Stone house and solar backup

[newalarm]

Regarding solar, it was more a means of back up. Not sure how much power is generated on solar panels on a cloudy day, but generally, they still provide some power.
 
Probably the best bet is to provide an alarm signal when power is lost for more than a certain time.
 
I will look are wired options. Problem is how to get into the blgs.
 
Thanks for responses.

 

[LarrylLix]

Put in PVC conduit big enough for future wants. place a few inches of sand on top of the pipe to pad it, make it easy to dig up later, and it flows around the pipe when the ground sinks or frost heaves seasonally. The sand flows like a liquid and prevents breaking the pipe. At least at both ends where the pipe exits the ground.
 
Frost can tear meter bases off  brick walls no matter how strong you make it. I have seen it tear bricks apart when the fastening was good.

 

[NeverDie]

How long does the system need to run without power?  The solar isn't going to help at night, but the extra batteries it charges will.  Since the site normally has power, why not charge extra batteries using regular mains electricity?  The ongoing energy cost would be low, as you're normally just replacing battery self-discharged voltage.  If the system needs to keep working for weeks or months even with mains  power knocked out, then at some point the requirements and battery economics will favor adding solar or some other kind of alternate power source, but only so that you don't need to buy a truckload of batteries.

 

[NeverDie]

How long does the system need to run without power?  The solar isn't going to help at night, but the extra batteries it charges will.  Since the site normally has power, why not charge extra batteries using regular mains electricity?  The ongoing energy cost would be low, as you're normally just replacing battery self-discharged voltage.  If the system needs to keep working for weeks or months even with mains  power knocked out, then at some point the requirements and battery economics will favor adding solar or some other kind of alternate power source, but only so that you don't need to buy a truckload of batteries.

Here we go: Tesla just announced a 10kWh battery backup intended  for home use:  http://www.teslamotors.com/presskit/teslaenergy
Comes with a 10 year warranty.  Problem solved.

 

[newalarm]

Yeah. I saw that. Bad ass... Tesla is moving to take over the world.
 
Ok, so essentially, the reason for the backup is really for some crafty thieves that would know about alarm, cut power, and cut back a few days later. The elec panel is accessible outside (locked i think). But with cell communication, and phone backup, it could notify of a loss of power. Siren could notify neighbors of problems. House stays vacant for good part of the year.
 
Of course a good thief could also jam cellular signal and cut phone line.

 

[LarrylLix]

Lead-acid is a lot cheaper for a mid-size  battery bank. After buying the MPPT chargers, PV panels, inverters and switching and monitoring logic $10K-15K is an expensive backup system for that size. I am sure the price should improve with time and technology though.
 
The $3500 is just for the 10kWh battery. Flooded lead-acid about the same size can be had for about a tenth of the cost and will probably last longer, with maintenance and proper logic to cycle properly.
 
Cool technology though.

 

[NeverDie]

Lead-acid is a lot cheaper for a mid-size  battery bank. After buying the MPPT chargers, PV panels, inverters and switching and monitoring logic $10K-15K is an expensive backup system for that size. I am sure the price should improve with time and technology though.
 
The $3500 is just for the 10kWh battery. Flooded lead-acid about the same size can be had for about a tenth of the cost and will probably last longer, with maintenance and proper logic to cycle properly.
 
Cool technology though.

I seem to have missed where the $10K-15K number came from (?).  I had the impression the entire unit, including batteries, charger (from the grid), inverter, and case was $3,500. Installation would be extra.
 
Nonetheless, it would be interesting to know what the cost of an equivalent SLA system would be, good for 10 years, and also what volume of space it would occupy. Then it would be easier to compare the two.  It might be hard for the SLA systm to beat the $3,500 price for 10kWh, and if so, that would mark a turining point.  Just now glancing at some prices of powersonic SLA's, and it looks like they would lose the bake-off.  Which SLA batteries would you use?  The Tesla guys say their battery prices will continue to drop in cost, whereas I would think SLA's are a mature technology and aren't going to do that.

 

[RAL]

I seem to have missed where the $10K-15K number came from (?).  I had the impression the entire unit, including batteries, charger (from the grid), inverter, and case was $3,500. Installation would be extra.
 
Nonetheless, it would be interesting to know what the cost of an equivalent SLA system would be, good for 10 years, and also what volume of space it would occupy. Then it would be easier to compare the two.  It might be hard for the SLA systm to beat the $3,500 price for 10kWh, and if so, that would mark a turining point.  Just now glancing at some prices of powersonic SLA's, and it looks like they would lose the bake-off.  Which SLA batteries would you use?  The Tesla guys say their battery prices will continue to drop in cost, whereas I would think SLA's are a mature technology and aren't going to do that.

 
I agree.  An SLA system would have a hard time competing on price.
 
If you were to use 100 Ah batteries, you would need 8 of them to approximate the 10 kWh capacity of the Tesla system.  A deep cycle 100 Ah battery sells for about $250, so there's $2000 worth of battery cost right there.  With the SLAs, you'd probably have to replace them at least every 3 years, assuming frequent discharge cycles.  So over a 10 year span, your battery cost is now $6000+.   Now add in the cost of the chargers and inverters, and it seems like the Tesla wins hands down.

 

[newalarm]

Tesla wins anyway. If you look at the whole solar city scam, they get you to sign up for your panels, but they have no interest in a homeowner owning their panels. They push to lease them to you. and they collect the SRECs. That is where the real money is, especially in certain states.

 

[LarrylLix]

I guess a few haven't actually read the struggling company's website hype titles and brag.  $3500 for just a battery is way too expensive.

Tesla’s selling price to installers is $3500 for 10kWh and $3000 for 7kWh. (Price excludes inverter and installation.) Deliveries begin in late Summer.

Powerwall specs:
•Mounting: Wall Mounted Indoor/Outdoor
•Inverter: Pairs with growing list of inverters
•Energy: 7 kWh or 10 kWh
•Continuous Power: 2 kW
•Peak Power: 3.3 kW
•Round Trip Efficiency: >92%
•Operating Temperature Range: -20C (-4F) to 43C (110F)
•Warranty: 10 years
•Dimensions: H: 1300mm W: 860mm D:180mm


 
 
A 48 volt bank of flooded LA batteries would require 208 amperehour cells runs about $800 for decent quality deep cycle types. To only have a capacity of 2kw an equivalent battery would be so lightly loaded. Don't try to start two motor loads  at the same time.
 
Much cleaner and smaller in a house though. You still need a large inverter and switching panels , smart control centre, contactors, lockout safety systems, etc.. It's going to be $15k by the time it's done...easy.
 
Battery storage of energy has never been as cheap as grid power yet. Hopefully that can change but on the battery end this time.
 
Correction: I guess we are only talking about shaving off up to 2kw of peak energy usage anyway and the batteries would not have to handle any real power surges so 2kw may not do to bad and let the grid handle any motor startups or bigger appliances.  Hairdryers will almost load this battery to it's limited capacity but I guess that is what LioN is good for, light continuous loads and high exergy.