Getting started

New 1800 sq ft mfg house going in, 2x6 construction, R38 insulated, dual pane windows w/low E, etc. 20 Miles NE of Snowflake AZ, elevation 5500'. Nearly 300 sunny days a year. We've minimized planned power as much as possible, no A/C (duh), no big power eaters, florescent lighting, gas everything possible, gravity fed water, etc. But it will be a "normal" house, with refrigerator, TV's, fans, some appliances (washer). My neighbor has a 10 panel tracker with wind supplement, some number of ?Trojan? batteries, I think a 30 or 40 amp 120 v service. This seems kind of undersized to me.

What do I need to ask my local solar power supplier about - key points, installations, etc? I don't know what is too little, too much, too dumb, etc. I'm prepared in the $30 K range.

Please give me some advice.

Thank you
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,642 admin
    Re: Getting started

    First, get yourself a kill-a-watt meter from amazon.com or other place (or other power/current meter you may feel competent in using) to measure your long term and peak usages for all of your appliances.

    Create a spread sheet (or on lined paper), list all of your usages with the power needed (120 vac, 240 vac, 12 vdc, etc.) and starting power, average operating power, and total power used (per day or per month).

    Add up all of the average power for things you will be running at the same time (example, fridge, TV, lights, fans, stereo in evening; fridge/washer/drier no-lights/tv/etc. during the day). This will give your typical worst case load (minimum continuous rating for Inverter).

    Next, take your max typical running power, and add worst case starting load (typically motors for fridges, wells, etc.) to your average load, and this should be under the peak load rating of the inverter.

    The above will size your inverter and power distribution (to save a few bucks, you can turn off your washer/drier/fridge while pumping water and other tricks like that). It should also tell you if you need 120 VAC or 120/240 VAC type inverter installation. To give your self some head room and run your inverters efficiently, you should probably have your average load be 40-60% of the rated inverter capacity. And, for a home, you should spend the bucks for a "true sinewave" as opposed to a "modified sinewave" inverter (mod-sinewave inverters tend to make motors run hotter, and may case some appliances to fail much sooner than when running on a true sinewave inverter).

    Next, you will need to add up the power requirements (kWhours) for all of your appliances (perhaps by season--depending on climate you may need more power in winter when the sun does not shine as long; for example).

    One way to calculate how many solar panels you will need, is to look at a web site like this one where they tell you how many kWhours/day of sun you will have for your site:

    http://rredc.nrel.gov/solar/pubs/redbook/

    To use this, basically, the sun puts out about 1kWhr per sq meter at noon--so, if you look up a city near you in the above, you will see a list of kWhrs/day (average) over a 12 month period (the PDF files also show min/max values too). This link also lists how much power you will get depending on how you tilt your area (up/down--winter/summer) and how two and three axis trackers will work too.

    For example, my area (near SF CA) is roughly 3.4 kWhr/day in the winter and about 6.5 kWhrs/day in the summer (flat plate, no tracking, at latitude).

    And, from my Grid Tie Array (installed 1 year ago), 6.5 kWhrs/day * 3kW (my peak array rating) = 19.5 kWhrs per day. And, low and behold, my array genrated about 18.2 kWhrs / day last June and July. My worst winter month (December) was 4.5 kWhrs per day average; should have been around 10.2 kWhrs per day (wet, rainy winter last year for me).

    I tend to subtract 10-20% from my predicted numbers to avoid unhappiness (my array produced about 4,800 kWhrs last 12 months, although the installer predicted an average of ~5,400 kWhrs/year--but I have some morning/evening trees, not ideal roof slope and SE facing, dust/dirt, etc.).

    For you, you will need to add (multiply) all of your inefficiencies together... For example: 93% (solar charger) * 85% (battery charger) * 85% (Inverter) = ~67% efficiency or you will need, very roughly, 1/0.67=1.49 more panels than the "daily" average load you will have calculated.

    For batteries, you should pick how many days of "no sun" you will want the batteries to supply... Just as a rough guess, 3 days is a good place to start. And with typical lead acid batteries, you should only use them to about 50% of capacity (i.e., you will need 2x the amount of battery for energy storage)...

    Overall, electric use is a very personal issue... Just some rough numbers, if you are under 100 kWhrs per month, your are a true solar kind of guy. If you are in the 200-600 kWhrs per month, that is an average usage for a grid connected home in our neck of the woods. 1,000-2,500kWhrs / month + is what the folks in Arizona, Texas, and others seem to use with AC.

    There are lots of other issues too (types of batteries, inverters, chargers, tracking vs non-tracking, generators to make up power deficits, panel aging, battery aging/maintenance, etc.) that all will go into the issues too. Much of this is no right or wrong answers--just the ones that work best for you.

