, but for now it's best to focus on load requirements.

That's a good point. A lot of people think that refrigeration creates cold air when all it does is move heat energy. Having been working in Automotive AC I understand the concepts, not everyone has that experience.

It occurred to me that maybe a different type of power to run the compressor on an AC system would be helpful to off grid use. Like a small propane powered engine as is found on some newer generators. It would be an interesting experiment, using automotive refrigeration parts to control the clutch, etc.

mcgivor · March 2017

Lumisol said:

Using 1717. as a needed daily wh usage, I found a calculator that says

* Number of Solar Panels (80-100 watt) =4
* Number of Batteries (12v @ 105 AH) =9
Refrigerator watts =80 WattHours =480
Television watts    =40 WattHours =160
MicroWave watts =750 WattHours =247.5
House lights watts =50 WattHours =150
Cooling system =80 WattHours =480
Misc items watts =50 WattHours =200
Summary of WattHours required
Total daily WattHours required     = 1717.5
WattHours required for 3 days     = 5152.5
Battery capacity (50% discharge) = 10305
Battery Bank size in AmpHours
12 Volt 858, 24 Volt 429, 48 Volt 214
It says that using 285 watt panels, I'd need 2 apx, so 2 in reality. 9x 105 ah 12volt batteries, volt 255 ah batteries with 214ah bank needed at 48 volts and I'll be using 8 6 and I'll have 255 ah at 48 volts.

Does this sound about right?

(edited to add cooling power)

One item missing is the inverter consumption, a reasonable one with sleep mode needs to be included, something with a round 30W no load, 7w standby needs to be factored in. The refrigerator load still seems conservative, in my opinion, but as you have good sun, cool temperatures and high altitude on your side, coupled with the fact the calculation supplied is for 3 days autonomy, my estimation is you are pretty close if 2 days autonomy were used, with the 225Ah, 48v setup.
As far as panels are concerned it would be prudent to lean towards 250W rather than 100W, cheaper and fewer modules and 400w is not sufficient, again my opinion, my thoughts would be to have 1000-1500W, but then again this is not a full time off grid situation, so perhaps you could get away with less, bare in mind that panels will generally produce around 75% of their rating.

Lumisol · March 2017

mcgivor said:

Lumisol said:

Using 1717. as a needed daily wh usage, I found a calculator that says

* Number of Solar Panels (80-100 watt) =4
* Number of Batteries (12v @ 105 AH) =9
Refrigerator watts =80 WattHours =480
Television watts    =40 WattHours =160
MicroWave watts =750 WattHours =247.5
House lights watts =50 WattHours =150
Cooling system =80 WattHours =480
Misc items watts =50 WattHours =200
Summary of WattHours required
Total daily WattHours required     = 1717.5
WattHours required for 3 days     = 5152.5
Battery capacity (50% discharge) = 10305
Battery Bank size in AmpHours
12 Volt 858, 24 Volt 429, 48 Volt 214
It says that using 285 watt panels, I'd need 2 apx, so 2 in reality. 9x 105 ah 12volt batteries, volt 255 ah batteries with 214ah bank needed at 48 volts and I'll be using 8 6 and I'll have 255 ah at 48 volts.

Does this sound about right?

(edited to add cooling power)

One item missing is the inverter consumption, a reasonable one with sleep mode needs to be included, something with a round 30W no load, 7w standby needs to be factored in. The refrigerator load still seems conservative, in my opinion, but as you have good sun, cool temperatures and high altitude on your side, coupled with the fact the calculation supplied is for 3 days autonomy, my estimation is you are pretty close if 2 days autonomy were used, with the 225Ah, 48v setup.
As far as panels are concerned it would be prudent to lean towards 250W rather than 100W, cheaper and fewer modules and 400w is not sufficient, again my opinion, my thoughts would be to have 1000-1500W, but then again this is not a full time off grid situation, so perhaps you could get away with less, bare in mind that panels will generally produce around 75% of their rating.

Yes, the panels are 285 watts and I am still looking at getting 4 of them if not 5. The calculator said 4 100 watt panels, but I tend to agree that is a bit small, besides, the panels will be on a porch and provide some shade for us too.

