Planning for an upgrade

Rybren

Re: Planning for an upgrade

Gents,

As always, thank you for the thoughtful insight.

For my particular application, the winter months are not a player. The road to the camp is not plowed and I won't be using the camp from mid-November until the snow is gone and the road dries out. Primary usage will be May through Sep (trout fishing season) and the insolation during that time is 4.5+ hrs.

I do believe that I should have enough power, particularly if I can load-shift. For the near term, I've calculated that I need less than 600WH/day - more like 200-300WH.

Jerry

westbranch

Re: Planning for an upgrade

Is there a SkiDoo on your Christmas list???

Rybren

Re: Planning for an upgrade

I floated the idea to my wife - and it drifted right by her :grr

A 4-wheeler would be ideal - there are lots of trails around (and I'd be able to take it to my hidden small-mouth lake, saving me an hour and a half round-trip hike). Unfortunately, she didn't grab ahold of that idea either.

I could cross-country ski or snowshoe to the camp - the nearest plowed road is about 1 1/2 miles away. It would be tough slogging - it's nothing but big, steep hills and I'm not as young as I once was.

Rybren

Re: Planning for an upgrade

I haven't updated this for a while.

I had been waiting for Marc and the new Rouge, but Midnite had a Classic 150 going cheap in their garage sale today, so I picked one up (they still have a number of controllers available).

Still thinking through my inverter selection and wiring. Will be going with 24V.

Once I get everything but the batteries sorted and installed, guess I'll head down to Sam's Club in Watertown, NY to pick up some batteries.

Rybren

Re: Planning for an upgrade

I'm still plodding along on my design and the gathering of all the bits and pieces required for the build. At the rate that we're going, it will be another couple of months before I can even drive into the camp (we got another foot or so of snow today)

After doing a fair bit of reading and searching, I think that I've settled on the Samlex PST-1500-24 inverter. It can be hard-wired and has a high-voltage cutoff of 33V, whereas the majority of the lower end inverters cut off at 30V.

I've been playing with drawing out a wiring diagram and would appreciate it if you could point out anything that looks to be off. I've left off the grounding for now. Samlex calls for a 100A fuse/breaker in the manual, but on some of their other 24V 1500W models they call for 125A. Not sure why they'd be different.

Thanks,

Jerry

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Photowhit

Re: Planning for an upgrade

Running panels 2x2 you'll want more than a 15 amp breaker...

Rybren

Re: Planning for an upgrade

I wasn't sure about the panel breaker - I guess thinking about it again, 2 x 7.7 Isc would be 15.4A, so would a 20A breaker be more appropriate?

Thanks.

BB.

Re: Planning for an upgrade

20 amp minimum wiring/breaker... If you want to be conservative, multiply by another 1.25 (NEC suggestion):

15.4 a * 1.25 * 1.25 = 24 amp minimum (round up to 25-30 amp wire+breaker)

Not so much worried about danger, but trying to avoid false trips on the break from the solar array.

Remember, the place you usually use fuses/breakers on the solar array is when you have three or more panels strings in parallel. The panel should have a maximum series protection fuse listed (probably around 15 amps for that panel). This is to protect against one shorted panel from being fed too much current from the two or more parallel panels.

You really do not need a circuit breaker in the PV array to the charge controller input--Unless you want an on/off switch and/or are doing something out of the ordinary (a very large array or direct feed from a higher voltage battery bank to an MPPT charge controller).

Regarding the inverter:

1,500 watt * 1/0.85 inverter eff * 1/21 volts minimum battery cutoff = 105 amp branch circuit+breaker minimum

So, rounding up to next standard fuse/breaker (125 amps) gives you a bit of extra head room with the inverter.

If you don't run the inverter at 1,500 watts and/or don't have a lot of surge loading (well pump, etc.), then a 100 amp would probably work for you OK. Just have a spare fuse or two on hand "just in case" of false trip.

-Bill

Rybren

Re: Planning for an upgrade

Thank you for the thoughts Bill,

My reasoning for a breaker on the PVs is primarily to act as a switch/disconnect. I don't know whether I'll have much need for it, but Midnite does include one in all of their wiring diagrams.