    Please ask lots of questions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RoderickRoderick Solar Expert Posts: 253 ✭✭
    Re: Getting started

    Wow, what an ideal location!

    I don't have expertise in the costs and stuff, unfortunately, but have a thought.

    Since you mention a tracker, maybe you were thinking of an array on the ground, but if you have the luxury of designing and orienting your house, you could, of course, have a large area on the roof facing due south, uninterrupted by vent pipes, and tilted at the optimum angle.  And make it strong enough to support solar hot water, even if you only planned photovoltaic, or nothing up there.  And again, only if you were thinking about putting things on the roof, it's a lot easier and better to secure the solar mounting system to the rafters before the roofing felt goes on.  If you're going ground mount, just ignore me.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    sakamochi,
    seeing as how it's a new construction and no ac utility power you cannot measure your power needs. you could get a better feel for what you need based on your neighbor's consumption and his loads and at how often. as an example he may have a small refrig that is very efficient, but you may need to have a larger one and wish to keep costs down more so it's efficiency would be mediocre then. this adds more power needed to be generated in a day by the difference in draw and the full addition time it's in operation over your neighbor's refrig. on the other hand you may need less in lighting and shorter times of usage. if you intend washer/dryers in addition to air conditioning or electric resistance heat these are huge power drawers and will drastically up you needs for generation by solar or any other source. not many design with those huge items in mind, but it can be done. ask your neighbor if he has the time to show you how his was figured too.
    30 grand is enough to obtain a fairly good system if installing yourself, but with it's install costs this does further limit you on your current power affordability. with this amount and say a cost prerebate of $7-$10 per watt installed this does mean you will get a system between 3 and 4kw in pv stc rated. don't forget some states allow for state rebates and this may be extra money your installer already figured on in his quote to you so ask him ahead of time if rebates are accounted for in his quote. i believe az has the rebates and you can check it out at www.dsireusa.org . if he's got a rate of $9 per watt with a big rebate accounted for then his costs to you are much higher than maybe they should be. remember that knowing your power needs is paramount in a design, but you may be limited as to your affordability making the design you should get with expandability. you may later on down the road be able to ge more pvs to add to your system and if the wires and battery capaccity is already accomodating it could be as simple as wiring the newer pvs into possibly another controller, but readilly accepted and engineered for it.
    i hope this hasn't confused you any and others here can chime in with even more i may not be explaining right or overlooking.
  • mike95490mike95490 Solar Expert Posts: 9,582 ✭✭✭✭✭
    Re: Getting started
    Sakamochi wrote:

    What do I need to ask my local solar power supplier about - key points, installations, etc? I don't know what is too little, too much, too dumb, etc. I'm prepared in the $30 K range.

    I just spent about 27K after rebate, and only got a 4.5KW array & grid tie inverter. (Los Angeles, installed) Are you going to have grid power, or off grid? How many "dark/cloudy days" do you want your battery bank to carry you thru? Will you have a generator - run the house size, or charger only ??
    $ 30K sounds a little short if you are wanting to run a house off it, and have a battery backup. If totally off grid, you will need a gen for emergencies, or risk loseing your batteries to deep discharge.
    I'd look for as high as voltage as possible for the inverter, saves on copper losses in the wireing, and makes for a all series string, no paralleling worries, go for 12V cells, cuts interconnections down. Gell batteries need no water, but cannot recharge fast, flooded can charge fast, but need watering and matainance - 48V, 96V whatever is highest.
    Mike
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    mike90045,
    another battery type is out there as crewzer, brock and myself can attest to. agm or absorbed glass matt. this is sealed so no watering and they can take high charges unlike your gells. there are many out there to choose from and i have a concorde sunxtender that a company rep told me can take charge rates of an amp for an amp. in other words mine being rated at 104ah can take 104ah for 1 hour. other agms aren't going to do that, but can take high charges like quality lead acid batteries can. they will cost more than other types though. the only dissadvantage is they can't take overvoltage/overcharge as well as standard lead acids can.
  • System2System2 Posts: 6,290 admin
    Re: Getting started

    Wow! Great repsonses!!

    A little more info based on questions:

    We're nearlly parallel with Flagstaff AZ - 125 miles to the east. Flag gets a sun high of 11 kw/m2 and a low of 6.5 in the winter. with an average of 8.4 for dual axis direct panels. Flag is 2,000 feet higher, so they get more intensity to some degree than our 5500 ft.

    There is NO possibility of tie grid anything anytime soon where we are. Lightning is all the electricity we've got.

    Our house will face SE at almost exactly 45 degrees, so roof mount is not good. We have 80 acres to work with so unobstructed top of a ridge sun is what we have.


