Am I getting close to correct system setup

[northshoremb]

Hello I posted a topic few days ago on my small load solar build for camp. This is what I'm thinking so far from info I have gotten from SUNKING and others and just need to figure out few more things like what size breakers to get from battery to inverter and do I need fuses between the panels and controller?

4- 100w panels in series at 17.1v/5.8a a piece will equal 85.5v Isc and 5.8a output?

So with the 4 panels in series a Tracer 2210a MPPT charge controller that has 100v/20a max inputs will work I presume and will run at 24v?

4- BATTERIES 6V 235AH 478RC/25A DEEP CYCLE (BIG 6) in series to make 24volt system

SAMLEX PST-600-24 Pure Sine 24volt inverter

35 feet of 12awg wire between Arrays and Controller?

2 feet of (what size I need) wire between mppt controller and batteries?

1/0 cable to hook up batteries in series?

1/0 cable from batteries to inverter?

What size cable from Inverter to AC panel 15 feet away??

If batteries get low due to lack of sun or night time is it best to charge the batteries via a marine charger with the 2000w genny and still use the battery bank to run the camp while charging or run the camp with the genny and have the inverter turned off and wait for the sun to charge the battery bank?

Here is original post with my specs for camp
Small load AC camp in Northern Ontario setup and suggestion

Want to start of by saying hi to everyone as I'm a greenhorn and this is my first post.
From what I've been reading and studying he's last 2 weeks solar can get complicated with all different parameters to consider. Every hour I read I learn something new that actual contridicts my previous thinking. My father in law and me are installing solar at our Northern Ontario camp that currently is being powered my AC and a 2000 watt Honda suitcase genny. All of our appliances (hot water, stove, fridge, freezer) all run off Propane so no big loads.

Here is what we would run off solar and all specs of what we would need and use it for

Led lighting 3w
Satellite 30w
Lcd TV 110w
DVD player 35w
Small Table fan 15w

At one time we will not be more then 180w with usage around 700-900w for the day. In the no snow months we usually get up to camp around noon-2pm on a fri and stay till noon on a Sunday so rely only using power the Friday night and Saturday cause Sunday is wake up and pack to come home. Maybe twice a summer we might stay 4-5 days but can suppliment power if needed with the 2000w Genny

[sensij]

Do you already own the panels? I think 4 of those in series will exceed the 100 Voc limit as far north as you are, but buying 400 W of 60 cell or 72 cell panels would be cheaper anyway.

[northshoremb]

Do you already own the panels? I think 4 of those in series will exceed the 100 Voc limit as far north as you are, but buying 400 W of 60 cell or 72 cell panels would be cheaper anyway.

Yes we already own them and installed them on the roof last week.
They are sunforce 100w panels and only stats they show are 17.1 volts and 5.8amps. Wouldn't 17.1 volts at short circuit be 17.1x1.25 for 21.38v so that's 85.5 volts overall isn't it?
Just want to know what I'm missing on how you got over 100v for the 4 panels
On sale we got them for $100 Canadian each so that seemed pretty good
http://sunforceproducts.com/products...e-solar-panel/

[SunEagle]

Yes we already own them and installed them on the roof last week.
They are sunforce 100w panels and only stats they show are 17.1 volts and 5.8amps. Wouldn't 17.1 volts at short circuit be 17.1x1.25 for 21.38v so that's 85.5 volts overall isn't it?
Just want to know what I'm missing on how you got over 100v for the 4 panels
On sale we got them for $100 Canadian each so that seemed pretty good
http://sunforceproducts.com/products...e-solar-panel/

sensij has a valid concern.

While it does not state the Voc on the panel spec the manual states that you can measure 20 to 22V. So to be safe you should use a Voc ~ 22v.

That would calculate to 22v x 4 x 1.15 = 101 volt input during early morning in cold temperatures.

[sensij]

sensij has a valid concern.

While it does not state the Voc on the panel spec the manual states that you can measure 20 to 22V. So to be safe you should use a Voc ~ 22v.

That would calculate to 22v x 4 x 1.15 = 101 volt input during early morning in cold temperatures.

We are talking about northern Ontario here. I think that 1.15 might actually be too conservative for the temperature correction. If you use -0.35% per deg C, that means the Voc will increase about 0.3 V for every deg C less than 25. At -22 deg C, the Voc will hit the limit of 100. I don't know what the minimum temperature to design around for northern Ontario, but in northern minnesota the reference temps are approaching -40 deg C, so I'm guessing that temps in that range are applicable here, as well.

A 2nd concern is that 400 W really aren't enough to take care of that battery bank. It should be capable of providing 20-25 A at 24 V, which suggests 500 W is necessary before any loss actual insolation is considered. Insolation that far north is tough, and I could easily see 1000 W or more being necessary to maintain as many hours as possible of peak current through the limited daylight in wintertime.

[SunEagle]

We are talking about northern Ontario here. I think that 1.15 might actually be too conservative for the temperature correction. If you use -0.35% per deg C, that means the Voc will increase about 0.3 V for every deg C less than 25. At -22 deg C, the Voc will hit the limit of 100. I don't know what the minimum temperature to design around for northern Ontario, but in northern minnesota the reference temps are approaching -40 deg C, so I'm guessing that temps in that range are applicable here, as well.

A 2nd concern is that 400 W really aren't enough to take care of that battery bank. It should be capable of providing 20-25 A at 24 V, which suggests 500 W is necessary before any loss actual insolation is considered. Insolation that far north is tough, and I could easily see 1000 W or more being necessary to maintain as many hours as possible of peak current through the limited daylight in wintertime.

I agree with your math. Using my multiplier of 1.15 gets you to the max DC input voltage. Reality would probably be a bigger multiplier and a higher voltage input.

