The hybrid or bimodal inverter itself costs quite a bit more than non bimodal inverters and almost all of them require batteries. ( storedge being one exception to battery requirement but not cost difference )
we do sell storedge edge systems as battery ready but not that many because you can just get the solaredge se7600 and upgrade it latter if you like to the storedge
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If hybrid allows so much flexibility I really don't understand why people wouldnt want it.
Couldn't you simply get a hybrid inverter without the things that add extra costs like batteries. Justifiable or not the added flexibility is very desirous ( newbie opinion). If the only difference would be in the price of a standard grid tie inverter why not shell out the little bit extra for the added flexibility in case you decide you need another source at a later time? or does going hybrid mean added costs even if you are only connecting PV to it?Leave a comment:
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Thanks for the insightful replies. Nothing super-critical today beyond what a small UPS can handle to bridge the generator start-up & stabilization period.
Time to have a conversation with my contractor, me thinks...Leave a comment:
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Most home critical loads can be handled with small UPS systems sized for computers or electronics. Not worth sizing them for large appliances like a refrigerator which can wait for a generator to start up. The only other critical loads would be medical equipment like an oxygen generator. Then you should have something sized by the manufacturer and it should be right next to that equpment.Leave a comment:
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I think in your case, all a battery is probably going to achieve for you is uninterrupted loads. You can install no battery and only a generator, a big battery and small generator or a small battery and a big generator. You don't need a battery unless you want the UPS-type of power or need to stretch fuel for some reason.
If you need or want a battery, then you have to find your own sweet spot between generator and battery usage. Bigger generator means more fuel and fuel storage, smaller generator with a battery means less fuel and fuel storage. Batteries aren't cheap or maintenance free, nor is a generator. Both have pros and cons. I personally don't believe that it's generator vs battery, but generator or generator and battery. Battery without a generator is not something I would do unless you have a purpose-built designed to consume only PV power.
If your residential area isn't conducive to fuel storage corresponding to your goals, then a battery might help. For example - if you don't have the ability for large fuel tanks (diesel, propane) because of space, or restrictions, no natural gas service, and you don't want to keep a bunch of fuel in your home/shed/garage/etc, then some battery power might help as it will reduce your fuel needs.
If you decide a battery will be part of the equation, figure out how much time you could have your generator run in the power outage scenario you have in mind. This is a matter of considering the fuel storage you are willing to maintain multiplied by your generators consumption rate. ie. If a generator burned 1gph and you were willing to keep 50g of fuel, then you could run for ~50 hours. Now, is that sufficient for the outages you are planning for? If not, some combination of battery and generator might be helpful.Leave a comment:
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To me there are only three reasons you might consider battery:
1) If you have very unreliable power, and the blackouts are a weekly problem, then batteries will significantly reduce your generator run time.
2) If you have critical loads (i.e. a server for a business, or a medical device that can't have its power interrupted) then a battery system will function as a UPS and allow continuous power to those systems.
3) If you live in a place where grid tie is legal but backfeed is not (i.e. places like Hawaii) a battery system allows better utilization of solar power.
In general, you're not going to save any money over straight grid once you add batteries due to replacement costs - so you need another reason (like reliable power) to justify them,
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Hello atebit and welcome to Solar Panel Talk
Depending where you live and what the cost of electricity is a battery system probably will not have a pay back. People in Hawaii might get some type of financial return due to their high cost of electricity but the installation cost of the battery has to be reasonable.
So I believe you having second thoughts is a smart thing.Leave a comment:
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Hi gang,
Brand new to the forum here. I recently signed a contract with a local installer for a grid-tied 20kW PV system with battery & generator backup. From the discussion here, seems like I might want to re-consider the battery part.
I was was planning on going with a low kW "peaking" generator to help out the battery during periods when the power's out and there's not much sun. It sounds like I'd be better off spending the money on a higher output generator and skipping the battery altogether for the extended "island" scenario. After reading these posts, it really makes me wonder why they would've proposed battery at all for our residential application...Leave a comment:
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I talked to the Schneider guy, he was helpful.
The XW and XW+ inverters have something called "enhanced grid support" or "enhanced interactive mode". It is not shown in my XW4024 manual, but it is basically there, described differently (especially since I have upgraded my firmware). Anyway, it is documented in the following place:
go to "downloads", "user documentation", english.
The PDF describes this on page 3-30. The firmware version for this unit is 1.07.
By the way, when you first crank up sell mode, it waits 5 minutes to be sure it is indeed talking to the grid (that has screwed me up before).
