Slow blow fuses for inverter?

Any such thing?

The ones I have now are expensive and they go quick...which is reassuring, but a bit of a lag (like 2 secs) might be useful.

Quote from: MountainDon on July 12, 2012, 09:06:39 PM
An observation. The daytime temperatures have been reaching 88 at the cabin for a couple of weeks. It doesn't stay that high for too long; maybe 84 by noon, hits 88 between 2 and 3 PM and then falls to below 80 by 6 or 7 PM.

The battery electrolyte is now at a reasonably constant 65 F degrees. I wonder how high it will get by mid August?  Nights are still cool; in the 50's.

They last about 4 years in the low desert inside insulated sheds at 95F. We are lucky Don ! Thanks for the nice card!

Quote from: alextrent on July 17, 2012, 10:00:51 AM
Slow blow fuses for inverter?

Any such thing?

The ones I have now are expensive and they go quick...which is reassuring, but a bit of a lag (like 2 secs) might be useful.

There are two basic classes of fuses; Overcurrent Protection and Short Circuit Protection. What type/class are you using?

Overcurrent types will often have a built in surge capacity. Short Circuit Protection types should blow very quickly at their rated capacity.

EG: a 100 Class R amp time delay fuse may be able to handle two or three hundred amps for up to ten seconds before it blows. A class T has a very quick blow and usually a very high AIR rating. (Arc Interrupt rating). This can be important in a DC circuit as a battery can release a great deal of energy in a short time when short circuited. An AIR rating of 20,000 amps is common in class T.

If the overcurrent fuse will pass more current in a surge than the short circuit protection fuse then the short circuit fuse may blow before the overcurrent device.

Well...the adventure continues. I've always pined for more solar panels, thinking I'd like to run off them more than I run off the gens. (Duhh!)  Current research seems to show that the 160/170watt 12v panels are a dying breed. Cannot seem to find even a close equivalent in the Sharp brand I currently own let alone any other brand I'm remotely familiar with.

However, in a bittersweet stroke of apparent luck, I've located some 170 watt panels...they appear to be 12v.  I've always had to really stretch to understand the whole PV system, but I think these would work.  I'm not wild about the brand "Jinshi" (fill in the source country blank and my personal leaning), but the fact that they even exist...and the price...so; if some more knowledgeable forum participant would like to look at these with me and respond with their wisdom/opinion, I'd be appreciative.  I'd like to get 4, but with racks and shipping, likely less.

I believe I'm supposed to add PV panels that do not vary more than 10% in specifications.

The system is 12v

I have 2 Sharp 160w 12v panels up and running.

My charge controller is a Xantrex C40.

The breaker is a DC 60 amp

The inverter is a Prosine 2.0

The Jinshi panels have MC connectors, which I'm familiar with and like.

http://www.solarsystemsusa.net/solar-panels/panels/jinshi/nbj-170p/

Jinshi:                                                                                  Sharp
Maximum Power at STC (Pmax)    170Wp                                                160w
Maximum Power Voltage (Vmp)    23.6V                                                  22.8v
Minimum Power                         Not listed                                             144w
Maximum Power Current (Imp)    7.20A                                                  7.02A
Open-circuit Voltage (Voc)    28.5V                                                          28.4v
Short-circuit Current (Isc)    7.70A                                                          7.82
Module Efficiency (%)    12.9%                                                        12.21%
Operating Temperature (℃)    -40℃～+90℃                                  -40C - +90C
Maximum System Voltage (V)    DC 1000V(TUV) / DC600V(UL)              600VDC
Maximum Rated Current Series (A)    12A                                           Not listed
Series fuse rating                           Not listed                                             15A
Power Tolerance    0～+3%                                                             Not listed
Temperature Coefficients of Pmax    (-0.45±0.05)%/℃
Temperature Coefficients of Voc    (-0.35±0.02)%/℃
Temperature Coefficients of Isc    (0.05±0.01) %/℃
NOTC (℃)    (47±2)℃

Any brave souls who would like to chime in here?

The existing panels are connected in parallel I suppose and feed to a 12 volt battery system. So I imagine the thought is to add the new panel in parallel also. Those panels are a good match to the existing ones.  Question: what will the Isc of all the panels wired together in parallel be? Will it exceed the rating of the controller. There should be a 25% safety factor between panel Isc and the controller rating. It seems to me with my rough off the top of my head math, that you can not add many panels to that controller; 2 might be pushing it.  Many times when adding panels it is simplest to add a new controller and have the two run side by side. That's especially true when the panels are not well matched.

The controllers I am most familiar with also have a maximum PV wattage rating. For example at 24 volts (battery) ours can handle 1600 watts and at 12 volts only 800 watts. What's the C40?.  This may be because ours is an MPPT; I don't know for certain if that is a factor with the C40. It may not be because it is simpler... max may jusy be the volts x amps compared to the unit ratings. Sorry I/m fuzzy on that/

What about batteries? Needing more? How old are the existing ones? Or is this just to increase PV capacity because you don't get enough charge in a day from the sunshine you have?