(the porch currently has shadescreen mesh on it and the panels will be on top of that.) AT 100.00 each I think getting an extra one is a good idea. I had set aside 10,000.00 for the project and it looks now like it will be well short of that mark.

I still need to find out what sort of a disconnect and fuses I should have on the board bearing in mind that it will have the built in circuit breakers in the RV as well.
Any ideas? What about the charge controller and inverter, What do you think is a good fir for the system described above?

Lumisol · March 2017

The PV panels say on the sticker they are 44.5 volt, and 285 watt . How should they be wired in the array to run a wire about 20 to 25 feet (estimating, could be less, the rv is only 29 feet long and the wire will be going half that distance or less) The panels are SF260-36-P285L made by Hanwha Solar One and say a minimum No. 12 AWG copper wires insulated for a minimum of 90 C if that helps. Do I make a junction box and run them to that?
Any advice is welcome.

mcgivor · March 2017

Panels listed are 36.2Vmp, 44.5Voc, they need to be run in strings of 2or 3 with an MPPT charge controller, depending on the maximum input voltage limitations, coldest temperature etcetera. Most good quality controllers will have a string calculator tool on their website, where you can input your data and the optimum configurations will be displayed. There are various good manufacturers, Outback, Midnight, Victron, Morningstar, Schneider to name a few, there are others, check the host's store at top of page. You will need a 30A MPPT controller for 6 panels, my suggestion is to avoid the really cheap ones, so choose one, then the wiring can be configured, best to go one step at a time.

Estragon · March 2017

You will likely want to go with either 4 (for 2 strings of 2 panels) or 6 panels (for 3 strings, or 2 strings of 3 if the controller will handle the voltage).

Athough you could get away with a junction box if doing only 2 strings, using something like a Midnite combiner box with breakers is safer, neater, and makes it easier to switch pv power off when needed.

Lumisol · March 2017

Image: https://us.v-cdn.net/6024911/uploads/editor/vb/5tmtubmthnxr.jpg

mcgivor said:

Panels listed are 36.2Vmp, 44.5Voc, they need to be run in strings of 2or 3 with an MPPT charge controller, depending on the maximum input voltage limitations, coldest temperature etcetera. Most good quality controllers will have a string calculator tool on their website, where you can input your data and the optimum configurations will be displayed. There are various good manufacturers, Outback, Midnight, Victron, Morningstar, Schneider to name a few, there are others, check the host's store at top of page. You will need a 30A MPPT controller for 6 panels, my suggestion is to avoid the really cheap ones, so choose one, then the wiring can be configured, best to go one step at a time.

Yes. Here is the sticker on them.
I assume you go by the open circuit voltage for safety reasons and wire accordingly?
Do you have a link to the combiner box you mentioned @Estragon ?

mcgivor · March 2017

Here is an example of a string combinerror box with breakers.
https://www.solar-electric.com/mnpv3.html

mcgivor · March 2017

@Lumisol asks: I assume you go by the open circuit voltage for safety reasons and wire accordingly

That's correct, the voltage limitations govern how many panels can be in a string, which is why using the string calculator is such a useful tool, the manufacturer will determine, based on the panels, if it a good fit.

Lumisol · March 2017

mcgivor said:

Here is an example of a string combinerror box with breakers.
https://www.solar-electric.com/mnpv3.html

I looked at the linked product. I am a little leery of buying something that has no reviews on it though. I'll see if I can find more information. Thanks for all the help.

God Bless.