And with only a maximum of 17 charging amps for that 235AH battery system will not be fast enough to keep them healthy.

The OP needs more wattage and a different panel wiring circuit to protect the CC.

[northshoremb]

sensij has a valid concern.

While it does not state the Voc on the panel spec the manual states that you can measure 20 to 22V. So to be safe you should use a Voc ~ 22v.

That would calculate to 22v x 4 x 1.15 = 101 volt input during early morning in cold temperatures.

OK I see what you are say. I was taking it that since they are so vague on actual short circuit voltage and other specs they were telling the end user they can see 20-22volts which to me was them talking Short circuit voltage

[northshoremb]

I agree with your math. Using my multiplier of 1.15 gets you to the max DC input voltage. Reality would probably be a bigger multiplier and a higher voltage input.

And with only a maximum of 17 charging amps for that 235AH battery system will not be fast enough to keep them healthy.

The OP needs more wattage and a different panel wiring circuit to protect the CC.

OK I was just going by what SUNKING told me in a previous thread. Said to run those 4 panels in series with a 100v/25a MPPT controller, set up my 4-6v 235ah batteries in series for 24v and get a 600w 24v inverter. Is that not correct for only using max 185w at any one time during the day and only 700-800w total during the day? 95% of the time we are only there 2 nights and 2-4 times a summer there for 4-5 days. Also have a 2000w Honda generator when needed.

So from what you guys are saying should I do panels in 2s2p? So confusing when 1 person with 20,000+ posts says one thing and other guys with lots of posts contradict each other.

Thought I had it all figured out and was going to start ordering things but now confused again

[sensij]

Ok, so the panels are roof mounted. What azimuth and tilt are they at? What latitude are you at? Do you have any shade problems? If you can truly keep consumption less than 800 Wh, it looks better, but is still challenging. The advice you get here is free, and sometimes, you get what you pay for. The finer details of system design are difficult to walk through in a forum like this. Adding more panels later isn't terrible if you have the roof space, although once you go to the 3rd string, you'll need fuses on each string. I would suggest oversizing the conductors from the array junction box to the charge controller to handle 3X Isc, so you could eventually grow to 900 W (3s3p) without major changes.

[northshoremb]

47.9924 lat
Roof is maybe 20* and facing south. The four panels are mounted flush to the right of the chimney centered on the roof

[Brian53713]

400 watts of PV, and an mppt get you more than 17 amps of power. 100 watt Renogy get free delivery at $130 a panel. And 100w panels are more sturdy and easier to handle. Victron makes affordable and respected charge controllers. I haven't seen anyone explain the temperature rating that causes voltage to go higher.2s2p will keep the voltage in safe range. You need a 30 amp charge controller.

[sensij]

47.9924 lat
Roof is maybe 20* and facing south. The four panels are mounted flush to the right of the chimney centered on the roof

Hopefully the chimney isn't going to cause much shade. The 20 deg tilt is much better suited to summer production than winter in your location. PVWatts includes a typical weather file for Thunder Bay, which looks like it is about the right latitude. Here is a snip showing what the daily production might look like in a typical year for a grid tie system. If you are using 800 Wh daily, you need to be capable of generating at least 1100 Wh to replace it. Any day in this example in which doesn't hit that bar is shaded red. Really, with charge controller losses, you might need even more than this, but some of that you'll need to pin down with experience.
PVWatts.JPG



Winter is going to be tough, and this isn't even accounting for snow. Do you have a plan for brushing the panels off?

[northshoremb]

Hopefully the chimney isn't going to cause much shade. The 20 deg tilt is much better suited to summer production than winter in your location. PVWatts includes a typical weather file for Thunder Bay, which looks like it is about the right latitude. Here is a snip showing what the daily production might look like in a typical year for a grid tie system. If you are using 800 Wh daily, you need to be capable of generating at least 1100 Wh to replace it. Any day in this example in which doesn't hit that bar is shaded red. Really, with charge controller losses, you might need even more than this, but some of that you'll need to pin down with experience.
PVWatts.JPG



Winter is going to be tough, and this isn't even accounting for snow. Do you have a plan for brushing the panels off?

Ya we arnt worried at all about winter cause whenever we are watching TV we will use the genny. Only things we will use of solar in the winter would be a light in am and at night when we have to poss so 5 minutes here and there for 3-6w of use.....lol. As for brushing off panels we will use a snow rake with a pool noodle over the blade. When we set up last week we watched the shade from chimney in evening and never shaded the panels. The birch tree however will cause some shade I would think when it gets leaves but then at that time the sun is higher in the sky so maybe not.

[northshoremb]

400 watts of PV, and an mppt get you more than 17 amps of power. 100 watt Renogy get free delivery at $130 a panel. And 100w panels are more sturdy and easier to handle. Victron makes affordable and respected charge controllers. I haven't seen anyone explain the temperature rating that causes voltage to go higher.2s2p will keep the voltage in safe range. You need a 30 amp charge controller.

I'm just new to this but just inquiring about the need for a 30amp controller is amps will be 11.6? Even at 25% overcharge that's like 15a isn't it? Can get same controller in 30amp for $60 more so if that's needed I can get just wondering how it would be more then 20amp input

[SunEagle]

400 watts of PV, and an mppt get you more than 17 amps of power. 100 watt Renogy get free delivery at $130 a panel. And 100w panels are more sturdy and easier to handle. Victron makes affordable and respected charge controllers. I haven't seen anyone explain the temperature rating that causes voltage to go higher.2s2p will keep the voltage in safe range. You need a 30 amp charge controller.

If the battery system is 24volt then with an MPPT CC the most you will get out of 400 watts is 17Amps ( 400w / 24v = 16.7a).

Although going to a 30 amp CC allows room to add more panels.