"What about batteries? Needing more? How old are the existing ones? Or is this just to increase PV capacity because you don't get enough charge in a day from the sunshine you have?"

Current system runs the house on a sunny day if I'm not working on the computer. Plus a few extra hours grace.

Talked to Xantrex a few minutes ago...OMG they are now using a foreign call center and calling themselves Schneider Electric.

Not encouraging. 

Anyhow, after a bunch of verbal wrangling, I sort of got the impression that 2 more panels would be OK, but the panels I have and the ones I want (according to the call center) are all supposedly designed for a 24v system, even though the ones I own were listed for 12v systems when I bought them and I'm apparently just throttling the charging down somehow by using a 12v charge controller and system. 

Yes, I would l like to go longer between generator uses.    Batteries are also part of the plan...I just figured one learning curve at a time....but if you think more batteries are a faster and easier answer, I'm listening.

QuoteSchneider Electric.

is a large corporation with fingers in all sorts of electrical supplies. Big as in HUGE.  Global.

The panels you have are NOT for a 24 volt system. ... A 12 volt system needs panels with a minimum Vmp of around 18 volts to charge batteries. That covers some for clouds and hot weather which decrease voltage output. To charge a 12 volt battery one needs to be able to apply 14 to 15 volts. If the panels were only putting out 12 volts the batteries would not charge.   

Ditto on those panels (Vmp = 23.6) on a 24 volt system. They would never charge the batteries in a 24 volt system.

MPPT comes into its own though by taking the excess volts and transforming the voltage down while increasing the amps.   Your panels may waste some power but you are reasonably well covered for cloudy day performance.

If the big problem is not having sufficient PV output to recharge the last 24 hours of battery use virtually every day, then more PV panels are needed. The system should recharge fully everyday and go into float charge everyday. If it is not the batteries will be unhappy and you will be unhappy with their shortened life. A day here and there that does not result in a full charge and float cycle is not terrible. It happens to us and I can usually point a finger to the cause; clouds, I ran the air compressor or table saw quite a bit, etc. But if the failure to reach full charge and float is commonplace something should be done about that.


If your batteries are more than a year old it may not be a good idea to add batteries. Batteries all lose performance as they age. The degree of decrease varies with how they have been treated and used, average temperatures of the batteries, etc. When adding new batteries to old ones, the old ones drag down the performance of the new ones. It's a little like buying old batteries but paying for new ones.

How deep is the typical average daily discharge, as measured with a hydrometer? 

"The panels you have are NOT for a 24 volt system. .. Ditto on those panels (Vmp = 23.6) on a 24 volt system. They would never charge the batteries in a 24 volt system."

Whew. I didn't think she was right, but it rattled me.

"But if the failure to reach full charge and float is commonplace something should be done about that."

They hit full charge every day...by running the gen...but it isn't cheap.   

"How deep is the typical average daily discharge, as measured with a hydrometer?"

I cannot answer this as I use the readout on the Prosine 2.0 to gauge when to power up the gen again.  I start with a 14.7volt battery bank readout on the Prosine, and start the gen when the battery bank readout gets to 12.3v.  The inverter is set to charge the batteries any time they need to be, as well as supplying the AC into the house. There have only been a few times in the last several years that I've had the power wink out because the battery bank got too low and the gen was not on. Not enough times to cause any of the trouble you've described.  The Prosine 2.0 inverter shuts down battery power at 11.9v so I think I'm staying above the "trouble" range.

I'd like to develop this system to the point that I can go 3 days or so on PV and batteries before needing the gen.  I know 5 days would be better, but 3 would be a vast improvement.  I know I can create 2 PV arrays...by adding another charge controller, that would eliminate any "concerns" about hooking up PVs that are not exactly the same to one controller.

I wonder if I can create a second battery bank...I'll have to explore that.  This would eliminate the issue of combining older batteries with new ones.  Just thinking out loud.

Quote from: considerations on September 06, 2012, 02:23:37 PM
They hit full charge every day...by running the gen...

The first thing you need is more PV capacity so the existing batteries can be recharged by solar power. For reference here's the temperature corrected state of charge chart for a 12 volt battery system. That's temperature of the battery electrolyte, not ambient air temperature.

  Depending on temperature 11.9 could be classed as dead, as a problem. Also readings taken while in use (charge or discharge) are inaccurate. batteries should be at rest for a few hours before believing what the voltage indicates, in most cases.

Seems to me that running a second independent battery bank makes for a more difficult to manage system. But then I do not like systems that require a lot of user intervention as a normal everyday thing. So that may just be me. ... like how does one decide what to run off what? If they are interconnected at all they act as one for the most part.

