Newbie system questions

Particle

Hello. It’s great to see that there is a community out there for off-grid energy. In my case, I only plan to experiment with it on a small scale as a hobby since I’m a renter. By contrast I see that many of you I see are quite invested.

When selecting components that I should buy, I had a few questions. I’m hoping that you guys might be able to shed some light in the form of answers to those questions I have.

1) Respected Inverter Manufacturers
I was surprised that there isn’t an easier to find list of inverter brands that are considered to be reliable in this world. I’ve gathered some brands from context during my research such as OutBack, ExelTech, and Xantrex. Other brands like Samlex, Go Power!, and Cotek appear to be a bit more affordable and perhaps exist as a second tier after the very expensive brands listed first. Can you guys list inverter brands along with how confident you feel in that brand name? It would also be good if you could list brands to absolutely stay away from (such as Power Jack, right?) or other generic buying tips. I’m trying to establish a gradient of affordability versus perceived reliability.

2) Respected Solar Charger Manufacturers
This is similar to the point above. There seem to be many inexpensive MPPT chargers on eBay. Charge controllers from the likes of Morningstar are many times more expensive for the same current capability. I suspect the danger is largely the same—cheaper controllers double as magic smoke shows. What brands of controllers are reliable? I’ve got a Steca 10A PWM controller right now that I’ve commandeered from my father. It seems to be a passable choice but I may want something MPPT later if this turns out to be fun.

3) Inverter?
Is there any particular reason to buy a traditional inverter as opposed to using a quality UPS if your goals are small? A $500 budget seems to be able to get a true sine inverter in the range of 1000W while that same budget could fetch a 3000 VA APC SmartUPS. They’re designed for prolonged usage, have true sine output, have load & battery indicators, and feature higher conversion efficiency (95%) than most of the inverters I’ve looked at. I’d just not plug it into the wall and use external batteries if I went that way. I’d probably get a 1500 or whatever the largest model that still features a 24V inverter inside would be and apply the saved money elsewhere.

4) MPPT vs PWM
As I understand it, MPPT is really only of a significant benefit when panels aren’t at peak production (shadowing, winter, clouds, etc). Is this correct?

5) Load Connection Point
Small charge controllers are fairly limited in terms of how much load current they can supply. Why is it that the load is usually connected to the charge controller instead of to the batteries directly? Is it just to be able to provide statistics and low battery voltage cutoff?

waynefromnscanada

Re: Newbie system questions

Welcome to the form "Particle"
First, we need some info on you're proposed system. What to you, does "small hobby" mean? A 1000 watt inverter is not what most of us would consider small, or hobby.
What are you're planned, or expected loads?
That old saw: "Ready, Fire, Aim" comes to mind. It applies to many, many new solar projects who's owners make that mistake.
Re the controllers: Many of the cheap "junk" so-called controllers are not controllers at all, rather they are just voltage regulators. If you value you're batteris, get enough panel wattage to properly change them, and a proper controller to look after them.
MPPT controllers shine in cold weather, when they turn extra panel voltage into extra charging amps. They also allow the use of higher voltage, or non-standard voltage panels to be used to max advantage, and they allow higher voltages from the panels to be used for long wire runs with min power loss as they down-convert those higher voltages and turn those higher voltages into higher charging voltages. Nothing to do with non-peak production, or cloud cover etc.
Charge controllers and loads, inverters etc are normally connected to the same battery terminals, not different ones, and there is good reason for that.
Hope this helps, it's a start anyway and I'm sure others will join in.

Cariboocoot

Re: Newbie system questions

Particle wrote: »

1) Respected Inverter Manufacturers

You're on the right track, in my opinion. Ones that don't have recognizable brand names (or are "store brands") tend to be fly-by-night outfits that change models/specs/manufacturers more often than they change their socks. Within the "good" brands it's a matter of price/features/quality: for any given price weigh up the features in the different offerings. Some of that $ goes to value. For instance the small Samlex inverters have practically no surge time. Not important if you don't start motors.

2) Respected Solar Charger Manufacturers

As you suspect; same as with inverters. In my opinion the best MPPT controllers are MidNite and Outback. Morningstar makes the best PWM controllers. I am not keen on Xantrex products due to poor customer service/support and products that seem to be excessively "buggy", but they still have their place.

