Just make sure you have a good handle on the cost of storage per KWHR, and how realistic the mfr claims are. If you think you are buying and selling for (say) 15 cents per KWHR and it's really 25 cents because your batteries don't last as long as you expect, or you forgot to figure inefficiencies, or the regulatory landscape changes, then you go broke at year 5. And don't get me started on the time value of money.
I usually don't grid charge and sell if profit is less than 20c/kWh. My best so far has been charging with 12c and selling with 235c. That was a good day. You need to remember that batt prices are getting down and for example I pay 125e/kWh (133$) for prebuilt LFP rack batt at the moment. I keep them in temperature controlled room (~20C) with max 0,2C charge/discharge so they should do easily 6000 cycles. For me it's more like a hobby.Just make sure you have a good handle on the cost of storage per KWHR, and how realistic the mfr claims are. If you think you are buying and selling for (say) 15 cents per KWHR and it's really 25 cents because your batteries don't last as long as you expect, or you forgot to figure inefficiencies, or the regulatory landscape changes, then you go broke at year 5. And don't get me started on the time value of money.
Thank you for the information. I am designing this for a class but it is a real design for a client. The client does not like the idea of a large central inverter or other large structures; which is why we were recommended string inverters. Thank you for the suggestions and info; that is very helpful to know about cost differences and I didn't consider the shipping costs since I thought these were US made. I am also in the middle of specifying the electrical distribution panel system and transformers, so any recommendations for those would be great as well. Later tonight I will be finishing up other aspects of the project and then focusing on identifying new inverters per the recommendations and suggestions here, then I will finish with the distribution system (breakers/circuits/etc. - I had trouble finding many options online for such high current, so was thinking about splitting it into 3 smaller systems and transformers and then tying together before it would go onto the grid). This is a really big project and I have been working and have a full school schedule, so I have not only been working on this. I will attach my most recent electrical transmission plan; however, I am already researching higher wattage panels, and need to make changes as mentioned earlier on the inverters before I finish with specifying the distribution systems and transformers.I know nothing about grid scale solar and very little about solar overall.I do know that both my hybrid Deye12K and US market only Sol-Ark15K have about the same specs and both are manufactured by Deye (China). Deye12K is 2450$ (all included) and S-A15K is ~7000$ (don't know if you still need to pay postage or something) so about three times more while being almost identical. Then I have two Bluesun15K (China also) grid tied inverters (=no battery/storage possible) which have 3kW more inverting and PV capacity but costs only about 950$/pc.
For 2MW PV you'd need about 30pc S-A60K units and they seem to be around 19-20k$/pc so assumed getting those cheap with only 15k$/pc would still be 450k$. That's insane. Even more if you aren't planning any battery storage (=no need for hybrid inverting). Using Bluesun15Ks you'd need 133pcs so it would cost only about 126k$ and they'd probably even give you a nice discount from the price I paid.
But like @400bird said there are utility scale grid tied inverters which are more robust and probably give you more bang for your buck. Playing with more than hundred small Bluesuns or alike would be utterly stupid.
In here our selling prices change every hour depending how much grid scale hydro, wind, solar, nuclear, etc. power is predicted to be available. We get next day predictions (=spot prices) at 14.00 every day. Having hybrid inverters and battery storage means you can sell your PV production when it is most profitable and also charge your batteries from grid when spot prices are low and sell it away when prices are high.
"Do you walk to school or bring your lunch?" These concepts are orthogonal to each other.
It's usually the other way around, during peak solar hours the price of power is lowest (because of all the grid-tied inverters without storage), and in some places goes NEGATIVE(!)
Thank you for the information. I thought that the consumer was charged the most during "peak hours", so I assumed that during those "peak hours" of consumption that the selling price would reflect that. That is good news though since I have specified the Sol-ark hybrid inverters as they can act as a battery storage for our client. Do you have recommendations on how to combine the many string inverter's power before it would enter the transformers? I am having a difficult time finding a good source for a panel distribution system (breakers, circuits, etc.). The string inverters were recommended from a local solar farm operator who has had issues with the large central inverters and has very strongly recommended these string inverters. One reason is that when there is an issue with panels or other aspects of the electrical system, the repairs and other issues will be easier to identify, isolate, and solve. I originally had a plan with a nice central inverter system, but was recommended to this which changed the plans drastically. Any recommendations for inverters, panel distribution systems (breakers, circuits, etc.), and transformers would be greatly appreciated.
Well, there's peak solar hours, which is when the sun is brightest and solar electricity production is at it's maximum (and prices may hit a minimum), and there's peak grid consumption hours, which is when the grid is most heavily loaded (and prices may hit a maximum).
2 MW systems are "slightly" outside of the scope of DIY-solarforum. Also sounds totally nuts that someone would order this scale of investment as a school project
Thank you this is extremely helpful. Sorry for the lack in response, I am in a time crunch to get this complete.
Thank you for the information; these seem like some good inverters! I appreciate the help!2 MW systems are "slightly" outside of the scope of DIY-solarforum. Also sounds totally nuts that someone would order this scale of investment as a school project
You probably get better idea what is typically done by googling other MW-range solar farms how they are built.
ABB, Schneider, GE and Siemens are some names in industry that can deliver anything from transformer to inverters.
Sungrown for example has 350kW string inverters or 7MW central inverters : https://info-support.sungrowpower.c...2/29/DS_20231208_SG350HX_Datasheet_V20_EN.pdf
Like @wpns already said there are many different size of string inverters. I would think it would be wise to stay within max 10-20 individual inverters so you should be looking 100-200kW units or even bigger. I know nothing about these monster sized inverters, but I hope they have many MPPTs in them so they can be monitored individually if something goes wrong. I know there are grid tied ones and hybrid ones to choose, but if battery storage isn't needed then cheaper grid tied is the way to go.
Thank you for the info on the inverters. I have changed my plans to include the SG350HX as recommended in this thread. I edited my calculations after changing to the larger string inverters and also have specified Canadian solar 715W panels; these have a bifacial factor of 80% I believe which has helped to reduce the number of panels drastically. I will include my updated plan here. I am struggling to figure out the transformer aspect of the design. The grid is 12kV so after doing a quick calculation I believe that is 15kVA. The only problem is that I was able to find a transformer from the old string inverters up to 15kVA, but now I am calculating the SG350HX's kVA's to be ~234kVA per inverter and with 5 of those we would be up to ~1,168kVA. I will upload my updated electrical calculations here, but any help on a recommendation for a step-down inverter would be helpful, and if someone wanted to look over my calculations and possibly the SG350HX specs to make sure I am identifying the kVA correctly, that would be very great. Thank you again everyone for all of your help I truly appreciate all of the tips and info!!!
What? No. Again, understanding the terms is crucial. VA is volts times amps and is similar to watts but different enough that you need to understand the difference.
I see. I was extremely tired when doing those calculations and switched volts with watts. I have made the correction and believe we will be using the transformer to change the 1,168.4 kVA into 15,240 kVA. I will attach my updated calculations here.
Wow, I have no idea what you are talking about.
What school and class is that? You should not be soliciting external advice on your homework.
I have been running on very low sleep and confused myself about the kVA. I believe I understand now.
