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Re: khalidusman: Sizing breakers for my off grid system

Very kind of you Dave--My wife has always been a bit of a city girl... However if California gets even crazier (if that is possible), then may be out of state next.

But the reality is that taking care of in-laws, and our kids are here. Will probably just run the clock out.

-Bill

BB.

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Re: 7KW PV with 10KW Inverter

You are 1/2 a world away from most of us... So I do not have much I can add regarding specific manufactures... But with the low prices for solar panels and hardware, expecting that you will be responsible for warranty costs is a good assumption (solar mfg and distributors come and go--Even some of the "good/well financed companies" seem to have failed or exited the market).

GT solar is pretty straight forwards these days.. Well made panels should last 10-20 years pretty easily... If you need replacement/more panels 5+ years down the road--Do not count on being able to match size/wattage/Vmp/Imp with your existing panels. As manufacturing cost reductions and market demands change, available panel models charge too. My 15 year old array of 175 Watt panels--It would probably be more cost effective to buy a whole new set of panels rather than try to replace a few damaged by hail or early life failures (my original panels were probably USD$10 per Watt, now there are panels in the $0.50 per Watt range).

Inverter wise, I would budget for a replacement every ~10+ years... Power electronics (and electronics in general) tend to go out of production in 5+ years (5 year warranty, although 10 year inverter warranty is required for some markets in the USA)--And repairing 5+ year old inverters can be difficult (finding parts/boards, and a facility that can repair them--Let alone if the computer/memory goes bad and no replacement software/memory).

Circuit breakers require a specific chosen GT inverter and array configuration. Also code requirements for your country. In North America, our breakers and wiring following the National Electric Code are for "typical" installations with intermittent/relatively low average current usage. However, solar power (and battery banks) can pull 5+ hours of rated current. Breakers and Fuses for our market generally are specified to not trip at 80% or less of rated current, and will trip at 100%+ rated current (can take hours to trip)... So, for solar/battery/inverter wiring, suggest that if you have a rated current for wiring and breakers of (for example, 10 amp continuous current) of 10a*1/0.80derate=12.5a or ~15 amp minimum breaker/wiring.

You seem to have chosen the array Wattage to meet your average monthly energy requirements and amount of sun for your city--So sizing looks OK.

For solar--Make sure you have no shading at all on your array (at least around 9am to 3pm at least)... Solar electric panels do not work well if there is any shading on the panel(s). Overhead electrical wiring, a vent pipe/chimney, etc. anywhere on the array can pretty easily kill 50% of the array harvest (details do matter--But in general--NO SHADE during harvest time). There is equipment that, in theory, is supposed to help reduce losses from shading--But they add complexity (and costs).

You can also look at "micro inverters" (a single inverter every one or two panels) which can help reduce shading losses--Although there are complexities with micro inverters too (needing a inverter monitoring system, if one fails, having to pull up panels to get to the failed micro inverter to replace, etc.). A single central inverter is generally easier to maintain/service.

If you have lightning in your area--Then using surge suppressor(s) is a good thing. Having suppressors on both the solar input to the GT inverter and on the AC output of the GT inverter is the better solution. These are good suppressors--They help with nearby strikes, but few inverters will survive a direct hit to the array. Using lightning rods to redirect strikes away from the array can help (added expenses and complexity of design).

http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=23&productCatName=Surge Protection Devices

Look very closely at the Net Metering Billing rate plan... In the USA, they started out with very good terms for the solar customer (subsidizing GT Solar systems)--Basically, they would pay us back the retail power rate for every kWH we generated... Very easy to "break even" (we could not "make money" selling power to utility).

HOWEVER, as GT solar became more popular, and the politics changed, the rate plans have become much less "GT Solar friendly". We now have time of use (high cost power all they way to 9pm at night--Obviously no sun to generate power), some places have high "GT Solar connection fees" ($48 to $96 per month), and low payments for power ($0.06 per kWH paid by utility vs $0.10 to $0.40 per kWH paid by customer for power). And in some regions, new GT solar installations have been made illegal--Or at the very least, not cost effective (I understand why--Lots of GT Solar, utilities do not make money, and subsidies from state/utilities raise prices and taxes for the non-solar customers and tax payers).

From "your" point of view--A well functioning GT Solar system is "transparent" to you. Your appliances/lights/electronics all work exactly as they have before. And you (hopefully) see a greatly reduced power bill. My electric bill is $10 per month (minimum connection fee) vs $60-$100 per month without GT Solar.