3) Inverter?
Is there any particular reason to buy a traditional inverter as opposed to using a quality UPS if your goals are small? A $500 budget seems to be able to get a true sine inverter in the range of 1000W while that same budget could fetch a 3000 VA APC SmartUPS. They’re designed for prolonged usage, have true sine output, have load & battery indicators, and feature higher conversion efficiency (95%) than most of the inverters I’ve looked at. I’d just not plug it into the wall and use external batteries if I went that way. I’d probably get a 1500 or whatever the largest model that still features a 24V inverter inside would be and apply the saved money elsewhere.

Make sure you are getting exactly what you think you are getting. As far as I know $500 UPS is not true sine nor designed for continuous use.

4) MPPT vs PWM
As I understand it, MPPT is really only of a significant benefit when panels aren’t at peak production (shadowing, winter, clouds, etc). Is this correct?

No. MPPT controllers offer these advantages: 1). greater flexibility in array design; 2). higher current output from any additional array Voltage. They can not make up for clouds, shading, et cetera. They can make up for "oddball" panels (Vmp not ideal for the battery Voltage) and long wire runs from array to controller (by utilizing higher array Voltage to reduce V-drop). In addition, when temps are cold panel Voltage rises and the MPPT controller can turn this into additional charge current. This also comes with a downside: the Voc will rise in cold temps too, and can exceed the controller's maximum input Voltage.

5) Load Connection Point
Small charge controllers are fairly limited in terms of how much load current they can supply. Why is it that the load is usually connected to the charge controller instead of to the batteries directly? Is it just to be able to provide statistics and low battery voltage cutoff?

Only light loads can be connected to the LOAD terminals on a charge controller. You see these chiefly on small PWM type controllers. This is designed to facilitate DC only systems where the load may be nighttime lighting (indeed Morningstar makes units that can detect dark and automatically turn the loads on). Never connect an inverter to these terminals. Larger charge controllers do not have "LOAD" connections. You can connect any size load to the batteries directly, providing the batteries can handle it, despite having a small charge controller (which may/may not be able to recharge the batteries). The rule in most cases is: batteries run the loads, charge controllers replenish the batteries (even though it may appear the loads are running off the controller and it may actually be supplying the full current need at the time).

niel

Re: Newbie system questions

in general the old adage that, you get what you pay for, kind of holds true. there are other manufacturers that are good such as magnum and rogue. some others may be out there that are good, but we have focused on certain ones as are mostly applicable to the north american continent. europe does produce products that may be little known to us that could be applicable and of quality and china is slowly realizing garbage won't get them anywhere in our marketplace.

your steca is such a european product if i remember correctly and it will function fine. it is a pwm design that is of the shunt style. this can be bad as excess power is shunted to ground rather than series regulated that just feeds through that which it calls for. this means you don't want to put it at its max or more as it will heat it up and possibly blow it out.

as to mppt, in 90% of cases this is the best to have for battery run systems, but if you factor in costs this figure can be brought down further. oversimplifying it, an mppt controller is a dc to dc converter that adjusts itself to optimize the given input current and volts to better match up with that required for an output current and volts. now the drawbacks are the mppt will cost more and it will add a bit more power lost in self consumption to operate, but is usually a no brainer trade-off as you gain so much more in current compared to that consumed.

another avenue to take could be the grid tied way of solar which is more efficient (no batteries), but does nothing for periods of power outages. there are also a few hybrid inverters that will allow both gt and battery backup and this could allow smaller pv voltages and thereby allow smaller costs for pv strings. this means it may have some growth potential as well as being more versatile, but won't be as efficient as the batteryless gt system. sma and outback have some of these hybrids as does xantrex.

another gt inverter allows each pv to be separately inverted and tied to the grid (batteryless) like enphase and is often easy to expand upon even though reinspection of the installation may be required in each expansion. yes, inspections are often required for gt systems and are technically required for off grid systems too in many cases.

you need to get a better feel for what you want and what equipment can get you there. this is not always an easy task as it requires much learning. even we old farts constantly learn and as you start reading you'll come to know just how involved something like solar can get.

