Closer to "real mileage" solar panel stats
 

All solar panel manufacturers rate their panels using STC ( standard test conditions )....which is something like the EPA mileage sticker on a car window.

But just like the EPA mileage sticker, 'your mileage may vary'.....because often you don't GET 1000 watts/square meter of sun, and you likely DON'T have you panels perfectly perpendicular to the sun all the time, and so on....

Here is a California website that lists closer to "real world" conditions for just about every panel made....

http://www.gosolarcalifornia.org/equ.../pvmodule.html


For example, my panel is the Solar World 175.....which the website says you will only get 156 watts out of.....and typically, I see about 145 watts best day out of mine at any given time.

Re: Closer to "real mileage" solar panel stats
 

Re: Closer to "real mileage" solar panel stats
 

Hi ya TN Andy!

We have a 10 panel X 165 watt array = 1650 watts, and like your array, about the best output we manage to achieve is about 1375 or 137 true watts per panel ... sure glad we opted for the two additional panels. Me thinks one should always opt to purchase more solar panels than one anticipates. But keep in mind we are completely off-grid with wind and gen back-up!

Cheers,

BB

Re: Closer to "real mileage" solar panel stats
 

Agreed Bob,

My total is a shade over 3kw rated, and the very best it seems to do is about 2kw on the AC side. One thing I did not allow for was the fact I'm using two inverters, and each one is taking about 200 watts loss....but in order to grid tie with battery backup, I was required to turn out 120/240 by the local utility. In an off grid situation, I'd go with a bigger, single inverter, and just fire up a generator if I needed anything to run off 240v.

My charge controllers ( Outback MX60 ) ( 2 of them ) are only rated to handle 1600 watts each....but I'm trying 10 panels on one array, which is 1750 'rated', but never see over mid-1400's.....so I think I could add 2 more panels to the other array ( which now has 8 ) and be fine......I don't think on their very best day they are ever gonna do 1600.

Also thinking I'll add another array of 10 and another charge controller, because at this point, the more I add, the more efficient the system will become, since the inverter loss will remain the same....by adding 10 more, I should get a TRUE increase of about 1.4-1.5kw.

Re: Closer to "real mileage" solar panel stats
 

Andy,

At your current system size are you meeting your needs or do you still augment them with grid power? I am assuming you are not meeting your needs based on your comments to expand the array.

Dave

Re: Closer to "real mileage" solar panel stats
 

Dave,

No...it only meets about 1/3 to 1/2 our needs....it generates 15kw/hrs on a good solar day, but unfortunately, we've been DANG short of good solar days this year......so we end up with 300kw/hrs a month or so.

Our use is about 7-900kw/hrs month, depending on the month. I've "tightened up" thing like lighting....pretty much all CFLs now.....we're looking at a new fridge that will use 5-600kw/hrs/yr compared to the old energy hog 1200/yr model we have now.....and when I get to a kitchen remodel this summer, the electric range is out and a propane model is in, along with a wood cook stove. But my guess with 3 freezers and such, the best we're ever gonna get to is about 5-600/month...IF we continue to live like today.

My original plan was to be able to replace about what I aimed for....1/3 to 1/2.....figuring if the world went to crap, we 'could' get by on that amount and give us the basics.....some refrigeration, some lights, and use of a washing machine ( which we did just replace with an HEff model )......the rest of our use is entertainment, convenience stuff like the dryer, the microwave, etc.....and we'd get by fine on one small chest freezer, and simply make up the difference on canned and dried foods.

