Stand-alone system with DC

System

Yesterday, I had a conversation with a nice gentleman who has decided to get into the international PV business.  He is planning a project in the United Arab Emirates.  This project involves a stand-alone system of 10kW DC without an inverter with UPS battery backup for 24 hours or more.  All loads will be also DC(lighting, refrigerator, etc).  Now, I am not the most knowledgeable person in the PV field, but wouldn't the project require one heck of a lot of batteries? And what about no inverter being involved???` Is this project even feasible?  Would appreciate any input/insight.

Thanks,
Al

System2

Re: Stand-alone system with DC

Hummmm - not much info to go on, like what voltage does he plan on running things on; does he intend to run his rather massive loads only when the sun shines, or will it be at night as well, or only at night; how far away will the loads be from the PV's? What are the loads he has planned? Is this for personal use or is it an industrial setup?
Interesting.
Wayne

System2

Re: Stand-alone system with DC

I forgot to mention that the array will be on a residential-flat roof. I also imagine that there will be an air conditioner involved(middle of the darn desert).  I do not know exactly what kind of voltage is required(I think 230V is the load norm in Europe and Middle East).  Loads will be running day and at night.  I think the guy mentioned that the loads involved would be typical everyday use products.  Don't know what the power consumption is per month, but let's say 1500 kWh(just a guess).  Hope this helped a little.
Thanks,
Al

P.S.  Just found out that average energy consumption is around 1700 kWh

niel

Re: Stand-alone system with DC

it is possible to run everything without an inverter and it is actually better. an inverter requires more power because of its efficiency rating than that of just a dc system. now i don't know how many hours of full sun they may get there, but at 5hrs for a 10kw system that's 50kwhrs/day. at 30 days per month that's 1500 kwhrs/month. i'm betting you did this for your guess. losses will be involved with the wires, heat, and charging so it probably is more than 5hrs of full sun/day. i do doubt the air conditioner, but could very well be a swamp type air cooler if in a low humidity area as deserts usually are in. :-o

BB.

Re: Stand-alone system with DC

And you are probably looking at $150-$200,000 for the entire installation (including batteries, excluding appliances). Sounds expensive to some--not to us in the land of $1,000,000 starter homes (Kalifornia). Who knows how much the guys in the UAE have...

-Bill

niel

Re: Stand-alone system with DC

you're right bill, it is up there. $$$$$ kinda makes me salivate and sick at the same time.

System2

Re: Stand-alone system with DC

Having been to the UAE, you can safely think of 8h full sun a day. Basically every day. According to my counter on my controller, even I get 8h full charge and 10h total charge here in Spain (my panels however are moving with the sun,cheaper then more panels)) and I am 1700km north from there.Nearly no clouds for 3 month now.

Chris

niel

Re: Stand-alone system with DC

hey chris, do you want some clouds as i'm starting to get sick of them? :? lately it seems 3 to 4 days of the week is cloudy or rainy. now that hurricane season is here cloud cover comes up from the south and just seems to hang around, like we didn't have enough clouds to begin with. :roll:

System2

Re: Stand-alone system with DC

I'm sorry to hear that and hope, the hurricane season will be a bearable one.For us here in Europe it is hard to understand, what a storm like that can do. I have been in Florida during a storm called Wilma, an event locals told me was nothing compared to a real one but it was enough for me.I was however in the center of Florida, in the south I guess they thought differend about it.

Greetings

Chris

niel

Re: Stand-alone system with DC

i personnaly haven't gone through a hurricane and i don't want to. the closest i have to that kind of experience is a tornado and it wasn't hitting the ground when it went over me and i looked straight up into it. the weather here in the states is getting a bit more wild with more extremes occurring. i guess you don't experience bad weather there do you? have you noticed any changes in your weather in recent years?

System2

Re: Stand-alone system with DC

The weather is changing, no doubt about it. But it seems, the states got the wrong end of the stick. While it is getting warmer earlier in the year and lasting longer here, you seem to get more and more storms where you are. Last year, 2005, we had 310 sunny days here where I live, north of Barcelona. This year we are at 130 sunny days and 14 days rainy-ish (my computer keeps great statistics) Our problem here is slowly but more and more alarmingly water supply. In the south of the country, some villages and cities have to ration tap water to a few hours a day. We here live close to the Pyrenees mountains, there is a lot of water there but still......

Of course,you know what they say,there is no proof of global warming, its all in the statistical boundaries, go and buy 2 more SUVs....

SUNNY greetings

Chris

System2

Re: Stand-alone system with DC

Neil, have you noted more wind this spring season in PA? would you have noticed that? My wife doesn;t think so but it definitely seems we have more and stronger winds (yes in addition to MUCH more rain andf cloudy days).

BB.

Re: Stand-alone system with DC

http://www.canadafreepress.com/2006/harris061206.htm (article about quotes from climate scientists)

Hurricanes run in cycles... From about 1900 to 1950, for the US, were more intense (an average) seasons. From 1950-~2000 was were (on average) low intensity seasons. And, a major destructive storm can come anytime and much of the damage just depends on where any particular storm hits (or misses).

In my area, I notice that our weather changes with sun spot cycles too... When I was a little kid, early 1960's, I remembered very heavy rain storms, and a few hail/freeze/snow/thunder/lighting events. Then, for a number of years nothing. I remember thinking (10 years older) that as a little kid I must have imagined the more intense storms. A few years later, boy--Thunder/lightning/hail/hard freezes/rain so heavy that you could not even see to drive on a city street. Now, 5 decades old, I have seen many of these storm cycles.

One major issue now that was not there 50 years ago is the massive amount of building right up along the coasts during the 2nd half of the 20th century. And out here, we don't get a lot of rain, and much of California is pumping more ground water than is being naturally recharged (causes settlement and deeper wells)--more people just make it a bit worse (of course, farming here has always used a lot of water; rivers and wells.

The US is pretty big, so different regions have different weather problems / issues... Other than the occasional droughts here on the west coast, our weather is pretty tame compared to much of the US/world... Hmmm, feels like earthquake weather... :roll:

-Bill

niel

Re: Stand-alone system with DC

matt,
i couldn't say for sure without noaa stats to back me, but yes i'd say that we have had more clouds/rain and with this i would think more wind, but we also experienced a lack of precip during the beginning of the year. i have to say that more records were broken last year and it just seems that every year more of them are being broken. it's a kind of can you top this and the records have been compiled for this area for greater than 125yrs. that doesn't seem like a long time span to collect and compare data, but it really is for general trends.