    I forgot to mention our RV trailer is there all the time and it has a 130W 12v panel on it flat mount with 2 golf cart batteries. I've seen the controller kick up a few hundred ma at 4:30AM in the summer. This runs for months with a propane refrig (electronic control and igniter) in it that keeps the freezer at -3degrees no problem (at least until I get there and use too much). I suppose I could put in a "houseboat" type refrig. in the new house, but they use a fair amount of propane all by themselves. My 8 cu ft refrig. in the trailer uses about a pound (or a quart) of propane a day.

    We plan to solar tank hot water and see about putting some radiators for heating in the winter to reduce propane use. It does get cold there.
    Snowflake, AZ Weather Facts
    On average, the warmest month is July (high avg 90).
    The highest recorded temperature was 104°F in 2003.
    January is the average coolest month.
    The lowest recorded temperature was -30°F in 1937 (low avg 20).
    The most precipitation on average occurs in August

    Three consecutive cloudy days would the the average longest. This probably happens less than 10 times a year. Occaisionally worst case there may be back to back 2-3 day winter storms with only a few days inbetween.

    Neighbor has 20 cu ft refrig.
    Obviously I need to talk to him some more, but so far he does'nt seem to know what he had put in, just went with the local suppliers recommendations. He has a 6kw honda aircooled backup genny. Not a mainline unit - a "sometimes in the winter" unit.

    Good advice on the 240V. Transmission losses are lower. I'm a EE, so I understand this stuff (somewhat).

    No BIG Power - NO AC, No Pumps. Microwave and washer are the biggest eaters.

    We plan an expandable solar power plant, as our daughter is putting a house later on and the plan was to build one solar plant for both.
    I see the rebate - so I'll let all know what this means in AZ when I get down to it.

    Thanks again for the great advice!!!






  • BB.BB. Super Moderators, Administrators Posts: 32,642 admin
    Re: Getting started

    For the fridges and freezers, the energy tags seem to be pretty accurate for ~70F room... If it is substantially hotter or cooler, it will affect the energy used.

    Regarding expandability, the one caveat for this installation is that storage batteries age and, typically, the entire bank will only be as good as its weakest link... Say you expect 7-15 years from your batteries, and 5 years in you want to double the bank size (for any reason), the new batteries will tend to take the load before the older batteries and have their life reduced substantially (especially for a parallel string of batteries). The rough expectation are that the new batteries will not substantially outlast the rest of the older batteries in the string(s).

    So, for sizing, battery capacity is the most important. If, for example, you expect your daughter to build her home in 6 years--you may choose to purchase less expensive batteries and replace/rebuild the entire bank when the new home is on-line.

    There are other options available (like keeping the old and new banks separate and use the solar panels to charge the banks separately or other methods), but adding battery capacity is one of those less than ideal projects.

    The 240 VAC will probably not save much energy if you have all 120 VAC appliances and reasonable runs--but could save you some copper costs if you use the common neutral to distribute power (given the high costs of copper these days), but would need to be weighed against the 2nd inverter usually required for 240 VAC.

    Also, having separate generator/battery/inverter banks may keep the power accounting/budgeting a little more clear (those that shiver in winter vs those that use electric hair driers / husband/wife/in-laws / sell property later, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,582 ✭✭✭✭✭
    Re: Getting started
    Sakamochi wrote:
    Our house will face SE at almost exactly 45 degrees, so roof mount is not good. We have 80 acres to work with so unobstructed top of a ridge sun is what we have.

    In Calif, rebates vary according to if you are on grid or not.

    Ridgeline + PV array = Lighting Rod and melted panels. Get a good consult about lighting protection. Lighting voids most inverter warranties and anything connected to the outlets. (but there is nothing inside, just smoke !)
    Any chance for wind power on the ridge?
    Maybe you could split circuits, so if one inverter fails, the kitchen is not dark, put half of each rooms outlets/overhead lights on different inverters. Just an idea.
    Just build a battery bank for 1 day, and plan on useing generator on day 2 to recharge, and drop into minimum power mode. Otherwise, it's lots of panels and big battery banks.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    mike, you do bring up an interesting point about requiring grid tie, but i have not seen it specified as a requirement in az at first glance. maybe winds-2 could elaborate for sakamochi on what they may know of it.
  • System2System2 Posts: 6,290 admin
    Re: Getting started

    Wind is highly considered. March thru May we have a lot of wind. We have 60+mph days. When the wind blows there, it roars. For days. It tore the metal trespass signs off my barb wire fence! The wind is seasonal, spring and fall. Winter is generally pretty still (too bad). Neighbors wind genny survived it all, so I can too.