BUT ( the best laid plans o' mice 'n men gang OFT astray, laddie )....now I'm thinking I'd like the capacity to completely replace our use, because I suspect this cap and trade BS is going to put anyone that is on grid in a world of hurt before long....so plan B is "add more"

Re: Closer to "real mileage" solar panel stats
 

Tn..Andy, are you using some kind of LED lightning in your home? Or CFLs?

edit: I didn't even read your last post. You're using CFLs.:thumb.aspx:

Re: Closer to "real mileage" solar panel stats
 

tn andy if i can ask . how much money do you have in your solar system so far . i know you do all the work yourself so i know that help alot

Re: Closer to "real mileage" solar panel stats
 

I've been building my own LED lights for the bathroom and the bedroom. They're very efficient and extremely long lasting (100000 hours +). This should be good for survival purpuses when you want the light to last *forever*. Slightly underdriven and w. good heatsinking they should.

edit: LEDs never fail abruptly. They dim over their lifetime.

Re: Closer to "real mileage" solar panel stats
 

Mick:

It's somewhere around 21-22k.....I haven't really totaled it.

Re: Closer to "real mileage" solar panel stats
 

You guys seem to know alot being off grid and all, can anyone answer a question for me, I have 20- 180 watt panels, the battery bank is shot and I will be replacing it with a 1381 amp hour bank, our system is 48 volt, but in the meantime I have to run the generator everynight for at least an hour or two, low battery. I usually run a computer, LCD tv, small fridge, and a couple of lights cfl.

So my question, the inverter says I am using 5 amps per hour 24/7, Am I a power hog?

Thanks in advance

Re: Closer to "real mileage" solar panel stats
 

Mrs Nub,

I'm not off grid, so some other here would likely be more qualified to answer. Also, check in over at this forum: http://www.wind-sun.com/ForumVB/index.php which is sponsored by Arizona Wind/Sun ( a dealer )....there are a lot of off grid folks there that may help you more.

That said, my question is the 5 amps.....is that on the AC or DC side that reading is coming from....

DC, 5amps x 48v x 24hrs = 5,760 watt/hrs or nearly 6kw/hrs a day. That seems a bit high for what you appear to be running....but without knowing the power use of them, hard to say.

How old is the battery bank ? What batteries are in it now, and what are you replacing it with ?

What does a 'decent solar' day turn out on your panels in kw/hrs ?

Re: Closer to "real mileage" solar panel stats
 

Tn Andy,

Inverter says load amps ac, we have 16 rolls surrette batteries, the battery bank is about 9 yrs old, I'm sure we ruined them by not equalizing them properly, Nub had new batteries ordered, they are crown industrial, I think the are forklift batteries, they should have been here by now.
Thankyou for your reply, I have been all over the internet and no luck, that is why I asked the question here , it gets frustrating. I haven't checked on a decent solar day, just now finally getting my self together, and It has rained the last 2 days

Re: Closer to "real mileage" solar panel stats
 

Tn Andy,

Today is the first day the panels charged all day, the reading at the charge controller says 10.5 kwh, it also gives me total amp hrs 197. I will try over at the other site thankyou.

Re: Closer to "real mileage" solar panel stats
 

ms nub, your numbers seem to indicate that your power usage is around 5.7 Kilowatt Hours per day, Not quite a "power hog" but, you may be able to reduce your usage a bit, if you dont have a lot of teenagers, or guests taking long showers, leaving lights on all over the house, simultaneous stereo, computer, laundry, etc.
Your charging input of 10 kilowatt hours for a nice sunny day is looking promising.
I hope you have a couple strong backs available to help you install the new battery bank.
PLEASE be very sure to wear safety glasses when working close to the batteries, and keep a LARGE open box ( bag) of baking soda on hand in the battery room.
Please be very careful when handling tools around the batteries, if you are able, wrap tape, or heat shrink the handles of all your battery wrenches, just in case one should slip out of your grasp, and accidentally lay across two battery terminals.
WASH hands after handling battery cables, or watering the batteries, and try to remember NOT to touch your eyes/ face when working around batteries.
The acid will not bother your hands much, but is VERY dangerous to your eyeballs.
I will pm you my work number. if you need battery handling, measuring or care instructions, I will be happy to answer questions.... good luck, and please be careful.