PV system at home - Page 1
Forum section: electronics / projects

author: tecman
author_rank: Frequent Contributor
timestamp: October 07, 2011, 05:51:42 pm
content: Well I finally finished my new 9.2 KW solar system. Things started slowly. I was very optimistic back in March, expecting to be on line in a month or so. Well permits, approvals by the local utility and getting all of the required drawings, etc took nearly 3 months.So I cleared some trees and had the neighbor (he has an excavating business) clear about 120' x 100'. After clearing, I waited for the final drawings of the ground mount, showing the footer locations. Once that arrived, my Kubota TLB was put into action to dig the footers. A few heavy storms later, I dug them again, and then Hurricane Irene let me dig them a third time. Finally I got to put some yards on concrete in. I also dug 120' of trench for the conduit from the house to the solar array location.In parallel, I got all of the inside work done at night. This included mounting and wiring the inverter, watt-hour meter and external AC disconnect. The DC wiring from the array requires metal conduit in the house, and the main breaker on my service panel had to be changed to meet code requirements for max. allowable currents.Got the outside DC wire pulled and terminated in j-boxes at the array. The panels arrived within a few days of needing them (scheduled that way). It was a long day, but I got them all mounted in one long Saturday. The last of the wiring was completed, and I got the electrical inspector out for the final inspection. Once that was done, I submitted the signed paperwork to the local utility. Finally switched on , setup the inverter and started seeing the meter spin.After switching on, we have had only one partly sunny day. That day resulted in 39 KWH of generation. But then in the northeast US we have had weeks of rain. This delayed assembly/install process, and has limited the output since it was switched on to a low day producing 10 KWH to upwards of 30 KWH generation when things were better. I have been impressed with the surprising amount of power on damp, totally overcast days. Outputs range from 2.5 KW to 400 watts when it is completely overcast.Finally this week the sun finally appeared and the last three days have been 55-58 KWH total output. We have "net metering" here so excess power goes into the utility, who is a 100% efficient storage device. Over a year this should reduce my electric bill by about 60%.paul

author: Lightages
author_rank: Unknown
timestamp: October 07, 2011, 06:26:20 pm
content: Very nice and tidy work there. It is a nice feeling to grab some "free" energy and use it. I have been running a 1.8kW here in Chile, totally off the grid. I am installing another set of panels to bring me up to 3.2kW.One thing I don't see in your installation is lightning protection. Do you have any lightning arrestors in your system? Also you seem to have no breakers for each bank of panels in your combiner boxes. Am I correct?

author: Kibi
author_rank: Unknown
timestamp: October 07, 2011, 08:15:32 pm
content: Very nice work there.This is one of my ambitions, but I'm leaning towards the off grid option.

author: shadowless
author_rank: Regular Contributor
timestamp: October 07, 2011, 08:17:23 pm
content: Can you share more about your system. Batteries, charge system etc

author: Lightages
author_rank: Unknown
timestamp: October 07, 2011, 09:11:12 pm
content: Quote from: shadowless on October 07, 2011, 08:17:23 pmAre you asking me? If so I will start another thread so as to not hijack tecman's. If you are asking tecman it appears he does not have any batteries as it looks like he is doing a grid tie sell to grid system only. I could be wrong.

author: PetrosA
author_rank: Frequent Contributor
timestamp: October 07, 2011, 11:09:32 pm
content: Many jurisdictions here in the US don't allow you to go off the grid with an alternate power source. You can't even get an occupancy permit without being tied in unless you're Amish.I'm also surprised that tecman didn't have to provide DC fusing at the junction box. Maybe because he didn't use it as a combiner box?