    Lightning is ever present in my mind. I have probably 3 hundred trees on the parcel. The tallest is 30 feet. At least 40 of these trees have been hit by lightning sometime in the last 50 years (the trees live to be about 2 hundred years old - true fact!). I've been thru a few summer storms that I wished I had a hole to crawl into!! Neighbor has a 2 story log cabin with NO lightning protection. It's just a matter of time......

    Splitting inverters doe'snt look good. The mfg. home is prewired with a regular 200a service box. Since nothing in the home is 240v line, use of "one side" or 120v should work out.

    I did a quick calculation, I know I did not factor in % efficiencies etc - the idea was to take a rough cut. I came up with about 430kw per month. My 1800 sq ft home in Scottsdale uses 3x or 1200 kwh in May, the lowest energy month of the year. That would be a bill with no AC, but 12hrs pool pump, 2 refers, a freezer, elect. hot water heater (4 hrs a day). I think that if I cut those power eaters out it might be close.

    Here's my stab - please comment if I'm close:
    14 panels
    1820 watts out @130W
    8 average hrs output
    14560 watts to play with per day
    120 volts
    121.3333333 amps to play with
    606.6666667 kw per hr avail on avg




    24 hrs to use watts
    606.6666667 hourly watts to burn avg
    5.055555556 amps avg per hr to burn

    436800 watts per month to burn

    720 hr per month
    436800 watt hrs / month
    436.8 kwhrs per month
  • mike95490mike95490 Solar Expert Posts: 9,582 ✭✭✭✭✭
    Re: Getting started
    Sakamochi wrote:

    Here's my stab - please comment if I'm close:
    14 panels
    1820 watts out @130W
    8 average hrs output
    14560 watts to play with per day
    120 volts
    121.3333333 amps to play with
    606.6666667 kw per hr avail on avg

    Now take 25 or 30% off the STC rating, and see what you get.
    read this page: http://california.realgoodssolar.com/systemproduction.html
    excerpt:
    Real Life Expectations: Many industry professionals have studied the issue of photovoltaic ratings and are uncomfortable with both STC and PTC ratings as they seem overrated to real world conditions. Real Goods recently attended an excellent seminar at the national solar conference in Reno and the consensus was that to be conservative in your expectations you should expect your solar system to yield in AC output to your electrical panel about 2/3 of STC (manufacturer’s name plate) ratings or multiply by .66.*

    I get about 2 really good hours of output ( 70% of STC ), then it drops off from that as the sun angle gets worse

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 32,642 admin
    Re: Getting started

    Numbers wise... The "606.6666667 kw per hr avail on avg", should be 607 watts average over 24 hours--is what I think you intended to say.

    Couple of points... As you probably know, continuous loads are expensive to support via solar/battery (or generator) power and I would suggest that you really measure your loads and plan on how to reduce them. Conservation is almost always a much better bang for your buck instead of buying more batteries/panels/fuel.

    So, from what I have seen, your electric water heater (for your existing home) is probably a huge load and may be confusing your monthly load estimates.

    With 2 adults, 2 kids, 24x7 (home work, home school), natural gas for cooking/heating/hot water, I can get down to about 180 kWhrs per month (1x 20cu' fridge, washer/gas-drier, CF lamps everywhere, laptop 16 hours/day, TV, installed skylights in dark stairwell/study room). Otherwise, about 200-300 kWhrs per month (another 17cu' freezer ~50kWhrs/month was added). All appliances are new and most appliances (washer, drier, computers, auto-light stove, microwave, toaster oven, intercom, burglar alarm, printers, TV, DVD, Video Player, Digital TV HD Receiver, and random wall worts) are on power strips to kill their standby power (probably 10 devices with an average of 5-10 watts of standby power each).

    When you look at 180 kWhrs per month, that becomes a steady state load of 250 watts--Those misc. appliances would close to 1/2 of my monthly kWhr load or increase my kWhrs by another 40%.

    Looking at your system design, I am guessing that you are using the 1-axis tracking numbers, and assuming that it works well in you area (winds don't blow it down), it does seem to add quite a bit to your daily power budget.

    My numbers I posted earlier (using SF Airport radiation numbers) and my system... It was rated PTC at ~3 kW peak (STC of 3.5 kWatts), and I got less than the SF Airport numbers implied--and my home is in a much sunnier, and warmer, climate. I would certainly agree that 25-50% fudge factor numbers (location, weather, not all panels at 100%, 20% loss after 25 years of life) be considered when estimating panel output (from mfg. wildly optimistic STC ratings). And that is just for Grid Tied systems.