Particle

Re: Newbie system questions

We're off to a good start, thank you both. As for "Ready, Fire, Aim", no worries. That's why I've posted here. I've only been researching and have so far spent exactly $0 on equipment.

First, we need some info on you're proposed system. What to you, does "small hobby" mean? A 1000 watt inverter is not what most of us would consider small, or hobby.

In my case, I consider this a hobbyist project since I have no plans to depend on it for anything. It's a project that will be done purely for the fun of seeing cool technology at work. I wouldn't need to store charge at the rate I'm using it at since using it will be infrequent.

What are you're planned, or expected loads?

Off most of the time. When on, less than 100W. I'd like to oversize it so that I at least have the option to play with larger loads stretching into the 750W range at times if desired.

Charge controllers and loads, inverters etc are normally connected to the same battery terminals, not different ones, and there is good reason for that.

Only light loads can be connected to the LOAD terminals on a charge controller.

This is good news because that's exactly what I would have preferred to do (and why I asked if it's safe). I thought it was kind of strange that the charge controllers would be involved in the discharge cycle, but coming from the outside that's just how things appeared to be.

---

Further notes: I'm planning on going with AGM batteries. A brand I've used in the past for other projects is Univeral Battery and I've come to like their products. I'd want to get a pair of 12V 55 Ah or 75 Ah batteries to run as a 24V bank to start with. Their 12V products run about $2/Ah. I'd probably need two series of them (as in 2S2P) to do 750W well. I gather that marine duplex cable works well for connecting to panels since it's UV resistant, double insulated, etc. I've also gathered that only authentic MC4 connectors should be used as knock-offs tend to suffer problems.

Cariboocoot

Re: Newbie system questions

Particle wrote: »

Further notes: I'm planning on going with AGM batteries. A brand I've used in the past for other projects is Univeral Battery and I've come to like their products. I'd want to get a pair of 12V 55 Ah or 75 Ah batteries to run as a 24V bank to start with. Their 12V products run about $2/Ah. I'd probably need two series of them (as in 2S2P) to do 750W well. I gather that marine duplex cable works well for connecting to panels since it's UV resistant, double insulated, etc. I've also gathered that only authentic MC4 connectors should be used as knock-offs tend to suffer problems.

Whoa on the AGM's. There's nothing wrong with them (or Universal Battery) but; they cost more per Amp hour and are unforgiving of mistakes. Very easy to make mistakes first time out with solar. Way too easy. This forum is full of posts about such mistakes!

Odd that you want to start out with 24 Volts, especially for such small power demands. 12 Volt can handle 750 Watts continuous without difficulty. (And I can't believe I'm suggesting someone go down to 12 V from 24!)

Anyway. What you can expect from 75 Amp hours @ 24 VDC: about 750 to 800 Watts hours @ 120 VAC. You won't need too much panel to recharge that either: perhaps as little as 60 Watts.

You will then immediately become addicted and want to build a bigger system. Just thought you should be warned.

Particle

Re: Newbie system questions

I like the idea of a sealed battery, especially in a situation where I'll be living in the same space and won't be building a fume vent. A 24V system seemed desirable so that I could reduce system current. It will let me use smaller wire and should also help me get more capacity out of my batteries since the discharge curves will be much stiffer at the lower current. It does really throw a monkey wrench into inverter selection, however.

I was looking at panels and found a 190W Astroenergy module at affordable-solar.com for $230. It's just small enough to where it can be shipped FedEx for $25 which is convenient. Shipping via a commercial freight carrier would be expensive when it's just one panel. Does that seem like a reasonable choice?

icarus

Re: Newbie system questions

Of all the "no name brand" charge controllers, the only one worth a darn IMHO is the Rogue. For the price it is a great controller, and a good value. a pretty god controller with good display function,which is important to a newbie.

as for inverters, the Morningstar Suresine 300 is very hard to beat. Very efficient, not very expensive, and very rugged. For a small battery system, there is little chance with few watts of panels and few ah of batteries that you are going to be powering anything bigger than 300 watts. The biggest (or nearly the biggest) mistakes that newbies make, is assuming that because they have a 1500 watt inverter, they should be able to power a 1500 watt load.

PV systems need to be balanced between the loads, the PV input potential, the battery size etc, and all calcs begin with the loads. Define the loads, and work backward to size the battery, PV , the inverter, charge controller and line voltge battery charger. Any other strategy is bassackwards?

