150 amp service sizing

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solar was permitted. he has a pretty good array. i think it accounts for 30%. it is grid tied with a syncronizing inverter and backfed on 2 pole 30amp breaker that goes into his existing panel that was "updated" by some dip. the inspector took one look at the panel and said that he needed to move it out of the little cubby down low and have a proper main disconnect that is accessible.

i mean i get the argument that his energy need will increase in the future. but the tankless electric whole house water heaters on the market now...i really didnt see any that pulled 100a! the average was 2pole 50a.
 
Of course the beauty of the tankless heaters is that they are only using power while the water is flowing. So while the current flow may be large while in use, it may not be much power monthly. If you think of the grid as a battery, then your friend is just storing the solar energy to be ready for his peak current use while heating water.
 
Volta said:
So while the current flow may be large while in use, it may not be much power monthly.
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True, but the system as a whole must be sized to carry that short-term peak.

A water heater must be selectred before a new load calculation can be made.
 
LarryFine said:
True, but the system as a whole must be sized to carry that short-term peak.

A water heater must be selectred before a new load calculation can be made.
Click to expand...

Absolutely!

To Cali: In this thread the home owners want an insty-hot that may draw over 100 amps. It is not the sq ft that matter, it is laundry during a shower that matters.
 
i only stated sq/ft because of its relevance in terms of calculating loads...mainly lighting loads and such. my friend is berkeley "eco". his whole deal is to try and reduce his carbon footprint. he installed solar panels. he wants to purchase an electric water heater in the future. and when he does that he will probably go with the best technology at the time. one that uses LESS enegy. yes there are water heaters on the market that use 100a. but there are also ones that are just as capable and use 67% less energy.
i'm going to out in a 200a service. 2/0 wire and 2" rigid. because why take the chance. i hear ya'll. thank you so much for the advice. this forum is great.
 
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