    For off-grid systems, you also have the losses from battery charging (85% efficiency for wet cell lead acid, something like 95-98% for AGM type batteries), and another 85% or so efficiency for your DC to AC inverter. Taking all the factors together:

    Rated peak Panel power * 70% (real panel rating) * 94% (charger) * 85% (wet battery charging) * 85% (inverter) * 80% (end of 25 year panel output)
    Actual System power available = 38% power available at AC wall outlet or 1/0.38 = 2.6x panel PTC * Solar Hours from table

    Also, how do you plan to recharge your batteries after a few days of no sun--if you have exactly the correct amount of panels to load--your panels will never recharge the batteries unless you temporally cut the load and/or use a generator to top them off.

    Also, your loads and sun will not always match--if you have 3 days of storage battery, that is your buffer. If there are times when you have lots of sun, full batteries, and little power use, that energy will be loss, so monthly usage/charge numbers could be a little bit misleading.

    Also, you assume 8 hours of sun, but in the winter months, you would be closer to 6 (and could be 5 or 4 for a bad winter month). You will need to either adjust your loads and/or use other sources for power (i.e., wind, fuel generator).

    Fortunately, even relatively small (and cheaper) gas and diesel generators can supply more than enough power charge your batteries and run occasional heavy loads--so planning a solar power system that more or less matches your anticipated load (say in summer) can be helped along in the winter for not too much extra costs in fuel--assuming that you don't waste electricity (using electricity for heating, hot water, electric stove, etc.).

    As an aside for generator fuel costs, I have been using a rough number of 5.5 kWhrs per gallon of gasoline (Honda eu2000i spec.) to make estimates. 430kWhr per month / 5.5 kWhrs per gallon = 78 gallons of gasoline (~$200) per month at $2.50 per gallon that is $0.45 per kWhr (not including generator wear and tear, etc.)... If your home's electric costs were $0.50 per kWhr, would you try and cut down from 430 kWhrs per month? Your solar system should cost you less per kWhr--but it is still not cheap ($0.11 per kWhr or so for my Grid Power). Diesel and real prime-power type generators probably are more fuel (cost) efficient--however, they will cost more upfront--so these types of estmates are probably still good enough for initial system planing.

    I think you would be happy with your off-grid solar/battery powered/generator backed system--but I would believe that if you wanted to supply 430kWhrs per month summer and winter and a few days of battery backed off-grid power, you will have a heart attack over the size and costs of such a system (plus the maintenance--i.e., checking water monthly, replacing the batteries every 7-15 years).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    sakamochi,
    it's good you gave your daily needs as you can work backwards off of that. that 14560w divided by your worst winter solar insolation at your lat would give 4 full sun hours minimumly. dividing 14560 by 4 gives 3640w needed to be produced for every hour of full sunshine to give you what's needed for the whole 24hr period. now you need to add to that another 20% for inefficiencies and that now gives us 4368w. this would be ptc though and adding around another 10% should account for the approximate stc ratings so the total would be 4804.8w of pvs in stc. mind you that if you use thicker than required wires to keep losses way down and go with mppt controllers, an efficient inverter, and agm batteries in a 48v configuration you could reduce the pv requirement some on the supply side of the equation. reducing your loads or the length of time for those loads also cuts into the required number of pvs.
    you could go lower in the numbers of pvs with wind power and a generator supplementing. the pvs could be expanded upon later too as many of us do because of the costs initially involved.
    some may say i went too high in my estimate because i gave the worst case scenario which will not be a typical scenario. this would offset those timeperiods of no sun(even though it rarely happens for you) or days of higher usages. do keep in mind that the battery design is more critical than most will give credit for as you firstly shouldn't design for using more than half of the batteries' capacity to keep long life in them. also the battery voltage used can help keep losses down by keeping the currents down and by ohm's law this keeps resistive losses down farther. 24v is better than 12v and 48v is better than 24v. these 3 are the common battery voltage designs used. also the high efficiency of an agm and the flexability of them in their requirements helps the overall system efficiency. you may also wish to have a few days backup capacity if at all possible, but care must be followed in that the charge percentage isn't allowed to go too low and we like to use 5% as that figure with a few percentage higher even more desirable with the maximum percentage dependant upon the battery type and quality purchased. doubling to 10% can be done will all types and maybe even 13% with caution, but the better batteries do go higher in their charge % abilities so know what you want ahead of time.
    do note that a quality mppt controller with the battery temperature sensor is pretty much standard in the best handling of medium to large pv systems as they have high efficiencies due to the recovery of some of the lost power. smaller systems too benefit from mppt depending on the controller and the wattage available from the pvs, but they cost more.
  • System2System2 Posts: 6,290 admin
    Re: Getting started

    Thanks once again for all the time and great quality if responses! All of this has helped immensely!!