"Seems to me that running a second independent battery bank makes for a more difficult to manage system."

I agree. Just seems that if one gets additional batteries, and the first bank is already several years old, and the old ones drag the new ones down, that a separate bank would be better than the combination.

"But then I do not like systems that require a lot of user intervention as a normal everyday thing."

I also have plenty to do besides fussing with Flint Light and Power. I also didn't move out here to listen to gennies humming...plus its not the cheapest option. Sunlight is free (for the time being).

In any event, after your reassurance about the PV voltage being proper for 12v, not 24, I'm going to start with at least 2 more....then study the battery situation after I get the panels up and running. 

Thanks for the conversation. And I'll study the table you sent....I should learn that part of the equation before making choices about new batteries.

So all off grid experts (or more expert than I), I am wanting to start up building an off-grid system.  My goal is to build slowly as money permits but be able to make monthly investments in it.  I would like a working system as soon as possible.  This doesn't mean large.  Ultimately, I would like to run my entire place.  This will take several years to build up.  I would like to start moving things over to it soon though.  Just so I can enjoy it .  I was thinking about buying 4 235watt Kyocera or 315 watt Kyocera panels to start.  I have pretty much figured out that an MPPT charger is key.  I want to be able to charge a battery bank and supplement with a generator when the sun isn't shining.  I have done research over the years on this and read a lot.  But, I think all of your input is better and many of you are excellent users of these systems.  My ultimate system will need to be 220V.  I need to run my well pump which is 3hp, 220v.  Anyway, what are you thoughts on how to grow it properly?

I had two first immediate thoughts while reading your post. Number one was that you should, IMO, plan to never need to use a smelly, potentially troublesome, noisy generator. The main reason we have a generator up at our place is that I owned it long before buying the property. I run it more just to keep it in good shape and the fuel fresh than I ever need to run it for electricity.  The second thought was that it is my belief that a system should ideally be sized for the use you envision and then built and put into service in one fell swoop as a "fait accompii". 

for one thing, PV modules are constantly evolving, growing. That can make it difficult to get a good match when adding panels if the plan is to feed all their output to the same charge controller. An alternative would be to plan on adding a second controller when adding more PV modules. That has the benefit of redundancy.

There can be even greater problems when at some later date, say a year or more from the original installation, the desire to add more battery capacity comes up. Adding new batteries to old batteries can, more or less, simply put make the new batteries act like older batteries.

You will also have logistical problems with running a combination of grid tied and off grid. Nothing that can't be resolved, but I wonder if that is the best way?

Obviously you are presently connected to the power grid. Personally I would set money aside and save up as rapidly as I could to have sufficient funds to build the PV system once and in its more or less finalized stage. But that's just the way I would do it; in fact that was how we built our cabin including the PV system. OK, we did take out a home equity LOC when we acquired some adjacent land, but that was paid back quickly. Our PV system has no more components than we started with. Our use has grown as I was sure it would, but I managed to build in sufficient capacity to make the increase in use painless.

The current federal tax credit of 30% can help a lot with the final actual costs. It's 30%, runs through 12/31/2016 and has no maximum dollar amount. You probably knew that.

Anyhow, those are my primary thoughts on the matter. I think you will find the opinions shared by many who have been through growing a system over time. I also know that it's not always possible to do things in the ideal manner. Good luck. It is nice having a utility bill.

MountainDon, you bring up good points.  Some I think I had worked through, others, not really.

Generator- ideally, you are correct.  My concern here is during times of long rainy days, I may not end up with enough power to run the well pump.  The generator would be to charge it up enough to do that. 

Charge controller - I follow you and thought about it like this to "grow".  Buy the PV modules 4 at a time and adjust the strings to compensate.  For instance, 315W panels - run 2 strings of 2.  When I go for the next 4, if they original aren't available, I can, I think, create 4 strings with 1 new and 1 old in each running in series.  I believe that it how you would connect mismatched panels.  That was a way I came up with to "grow" it.  But, I could be wrong.

Batteries - I didn't think about mismatching old and new batteries.  The could very well be a problem although, I suppose it could be solved by mixing them in strings like the pv panels.  Wouldn't that equalize the voltages across an average rather than trying to keep a new set = to an old set.  thoughts?

I would really like to grow it rather than a mass purchase..... only because I know me. If I let that money sit there too long.... I'll have another building

Perhaps Dave Sparks will drop by. I would trust his opinions on the panel and battery mixing. He has designed or built over 50 PV systems and does so in a manner to keep the clients happy with a minimum amount of involvement. I haven't seen him here for almost a month so maybe he will, maybe he won't.

I'd recommend dropping by the Outback Power Equipment forum and posing the question there. They have many experienced system builders and system users among their members and admins.