Good luck and keep in touch.

Tony

waynefromnscanada

Re: Newbie system questions

I too was going to recommend the Morningstar 300. as did Icarus, but since you plan on going 24 volts, that one is out
Too bad, as it's one of the best little inverters ever.

Cariboocoot

Re: Newbie system questions

Both Exeltech and Samlex have small 24 Volt inverters. Of the two the Exeltech units are better in my opinion. Guess what; they cost more.

As Tony and Wayne said, the Morningstar 300 can't be beat for quality/price/performance. But it it 12 Volt only.

icarus

Re: Newbie system questions

Maybe we can work on Morningstar to build a 24 vdc unit. That is the single reason I haven't changed out to 24 vdc, since I have few 12 vdc loads any more.

Tony

Particle

Re: Newbie system questions

It may be unconventional, but remember folks that I don't have any particular load to run. The dimensions of this project that matter are generation and conversion. I have a target for how large of a load I want to be capable of running, but run time itself for any particular load is largely unimportant. It will run as long as it runs and when it's done the entertainment is over until it's recharged. My case isn't like the normal one where a person might say "I want to be able to run my TV for 90 minutes per day which averages 135 watts from the wall so I need 205 watt hours of inverted output per day meaning 310 watt hours of charging per day after typical losses." My loads will vary depending on what seems entertaining, and both charge and discharge will be sporadic--likely on random weekends when the itch to play arises.

Are the Morningstar Tristar controllers respected? They're quite affordable from the look of it. While I'm glad they're affordable, I'm also suspicious of why they are. In addition to being affordable, that series would also enable the use of a 48V system. Conceptually I like higher voltages, but I'm not certain how much more serious the shock hazard is with 48V versus 24V. Higher voltage may not be necessary, and I'll certainly acknowledge that before you all post asking why I'd bother. heh The lower the current I pull from the batteries for a given load the better off I am for runtime as I'm sure you're all familiar with. Since I own no equipment yet, it makes very little difference cost wise. A 48V inverter runs $5-20 more than the 24V of any given model. Four batteries do add a bit of cost, but it's still reasonable.

Cariboocoot

Re: Newbie system questions

TriStar controllers come in two types: PWM and MPPT. The latter is considerably more expensive, of course (about $250 more). The shortcomings are that you have to spring for the display separately (around $90) and they are a little bit odd in their programming/function by my way of thinking. But perfectly usable. They also have the nice battery sense wires which improve the accuracy of Voltage reading.

48 Volts isn't any bigger shock hazard than 24 really. Once you pass 15 Volts the sustainable arc problem occurs, otherwise all these battery-powered units are quite safe on the DC side. The biggest problem is with shorts and too high current for the wire size, which applies to any system Voltage.

You are perfectly correct that the lower the discharge rate of the batteries the longer they last.

Particle

Re: Newbie system questions

How is the prevention of power dissipation in the cells themselves accomplished when their potential falls below that of the battery bank? Do panels come with diodes integrated or is that something that I'll have to do externally? If I do have to do it externally, where is it preferable to install a diode--in line at one of the panels or at the bank?

BB.

Re: Newbie system questions

Solar panels are really giant diodes themselves... Basically, you don't need blocking diodes for 12 volt battery systems, maybe for 24 volt, and required for 48 volt (low voltage batteries do not drive very much reverse current through solar panels so the batteries do not discharge very much through panels at night).

In the olden days, you could buy a "self regulating" solar panels (typically Vmp~15 volts) for direct connection to the battery (and other voltages).

Today, most everyone uses some sort of PWM/MPPT type of series connected charge controller which does the "blocking" at night (as well as prevent battery overcharging)... So we don't worry/ask about blocking diodes.

NAWS Tech Tips

-Bill

niel

Re: Newbie system questions

" It will run as long as it runs and when it's done the entertainment is over until it's recharged."

ah, you can't do that to batteries as they aren't made to be 100% discharged (100% dod). we recommend no more than 50% discharged to preserve some battery life. going 80% discharged or more can literally damage the battery. you may want some means of monitoring the battery to avoid going too far discharged.