    This is where I am now:
    Wattsun AZ125 2 axis tracker, 12 - 130w pv panels, Xantrex-Trace true sine 4kw inverter - charge controller, some number (8, 10?) of Trojan LC16HC Batteries (I think - from memory, I left my quote at home), Lightning arrestor protection, Whisper H40 900Watt wind turbine, 35 ft tower, battery box, all wiring to the house, the array, the generator, remote start generator connection, monitor panel and a bunch of parts I can't recall. Rebates are significant, being off grid and in APS service area we get $3,000 from the power company, plus $2,000 Fed plus $1,000 a year state for 5 years. Net is $10,000 help. Cost I have contracted for including labor is about $25,000 for the array, tracker, wiring, controller, inverter, arrestor, batteries and box, and "the parts I can't remember". The wind gen installed is about $5,000. So the cost to me for the entire system installed should be $20,000. We are building a 100 ft square power & water (85 gallon pressure tank) shed for the whole deal, and need to figure out what generator to get.

    I need to check if this is a MPPT controller or not. It does'nt look like it, but I'll see...

    BTW - our average wind is 14.1 mph on a yearly basis, so the wind gen makes perfect sense - its like getting a bunch of PV panels at deep discount, no need to go to a really big Wattsun tracker, plus night time gen, etc, etc. The quoted price differential to the 16 panel system was $10,000 more - meaning 4 more panels, a 16 inch pipe support for the bigger tracker instead of 12 inch, etc and NO wind generator. This looks pretty smart to me!

    I asked about AGM batteries. The story over here in the land of single digit humidity (less than 10%) is that the AGM's dry up and do not last very long. Something about a study that Sandia labs did....

    The word here on the Outbacks is that they are more difficult to program, require extra solenoids and controls for remote generator start. Dealer has both, but recommended Xantrex-Trace system.

    The 1775 sq ft house on order has 6 solartube skylights.




  • BB.BB. Super Moderators, Administrators Posts: 32,642 admin
    Re: Getting started

    Regarding the wind, you probably have been through this site?

    http://www.eere.energy.gov/windandhydro/windpoweringamerica/small_wind.asp

    A thirty-five foot tower sounds pretty short unless you have a great site on a ridge... Even raising it to 60 or 80 feet can dramatically increase the power generated (according to the above site, 90' can increase power generated by 75% wrt a 30 foot tower).

    The wind resource map for Arizona (anyway from this one site):

    http://www.eere.energy.gov/windandhydro/windpoweringamerica/wind_maps.asp

    show that Arizona is not a particularly windy state and these maps were for 50 meter tall towers (~165 feet)... Wind is a very geographically dependent resource--So you have reasonably accurate data from somebody showing the 14.1 mph at 30 feet for your location?

    Regarding the battery capacity--assuming 10 batteries with a 420 amphour rate (20 hour rate), 6 volt and 50% capacity discharge running a home at 300 kWhrs per month:

    Days of storage = 10 bat * 0.420 kamphr * 6 volts * 50% capacity * (30 days/month) / (300 kWhr/month) = 1.26 days of storage

    Is the above what you are planning this system for (300 kWhrs/month and 10 batteries)?

    I am certainly not the expert here--but those are some of the questions that I have...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    "I asked about AGM batteries. The story over here in the land of single digit humidity (less than 10%) is that the AGM's dry up and do not last very long. Something about a study that Sandia labs did...."

    that's interesting. i think on behalf of myself and others here that use agms, we would like you to ask them more specifically what it is they are talking about as agms are sealed batteries and the only time they could dry out is due to an overcharge that blows the safety valve open and you permanently lose that much water/electrolyte. this would dry out a standard wet cell under the same conditions as well, but you can add the water to them. in either case the charging isn't proper and will take away from the battery life.
    as to the controller you have we really couldn't say if it's an mppt or not unless you were to say the make and model, but then you could look it up yourself too. did it come with a battery temp sensor or is one available for it?
    i am also confused as to why you posted as to getting started as you had already started. it doesn't matter to me, but why ask us if you already started?
  • System2System2 Posts: 6,290 admin
    Re: Getting started

    The tone from the last responses is getting pretty edgy. I signed a contract to get started just last saturday 10/8 based on all of what I have gathered in the last year or so, and the great help I got in the last few weeks on this site. I asked plenty of questions first, so I don't know the issues are with Niel as to what I did when. Maybe there's a special club protocol that I'm not aware of.


    Fed wind maps shows me squarely at a "6" with avg from 17.9 - 19.7 mph. The 14.1 reported by my installer was taken at a location which is east of me by 18 miles.