Lumisol · March 2017

I see a lot of 30 amp controllers, but all say 12 and 24 volt, do I need to have a 48 volt to charge 48 volt battery array, or does that just apply to the inverter input voltage?

mcgivor · March 2017

The link is the sponsors store, where you can find charge controllers to fit your needs, they do not deal in junk, Midnight equipment is good quality and yes you need a controller that outputs 48v nominal, 24v will not work.

mcgivor · March 2017

There are not too many controllers rated at 30A for 48V, but a larger one can be used as well, there are more choices in the 60A up, the electronics would be less stressed than running close to the limit, that's all.

https://www.solar-electric.com/morningstar-tristar-ts-mppt-30.html
https://www.solar-electric.com/blue-sky-sb3048dl-mppt-charge-controller.html
https://www.solar-electric.com/midnite-solar-kid-mppt-solar-charge-controller-white.html

mike95490 · March 2017

Lumisol said:

I looked at the linked product. I am a little leery of buying something that has no reviews on it though. I'll see if I can find more information. Thanks for all the help.
God Bless.

I just made a review, it may take a couple hours to go live. Rest assured it's an good product. The hardest part is that the NAWS store didn't link the breakers it uses to the page.

Estragon · March 2017

@Lumisol

I use the disconnecting version of the midnight box. Not much to review as it's just a box, but it does what it's supposed to if that helps. The disconnecting version has a handle on the outside that allows for all breakers to be flipped at once. I got that type as I have 8 strings of pv and wanted to be able to cut power quickly from all if need be.

Open circuit voltage is used in string sizing because max voltage is likely to happen with cold panels first thing in the morning. There will be little current being produced, but voltage will be high. It's important to adjust the Voc on the panel for the record low temp for your area.

Midnite controllers have the ability to protect themselves from overvoltage to an extent, but some others will be damaged if they get overvoltaged on a clear cold winter morning, and this damage typically isn't covered by warranties.

westbranch · March 2017

Lumisol said:

mcgivor said:

Here is an example of a string combinerror box with breakers.
https://www.solar-electric.com/mnpv3.html

I looked at the linked product. I am a little leery of buying something that has no reviews on it though. I'll see if I can find more information. Thanks for all the help.
God Bless.

AS Mike said MidNite Solar makes some of of the best equipment in the solar business... if you order what you need, it will work as planned... you won't go wrong there!

Lumisol · April 2017

Is Victron a good quality brand name? I like the app they have to monitor use.

westbranch · April 2017

A Dutch company, so not many over here with them... I have seen most ads for them in yachting magazines. They do have , or had?, a NA rep and he was quite informative when I asked about the differences in similar models...

Lumisol · April 2017

If they are good enough for a million dollar yacht, they are probably good enough for my $200,000 Rv lol.

Lumisol · April 2017

Does anyone have an inverter they recommend for use in a system using 4 290 watt panels, and a 48 volt 225ah battery bank.
How about a charge controller?
Would I have more choices using a 24 volt bank?

I tried adding things to a shopping cart on the sponsors site but it keeps deleting the items before I can make a purchase.
I will have to buy from another vendor I suppose.

Will this be sufficient as the biggest load is the 700 watt microwave?
https://www.solar-electric.com/sa2wa24vosiw.html

Photowhit · April 2017

Lumisol said:
I tried adding things to a shopping cart on the sponsors site but it keeps deleting the items before I can make a purchase.
I will have to buy from another vendor I suppose.

I think you have to create an account first, I recall someone else having a problem, I haven't purchased from them since the new web site.

Estragon · April 2017

I bought some stuff recently and had no problem with losing the list.

You probably do need to create an "account" though I think. Doing that will allow for the list of stuff you're looking at to be associated with a specific userid on server side. Carts typically rely on persistance of client side "cookies". The persistance of these will depend on your device configuration, and could be limited to a single browser session.

I don't work for NAWS. Just guessing how it works.

mcgivor · April 2017

Lumisol said:

Does anyone have an inverter they recommend for use in a system using 4 290 watt panels, and a 48 volt 225ah battery bank.
How about a charge controller?
Would I have more choices using a 24 volt bank?

I tried adding things to a shopping cart on the sponsors site but it keeps deleting the items before I can make a purchase.
I will have to buy from another vendor I suppose.

Will this be sufficient as the biggest load is the 700 watt microwave?
https://www.solar-electric.com/sa2wa24vosiw.html

Re Samlex inverter, that one is made by Cotek, have the identical one in Cotek clothing, been very good for the price, only drawback is the maximum input voltage 30V , if you have flooded batteries it is lower than EQ voltage, however with AGM it would not be a problem. It would cover the microwave load no problem.