PNjunction

Re: Newbie system questions

Particle wrote: »

It may be unconventional, but remember folks that I don't have any particular load to run.

Maybe before buying anything else, grab a P3-International "Kill-A-Watt" meter to start measuring the wattage of devices you may like to run. And maybe get a decent quality multimeter for measuring the resting SOC voltage for your future AGM's to ensure that you don't go below 50% DOD.

This may sound really dumb, but how about going really small just to start - say a cellphone or D/C/AA/AAA recharger? The math is all the same, just on a smaller scale.

For instance, I have a 60-watt panel > Morningstar Sunguard PWM controller > UPG UB-12120 AGM > mobile cigarette usb adapter > cellphone charger. For the rechargeable nimh batteries (ahem, low-self-discharge types such as Sanyo Eneloops) a Samlex pure sine wave 120 watt inverter feeds a Maha/Powerex MH-C808M nimh charger setup.

Overkill maybe. Fun? You bet. After each charge session I let the battery sit for about 4 hours or more, and take my readings. OR, I could really do it right by measuring the wattage and make calculations that way. Very small system - yet obeys everything I've read on the forums. I just pretend that the AGM is really a very expensive Rolls-Surrette that I don't want to destroy with bad maintenance. Then I start measuring my solar insolation hours. then..... the fun never stops!

Particle

Re: Newbie system questions

niel wrote: »

" It will run as long as it runs and when it's done the entertainment is over until it's recharged."

ah, you can't do that to batteries as they aren't made to be 100% discharged (100% dod). we recommend no more than 50% discharged to preserve some battery life. going 80% discharged or more can literally damage the battery. you may want some means of monitoring the battery to avoid going too far discharged.

Don't worry, I didn't mean I'd run it until the inverter literally shut down. I've been doing electronics projects for a long time and do have a grasp of what it takes to destroy a lead-acid battery since I've certainly done it more than once.

PNjunction wrote: »

Maybe before buying anything else, grab a P3-International "Kill-A-Watt" meter to start measuring the wattage of devices you may like to run. And maybe get a decent quality multimeter for measuring the resting SOC voltage for your future AGM's to ensure that you don't go below 50% DOD.

This may sound really dumb, but how about going really small just to start - say a cellphone or D/C/AA/AAA recharger? The math is all the same, just on a smaller scale.

For instance, I have a 60-watt panel > Morningstar Sunguard PWM controller > UPG UB-12120 AGM > mobile cigarette usb adapter > cellphone charger. For the rechargeable nimh batteries (ahem, low-self-discharge types such as Sanyo Eneloops) a Samlex pure sine wave 120 watt inverter feeds a Maha/Powerex MH-C808M nimh charger setup.

Overkill maybe. Fun? You bet. After each charge session I let the battery sit for about 4 hours or more, and take my readings. OR, I could really do it right by measuring the wattage and make calculations that way. Very small system - yet obeys everything I've read on the forums. I just pretend that the AGM is really a very expensive Rolls-Surrette that I don't want to destroy with bad maintenance. Then I start measuring my solar insolation hours. then..... the fun never stops!

Fortunately, since I do other projects (mainly digital logic and amplification) I have some sophisticated tools on my bench. I've got a 6.5 digit Fluke 8846A bench-top DMM, a 100 MHz / 1 GS/s GW Instek GDS-1102A DSO, a Kill-A-Watt meter, and others. Rest assured, I'll do what I can to take decent care of the bank.

Particle

Re: Newbie system questions

Will a 60-cell panel generate sufficient voltage to charge a 24 volt system or do I need to look at 72s?

BB.

Re: Newbie system questions

In general, we recommend Vmp~35 to 38 volts minimum for solar panels charging a 24 volt battery bank.

I believe a 60 cell panel is around Vmp~30 VDC--which is too low.

Batteries need ~29-31 volts for proper charging and Vmp fall with rising temperatures (as well as wiring drop, voltage drop across charge controller, etc.).

You can still use Vmp~30vdc panels with 24 vdc battery bank--You can put two to three Vmp=30 volts in series behind a MPPT charge controller (a ~140-150 DC max input controller can manage an STC Vmp of around 100 VDC--depending on your local temperatures--very cold temperatures raise Voc-cold over STC panel rating number).