    Yeah - my wind gen at 35 ft would be the highest thing for probably 200 square miles. Its on the ridge line. This is no joke. You have to go 45 miles east, 125 miles west, 60 miles north and 45 miles south to get to a higher elevation.

    It is 12 batteries after I checked the quote.

    One more time: My neighbor 1/4 mile away in direct flat line of sight has a bigger house, a smaller system (10 panels) and an identical wind gen. He's been 100%living there for a year and a 1/2. He runs his generator once in a blue moon. He lives there full time.

    If it works for him, I'm sure it'll work for me.

    Thanks for the tech help.

  • BB.BB. Super Moderators, Administrators Posts: 32,642 admin
    Re: Getting started

    It sounds great--having an installation near you that is working well is good thing.

    If you can ask your neighbor the details of how much power he generates and uses would be helpful too...

    I believe, if you are conservative in your power use, you should be almost 1/2 of the 300 kWatt hours per month you were planing for. Especially if you have newer appliances, CPF Lamps, and have power strips (or wall switches) to turn off phantom loads.

    Power use is a pretty personal choice--and two families in the same home can have dramatically different power usage... In my home, the previous folks had $400-$500 per month power bills--my family never got above $75 per month...

    As long as you are watching your usage--I am sure you will be happy.

    Good Luck!
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    i'm glad we helped in answering your questions, but i'm still a bit confused why you couldn't answer all of mine. it doesn't matter to me if you answer or not, but edgy? i didn't realize i was putting you to trial with these simple things. consider them withdrawn.
  • Patman3Patman3 Solar Expert Posts: 62 ✭✭✭✭
    Re: Getting started

    I'm worried about my investment in Connie's AGM batteries now, since I too live in this dry arid climate of Arizona-Nevada. My Tysonic AGM's are developing corrosion on the screw posts, I was shocked when I saw this. If they are sealed is it still possible for both the neg and pos terminals to develope this 'crud' on the posts? My connies (Concorde sun extenders) are doing fine but less than 1 year old.

    Sakamochi, I live near Kingman/Meadview AZ, and love going to the Grand Canyon, that's where I met my wife, at the bottom of Phantom Ranch. How far from I-40 is Snowflake?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Getting started

    patman,
    it would seem that one of 2 things may be happening with your Tysonic AGM's. the obvious one that was already mentioned is an overcharge. agms are very voltage sensitive in that they must not exceed a manufacturer's determined max voltage point. see the manufacturer's recommendations for proper charging. the other may be galvanic in nature. that would be dissimilar metals in your connections and battery posts. sometimes even with similar metals if bad connections are present this could set up a galvanic like responce when battery voltages are present.
  • System2System2 Posts: 6,290 admin
    Re: Getting started


    I agree with Niel on the dissimilar metals. After cleaning
    buy some battery terminal sealing spray or if nothing else
    put a thin coat of wheel bearing grease on the exposed
    metal part. No air = No corrosion.

    brad
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Getting started
    Patman3 wrote:
    I'm worried about my investment in Connie's AGM batteries now, since I too live in this dry arid climate of Arizona-Nevada.  My Tysonic AGM's are developing corrosion on the screw posts, I was shocked when I saw this.  If they are sealed is it still possible for both the neg and pos terminals to develope this 'crud' on the posts?  My connies (Concorde sun extenders) are doing fine but less than 1 year old.

    Sakamochi, I live near Kingman/Meadview AZ, and love going to the Grand Canyon, that's where I met my wife, at the bottom of Phantom Ranch.  How far from I-40 is Snowflake?

    That should never happen on an AGM battery. But I have never heard of "Tysonic" AGM's before. I assume they are made by the same Chinese company that makes the small flashlight type batteries.

    Over the past several years we have sold thousands of the Concorde AGM's, and not once have we ever heard of any type of leakage or post corrosion.

    I have said it many times before, but just being AGM does not make them suitable for solar, nor does it have anything to do with the basic quality of the battery. AGM is just a type of technology used to make batteries.

    We have some installations here in Phoenix with the PVX AGM's that are still working after 5 years. So if your batteries are drying out, there is a problem with the batteries.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Getting started
    Sakamochi wrote:
    Thanks once again for all the time and great quality if responses! All of this has helped immensely!!

    This is where I am now:
    Wattsun AZ125 2 axis tracker, 12 - 130w pv panels,....

