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Old 09-10-12, 01:34 PM   #151
Xringer
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My solar PV back-up system has been supplying 120vac to the A7 a few days now, and seems to be keeping up.
At 2:30 AM this morning it ran off the battery pack for about 50 minutes.
It's partly cloudy today, but the pack's SOC is coming right back up.
http://i46.photobucket.com/albums/f1...Solar/z008.jpg
http://i46.photobucket.com/albums/f1...Solar/z203.jpg
It seems like just a few hours of good sun each day can supply the A7 with all it's power.
(At least during the summer)..


~~~

I've been doing a little experiment to determine if the temperature in the 40 gal tank is dropping down under 115 deg F.
That event should occur when our hot water usage exceeds the heating capacity of the A7.

I set the tank's thermostats to 115F, and plugged in the heating elements
to the grid 120vac, using Kil-a-volt-clone to monitor run time and kWh used.
At 120Vac power use is 1.130 kW. (3856 BTUh).
During the last 4 weeks, we've had two events of hotwater overuse.
In each case, the heating element burned up about 0.5 kWh.
I assume the heating element was running in sync with the A7.

So, this 15 cent test seems to show that a winter time slow-down in recovery time,
could be helped by the additional 3856 BTUh from the heating elements.

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Old 09-10-12, 02:39 PM   #152
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Xringer wrote:
It seems like just a few hours of good sun each day can supply the A7 with all it's power.

This is great having your new technology providing you with creature comforts without costing you an arm and a leg.

Would your system work if you had the A7 start at say 7:30 am to give you the hot water required for the day. If that days solar in-put didn't come, you may receive the solar required the next day. If not, you could make a fail safe maybe by noon switch to the utilities for the energy.

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Old 09-10-12, 04:44 PM   #153
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I had the oil burner on an early morning burn (using a timer) and it worked out okay..
But, when we did a wash or two, and both of us wanted to shower in the evening.?. Not so good..


Since the average A7 power use is only about 1 kWh per day,
I'm not really worried about paying 16 or 17 cents a day for hot water.

I'm just running it on solar now, just to see if it's possible. I guess it is.
I'll be switching back to the grid before long.. Once it gets a little rainy,
having the back-up power becomes much more important.
Need to have those amp hours in the bank.. Solar looks good for this week!

Woburn September Weather 2012 - AccuWeather Forecast for MA 01801

It's good to see the back-up system prove what it can do, and it might
be good for the battery bank to get a little work out once in a while.

~~~~~~

Edit 9/11/2012: Recharge check
The battery pack looked a little low last night (49.6v / 12.4v per), while the A7 was running.
Since it had been mostly cloudy yesterday, I decided to take the A7 off back-up power today, (the A7 stayed off all day) and let the sun fully recharge the back.
By mid afternoon, output from the charger put 1.2 kWh into the battery,
before the PWM got real low (10%), indicating a good SOC.

So, since the next few days are looking so good, the A7 will stay on solar this week.
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Old 09-17-12, 08:56 PM   #154
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Default Solar backup/A7 test results satisfactory

After 11 days of running mostly on solar PV & battery, it seems like using solar to power the A7 works pretty well.
Depending on hot water use, the charge controller (which typically shows 00 Ah) was
showing 22 Amp hours on average, per day. (With a peak of 34 Ah, & a low of 10 Ah).
Average bank voltage at 53v x 22 Ah = 1.166 kWh per day.


When the A7 was running during the day, I would clamp measure 14.5 Amps coming out of the battery bank (in Bulk mode).
If the sun was out, the PV would be providing about 50% of the power, with the 48V bank providing the remaining 50%.
When the A7 would stop, the PV would sent all it's power directly into the bank.
Normally, the bank would near or at full charge at night.

It's clear, the back-up system (using 500w PV array) can keep up with the A7 during the summer months.

Since there is rain and overcast days in the forecast, I'm going to discontinue this test and,
go back to spending 15 cents a day on grid power.
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Old 09-18-12, 08:12 AM   #155
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Xringer wrote:
Since there is rain and overcast days in the forecast, I'm going to discontinue this test and,
go back to spending 15 cents a day on grid power.

How much energy would you collect on an overcast day. Would you have a net loss of battery energy in an overcast condition??

