There is nothing you can do about it. It indicates you just have too much panel wattage. It is not so much about wasting energy in as much as you are not utilizing energy. Unfortunately any off grid system is not capable of utilizing all the potential energy it could produce. They have to be over sized especially in months with long Solar Hour Days. Otherwise if you had a cloudy day with no charging you would never be able to get caught up.
Only thing you can really do is once the batteries are fully charged start turning stuff on and use the excess for something like run the dishwasher, washing machine, irrigation, ect.. It just requires you change your daily routine and lifestyle.
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What you have to do is come up with a scheme to utilize the excess production after the system reaches 100% soc. I mentioned a second hot water heater as a possibility that most homes would have. It's set up with zone valves and diversion relays to only come on during high soc situations. You could utilize a 2 stage thermostat where the hot water heater you have temperature is based on time of day with a set back during non production time. A Mixing valve will determine the water temperature at the faucet, you store the water at 170 ° or so.
Some schemes only make sense if your having a shortfall in your production and use or storage capability. In Hawaii it may not be a issue to even try to save the excess. Sometimes it's just changing the time of day that you cook or wash clothes can make a huge difference.Leave a comment:
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Spoke with about 5 of the companies with the bright yellow or orange trucks and they all seemed to promise us lower electric bills, but when I mentioned off-grid it stopped their sales pitch immediately. I did some number crunching and it just didn't seem to make sense to let another company own my system, still charge me for electricity, and get the tax breaks.
Our electric rates in Hawaii are .36 per kWh, (now it's probably 10 times that because like Sunking said, something about power from any off-grid system is going to cost you many times more than buying it from the utility). Another company named NextEra out of Florida wants to take over Hawaiian Electric which made $12.2 million in 2014, and from what I've been hearing its not going to change our high rates here in Hawaii. They tell us they want to get into Solar but really the fine print is that they will still control the price. So now we are out of the Loop and I'm happy about that. Sorry about that, had to get that out of my system.
Our system seems to be doing fine, even with our big loads at night. We do use about 20% to 30% of our batteries from when the sun goes down till the morning and the sun starts doing its job.
What are your thoughts about our system being in float-mode from when our batteries reach a full charge? Seems to be wasting a lot of energy like some of you said. Have read the manual and can change the set points for when the system switches back to bulk mode. We are set on 3 stage charging Bulk-Absorption-Float. There is 2 stage charging that has no-float. I think the battery voltage can be set for when to get back to bulk mode. ???Leave a comment:
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It'd be a great system to do some diversionary and sequencing of loads on. Last year I paralleled a extra hot water heater into my system and the main heater has yet to come on. With 9 guest rooms that seems like a big load on the system.Leave a comment:
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Once the battery are charged the controller goes into float mode. Any power demand less than what the panels can produce comes from the panels and a battery system is designed to do that. If power demands exceed th epanels power or at night comes from the batteries.
All that is normal operation and nature of the beast. Grid tied is different where every usable watt hour is utilized either by the owner or his neighbors at the time the power is available. Otherwise if your batteries are fully charged by noon with no power being used, the system just shuts off and collects dust. All that potential power is lost forever.
Unfortunately it is not like money where you always have a place to store the excess to infinity.Leave a comment:
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I agree it seems to be wasting energy although the panels are still producing from noon to dark but since the battery system is not in a "charge" mode the panels cover just enough to meet his load. It is after 19:00 when the sun is down and he can't charge the battery that his loads goes up and the bat voltage goes down very quickly.You are correct. His panels set there from noon til dark and do nothing.
Not that unusual, in fact normal but clearly demonstrates what I have been saying on this forum for 6 or 7 years that off-grid solar battery systems are a waste of resources and will never obtain an EROI. The reason is even if you could utilize all the power the panels can generate in a day, the system will never generate more energy than it takes to make the system. They waste resources.
That is why power from any off-grid system is going to cost you many times more than buying it from the utility. The price of power generated by a battery system is always going to be a multiple of the base fuel that created the system. In the case of battery systems 5 to 10 more. The EROI is less than 1.
Another way to think about it is investing. Let's say you buy a 5 year CD from me for $10,000. You pay me me $10,000 today, and in 5 years I give you $1000 back. I will do that every day for you, and make you feel good about it.
The system seems to cover he power needs through the night but is still down to about 73% SOC before he starts to charge it back up. If the morning was cloudy or rainy then he would continue to discharge the battery and will need to fire up the generator.Leave a comment:
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You are correct. His panels set there from noon til dark and do nothing.
Not that unusual, in fact normal but clearly demonstrates what I have been saying on this forum for 6 or 7 years that off-grid solar battery systems are a waste of resources and will never obtain an EROI. The reason is even if you could utilize all the power the panels can generate in a day, the system will never generate more energy than it takes to make the system. They waste resources.
That is why power from any off-grid system is going to cost you many times more than buying it from the utility. The price of power generated by a battery system is always going to be a multiple of the base fuel that created the system. In the case of battery systems 5 to 10 more. The EROI is less than 1.
Another way to think about it is investing. Let's say you buy a 5 year CD from me for $10,000. You pay me me $10,000 today, and in 5 years I give you $1000 back. I will do that every day for you, and make you feel good about it.
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If I am reading those graphs correctly it looks like he starts to charge a little before 8 AM and continues until noon. During that same time frame since he is not exporting to the grid there seems to be a lot of energy wasted.
I am a little surprised that the "charging" cycle does not start again even though he is drawing down his battery voltage. (Unless the charging cycle requires the voltage to go below 52V which is doesn't until after 18:00).
Looks like he could actually use more "storage capacity" based on the Net kw input all morning or stagger his load usage to early instead of after 19:00 where it starts to drain the battery.
Great data. Will like to see more especially on not full sunny days.Leave a comment:
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Man he wasted a lot of solar power, at noon he actually not charging at all.Leave a comment:
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Wow your battery bank graph really demonstrates the very high internal resistance of the batteries and extremely steep discharge curve.Leave a comment:
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My 24 Aquion AHI batteries
Aloha,
This is my new system, installed about a month ago. 2 Schneider XW+ 6848 Inverter, with integrated Power Distribution Panel, and 3XWMPPT80-600Vdc Charge Controller,s 44 LG Optronics 265W High Efficiency Mono-crystalline PV Modules 11.66 kWdc Array producing an annual average of 16-54 kWH per day. **24 AQUION ENERGY Aqueous Hybrid Ion (AHI), Benign Salt WaterBatteryS10 Stack’s in a 48V parallel configuration, and a Honda EU7000si running on propane.
BTW this is the first system to use the Aquion S-10 batteries on the Big Island. As you all know Aquion Energy will be providing the power for the Bakken Hale, he's #2.
The Conext ComBox displays lots of information and here is snapshot of today until 9:55pm HST.
solar21515.jpg
BattBankSummary21515.jpgACPVSummary21515.jpg
Hope this helps
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