EcoRenovator - View Single Post - Dump the plumbing and use PV to heat water?

Xringer · 05-04-13, 10:51 AM

I've been doing some hot water heating with PV for a while now..

http://ecorenovator.org/forum/solar-...r-heating.html

http://ecorenovator.org/forum/geothe...html#post29717

Since the wattage required has always been the big question,
I wanted to post the above links, to give PVDHW DIYers
an idea of what's possible these days.

Keep in mind, I'm using PV to supplement our A7 ASHP water heater.
Recently, while using about 1kW of PV, the A7 isn't running at all.
(Unless it gets really over-cast, it won't come on).

From what I can tell right now, it seems that our household
could get by using about 1,000 watts of PV (or power from the grid) for hot water.
That's 3412 BTUh, or x6 hours ~ 6 kWh (20,472 BTUh per day).

That's only $1.00 USD from the grid, at today's NStar rates. (16.61 cents per kWh).
So, by running a GE water heater on 120vac using a Timex timer,
http://ecorenovator.org/forum/introd...html#post25549
A low usage family could get by on $1 day for hot water..

So, if you have an extra 1kW of PV that's not being used,
or you can afford to pay for 6kWh a day, to Mr. Grid,
and don't mind waiting for a slow recovery time..?.

It seems like using the grid at 120vac and a timer,
is the most cost effective way to cut hot water cost.
Using PV is going to cost more up front, but will be Greener..

05-04-13, 10:51 AM	#25
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Waking up this old idea I've been doing some hot water heating with PV for a while now.. http://ecorenovator.org/forum/solar-...r-heating.html http://ecorenovator.org/forum/geothe...html#post29717 Since the wattage required has always been the big question, I wanted to post the above links, to give PVDHW DIYers an idea of what's possible these days. Keep in mind, I'm using PV to supplement our A7 ASHP water heater. Recently, while using about 1kW of PV, the A7 isn't running at all. (Unless it gets really over-cast, it won't come on). From what I can tell right now, it seems that our household could get by using about 1,000 watts of PV (or power from the grid) for hot water. That's 3412 BTUh, or x6 hours ~ 6 kWh (20,472 BTUh per day). That's only $1.00 USD from the grid, at today's NStar rates. (16.61 cents per kWh). So, by running a GE water heater on 120vac using a Timex timer, http://ecorenovator.org/forum/introd...html#post25549 A low usage family could get by on $1 day for hot water.. So, if you have an extra 1kW of PV that's not being used, or you can afford to pay for 6kWh a day, to Mr. Grid, and don't mind waiting for a slow recovery time..?. It seems like using the grid at 120vac and a timer, is the most cost effective way to cut hot water cost. Using PV is going to cost more up front, but will be Greener.. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..