The advantage to running Vmp>>Vbatt-charging--If you have relatively long wire runs from solar array to Battery/Charger installation, high Vmp-array allows you to use much smaller awg wire and/or send power much longer distances.

-Bill

Particle

Re: Newbie system questions

Can an MPPT controller boost or only buck? The reason I ask is that 72 cell panels aren't as good of a buy currently.

Any feel for if "Blue Sky Energy" brand controllers are worth buying? They have kind of a middle-of-the-road MPPT controller and it's a brand that actually has a real website at least.

westbranch

Re: Newbie system questions

Blue sky are ok but old tech. I have one and it does me well for the application , see sig, but can no take 3 120w panels I have... hence an MX60 took its place, soon to be displaced by a Midnite Classic 150

poor choice IMHO

BB.

Re: Newbie system questions

Most MPPT controllers can only "buck" (they can only regulate by dropping the voltage) and they cannot boost.

At one point, it appeared the Midnite Classic could operate in "Boost" mode--But I have not read anything for a long time that discussed this function. You should contact Midnite Solar directly and see if that function was ever implemented.

In the end, Buck Down Converters are usually the most efficient and stable of the converter topologies (of the little that I know). So, even if you could do boost, you would usually be better off simply combining 2-3 of the "60 Cell" (Vmp < 35 VDC), and run a 60 to 90 VDC array. It will be efficient and operate in any conceivable conditions (hot array, cold array, upgrading to 48 VDC battery bank with three panel strings, with long cable runs from array back to battery shed, smaller AWG wiring, etc.).

The only drawback, usually, is that you need to add panels in groups of two or three when paralleling additional panels.

-Bill

Particle

Re: Newbie system questions

Ok. It's time to start putting pen to paper now that I've spent a few weeks researching.

I'm looking for ideas and feedback. Below is only meant to serve as a starting point proposal for something that sounds good to me.

Controller: Outback FM-60 / 60 A / 12-24-48V - $500
Panels: 3 x PLM-230P-60 / 230 W (Worthless STC) / 60 Cell - $805 (Shipping included)
PV Wire: 10/2 marine cable / 50' - $50
Connectors: 5 x Pairs MC4 (Genuine) - $20
Batteries: 4 x UB121100 / 12 V / 110 Ah / AGM - $920
Battery Wire: 4 AWG (Fine strand / flexible) / 20' - $20
Battery Jumper Connectors: Free
Inverter: APC SmartUPS 2200 VA XL / 1750 W / Used - $350 on a good day
Misc Stuff I've Forgotten: $Probably Lots

Total: $2,665

Ok, clearly this is going to have to scale back. This is a "just because it's neat" project, not an actual power system. $1500 is probably doable for something this potentially enjoyable, but no more.

Points of consideration:

• I know many will be concerned about the inverter, but really--it's solid. It's actively cooled and can run indefinitely. Being the XL model it's also meant for up to 10 external battery packs, so you can be assured of two things: 1) It really is meant for extended run time instead of short dips and 2) It has two modular welding cable plug connectors on the back for easy connect/disconnect. Sustained output isn't something I'm concerned about since I hail from the computing world, but I know it's something you guys will be suspicious of. It's meant to run on 48V. Efficiency at full load is an honest 95%. ~90% at 10% load. Below that it falls rapidly. True sine wave output. It also has the important advantage of being able to still be used should my interest in experimenting with the magic of solar energy fade in the future...or my landlord objects to me dragging large solar panels around in my yard on the weekends.
  
• I've heard tell that the MPPT tracking of the Outback FM series units isn't as good as that of the Morningstar. Is this concern legitimate? If legit, is it perhaps an outdated fear in light of modern firmware revisions?
  
• Clearly, these plans are too ambitious for the sort of project I'm trying to do. The price is simply too high. I'd still like to get the most fun out of it as possible for every dollar trimmed, so I'm open to suggestions.
  
• I'd really like to stay with 48V if possible. 24V is acceptable if there's just no way to do 48V in an affordable envelope, but if we get back to 12V then it's really just not going to be any fun.
  
• Still targeting the capability to drive a 1000 W load, but actual loads will vary with interests. Average load when the inverter is online will probably still be <= 100 W.