This is really great technology. Utilizing nature's energy for the human's creature comforts. Imagine having enough solar capacity & battery to run the Sanyos as well.

Good work Xringer

For our forcast here, the same, a week of overcast. Hmm maybe time to run the geothermal for some hot water. We will have to see how long our tank will stay hot. At-least a couple days.

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Old 09-18-12, 10:09 AM   #156
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Default Raining here.. :(

It's heavily overcast today, so the PV output isn't very high. Maybe a few watts.
But that's not real important, since 11.2 Ah total yesterday topped off the system.


When the SOC is high, even a overcast day will maintain the charge.

During the test period the SOC did get low a few times. When we used extra hotwater
and during bad solar days, we had lower nighttime bank voltage. (Red LED blinking)
But the reserve power in the bank was actually enough to run the A7 until the sun came back to recharge the bank.


The dual Sanyos use too much on startup to be driven by small solar.
And that project would require more PV, another battery bank(large), plus a large 230vac inverter. Way too much $$$

The very best way to use a small PV array is to go grid-tie.
But, even that's too expensive, compared to buying power at 16.33 cents per kWh.

GTI is the way to go. Maybe someday I'll plant a large post in the back yard for a high post mounted PV tracking array.
That would be almost as good as roof mounting.

Maybe like this, but with a taller post..
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Old 09-20-12, 11:55 AM   #157
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It's been cool, so the Sanyo ASHP crankcase heaters have been running a bit..
The TED says they used .7 kWh since midnight! 12 cents during the last 12 hours!

Wow, without even running the AC, we seem to be spending 24 cents a day, while the units are on standby!
(Yeah, we are using 15 cents to heat our hotwater)!

I just opened the Sanyo breakers!
Since the forecast seems to be saying we aren't going to be needing anymore cooling this year..
Woburn September Weather 2012 - AccuWeather Forecast for MA 01801
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Old 09-29-12, 01:46 PM   #158
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During the last few days, we've had some cool weather.
Yesterday, for the first time in months, I turned on the heat in the living room area. (Sanyo #1).
Had it set to 21C most of the day. The room temp stayed at 21 to 22 C (over-shoot).

In the evening (8PMish), I did some work down in my basement shop. (under the living room).
It felt kinda warm down there. I checked the basement temperature (3 feet from the A7) and it was just over 22 C
I've been logging room temp down there for over a month, and it should have been between 20 and 21C.
(I've just stopped logging. Waiting for some cold weather before resuming).

So, I suspect the warmth upstairs was heating the hardwood floor,
and some of that heat eventually leaked downstairs to the basement.

It seems, during the winter, the Sanyos will be helping the A7 heat the hot water tank.
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Old 10-02-12, 11:18 PM   #159
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Default Status Report 8/2/12 ~ 10/2/2012

It's been running for 62 days now and the power use has been 60.21 kWh.
That seems a little low, but it's what the meter is displaying tonight.

$9.83 (@ $00.1633 / kWh) isn't much when compared to what I would
have used burning 1/2 gallon of oil every day. (approx $124).

We've only had one problem. The GFI (built into the A7 plug) popped out
and we ended up with a lukewarm tank. Might have been caused by a grid failure.

Tonight after a couple of long showers, the A7 seemed to be taking more time to recover.
I went down to check on it and found the area was at 61 F. Outdoor temp is currently 60.4F.
The A7 needs more time (and power) when it's cooler..

I'm going to reset the power meter tonight (it's after midnight),
and start a new 'winter' measurement cycle today, 10/3/2012.

Edit:
The pre-heat water (from 800w of PV) isn't very warm today, since it's been overcast a lot lately.
So, when the old HS Tarm boiler is down at 66F (normally it's above 75F),
the 40 gallon A7 tank is going to drop below the set-point quicker and stay below longer.
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Old 10-03-12, 09:51 AM   #160
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I've had my GeoSpring up and running a few weeks now. Works great. It has a variable or stepped operation. It runs at light load after washing dishes, but ramps up to full power with showers. It's LOUD! I'm glad I put it in the utility room instead of keeping it in the hallway closet. The hassle of plumbing and wiring was worth it.

It runs on 240V, so I can't use my Kill-a-watt on it. I can only estimate the usage at the end of the month with the power bill. October is our lowest HVAC month so it's a good time to see the difference.

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