    I would highly recommend NOT spending the money on the 2-axis tracker. The extra power you get from 2nd axis tracking simply is not worth the money. For what it costs, you could get 2-4 more panels and a standard single axis Zomeworks or Wattsun tracker.
  • kc8adukc8adu Solar Expert Posts: 50 ✭✭✭
    Re: Getting started

    i am not surprised by the impending failure of the tysonic agm batts.
    a local medical dealer was installing them in wheelchairs and it was a disaster.
    several blew up and most failed in a few months.
    back to mk/east penn deka.
    end of problem.
  • System2System2 Posts: 6,290 admin
    Re: Getting started

    Sorry to be "away" so long before replying..

    Technically, Snowflake is 28 miles south of I-40 (from the Holbrook exit), We are directly south of I-40 by about 30 miles. The county line is west of us by about 5 miles (Apache-Navajo).

    I stand corrected on the wind avg speed, it is what the installer said, "Class 3", with average yearly at 14.1-15.7 mph. When I printed the map and enlarged it I saw it clearer.

    I am curious why the $395 dual axis drive is not a good idea? Seems like 2/3 of a panel cost for the drive (I have $658 for each Kyocera 130W). The Wattsun AZ-125 tracker is $2495 for the entire array. I looked it up and the installer is correct, it will only hold 12 panels of the type described - in order to go to the Wattsun AZ225 for 16 panels the price takes off, almost doubling. My array's location has a "below" horizon for sunrise and sunset (meaning we look "down" at sunrise and sunset), so maybe tracking this more accurately will pay off. I see the Zomeworks UTRF120, which hold 10-12 panels is $2,000 and not much cheaper.

    The Whisper 100 seems like a good alternative for the more panels & bigger array unit and far cheaper. I know it remains to be seen if this will be enough.

    The quote I have is for 12 L-16 batteries. The box holds up to 16 L16's or 20 T105's. I got an approximate price of $6-8,000 for the equivalent AGM's. I have a 12v AGM in my boat, which is only 2 years old - so I guess I'm doing a little "field research". Seems like the $2,800 for the wet batteries might be a good place to start for me.

    "Calling all experts"!!!

    Now I need advice on a backup generator!!! Diesel, gas, makes, models, capacities - etc.
  • BB.BB. Super Moderators, Administrators Posts: 32,642 admin
    Re: Getting started

    Don't buy a "cheap" Chinese diesel generator unless you have good local references...

    http://gpsinformation.net/generator/chinagen.htm

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Getting started
    Sakamochi wrote:


    I am curious why the $395 dual axis drive is not a good idea? Seems like 2/3 of a panel cost for the drive (I have $658 for each Kyocera 130W). The Wattsun AZ-125 tracker is $2495 for the entire array. I looked it up and the installer is correct, it will only hold 12 panels of the type described - in order to go to the Wattsun AZ225 for 16 panels the price takes off, almost doubling. My array's location has a "below" horizon for sunrise and sunset (meaning we look "down" at sunrise and sunset), so maybe tracking this more accurately will pay off.  I see the Zomeworks UTRF120, which hold 10-12 panels is $2,000 and not much cheaper.

    Hmm you are right, my mistake. The latest price list for Wattsun no longer offers dual tracking as an "option" for the 225. However, don't expect to get much extra from the early morning and late evening sun. You typically get around 90% of your power between around 9 am to 3 pm, depending somewhat on location. But for only $350 or so, not a big deal.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Getting started

    A few notes:

    On the wind generator - being in a class 3 area, don't expect much from it. You will get a lot of power occasionally, and very little most of the time. Consider as a booster, not something to count on. Winds in that area are highly variable - you can go days with almost no wind at all.

    1200 watts seems a bit undersized for that size house, but that depends on so many factors that about all I can say is that make sure you check your winter usage and estimated sun hours.

    If you are planning to live there for quite a while, you might want to upgrade from the L16 type batteries to something that will last longer, such as the Surrette 2KS or 4KS types.
  • System2System2 Posts: 6,290 admin
    Re: Getting started

    After all of the great tech info and experienced feedback, I decided that I was too light on the system. I've changed it up to an AZ225, 16 panel (130's), Outback MX60 MPPT charge controller, 16 L16's and Xantrex Model 5548 5500 watt Inverter.

    Would you please comment on my numbers?

    Old Order New Order Winter Summer
    12 16 panels 16
    1560 2080 watts out @130w/panel 2080
    6 6 average hrs output 8
    9,360 12,480 watts per day 16,640
    120 120 volts 120
    78 104 amps output 139
    390 520 w per hr avail on avg 693



    720 720 hr per month 720
    24 24 hrs to use watts 24
    390 520 hourly watts avg 693
    3.25 4.33 amps avg per hr 5.78
    2.35 3.13 amps Derated avg per hr 4.17
    202,878 270,504 watts derated per month 360,672
    202.88 270.50 kwhrs per month 360.67

    Derating factor:
    0.85
    0.85
    0.7225
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