I'm out of caffeine. Time for bed. To ensure I've said it though, I'm glad this community is here. You guys are very helpful.

Photowhit

Re: Newbie system questions

Suggested earlier the Rogue Charge Controller is "god"(I'm sure Marc will be happy to hear that!)

If you decide to go with true 12 or 24 volt nominal panels, there is one other brand of Charge Controllers which has been around for a long time over 20 years and is repected for their small PWM controllers and that is Specialty Concepts I have a 20 year old 30 watt 12V units that was/is still working when I took it out of service 5 years ago. They make some nice sealed units for marine use, my dad used on on his boat and it even survived a sinking in salt water, hard to beat that! (it did die a year or so later, perhaps from corosion I couldn't see, I did the wash in fresh water and blow dry thingy)

I don't have any problem with Trace/Xantrex PWM charge controlers, haven't a clue as to the MPPT, though I've heard issue here. they to have been around for a long time.

If your just doing it for fun... if you have a family member who's a home owner near by, you might do a micro inverter grid tie and set it up so you can monitor the production over the web, smaller solar projects can be done with small wattage panels directly charging NiMH batteries, some of which can take a c/8 charge infinetly with minimal damage (hence no CC) and can often be rigged to live in the object being powered. Here's a couple books on solar projects. I have a list some where in my Email(for my brothers kids, after I made a wood experiment box with 4 AA NiMH a 4 watt panel, and a bunch of dollar store electronic things, (the battery tree lights flickered nicely when they ran the fan at the same time, the kids though it was all part of the plan...lol) only caution is NiMH can discharge at a very high rate, think wire filament, as in light bulb, if shorted.

Photowhit

Re: Newbie system questions

So we're talking a 48V system or no fun, and we need to cut your budget...

Panel like the "190W Astroenergy" that you had originally suggested, it is a 'true' 24 volt panel with a VMP of 36+ volts, if you put 2 in series and a PWM charge controller, you'd save dollars on one less panel and be able to go with a less expensive CC like the Xantrex C40 or the Morning star tristar 45(I think that handles 48v?)

That should get you closer to 'budget'

Now we either need to switch to a cheaper battery or go 24V...

niel

Re: Newbie system questions

particle,
you are wanting to put a constraint of $1500 on the system and i don't think you'll be able to do it even with photowhit's good recommendations on corner cutting. you are forgetting some things like the shipping costs, especially of the batteries and pvs, not to mention the mounts for the pvs. solar is just not cheap to get into even with the lower prices appearing on pvs. even if you manage to corner cut enough you have to watch that you don't cut the quality and functionality. for instance, cutting back on the batteries to 24v will cut the cost in half, but the batteries would strain a bit when doing a 1000w load so we can't say for how long they would provide this power or how long the battery lifespan will wind up being by doing this. you are calling it an experiment, but no matter what you call it, it is what it is and that is expensive. it can actually be more expensive to do it too cheaply than to do it right.

Particle

Re: Newbie system questions

I would like to address some of the concerns you two have raised. A bulleted list might be the handiest way to do so since there isn't always enough content on each item for me to make a proper paragraph.

• System Voltage: I meant to communicate that 48V is preferred but 24V is an acceptable fallback. Only 12V as a system voltage is completely out of consideration. The lower the voltage the harder it makes everything else due to the increased current. Cable expense goes up, labor increases, losses in wiring and realized battery capacity both increase, etc.
• Panel Selection: The Astronergy 190W panel is nice in that it's just shy of the size limit that can no longer be shipped by FedEx. The reason I was initially interested in that one is because it can be shipped for $25. Price per watt (delivered), however, is not quite as attractive as the larger panels I brought up last night. The difference is about $1.17 for the 230s above versus $1.34 for the 190s. I do believe I may have little choice in the matter as you've suggested, however. Price efficiency doesn't mean much if the final price is too high.
• Charge Controller: I agree with you--PWM may be my only realistic choice. I'll have to switch back my consideration to only 72 cell panels.
• Batteries: I'd like to stay with a sealed battery of some sort if possible. They're a bit more expensive, but not having to worry about venting, corrosion, and electrolyte levels is a big attractor for me. I always remember back to a power system my dad had with flooded batteries where one cell in a large battery rapidly went dry and caused the entire battery to explode.
• Shipping Fees: Every price I have mentioned has had shipping rolled into it. No worries there about hidden costs.
• Mounting: In my scenario, these panels will not be permanently installed or mounted. No costs there to worry about.
• Cut Corners / Cheapness: I don't think anything I've selected could really be called going cheap. It's all quality gear as far as I can tell. Did you just mean this as a warning against doing so when trying to trim cost off my initial plan?