I don't have the technical abilities I'd like to have but there is something about intermixing panels and batteries that does not seem like a good thing. With widely varying age batteries in particular, I believe performance will be degraded. It may not be a great analogy but it seems to be akin to building an engine with cylinders that vary in size.     



Out of curiosity is it to be a 24 volt system? What type of refrigeration? Do you need A/C?

I'll drop back by the Outback forum.  Last time I was there it didn't seem like it was very active.  I had read through a few posts and ended up going back years.  I really want to go with a 48V system in the end.  I prefer to spend less on copper wire if possible.  The Fridge is going to be an issue as we use a lot.  A/C, we really enjoy.  We may end up designing the system to run almost everything except the big hogs.  I had designed out a system without any change in our electricity usage.  It was going to be about $98,000.    I am not interested in spending that much...  But you never know.

Originally, when I built this place, it was built ultra energy efficient.  With all of the add-ons...  much less so.  We currently have a 3 ton main AC, and 3 medium window units.  Then there is the large fridge, small fridge, deep freeze, and ice maker..   I love my electricity.  This is why the "growth" is important... Who'd tackle a $98K system in 1 shot.... 

A couple thoughts, phalynx.

Three horsepower water pump is big... I'm running a 1 1/2 hp and it pulls about 12 amps from both inverters (220v) when running.  I am running two 4024 Trace inverters.  Add a microwave and a couple freezers running ...maybe a fridge or two and it is close to capacity.

Grow it as you need it... that is what I did.  Maybe Don can post a picture so you can follow my example. 

Here is a site that I used as well.  Some pretty knowledgeable people .

http://www.otherpower.com/

Glenn,

My well guy said that I could pump with 6000 watts.  Yes, that is not small but I am shooting for the new 8000watt Outback 240V inverter for the ultimate use.  Another thought I had was to get a 3000 gallon tank and pump into it in 1 shot and then use a small pressure pump to provide water for the household.  This would give me extra breathing room if there is an extended period of bad weather/etc. 

I like the idea of a large storage tank.  How much rain could you collect and store in similar tanks. Your weather blesses you with the ability to use above ground tanks all year round.?

Technically speaking, we could live off rain water.  But I so love the generous amounts of great tasting well water we have.  There are several people around me that live off rain water, with livestock.

MPPT chargers can change voltages for battery bank or panel expansions.  Inverters cannot.  Usually you can go with a stackable inverter and add a second one later, or just get the initial bank voltage you want.

Generally there are cautions about mixing new and old batteries.  The old batteries will drain faster and drain the new ones faster.  It shouldn't be a problem.  If you battery bank is far undersized, you will use them up quickly and they will have to be replaced anyway.

Are you already on grid, and you are looking to disconnect?  With that much electric usage, it sounds like it is going to be a challenge.

I am on grid.  I am an electronic geek so I consume a lot...  I can curb some, some I cannot.  I have planned on living off the grid for about 12 years but never implemented.  I am at the point now where I want to implement.  I have pretty much mastered AC electrical so I figure I can rewire circuits and such to run off the grid while others, stay on the grid. 

I am sure my first setup will be enough to run a few of my computers and I'll just sit there and smile at them.  Then expand and add more and more. 

I am building a large greenhouse as well and want to start putting that stuff on it.  I have no intentions of any big lighting or anything in there, just want to play with aquaponics and such. 

I figure I'll have enough small electrical items that I can power on solar in the meantime.

The MPPT charge was what I had in mind.  That way, I could mix the pv panels as long as they all equaled.

Do you really need the capacity to pump all in one shot, or would pumping for say 1-3 hours daily suffice. I found with my own well application, that the difference in storage and PV capacity between my initial "one-shot" approach, and the pump a little every day approach was huge. Also, panel capacity is relativly cheap compared to batteries it seems. And like someone said earlier, you can't just add batteries willy nilly.

Another factor which seems often to be forgotten about is the cost of thick gauge cable runs between various system components.  Hundreds of feet of #6 UF rated copper wire is more costly that you might assume. And those runs suck/lose energy AC or DC.

Anyway, those are two factors that tripped me up.

Hey ! back in the saddle !  Hard to give advice without data. It needs to be accurate!  I have no idea how the "new" outback Radian performs in deep well situations. I only use the XW (deep wells) from Xantrex which is even better than the old SW's that Glen uses. They can surge 12,000 watts for five or ten seconds BTW. This surge ability makes the well pump and the inverter last longer because when the voltage sags the current goes up and damages equipment over time.

My experience is to ask the offgrid well driller guy's and they will tell you an XW.  Many just use a generator to get data.

Outback makes great gear also and they are second to none in support. I had some issues with their equipment in deep well applications only and find the new radian a step in the right direction for surging. Only time will tell and I let others do the beta testing for deep well applications. I know what works!