I was a little suspect of the 100A breaker for the inverter, especially considering the surge capability of 3000W (for <1 sec)

As an alternative to the Bussman breaker as shown in the diagram, I was considering using the Blue Sea Battery Terminal fuses and an ON/OFF Battery switch to turn off the inverter. Price would be about the same, but I don't know if one is better than the other.

-Jerry

BB.

Re: Planning for an upgrade

I am not sure either... Breakers (correctly rated for the job) are probably more rugged. Battery switches should probably only be used "when needed" and not daily.

Circuit breakers used daily as switches are probably not going to last as long either--I would have at least one back up breaker (or even battery switch) on the shelf "just in case".

-Bill

Rybren

Re: Planning for an upgrade

Thanks again.

Would there be any harm in installing one of those Blue Sea fuses on the battery post anyway - just in case there's a short at the Positive Bus? Or am I being paranoid?

-Jerry

BB.

Re: Planning for an upgrade

For "protection", I would use one of the Blue Sea post mounted fuses.

http://www.bluesea.com/products/2151

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For switching, it is not a bad idea--But you should be away from the battery caps/box in case there is enough hydrogen gas in the system to "get your attention" when throwing the switch under load.

-Bill

Rybren

Re: Planning for an upgrade

Yes, those are the fuses that I was thinking about. The switch would be located outside of the battery box.

As always, thanks for the insight,

Jerry

Rybren

Re: Planning for an upgrade

I stumbled upon a crazy deal for a 125A Outback epanel. So, after consulting with Halfcrazy on the Midnite forum to ensure it would work with a non-Outback inverter, I bought it.

Guess I'll have to rework the wiring diagram

Rybren

Re: Planning for an upgrade

Would there be any harm or benefit to adding one of the Blue Sea post mounted fuses between the batteries and the E-Panel? I ask because many inverters recommend a fuse within 8" to 10" of the battery. The epanel inverter breaker will likely end up being ~4' away from the batteries.

Thanks

BB.

Re: Planning for an upgrade

If the cables are well protected and built (i.e., crimped cables do not full out of connectors), no grounded metal floor/panels/boxes where exposed wiring can fall and short (and/or you have wiring bundled tied to wall to keep cabling "safe")--you probably don't "need" the extra fuses at the battery box.

However, if you have ever seen heavy copper wire burning the insulation off from a dead short, the feeling of helplessness really makes you wish you had a fire ax/bolt cutters next to the battery so you could cut the cable NOW.

So--personally--I would probably add a fuse at the battery post (one size up from the 125 amp breakers in the E-panel to avoid false trips that require a fuse replacement). Even if you are there when a short occurs (probably more likely if you are working the system and "something goes sideways"), it is still nice to have protection even if you are not present and something goes wrong. Fire/electrical safety around batteries is always a good idea to be paranoid about.

-Bill

Rybren

Re: Planning for an upgrade

Thanks for the advice Bill, I will include one in the build.

-Jerry

Rybren

Re: Planning for an upgrade

I feel like a little kid on Christmas morning. I drove down to the UPS Store in Ogdensburg, NY this morning and picked up my Classic, E-Panel, and Inverter. Woo Hoo!

Sure wish I had something to hook the Classic up to so that I could start playing with it. Unfortunately, hook up time will still be a few months away - I have to wait for the snow to melt and the road to dry out before I can get into the camp, then I have to build something to mount the panels to (I'm still not sure if I'll build a shed and mount the panels to the roof or if I'll build some type of ground mount)

BB.

Re: Planning for an upgrade

Well--if you are looking for suggestions on how/when to spend your money (:roll::p)--A few people here have build their off grid system at home (mounted everything to a sheet of 1" plywood or similar) and started wiring up the system, attach battery bank (perhaps a small one if this will be a large system), a couple of solar panels staked in the yard and had at it.

Sure make installing the system in the Middle of Nowhere a bit less of an "event".

By the way, even though I suggested mounting your electrical system on plywood--I am always very concerned about fire. If all the cabling and stuff in installed in metal raceways/conduit/boxes, then mounting on wood it not too bad.

However, if you will be doing exposed wiring bundles--I would suggest placing sheet rock (or concrete backer board) between the electrical and the plywood to reduce fire hazard.

Similarly, if this is to be mounted over a wooded sub floor or other flammable surface, I would use tile/backer board/sheet metal/etc. right under the installation.

Similar issues with backup generator and fuel supplies--Keep in a separate building, make sure that a gravity/pressure fed fuel line cannot break and feed a fire, etc.

