Off-Grid Solar Setups

[BitChin1]

One thing to look at though is any thermal bridging in the product - in NY the ground will get cold and you will need high r-value in the foundation (especially near top of walls) - the Xi+ seemed to have higher levels of insulation as well as some option to insulation the foundation as I recall.

 

[Redneck in training]

My brother lives in Europe. His house has, I think, about 9" brick wall inside and about 6" of closed cell Styrofoam outside. Triple pain windows. Since the heat source is air/liquid heat pump he had AC put in upper rooms but that is a luxury not common in that climate. He told me that unless it gets very cold for long just the fridge and lights will keep the house reasonably warm.

Spending 25k for power feed line is quite high. They can put the transformer by their pole and you could install the 240 feed by yourself for way less money. Our PV system is about 1000ft from the connection point. I bought direct burial cable calculated for 2V drop at 100A for about 1000 USD on ebay, the disconnect and ditchwitch rental added about another 500 USD.

Battery energy storage is still immature technology. But you can store energy in example in liquid. When the house doesn't require heat or AC the heat source (presumably heat pump) could be directed to heat or chill liquid. Since heating and AC are the biggest energy users they will use stored hot/cold liquid allowing for smaller battery.
That is something I am thinking about because we don't have net metering. When we supply energy to the grid we get paid 3.5 cent and when cloud goes over the sun we are charged 11.5 cent per kWh. It would be advantages for us to limit supply energy to the grid and use stored energy when sun is not shining.

We have 100% electric house but because our PV can't be "islanded" when power grid goes down we have two propane fireplaces for heat backup.

 

[dave1949]

Another approach to cutting a house's energy footprint is earth berming. A house with thick brick walls, earth berms, or one that is sealed to Passive Haus standards has virtually no air infiltration through the walls. That is as important as the R-value of the wall.

Besides cutting air infiltration to zero, earth berms replace ambient outdoor air temperatures with ground temperatures. Ground temps in winter can be 50-60 degrees warmer than air temps in northern climates.

Preventing frost penetration into the ground near the foundation is accomplished with 2-4 inches of Styrofoam sheets laid out as a apron surrounding the exterior walls--very much like a shallow frost-protected foundation is done. That can be combined with ICF walls or by using foam on the exterior of a poured concrete wall. The end result is no air infiltration, reasonable R-values for exterior walls, and a very low delta between the exterior and interior temperatures which means the rate of heat exchange between them will be very low.

 

[BitChin1]

Yep there are many different ways to solve this problem - your point on air-sealing is top priority (which SIPs installed properly do a very good job). Earth berm is very effective but may have esthetic issues depending on style of home.

The key for off-grid though is minimizing peak then total demand. the individual has a similar issue as the power company in that they need to build infrastructure to allow for the peak demand (and pay for it) - the individual though has considerably more control on their own homesite.

 

[BitChin1]

We have 100% electric house but because our PV can't be "islanded" when power grid goes down we have two propane fireplaces for heat backup.[/QUOTE]

Do you have any battery or just use the grid for backup electicity now?

 

[Mendonsy]

An off-grid PV system just does not seem to me like a viable alternative for the area you are looking at. PV systems work OK for applications where the primary demand is cooling because their output peaks when the demand is highest. Just the opposite is true for an area like CNY where the primary demand is heating. The maximum demand comes at times like at night in the winter when the PV array output is essentially zero.

 

[Got2BTru]

For heating, we're LOOKING at going strictly with hydroponic radiant floor (no HVAC) - it's a solar based system and would be really efficient.

....but that leaves me with how we cool the house for the relative little we need to in the summer.

 

[dave1949]

This is the third in a series of articles about the Tesla Power Wall and batteries in general for solar systems. The battery article is near the bottom of the web page, so scroll down. There is some good introductory info on whose products and what is needed to integrate the Tesla battery into a solar pv system.

ReVision Energy ? Growing Power at Eastman's Corner, the Future of Batteries

 

[dave1949]

Yep there are many different ways to solve this problem - your point on air-sealing is top priority (which SIPs installed properly do a very good job). Earth berm is very effective but may have esthetic issues depending on style of home.

The key for off-grid though is minimizing peak then total demand. the individual has a similar issue as the power company in that they need to build infrastructure to allow for the peak demand (and pay for it) - the individual though has considerably more control on their own homesite.

Very true. Earth berms do a lot to dictate the stlye of home built. If ya don't like it, and many do not, it's a non-starter.

We are very happy with our earth berm, passive solar house built in 2006. Except for the range propane cooktop, 45-50 gallons of propane/year for some hydroponic floor heat, and ~1.5 cords of wood, our house is all electric. Our average monthly usage is 585 kWh over the past year. That includes using our two mini-splits as needed for AC and occasionally a little heat. Obviously we aren't big electric users and it's just the wife and I. Our AC load is not very demanding in our climate which helps a lot.

 

[houstonscott]

I'm interested in reducing the draw so a battery system could get through the night. Example; Say I take a shower at night, I'd like the hot water heater to delay recovery until PV system is working to cover recovery rather that tax battery all night while it's running AC or heat? Same with a well pump, no need to fill cistron at night under battery. How can all that be managed. HS