My unit is a XW4024 (not Conext). The newest document is for the "Conext XW+". I don't know for sure if my older unit is compatible with "enhanced grid support", but my guess is that it is. The current firmware version is 1.07. I currently have 1.07, which I installed last year, so I should be OK. I also upgraded my charge controllers (to v1.05) at the same time. I did this because my Equalize function dropped out when I tried to start it up. The new firmware has a "soft start" on Equalize.
Apparently the (Xantrex 150) CC is indeed smart enough to engage in this complex dance. Through the network (Xanbus), it has access to "Grid Supp Volts", which is set in the inverter. So it can determine if that is higher than the battery voltage, and act accordingly. -
You must have an interesting story. Surely you didn't pre-plan a 24-volt inverter going with the 600-volt charge controller, since a 150 or 200 or 250 volt would have perhaps worked. I'm guessing that you already had the inverter when the CC came out. There are good reasons to have a single string, but not if you have a separate CC for each string.
I'm going to call Schneider soon, and try to get details. I have found those guys good for routine stuff, not so good for this kind of stuff.**
page 3-17 of the Xantrex configuration manual:
"To allow Grid Support to function after battery charging has completed, it is recommended to set the Charge Cycle to 2-stage. After completing the absorbtion charger stage the XW Inverter/Charger checks whether battery voltage is above the Grid Supp Volts Setting. If battery voltage is above the Grid Supp Volts Setting, the XW Inverter/Charger uses available DC power to support the loads."
** This still doesn't assure that the CC is wide open when the batteries are charged. I don't think it is smart enough.
So the Grid Supp Volts Setting can be a little (somewhat) below the voltage where the batteries are charged, and the above will work (maybe).
"Max Sell Amps" must be set high, whatever the inverter is capable of (maybe 80% of it). The AC1 breaker setting must also be set appropriately high. The default AC1 breaker seems to be set to 60 amps, plenty high. Max Sell Amps default seems to be 27, also reasonable, since 27 * 240 = 6480 watts (the 4024 would max out at 4000 watts). -
Our winters get reasonably cold here... we get plenty of days at 0 degrees, and some colder. I am running at 24v, so I have no means to even come close to the max voltage because I can only harvest 2560w per CC at 24v (per Schneider). I have my CC set to three-phase charging and my inverter to two-phase. Nearly all the time, my batteries are at 100% SoC. Sure, I could then self-consume, but I prefer to just turn off my main on occasion vs trying to do to use load shaving to do so. Some might choose to do try to harvest more during the day, then use at night, but I prefer to enter a grid-outage event at 100% SoC vs up to 50% depleted if such an outage took place in the early hours. This is just my preference. What I don't want to do is just sell my POCO my stored energy. I've not found the magic settings in the XW platform that gives me the best of everything. -
In response to gmaninPA:
If we consider what is going on: If the batteries move in the direction of getting charged up, then the CC will squeeze down on the charging current. So the inverter needs to pull juice out of the batteries (and send it to the loads or to Sell) to keep that from happening. It would be nice if the CC were smart enough to know that all the extra juice that can be harvested will be sold, but I don't think that's the case. Obviously the CC needs to be set to three-stage charging and the Inverter to 2-stage, but that may not be enough.
Concerning your 600V CC: I have gotten interested in the fact that it does not have over-voltage protection, and that the accumulated module voltage increases significantly when it gets cold. Let me know if there is something I am missing. Backing off on the number of modules diminishes the cost-effectiveness of the system. I have actually built a prototype of a protection unit. PA=Pennsylvania? Cold winters? I'm looking for someone to try this out on (Western Washington does not have cold winters.) Check the section of my website that discusses this (SolarWisdom.net). -
I too wonder if my XW system isn't running optimally. I have 4700w of available PV to make, but I've never seen a single moment where I appear to produce over 4kW, despite having optimal angle and tilt and no shading. This is with 600V CCs.
So far, I've theorized this is because the CCs will only capture the energy needed for the batteries + loads + grid sell-back up to the max amps defined in the inverter, which is quite low. However, I'd expect to see the sell-back amps at their limit if this were the case, It's really a mystery to me. If it is configuration-based, I can find nothing meaningful to help. -
This is in response to ncs55'scomment to this post. I have installed a system (DIY) using an XW, batteries and Sell Mode. I am not completely sure that it is operating at optimum, even though I have spoken with the Schneider folks a number of times. I would love to know the specifics of what you have done. I also note that you are using a 600-volt charge controller. I am particularly interested in that. Have you worried about input over-voltage problems associated with excessive Voc in cold tempreatures? See my earlier post (#18, 7/24, 9:53 pm).
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