Lumisol · April 2017

Thanks.
I am staying away from flooded cells, I have neither the time nor the inclination to be messing around with topping off batteries and venting hydrogen gas.

Max input voltage from the PV array is 30 volts? Or is that the maximum it can put out to the batteries?

I guess 24 volt set up will be better for me then.

One more question, if I go with a 24v bank, can I draw 12 volts off the charge controller for DC loads or will that be 24 volts as well?

mcgivor · April 2017

If you have a 24V nominal system, the inverter, is connected directly to the battery 24V, via a fuse or circuit breaker. The charge controller must supply a higher voltage to the battery, typically in the 29v range in order to charge, the output of the controller is also connected via a fuse or breaker to the battery, parallel seperate cables to the terminals of the battery. Therefore the inverter will be at the same voltage potential as the output of the controller, for this reason inverters have both a minimum (discharged battery) voltage and a maximum ( during charging) voltage limit, so it must be able to tolerate the changes without going into fault. The lower voltage would typically be the point at which the inverter shuts down to prevent damaging the battery.

The array voltage will be higher than the controller output, the voltages will be dependent on type of controller, either PWM around 36V, or MPPT typically around 60V, but can be double or more, for a 24V system. For a 48v system all voltages would be double the aforementioned values.

The design of a system works backwards from the aggregate loads multiplied by time to establish the battery requiments, the battery configuration /voltage would be designed to minimize the need for parallel battery strings. The voltage of the battery determines the inverter along with the controller and the amount of power the controller can process in order to satisfy the charging requirements. For example a 60A controller at 24V would be 1440W, the same unit at 48V would be 2880W, so using a higher voltage would allow for a larger array without the need to use a second controller to produce the same wattage at 24V. ( for simplicity I used nominal voltage )

As far as 12V loads there are ways to do this from 24V or 48V, but connecting directly to the battery is not possible without the use of a DC -DC converter for example.

Photowhit · April 2017

Lumisol said:
I am staying away from flooded cells, I have neither the time nor the inclination to be messing around with topping off batteries and venting hydrogen gas.

You might seriously reconsider doing solar, You need to pay attention daily to loads and state of charge of your battery bank. It will never be as simple as flipping a switch and you may well become frustrated and could well waste money very quickly, in dead batteries.

mcgivor · April 2017

As @Photowhit aludes to, the operation of an off grid system requires attention, albeit my thoughts were you were simply referring to the topping up and ventilation, which is why you chose AGM, despite the choice there is still maintenence involved and for various reasons flooded batteries are easier to monitor, the constant checking means a closer relationship with how the system is performing. It really takes time to understand the demand verses supply, which is why suggestions for capacity often appear to be larger than those based on simple calculations, to include a safty margin, less possibility of disappointment. Possessing an understanding of electrical systems in general, is a distinct advantage, however with some self education and guidance from others, my belief is that most can build and operate an off grid system, the learning curve is just a little steeper, it's rare to hit the nail square on the head with the first swing, so to speak.

Another option would be to hire a consultant, tell him/her these are my loads, build me a system that works and impress upon them that you don't want to know how it works, you just want it to work, the result would be an oversized very expensive setup to cover their ass.

Based on your location, you have envious sun, moderate temperatures, including altitude working in your favor, personally I like all to succeed, based on the loads presented, including the abandonment of A/C, my thoughts are, it's doable, despite your current ignorance, which doesn't imply stupidity in any way. Going to say it again, loads first, battery/voltage second, charging system third, in that order. Choose a voltage, personally I chose 24V, which I regret, should have gone 48v, but hind sight is 20/20, my loss is your gain, which is why networking is important.

Anyhow gone on a bit, it's 10 PM still 96°F and no A/C, consider yourself lucky, got to go to bed and perhaps sweat a little, but then again it's not too hot, during the day it was 104°F, so seems a little cooler somehow, the evaporation cooler should help somewhat.

Supply for 60 amp shore power connection

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