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https://www.amazon.com/ECO-WORTHY-Switch-Inverter-Limiter-System/dp/B076KBCHBM/ref=as_li_ss_tl?ie=UTF8&qid=1518933833&sr=8-1&keywords=grid+tie+inverter+with+limiter&linkCode=ll1&tag=pw016-20&linkId=14d80654bf39a2dbf6cd15fae100d83e
The inverter converts the solar power into a sine wave your house can use, the limiter prevents any of your power from going back into the grid. These have been around for a long time but they seem to be getting less black market and more gray.
Comments on use here?
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How exactly does this work? I looked at the listing, and it's not clear to me how your electrical system would "know" to use energy from the solar panels rather than from the grid, and how your appliances would "choose" to use the grid power when there isn't enough power being generated by the panels.
I just missed out on a grid-tied system before the PUC changes a few years back, but would be happy to add something if possible.
Leilani Estates, 2011 to Present
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You are right the listing is really short on details, there are many more products available on eBay with better descriptions (usually in broken English) but they generally involve a cabled sensor that gets clamped onto the electrical supply that "dials down" the inverter output if it's greater than what the house is consuming.
My biggest concern (after hooking up unlabeled Chinese electronics to the power grid, of course) is that lets say the unit works splendidly- a small solar array lowers my utility bill $10-$20 a month. I need to run a unit for ~20 months to get a pay back on it and it has a 12 month warranty. With my luck the unit would break before it paid for itself.
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Thank you!
Leilani Estates, 2011 to Present
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How it works: supply variations in a mixed-feed AC system cause the 60Hz sine to drift slightly; this drift can be measured to determine source/sink imbalance. Or something like that.
Does it work: yes ... but modern HELCO digital meters can (supposedly) detect any backfeed into the grid. Old-style mechanical meters will simply run backwards, resulting in a lower bill.
Practical application: put this on the same phase as the fridge, the compressor will eat the difference and help to buffer it from being discovered by HELCO.
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"but modern HELCO digital meters can (supposedly) detect any backfeed into the grid."
I had read in some solar forums that unless you're in a sanctioned solar program the digital meters charge the consumer for any power they feed into the grid.
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probably a better way, don't have to worry about backfeeding, or killing someone (even tho they say the inverter will disconnect from the grid if the powers goes out) I don't trust it much for that.
Anyway...... Probably the best way is to find crap in the house that is taking up a lot of wattage like the refrigerator and maybe a small AC unit, and make it an island. What that means is that it's isolated totally from the grid when the sun is out, and basically what happens is, if a cloud bank passes for 5 or 10 minutes no big deal, the battery bank (a small one) 1 or 2 deep cycle battery(s) can hold that charge for probably 3-5 hours. Anyway, it's basically a high voltage relay, that switches the system to isolate it to 100% solar... So you set a the time for it to switch on when the panels reach a certain level, usually high enough to compensate for the load. Then the system switch back to the grid at a certain time when the panels can't accommodate the load. This is usually where a sun tracker comes in handy... A system that keeps the panels pointed towards the sun for maximum output... say between 9:30AM ~ 4:30PM. So what happens when clouds come ... good question, the system will run off the batteries for a certain time, usually no more than 30% of the capacity of the batteries. If a huge storm rolls in and it drains the batteries down past 70%, then, the system will switch back over to the grid.
You may be thinking... well, if I have to buy a charge controller and batteries ... I might as well go off grid. Yes and No.
For one thing...
1) Won't have to buy a crap load of batteries, since the system would not be on for that long (normally) to begin with and of course the batteries will never be used for night time or long extended sun blockage.
2) Won't have to worry about running the batteries down, because the system would never take the batteries past 70% ... set it and forget it! Of course you'll have to clean the panels and check battery levels.
3) Will maximize the life of the battery since, most of the time, the batteries will just wait around to be used in trickle charge mode. One could expect 16-25 years of battery replacement.
4) Won't have to buy a generator ... as the batteries can charge from the grid if the sun is not out for a very long time. Like a 2 week rainstorm. They can also be put into trickle charge mode nightly from the grid if need be.
The savings would be worth it, and you could get a programmable relay or make your own.
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One could use something like this for a hybrid "grid tie" solar system. (Not really grid "tie" because the switch keeps the solar and grid isolated from each other, but the system can switch back and forth). The transfer switch is automatic and can be controlled by an appliance timer so nothing is draining your battery when the sun isn't out.
Basically, it allows one to use electricity as its generated, no reason to store it for later, no expensive battery banks, no permits, and no permission from helco.
https://www.amazon.com/Go-Power-TS-30-Automatic-Transfer/dp/B00153EYTO/ref=as_li_ss_tl?ie=UTF8&qid=1519060580&sr=8-8&keywords=transfer+switch&linkCode=ll1&tag=pw016-20&linkId=3a22ddfa2a4c0202aa0860ebce13b746
" Product description
Go Power! 30 Amp Transfer Switch is used to hardwire inverters into a system where there is an alternative source of AC. This transfer switch is made to only allow one source of AC power to pass through it to the loads and can handle 30 Amps of service. This ensures that the inverter will not be damaged if the generator or utility power is hooked up while the inverter is running as well as well as contains all instructions."
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None of the major players bother with a system that plugs into the wall in this fashion. The usability is limited in that if the grid power goes down, you can't use this to keep getting power. It might save you a few bucks but it would be less trouble to just buy from the power company until you can step up to a more functional system.