I'm currently trying to decide if I want to give up on 48V. If I do, it will reduce startup costs substantially. There are of course some down sides which we've covered. It's time to think some more by reviewing my data and merging this latest round of feedback with my objectives. I have to not only consider what I want now but also be careful to make an investment that doesn't become useless if this ends up being entertaining enough that I find myself wanting to grow into something larger.

Particle

Re: Newbie system questions

I have a revised proposal following last week's thoughts and decisions. I'm hoping for a new round of feedback.

Controller: Morningstar ProStar PS-15M-48V - $90
Panels: 2 x Astrogerny / 190W (STC) / 72 Cell - $510
PV Wire: 10/2 marine cable / 50' - $50
Connectors: 5 x Pairs MC4 (Genuine) - $20
Connectors: Anderson SB120 / 120 A / 600 VDC / 4 AWG Contacts (For Inverter) - $10
Batteries: 4 x UB12750 / 12 V / 75 Ah / AGM - $640
Battery Wire: 4 AWG (Fine strand / flexible) / 20' - $20
Battery Jumper Connectors - Free
Battery Fusing: 60A ANL & Block (80 VDC) - $10
Inverter: APC SmartUPS 2200 VA XL / 1750 W / Used - Free

Total: $1,350

I may also get a second-hand automatic transfer switch. It would let me flip back and forth between regular and solar power as desired for any given load with just a 5 ms switchover time.

waynefromnscanada

Re: Newbie system questions

Particle wrote: »

[*]Batteries: I'd like to stay with a sealed battery of some sort if possible. They're a bit more expensive, but not having to worry about venting, corrosion, and electrolyte levels is a big attractor for me. I always remember back to a power system my dad had with flooded batteries where one cell in a large battery rapidly went dry and caused the entire battery to explode.

[/LIST]

And you think this cannot happen with sealed batteries? Sealed batteries are Very unforgiving of abuse and improper handling by improper charging etc compared to flooded type. They cost more, have shorter life generally, and are unforgiving of our mistakes etc, making them a poor choice for both someone new to solar and for their higher prices. It is you're money, but on the other hand, it was you who came to this form asking questions of both the experts and the experienced folks here, and as always they gave excellent advice, trying to help you. With a wee bit of care and maintenance my flooded battery bank, 10 years old, show no signs whatever of corrosion on, around, or anywhere near them, including the connecting cables, although I have seen other systems that were left to fend for themselves, and in just a couple of years, were a nightmare of corrosion, and they weren't all flooded batteries. Do not expect to have a system as carefree and maintenance free as grid power, it ain't gonna happen. Having one's own off grid power system is like having a child, or a pet. It's a living thing that demands attention and care - - - or it dies.

Particle

Re: Newbie system questions

I've not experimented with solar power before, but I do have electronics experience. My other projects have always involved AGM and gel type lead-acid batteries. I've never had a project that required me to resort to using a flooded battery, and I've always avoided them due to their clear drawbacks. Due to this I have no experience with flooded cell types, but I am quite familiar with SLA. I'm not under the illusion of SLA batteries being magic and care-free, but they do have strong advantages. Their disadvantages are well known to me and should not be a problem for this project.

I came here asking primarily for advice on which brands are respected, had a few questions specific to solar technology, and was interested in people with experience saying yes or no to if my plans looked reasonable in that context. I do not know why people have a few times gone negative towards me. A possible exception here being that I do not exactly fit the common forum advice pattern of a person who knows nothing asking a question about what to buy and then buying it. I insist instead on learning about what my options are and making my own selections with the desire for feedback being geared toward two goals: The first is any post that helps me learn about the subject. There have been a lot of those here in this thread and the others I've been cruising. The second is if a particular selection I've made is or isn't a reasonable choice (and if not, ideally why not).