Solar with or without a battery

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timmmay

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#2258147 14-Jun-2019 13:02

A friend of mine has a lot of solar panels, he uses them to heat two hot water cylinders and a spa pool. They also run dishwasher and other appliances when the sun is shining, which take priority over hot water.

Not sure how he's faring financially, but he's an accountant and would've done the sums before he started. Not many people have that much hot water to heat though.

frankv

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#2258244 14-Jun-2019 15:11

rogercruse:

battery technology is still too expensive to store anything other than enough power to keep the lights running for a couple of hours.

Use your excess power to separate water into hydrogen and oxygen during the day, then use a fuel cell to convert them back to electricity in the evening?

richms

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#2258258 14-Jun-2019 15:31

frankv:

Use your excess power to separate water into hydrogen and oxygen during the day, then use a fuel cell to convert them back to electricity in the evening?

Lol see the hydrogen car thread for why thats a terrible efficiancy way to move or store energy ;)

Richard rich.ms

PhantomNVD

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#2258314 14-Jun-2019 16:16

Buy the Nissan Leaf and use V2G to store the daytime excess. The leaf will be cheaper than a power wall or equivalent battery backup, and you can use it as the second car to maximise its payback too 👍

tdgeek

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#2258316 14-Jun-2019 16:19

PhantomNVD: Buy the Nissan Leaf and use V2G to store the daytime excess. The leaf will be cheaper than a power wall or equivalent battery backup, and you can use it as the second car to maximise its payback too 👍

I think V2G is still a problem. It degrades the battery faster. But, buy a second hand Leaf and save fuel. Or to equate the panels and the battery, buy two Leafs and you and the wife save every day. After the payback has paidyou back, you still have them

rogercruse

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#2258370 14-Jun-2019 17:52

frankv:

rogercruse:

battery technology is still too expensive to store anything other than enough power to keep the lights running for a couple of hours.

Use your excess power to separate water into hydrogen and oxygen during the day, then use a fuel cell to convert them back to electricity in the evening?

What powers to you think I have?

Magical or superhuman!!

Lego

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raytaylor

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#2258534 14-Jun-2019 22:08

rogercruse:

Switch to a power company that provides a free 'hour of power' each day.

I have been trying to run the numbers in my head for buying a pallet of lead carbon batteries from china (benefits of lithium without the huge cost) and cranking up a massive array of battery chargers during that free hour of power.

:-P

Ray Taylor

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raytaylor

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#2258537 14-Jun-2019 22:15

frankv:

rogercruse:

battery technology is still too expensive to store anything other than enough power to keep the lights running for a couple of hours.

Use your excess power to separate water into hydrogen and oxygen during the day, then use a fuel cell to convert them back to electricity in the evening?

Somewhere near Te Marua i was reading that they are using solar to generate hydrogen, pumping it up the road to then power a weather station of some sort for NIWA or a government research project.

Cant seem to find a link right now.

Ray Taylor

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danielparker

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#2258547 14-Jun-2019 22:55

raytaylor:

rogercruse:

Switch to a power company that provides a free 'hour of power' each day.

I have been trying to run the numbers in my head for buying a pallet of lead carbon batteries from china (benefits of lithium without the huge cost) and cranking up a massive array of battery chargers during that free hour of power.

:-P

How did your calculations work out on this (seriously)

Add solar to this and does anything change?

raytaylor

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#2258574 14-Jun-2019 23:52

I think the fuse in the pedestal on the roadside is too small to make it worthwhile.

My contact energy bill says we have a 15kVA connection so assuming 15kw but i think the fuse might be smaller than that - the fuse has been replaced a couple of times but the linesman may have just used what he had on the truck at the time.

Looking at my usage for the lowest month of the last 12 months, I used 510kw or 17kw per day. So i wouldnt be able to divert all power usage to be within that hour but it seems most of it I could.

There would be a desire to hold off for the first 5 minutes and last 5 minutes of each hour just in case your timer clock isnt in sync with the billing clock.

Lead carbon batteries can be had for about $500 each for a 12v 100Ah and are supposed to be good for 5000 cycles if they stay above 90% state of charge.
A pallet of 32 batteries ($16k) would hold approx 38.4kw so assuming 2500 daily cycles before replacement (approx 7 years) then we are paying about 36 cents per kw stored and consumed.

At this point it doesnt really make sense unless i was to look at reducing power consumption by switching to solar hot water and probably solar water storage for plumbed radiator heating. Being a flat of 3x 20 somethings we dont really use much power.

Ray Taylor

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