Power systems are "hot" / operating 24 hours per day times 365 days a year--And things happen if you are there or not (or family sleeping, etc.)--An ounce of prevention is worth a pound of cure... Sorry for the fire safety rant.

-Bill

Rybren

Re: Planning for an upgrade

Thanks for the safety tips Bill.

My plan is to install everything on backer board here at home and wire up as much as possible before heading up to the camp. I hadn't thought of doing the stuff below with the backer board as well, but now that you mention it, I just might. I was also thinking of making the battery box out of the cement/backer board.

Unfortunately, we don't get very much sun in our yard, so I'd be hesitant to get the batteries and ahead of time for fear of not being able to keep them charged.

westbranch

Re: Planning for an upgrade

You can use an old functioning car battery for set up

Rybren

Re: Planning for an upgrade

Yeah, I could, but I'd have to buy one

westbranch

Re: Planning for an upgrade

borrow a neighbours, from their trailer/camper, offering a free battery test and recharge..8)

BB.

Re: Planning for an upgrade

Just think--In a few years, you will be swimming in old batteries. Sooner if there is a big "oops" somewhere along the line.

If an AC Generator is going to be part of your backup system--Then you could run it to your home's grid once in a while to keep batteries "fresh" (something like 24 hours per month or 1 hour per day would probably work well if you don't have any loads on the batteries.

-Bill

Rybren

Re: Planning for an upgrade

I'm hoping that there won't be a big oops. But if there is, it won't be a first for me.

Rybren

Re: Planning for an upgrade

Thoughts on AC power distribution...

As you may or may not recall, I will be powering two cabins with my off-grid system. My plan is to have the array, cc, batteries, inverter, etc co-located and then send 110V AC to each of the cabins. Both cabins are ~50feet from the array location. This is how my current DC system is set up and I already have buried 12/2 in place and operational (set up by the previous owner)

I will be running with a single 1500W PSW inverter that will be hardwired into the Epanel. I will also set up the Epanel to accept input from a generator and bypass the inverter if required. I currently have a 1400W/1750W cheapie Homelite Generator (word of advice - don't buy one of these).

I'm trying to decide the best approach for setting up the AC distribution and circuit protection. As I see it, there are a number of options:

1. Install two 15A breakers in the epanel and connect each of the existing 12/2 cable runs to the breakers. In the cabins, set up a power distribution centre using bus bars.

2. Connect the existing 12/2 cable runs to the bus bars in the Epanel. Install small 2/4 circuit subpanels in each of the cabins and distribute the power.

3. Install two 15A breakers in the epanel and connect each of the existing 12/2 cable runs to the breakers. Install small 2/4 circuit subpanels in each of the cabins and distribute the power.

I'm not bound by code, but I want to be safe. I'd appreciate your thoughts on these - or any other - options.

Thanks,

Jerry

BB.

Re: Planning for an upgrade

Practically speaking... A 20 amp breaker in power center to 12/2 to each cabin. In each cable, I would use 10-15 amp breakers. One to the AC outlets. A second to the lighting (assuming ceiling lighting). Ideally, if somebody plugs in a 1,800 watt hair drier in a 10 amp outlet, they would blow the 10 amp breaker and still leave the lights on/power to the other cabin.

10 Amp breaker may be impossible to find in a House type sub panel... So using a marine panel (or our host's various breaker options) may be the sub panel solution.

-Bill

NorthGuy

Re: Planning for an upgrade

Rybren wrote: »

3. Install two 15A breakers in the epanel and connect each of the existing 12/2 cable runs to the breakers. Install small 2/4 circuit subpanels in each of the cabins and distribute the power.

I would choose this one because this way you can disconnect loads on the panel as well as locally - very convenient. Except, I would use 20A breakers for 12/2 wire.

Rybren

Re: Planning for an upgrade

Thanks Bill,

The Midnite AC breakers are what I was planning to use in the Epanel. I'll see what I can find in the way of marine panels for the cabins.

As a side note... I was in a Lowes in New York this weekend. Their 2/4 circuit subpanels were $14. At the Lowes here in Ottawa, the same panel is $45. Once again, it pays to be Canadian - NOT!

- Jerry

Rybren

Re: Planning for an upgrade

Thanks NorthGuy