author: Joshua
author_rank: Regular Contributor
timestamp: October 08, 2011, 01:18:03 am
content: Awesome! What is your projected payback period and what is the general upfront cost?Do you have logging abilities to see how much money you have saved and to see the output at a certain time?Joshua

author: tecman
author_rank: Frequent Contributor
timestamp: October 08, 2011, 02:12:08 am
content: Well to a few questions. There are no fuses since the combiner is located in the inverter and individual string fuses are there. The array is 40 Bosch 230 watt panels, in 4 strings. Fronius grid tie inverter rated at 10 KW (9995 w actually). No batteries, just grid tie. Our local utility provides net metering, so the grid is the infinite, 100% efficient battery.I did all of the work myself and I have almost 12 acres to play with. Overall cost was $35K, and $10K after state and federal rebates and credits. With renewable generation credits, sold monthly at auction, payback is 3-4 years. NREL PVWatts estimates a generation at 12 MWH/year. Since I am an all electric home (geothermal heating) this will provide about 60% of my total usage.As for off-the-grid systems in the US, there is no prohibition on them. Actually quite a few people have them, but they are much costlier and harder to meet code with the batteries, ventilation, etcPaul

author: jackbob
author_rank: Regular Contributor
timestamp: October 08, 2011, 06:07:53 am
content: Now that's a pv system.. 10 kw inverter. I just started installing a 2.5kw grid tie system with an sma sunny boy inverter. I know how to install everything and I already wired the inverter. The scary part is living in California and getting it approved. I don't know how but I damn well will find a way. If California isn't making money, it probably won't fly. If it comes down to it I can do it on the low down since none of the equipment is obvious or easy to see from the ground.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 08, 2011, 10:27:25 pm
content: Don't make anything a permanent part of the building, so building codes would not apply.

author: jackbob
author_rank: Regular Contributor
timestamp: October 08, 2011, 10:54:01 pm
content: I did not know it doesn't have to meet building codes if it's not permanent. What exactly is considered permanent though? Because all of it could be romoved in the future if it must, so in that sense it's not permanent. But the inverter is bolted to the wall along with dc and ac disconnect panels with conduit going to them.

author: tecman
author_rank: Frequent Contributor
timestamp: October 09, 2011, 12:46:57 pm
content: Many jurisdictions will consider anything bolted to the house as "permanent". Since you will likely need an electrical inspection to be "legal", it would trigger some sort of permitting.I was tempted to do my system without all of the permits and inspections (I live 1/2 mile off the road, and nobody would see what is going on), but I needed my meter changed for "net metering". This awoke the utility and they require a certified inspector to sign off. Additionally the $7K rebate from the state requires a completion certificate from the local township. So in the end, all of the bureaucracy was required.paul

author: Lightages
author_rank: Unknown
timestamp: October 09, 2011, 03:49:50 pm
content: It would be nice if I could sell power back to the town where I live, but they won't give me a connection. And even if they did, they run a system so bad that I would probably end up powering the whole town.I hope your system pays off. I was wondering why you didn't go for a battery system? Too expensive? The city power is never down? It is really nice to have power when nobody else does

author: tecman
author_rank: Frequent Contributor
timestamp: October 09, 2011, 04:07:00 pm
content: Quote from: Lightages on October 09, 2011, 03:49:50 pmWe have very reliable power. In the event it does go out, like the hurricane we had two months ago knocking us out for 2 days, I have a 10KW water cooled diesel generator. Although we are in a rural/urban area, power loss means no water or heating, so the generator is for emergencies, and the solar is to minimize electric bills. Batteries are expensive and need replacement (as you know) and I have the local utility as my "battery".paul

author: tecman
author_rank: Frequent Contributor
timestamp: October 09, 2011, 04:08:02 pm
content: Quote from: Lightages on October 09, 2011, 03:49:50 pmWhat are you doing for your internet connection ?paul

author: Lightages
author_rank: Unknown
timestamp: October 09, 2011, 04:14:51 pm
content: My friend next door runs a business doing astronomy tours and hosts telescopes from around the world on his land. He has a 4 megabit microwave link to the internet here and he lets me use the connection. It will soon be upgraded to 10 megabit. I provide technical assistance with his internet in trade.