Another thing to be aware of... Standard GT Solar systems have no energy storage--So if you have a power outage, the GT Solar system provides ZERO POWER to your home... Utility power fails, it also fails to your home.

There are various "solutions" for solar and emergency backup power (one is SMA's "secure power" system--It can give you ~1,500 Watts of AC power when the sun is shining--And you can plug a few appliances into the the GT SMA--Another is to go with a battery bank and hybrid GT/Off Grid inverter--Batteries supply energy when the AC mains fail and there is no sun). But that add expense--And batteries are a cost/maintenance issue all of their own.

And my first suggestion... It is almost always cheaper to conserve energy than to generate it. Look at your present power usage. LED lighting, efficient appliances/TVs/Computers. Is your Heating and Air Conditioning system "efficient'. Is your home well insulated (walls, ceilings, windows, etc.)?

It sounds like you have done the research and are probably aware of most of the issues/suggestions I have made... When buying the hardware--Getting good quality is first choice. Second is look at costs... For the most part, a good quality XXX Watt solar panel (crystalline, glass cover, mono or poly crystalline). I would not "pay extra" for PERC or Mono Crystalline panels. In day to day usage, you probably could not measure the extra $$ spent. There are some advantages to Mono and other "high efficiency" panels--That you can harvest more energy from the same square meter space can be worth it to you--If you are limited for space.

Your thoughts?

-Bill

BB.

2 ·

Re: Newbie drowning in information needs help planning

if your utility is ok with you generating power, and it's simple to get the permission from the town and utility,
I am in favor of just simple grid tied solar. What you produce, you consume at the house, and extra power you don't use
can either be "lost" or sold to the utility to unwind your meter - depending on the utility regulations

If you are not off-grid and don't have a pressing need for power all the time, I would skip the batteries, their losses, and expense

mike95490

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Re: Does anyone know the Amperage rating on Schneider Conext XW PDP DC positive Busbar?

The main DC breaker for the XW+ is 250A, so should you assume the bussbar is the same?

MichaelK

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Re: Lithium Battery questions...Cold temps, capacity vs FLA etc

There have been a few small, incremental advances, but if that was my install, I'd use FLA or AGM and leave them on a light float charge over the winter

mike95490

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Re: Does anyone know the Amperage rating on Schneider Conext XW PDP DC positive Busbar?

Ticket with Schneider requesting the information has been submitted. I will happily post here whatever info they provide so others who are needing it has "easy" access to it.

While the PDP does come with one 250amp breaker, there is a spot for a 2nd breaker along with other power connections, then the bus bar that comes with the 865-1020-02 kit has spots for 3 inverter breakers. Code for a bus bar says it must handle the sum of all over current devices connected to it +25% (on the "line" side I assume). Using the expansion kit bus bar, that has three inverter spots on it, spots for four charge controllers and two spots for additional high amperage "devices" or batteries. Just doing the math for three Schneider XW+ inverts and four Schneider MPPT 60 charge controllers would give you 1,437.5 amps based on the breakers connected to it (excluding the battery breakers in this math, but that could potentially drive the number up even more). ((250+250+250+80+80+80+80+80)*1.25) This size of a setup has been drawn up as a solution on Schneider's own site. That's quite a bit of amps, I can see why the state/local inspector might want to see this manufacturer info. In reality would that bus bar ever see anything close to that... Never, not even close. The DC output of the inverters is much lower than the input, and the breakers are rated for the max DC input, but... Code says... So might as well CYA when asked. A good inspector probably will never question such a setup unless they are having a really bad day or someone is pushing them to do so. In my case the state is calling it out on the permit documents.

Midnight Solar provides this info in the documents for their combiner/PDP equipment, there is no reason Schneider or anyone affiliated with them should be so tight lipped about it. No trade secrets would be revealed by providing such info or even better, links to documents with that info. Providing manufacturer documentations would actually protect you from any potential suit if that really was your fear. But then again, if you really had any legit legal fear you would not be here providing as much help as you do. So logically the issue would then sound more on the capitalist side. While I do get it, everyone needs $$ to survive, but these forums are here to help provide info to the general public at no cost (or is there a fee for these forums that I missed somewhere?). I would totally understand requesting some kind of compensation for design help, but compensation for documentation that should already be accessible to the general public just doesn't sit well with me. If you have read this full reply, you have already spent more time reading than it would have taken to just post any manufacturer info.

I respect everyone who is in a trade industry. Many of them do things that others can not, or will not do, and they help keep society functional and safe. Asking for payment for manufacture documents on a free information forum is pushing the limits in my book though.

