SolarCity installing a 6.37kw system on my house!!!

   / SolarCity installing a 6.37kw system on my house!!! #1  

90cummins

Veteran Member
Joined
Mar 17, 2011
Messages
1,101
Location
Florida Ma.
Tractor
Ford 1720 SSS 4x4 Turbo Charged
I recently signed a contract with SolarCity for installation of a 6.37kw system; work should start in January with the system operational by March.
After many questions and additional research I realized that when the grid goes down the solar is inoperative also.
I have several generators but the system is not really compatible with portable power.
That got me thinking about a Grid tied battery backup system that will automatically switch over and power my home and also allow the Solar to continue operation while recharging the batteries.
This system addition also enables me to use a backup generator to recharge the system in the event the batteries get low or I need more capacity.

I just purchased a new (7 hp) Yanmar Diesel Model L70ABE-DEGMTAYC Military Surplus engine dated 2012 for $500 that has some unique features suited for long run times of up to 24 days non-stop.
It has an extended oil sump which triples the oil capacity and a spin-on oil filter which extends oil change intervals to 500 hours. There is also an intake grid heater for cold starts and the muffler outlet has a two bolt flange for a leak proof extension.
This engine is a replacement for the original L90 Yanmar that needs a rebuild.
The new smaller engine will drive a 5000 watt generator so max output will not be possible but should easily generate 3500 to 4000 watts.
This generator would be used to charge the batteries if needed and/or operate when power requirements are minimal.
The cost, lower fuel consumption and the fact that it will mate to my 5000 watt generator head is the main reason I purchased it. I have (2) gas Generac xl4000's (1) Yanmar YDG 3000E which was purchased for $250 not running and a 25kw PTO generator for my 1720 Ford. The features mentioned above and the lower fuel consumption were the selling points.
I have over 500 gallons of diesel on hand so fuel will not be a problem.
I'm looking to keep my lights on in the event of a long term grid outage.
Any thoughts on my plan?
 
   / SolarCity installing a 6.37kw system on my house!!! #2  
Have you looked into net metering? In the solar class I took earlier this year, net metering in NC was not recommended but this depends on the state/local regulations. The recommendation was to build a system that would generate the power you would use in the five hours of sunlight we have for power generation or spend even bigger dollars for batteries.

Batteries are expensive but if you want solar power when the grid is down you have to have them. On thing to consider with batteries is that they do not like cold temperatures so keeping them warm is beneficial. Looking at batteries, you get more power per dollar by buying bigger/heavier batteries. The batteries will have to be changed out one day so having access to move batteries than can weigh hundreds of pounds would be a good idea.

This year has been very wet in my area. At various times last winter and spring we were 30%-50% above average for rainfall. Usually at this time of year the local lakes are low in water but they are at near full pool because of recent rains. We have had several periods lasting 4-5 days of heavy clouds which is going to diminish PV power generation. Some recommendations are to have enough battery storage to last some number of days without solar power generation. Having two or three days of battery storage is expensive and a generator would have to be used to generate power if the grid was down and there was cloud cover that exceed the battery storage.

Later,
Dan
 
   / SolarCity installing a 6.37kw system on my house!!! #3  
Sounds like you have it covered. :) The grid-tied system with backup battery, and a generator, sounds like a good idea.

Hope you let us know how it works out later this year.
 
   / SolarCity installing a 6.37kw system on my house!!! #4  
Sound pretty neat to me. I'll assume you live someplace in the US, so like Dan said, keep the batteries warm in the winter. That Yanmar looks like a pretty nice setup too. Keep us in the loop, so to speak.
 
   / SolarCity installing a 6.37kw system on my house!!!
  • Thread Starter
#5  
I live in Florida Ma.
The system is Net Metering and the price per/kw is fixed at $0.103 per/kw or $67.00 for 20 years providing I don't go over 725kw/month.
Anything over would be at the current utility rate.
 
   / SolarCity installing a 6.37kw system on my house!!! #6  
What kind of batteries are you using?.......Flooded or sealed AGM.
Sealed AGM batteries can be stored inside with no venting of corrosive fumes like flooded batteries. Cost more but last longer and provide more power with deeper cycles.
 
   / SolarCity installing a 6.37kw system on my house!!! #7  
I guess you are doing a 20-year lease of the system? The fixed rate per kWh below 725 kWh must be about 2/3 of the normal rate? We pay 14-15 cents per kWh here.

Is the battery backup unit part of the regular lease offer, or is that something you added/changed for your installation?
 
   / SolarCity installing a 6.37kw system on my house!!! #8  
I have envy!

I am not an electrician, but to run the house off solar, you definitely need a battery bank. Aren't the Optima batteries sealed?

I am fascinated by the engine idea over a generator, sounds like a great idea! Definitely cheaper, I priced out generators recently, sheesh.
 
   / SolarCity installing a 6.37kw system on my house!!! #9  
I guess you are doing a 20-year lease of the system? The fixed rate per kWh below 725 kWh must be about 2/3 of the normal rate? We pay 14-15 cents per kWh here.

Is the battery backup unit part of the regular lease offer, or is that something you added/changed for your installation?
Ok then, we'll be expecting 20 years of post to see how things are going.:laughing:
 
   / SolarCity installing a 6.37kw system on my house!!! #10  
In CO the energy guys are trying to cut the rate for net metering down to $.04kw/hr making it harder to recoup the cost. Theyre also advocating the lowering of the credit for roof top systems. Just when it looked like it was starting to get a foothold, the big money guys want to change the rules.
 
 
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