Multiple Power backup sources - Discussion on best/efficient gear

LEDGuy · January 2013

Hey all... relatively new here, but many years of electronics and AC power experience....

As with a lot of (suspected) readers/contributors to this board, I am looking to take my all electric home and key business equipment off grid - or AT LEAST provide for continued uptime in the event of an unspecified outage.

I do run/operate an LED Lighting company which has helped me considerably reduce costs. 2 years ago, I installed a wood burning insert, so now I heat the house with a wood burner and rarely use the hog of a forced air Electric furnace.

Having said all of this, my requirements for AC load are relatively light... While if $$$ were no consideration, I would load up the roof with panels, install multiple turbines, have a huge battery bank and top of the line charge controllers/inverters with a tri-fuel (last resort) genset.

So minimum requirements for ME are relatively small. I could function just fine with a few LED bulbs, A few DC LED Fluorescents, DC circulating fans on my wood insert, 1 sump pump, laptop and small printer. a few other "nice to haves" would be a mini 'dorm type' fridge and a small dedicated electric hot water heater (for a quick shower). I have alternative means of washing clothes/drying, cooking and could care less about TV/Radio (although, if needed, I do have all the gear for UHF/VHF/Ham and CB - When needed). Would like the ability to feed 240VAC split phase to my off-grid system (more flexiblity upon expansion).

Solar/Wind: Currently, I have a 2 - 145W panels, 2 - 100ah/12v AGM D/C batteries, appropriate wiring/fuses - fronted by a RigRunner charge controller and all Anderson power pole connections.

Distribution: 1- Cobra 800W Inverter (120AC + 5vUSB), 1- Xantrex MSW 3000W/120v, hardwire OR two GFCI outlets, Misc small cell battery chargers and multi-voltage DC chargers for just about any equipment needing recharging (small devices), RigRunner fused distribution boxe(s) with power pole connectors.

Gas/Propane: Currently, a 5Kw gas genset, A reliance 10 ckt transfer switch/panel

Strong option: A large hardwire UPS (datacenter grade 12KVa or greater) - maintined by grid power, but swappable to the feed/input side of the 'off-grid' setup

CHALLENGE: How to best setup my front-end power generating sources to feed the "off grid" panel and implement auto switching or minimal 'manual' switching of sources as needed.

Backup/Additional Gear on hand or available: MorningStar Sun Saver MPPT 15, Step up/down transformers as needed. Additional/multiple gauges of wire/terminals, Availability to additional AGM batteries or even a PTO driven large output genset (diesel). Ability to add panels/turbines as needed. I have also been seriously looking into the Parallelax or ESCO options in auto transfer switches to help gracefully "move" my generating sources.

So in short, I would like to run, essentially off grid, a cable modem, wireless/wired router, a few network switches, laptop, mid sized printer, say a 6gal electric water heater (1500W - As needed - not full time), 1/6th sump pump (2.2A), Small fridge/freezer (let's say max 12A/120vAC) and about 100W of lighting during evening hours - maybe 6 hours). Also, most of the small electronics (even a possible small LCD TV, already has 12vDC inputs (although they give you the AC adapter for the coax/barrel plug 12vDC input. These things draw miliamps.

I'm working up a schematic on how I think all of this would come together, but initial input from the gurus here is always warmly welcomed! Thanks in advance
LED Guy

Cariboocoot · January 2013

Re: Multiple Power backup sources - Discussion on best/efficient gear

Well it's simple: just spend a ton of money. Off-grid power will cost way more than grid power in most cases, so it's about as practical as a chocolate hammer. For back up purposes it will cost more than generator power too. Hey, if you've got all this extra money laying around why not send it to me?

But seriously, it is expensive and so rather impractical if the grid is available. For outages you have to consider how often they occur and how long they typically last. With wind turbines the payback is even worse, as most of the "small" turbines just plain don't work worth beans. You have got to spend the money on good turbines and a good install in order to get anything back. A "400 Watt" Whoop-de-do up a ten foot pole will give you nothing but an empty feeling in the wallet.

If this hasn't dissuaded you and you're really going to do it, save yourself the hassle and set the piecemeal equipment aside. Figure out your critical loads and times and design a viable system around that, then see if anything you've got fits into the plan. Chances are it won't.

Here's what I mean:
You've got two 145 Watt panels. Good, 12 Volt panels. Together they could recharge 160 Amp hours @ 12 Volts. Your two 100 Amp hour 12 Volt batteries will be pressing things a bit, especially for "full time" use.
Those two batteries aren't the best idea, because you're already at "parallel battery connection point limit" with them. If you need more capacity you need to go up in Voltage, preferably using larger Amp hour units rather than making parallel connections. Check this out: http://forum.solar-electric.com/showthread.php?15989-Battery-System-Voltages-and-equivalent-power

So when you get that minimum Watt hour figure for emergency power and it turns out to be, say, 3kW hours you are already looking at needing A). higher system Voltage (goodbye to the 12 Volt inverters),

. larger battery capacity (goodbye to the batteries and wiring including fuses), C). greater charge capacity (goodbye to the 145 Watt panels and controllers), D). AC circuit integration (automatic transfer switch capability).

Now if you want to really crank down the power requirements and just keep the 'frige on while the power is off that's different. All you need to do is measure its consumption with a Kill-A-Watt and get a 12 Volt bank large enough to power it through the Xantrex 3kW MSW (I have one of those, btw: made the 'frige run with noisy clatter; switching to pure sine solved that issue) and recharge with the generator using the panels to keep the battery up inbetween outages.

