Less than the power company challenge!

[Newenough]

Well, we met the new neighbors today. They seem like really great people. We only spoke briefly, but planned a little get together for another day. They had noticed all the solar at my place and seemed intrigued, especially after they got a quote from the power company to get power where they plan to build a house. He said he likes his big screen TV and all the amenities (ac, lights, etc). So, that sounded like a challenge!

So let's make a game of "hold my beer"!

Assuming a traditional 3 Bedroom house. With 4 adults will occupy this house. They want AC, fridge, TVs, basically duplicating a grid on house for the most part. Rather than list all the crap in an energy audit, let's just say;

40kwh/day consumtion
24 or 48v System
5 hours/day of good sun
2 days of atonomy
Completely DIY

Can you come in under the $40k estimate they want just to get power to the house?

 

[snoobler]

Ignoring everything but "50kWh/day", which is about 60% above the national average. Ignoring seasons, available solar, etc.

$15K in DIY LFP batteries (100kWh)
$5K in parallel split phase inverters (no MPP Solar or Growatt crap)
$3K in SCC
$8K in 16kW of panels
$1K in stuff

$32K

Personally, I would cut the batteries to 1 day and spend $2-3K on a suitable auto-start genny saving another $4K or so.

 

[Dzl]

I'm not brave or informed enough to venture a guess. But I'm curious to see how this develops.

I'll pose the question that others will surely ask for. Where do you live, how many hours of full sun can you expect per day for your area in your worst month (and maybe in your worst cooling season month)

 

[Hedges]

Four Sunny Island, $2500 each on eBay, $10,000
Three Sunny Boy 7.7 kW, $1700 each, $5100
33 kW used panels from SanTan at $0.33/W, $11,000
20 kWh SunXtender AGM (14 kWh usable, enough for one night), $5000
Generator for cloudy days $1000.

Total $32,000 not counting wire, conduit, racks.

(And no, I didn't look at Snoobler's response and total price until I had typed in mine.)

 

[snoobler]

Wow. Totally different approaches. I assumed new panels at $0.50/W, but used could easily cut another $3-4K.

 

[Hedges]

Wow. Totally different approaches. I assumed new panels at $0.50/W, but used could easily cut another $3-4K.

Yes, I don't like to spend 50% on batteries, prefer to over-panel. As you said, less storage and buy a generator.
Could get by with 2 Sunny Island not four.

 

[toms]

Definitely go for zero autonomy and use a generator when the sun isn’t cooperating.

Remind your neighbours that after they pay the 40k for grid connect - they still have to pay power bills.

edit - we are completely off-grid and often use 30kwh/day in summer with a 20kwh battery and 6kw of PV.

I’m in Australia, the last system i installed used mainly second hand components- as they are very cheap, but also high quality.

2 Sunny Island SI8.0 (new) $9k
1 SunnyBoy 5.0 / 6kw PV (2nd hand, 3 years old) $2.5k
48V 400ah CALB LiFePO4 (new) $16k
1 Midnite Classic 100A (second hand) $500
5kw PV (2nd hand, 2 years old) $1k
Wiring etc $1.5k
REC BMS $1.5k
Kubota J108 generator (new) $4.5k

Total $36.5k

 

[Newenough]

One thing to consider is here in Georgia it gets very humid in the Summer requiring AC all the time. While over paneling will be needed to cover daytime consumption and still charge the batteries, about half of that 100kw of storage would be used in just AC alone (if no compromise was made) over the 2 days of atonomy. A generator would be a must as well. Also, recommending second hand items (especially panels) is guaranteed. My entire 9.6kw array is composed of seconds....

Thanks to those taking this challenge.