SomeJ

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Re: classic 150, etc versus Schneider Electric Charge controllers

Hi jt..,

The MidNite Classics sweep very fast, in "Solar" Mode. And are very rugged controllers, and are at least one generation newer tech, than the SE 150-60 (or whatever they are calling that CC, today).

MidNite does give superior Support for their products, vs Schneider -- you have recently gotten great Support via the MidNite Forum on that one Classsic that is not reporting into MyMidnite. Schneider has NO Forum. AND, several of the MidNite Founders are active on the MN Forum (boB and Robin).

Always a lot of tradeoffs on which CC is best. Just my opinions, Good Luck, Vic

Vic

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Re: 230vac single phase output to 220v with a center tap transformer

Welcome to the forum MrFCC1.

Is this for use in North America (central California?) or somewhere with 240/220 VAC as line voltage? In North America, the "center tap" of the 120/240 VAC line is a ground referenced neutral. In other 220/240 VAC native countries, one leg of the 2X0 VAC line is usually ground referenced (may vary by country).

Are you going to connect to the utility grid as a hybrid/GT capable inverter? Will this hybrid inverter+charger meet your UL/NEC requirements?

If you are planning on using this system in North America--You probably should get a wiring diagram from EAsun to ensure that the inverter is connected as they expect to the utility.

Transformer wise, you have two major choices... An "auto" transformer that has only one set of windings. You connect L1/L2 to 240 VAC, and the center tap gives you 120/240 VAC output... However the output of such a transformer is NOT isolated from the AC input... So the Neutral bonding of AC neutral/center tap of North America would require you to "float" L1 and L2 to the hybrid inverter.

Here is an example of an Auto-Wound Transformer that is used on off grid AC power systems:

https://www.solar-electric.com/x-240.html

The other major type is a two winding transformer... Isolated from AC In to AC Out of the system... You can have 240 native with ground bonded neutral on the 240 VAC side, and the Neutral Center Tap ground bonding on the 120/240 VAC output of the transformer.

I did not find many details on your inverter+charger... In the US, L1/N/L2 ground bonding must be done "right" or the typical hybrid/GT inverter will fault... I did not see any reference on how this product would behave with L1/L2 floating AC outputs (on a quick read):

http://www.easunpower.com/Products/Off-Grid/5000W_Parallel_Inverter/93.html (yours?)

Transformers add cost and complexity, as well as some additional losses--It does not usually make a lot of sense to try and "converter" a non-North America inverter to a North American grid connection (and it may not be to code either).

-Bill

BB.

1 ·

Re: Existing well hybrid power project.

Welcome to the forum @Revinvoss

Sometimes attempting to power an existing pump with solar ends up costing more than replacing the pump with one designed to operate directly off PV without the need for an inverter batteries charge controller, which to support a 1.5 hp pumps starting current.
Solar pumps typically come with a controller which converts the DC to 3 phase AC, or have brushless DC motors, some have controllers that accept batteries for backup.

mcgivor

1 ·

Re: Design parameters for lithium ion batteries

mike95490 said:

1) Lead acid batteries are forgiving, and generally "die" gracefully

2) Li batteries are unforgiving. 1 overcharge or 1 deep discharge, and they are toast. Might get a few more cycles out of them before they die, but either condition damages the battery.

3) LFP / LiFePo / LP4 (all the same battery, just different abbreviations) are the "safer" batteries that tend to just fail, or swell up and stink. Any of the other Li chemistry mixes, involve failure with fire or going bang.

4) Some Mfg's include the top and bottom 10% safety margins internal their BMS systems.
Some don't and you have to program that into your loads and chargers. Your Mileage May Vary. Some rate the full capacity, but only deliver 70% of capacity.
Lead acid batteries like 50% -100%, so same protocols will NOT work for each.

I was watching some training videos from SimpliPhi and they recognized using too high of a charge/discharge rate as the most common failure point in their batteries. It seems like this can be mitigated with proper programming/sizing, just like with a lead acid battery bank, although I guess the cost is far higher if one gets anything wrong or if the parameters were to be cleared for some reason. Lithium ion batteries seem conceptually attractive to me in the developing world as it seems like a system, if properly installed/programmed, can offer many years free of maintenance and issues..although has pretty much been my experience with AGM batteries down here as well. There are many off-grid locations that can take days and significant cost to arrive at in the jungle here..smaller batteries, less weight, more cycles...seems pretty attractive. The cost is still a serious barrier, but I imagine that in the coming years that the BMSs and technology will become more foolproof/refined and continue dropping in price.

alexj

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