It all can be done, but all at a cost. So it is vital to decide what the constraints are going to be on the system for both power needs and financing available.

LEDGuy · January 2013

Re: Multiple Power backup sources - Discussion on best/efficient gear

:cool:

Hehe! Like your train of thought CB! Yes, some of the on-hand stuff will be ancillary. I completely agree. I agree that the small charge controller is not adequate also, so something like a larger Xantrex 45 or 60 MPPT or Outback would work much better. The panels can be wired in series (in normal sun, I'm getting 17-21v - no load) on one panel, so another set or two of these, wiring two in series would get me up to a 24v system.

Same on the Batteries. Add 2 or 4 more (in 2 bat groups/series) and I have a smaller 24v bank.

Amen, need a much better inverter - and agree fully with the wind statements. One of my customers is Vestas, so maybe I can get a deal on a 100ft tower with a 3MW head on it, but I'll bet the airport would give me some grief!

Got the Kill-a-watt meter and a DC inline watt meter at my disposal, so I'll get busy adding up my loads.

I just missed an opportunity to pick up a "Best Power UPS / 16kva" used unit for $400.00. set of replacement batteries was about $1800.

I totally agree that my .06/kwh from the Utility is far cheaper than any of the previously mentioned 'gear'. Power outages in northern Ohio are infrequent, but I did live through the one about 7 years ago when the northeast main lines caught fire and took us out for 4 days straight. Would have definitely broken out the gen at that point.

Realistically, I would like to run one AC circuit, the sump pump and all of my small 'interface' (router, modem, switches) off the 12V system now, while keeping the 200AH current system with a utility power charger/maintainer, so in the event of the 2-8 hour occasional outage, everthing would just keep running off the batteries till the main juice came back on. Would like to start planning the system for much higher capacity and expandability as funds allow, so mainly don't want to get pigeon-holed into a 12v system or a 'cap' on where I could go with this (down the road).

I think I'll return the 3Kw inverter and order a proper 24 or 48 volt controller and some additional panels/batteries.... Recommendations? Want to stay with a MPPT controller and need a quality inverter.

Thanks for your input

LEDGuy

Cariboocoot · January 2013

Re: Multiple Power backup sources - Discussion on best/efficient gear

It's guesswork on an inverter without knowing what loads you need to run.

Magnum makes very nice inverters for back-up systems in my opinion, as you can get 24 or 48 Volt ones with either 120 or 240 VAC right out of the box for a reasonable price.
For more complicated arrangements Outback's systems are more flexible.
When you get one of these inverter-chargers it's easy, as there's a transfer switch built in: AC from grid present it runs loads and charges batteries. Grid goes down, inverter takes up the load without a blip.

MidNite makes the best MPPT charge controllers right now, but they are $600+. Outback is a better bargain with their FM series. It's a good idea to use MPPT because you can buy the less expensive "grid" panels with their odd Vmp's and make a big, cheap array fairly easily.

if you poke around on our host's website http://www.solar-electric.com/ you can see a lot of good equipment and reasonable prices and get an idea of what choices can be made for the money available.

LEDGuy · March 2013

Re: Multiple Power backup sources - Discussion on best/efficient gear

Ok Cariboocoot, Took your advice and trashed all the previous equipment (figure of speech - - it's now "backup Equipment" LOL!).

System is installed and running very nicely. Here's how she came out:
AC [Split Phase 240] out of utility power into ----> ESCO Auto Transfer Switch (AC "Shore" and Gen 240VAC inputs) out to ----> Midnite E-Panel (Split phase/240 Panel) hanging on front is a Magnum 4024-PAE (Split 240VAC Inverter/Charge Controller) out to

> (4) AGM 12vDC/100AH type 27 Batts (2 groups for 24VDC).

Hanging off the side of the E-Panel is a Midnite Classic 150 CC up to

> MidNite PV Combiner Box; up to ----> (4x) 145W Poly Panels.

Key for me was being able to expand the system as funds become (maybe never) available. I like the Magnum inverter(s) as they can be 'ganged' up together nicely. Absolutely LOVE the E-Panel - MidNite did their homework on this baby.... Highly recommend; and ability to add Freakin Expensive Cells (both PV and Storage) as needed.

So Cariboocoot - - Now I can make up a signature line like everyone else - LOL. (PS - Thanks for pointing me in the right direction)

LEDGuy -
4 x 145W Panels - Midnite E-Panel, Midnite 150 CC, 4 x 100AH, Magnum 4024PAE Head Unit
LEDGuy has 12/24vDC LED Lights in stock - shameless plug

Cariboocoot · March 2013

Re: Multiple Power backup sources - Discussion on best/efficient gear

Wow! It always amazes me when a system I helped design works.

Adding things like batteries "as needed" is problematic. PV not so much so.
What a shame we aren't all rich enough to put in The Great Solar Power System to begin with. Seems to be an absolute, though; we're all "on a budget". That's just a euphemism for "poor" of course.

LEDGuy · March 2013

Re: Multiple Power backup sources - Discussion on best/efficient gear

You da man.... seriously, you did point me into doing a LOT more research and looking at higher end equipment which will translate into better efficiency and configuration options. Appreciate the direction!

Multiple Power backup sources - Discussion on best/efficient gear

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