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  • #16
    Originally posted by Ampster View Post
    The EG4 has a certification from TUV, whatever that is?
    TUV is an inspection association that tests and certifies products, systems and procedures not unlike ISO 9000, etc.
    It's German in origin and been around a long time.
    Google it for more info.

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    • #17
      Originally posted by rebelrider.mike View Post
      ..........Where did you find it?
      It is not on the spec sheet but I thought I saw it on the Signature Solar website but now cannot find the exact reference. One of the EG4 models does show UL1547 listing.
      9 kW solar, 42kWh LFP storage. EV owner since 2012

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      • #18
        I don't know if this would be interesting or useful to folks, but its easy to share, so...

        InverterSpecsA.png
        These are the first of the specs I've compiled for each inverter I've researched. The cells I marked red are the deal-breakers for me. But they may not matter to others.

        Anyway, 4 of these didn't get eliminated, and I'm looking into a few more specs to see if I can choose one over the others.
        InverterSpecsB.png
        As you can see, this list is still incomplete, and I've got to go back and take a closer look. I did my best to find at least 1 product from each popular brand that I'm aware of.
        Washington, all electric, solar hopeful.

        Comment


        • #19
          Originally posted by rebelrider.mike View Post
          .....
          As you can see, this list is still incomplete, and I've got to go back and take a closer look. I did my best to find at least 1 product from each popular brand that I'm aware of.
          What is missing is what feature set is important to you? Since everyone is split phase that is a given and does not need to be listed Do you want back up. peak shaving or both? A lot of those are not UL listed. Is that important? Do you want AC coupling capability, grid interaction or grid selling capability?
          9 kW solar, 42kWh LFP storage. EV owner since 2012

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          • #20
            Well that's an interesting point. When I started this thread, I didn't know enough about inverters to answer most of those questions. I'm a bit further along now, so I can take a crack at it.

            In general, my highest priority is to have some power available to key circuits in the event of a grid outage. My area has short outages every year due to wind storms. Every few years we're hit with a big one, and there is so much damage that it can take days to get power back. Weeks in the more remote areas. I'd rather not have to be running into town for gasoline or propane every couple days, and assuming that's what everyone else will be doing too, there may be fuel shortages. So I'd like to employ a generator, battery and solar panels.

            My second general priority would be to have a reduced power bill. Since I'll have solar and a battery set up at some point, may as well use the free electricity instead of the stuff I have to pay for. It's too dark in the winter, and I use too much electricity to ever go off grid. But I can certainly collect enough solar power even in winter to cover a significant part of my overall power usage.

            One priority I don't have that a lot of other people do, is selling power back to the grid. I really have no interest in that for a couple reasons. Firstly, I don't think I'll be making much excess power most of the time. Maybe a little in the summer, but I don't think it'll be enough to be worth it. Secondly, my PUD and I have a philosophical disagreement about how solar should be used. They'll never approve a grid-tie system as long as the solar continues to power my house during a grid outage. Even if I have a lockout or transfer switch installed. They're fine with generators though. Makes no sense to me.

            On to specifics I'm looking for in an inverter. It took a while, but I finally figured out that I definitely want a split phase unit. I see that there are transformers out there to allow 120V inverters to power 240V devices. But as I want my key circuits to be able to use grid, generator, or inverter power, they will need to be compatible. As the grid and generator are both split phase, so must the inverter be.

            The next thing I'm looking for is cost. Not just in the short run, but also looking to the future. What I mean is that every inverter will eventually fail. Given the dismal state of tech support now a days, I'm assuming that if my inverter breaks, I'll have to buy a new one. Can't depend on companies to honor their own warrantees. I see that I could buy 5 EG4 inverters for the cost of a single Sol-Ark. Maybe the Sol-Ark is made of sterner stuff and would outlast 5 EG4s. I don't know. From my noob perspective I see people say stuff like that, but I have yet to see proof that less expensive devices are guarantied to be junk.

            Another consideration is whether the inverter can provide split phase by itself, or if it needs to be paired to a twin. Having to buy two inverters doubles the cost right from the start. It also doubles the idle power usage, and I'm sure it isn't great for efficiency either. Also, if one fails a few years down the road, will I be able to find a compatible replacement, or will I have to replace both? A single unit that provides split phase on its own makes a lot more sense to me.

            Related to single vs. paired units is the power output. I'm looing for about 6kW, but I could get by with a little less. Though a pair would only need to provide 3kW per unit. Not all brands have 6kW units or pairs. I was going back and fourth between the possibility of a pair vs. a unit for a while, so I researched both. Ultimately I decided to go with a single split phase unit.

            Inverter efficiency is another one. I decided 90% or higher would be the cutoff for me. This was sometimes a tricky value to find. A lot of inverters are advertised as 99% efficient. But that comes from how well it sends power from the grid to the load. I'm interested in the efficiency from DC to AC. There's also the efficiency from solar DC to battery/inverter DC. Also usually in the high 90s.

            Availability was pretty difficult for me at first, having no idea where to shop except maybe Amazon. A lot of brands' websites don't sell directly but have a "where to buy" link. Often the seller's website says "we have that brand, but not the model you're looking for." So for a while, many of these inverters I was interested in, I couldn't find a price or seller. That's mostly cleared up now.

            Having at least 1 integrated MPPT solar charge controller in the inverter makes a lot of sense to me. And almost all the inverters I found have at least 1. For the ones that have none... they aren't any cheaper, and in some cases are even more expensive. More than one isn't necessarily better. For example the EG4 only has one but it can handle a fairly large array. Vs. another, I think one of the MPPs that has two independent controllers, but they each can only handle a small array. For me the single larger one fits what I want to do a little better.

            Finally there's Total Harmonic Distortion, or THD. This was quite a rabbit hole! For one thing, not all companies are willing to put a number to this specification. Victron and SunGoldPower flat out refused to admit their inverters even had harmonic distortion. That was a deal killer to me. Turns out THD is a difficult number to nail down. In the case of "pure" sine inverters, you can have a different value of THD depending on whether the inverter is under load or not. And how much load. And whether the load is resistive, non-linear or inductive. Conventional generators also have harmonic distortion, though it's generated in a different way. And different kinds of loads can create harmonic distortion that adds to the whole system. A big system like the grid pretty much dilutes harmonic distortions. But a tiny system like an off grid house it can add up quick. So the best answer a company can give is a ballpark figure. From what I've seen most pure sine inverters are rated at <5% THD or better. 0% being an ideal perfect wave. Even the almighty grid has a THD of around 3%.

            Well that was a long-winded response, but you ask for it, LOL.
            Washington, all electric, solar hopeful.

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            • #21
              I am happy with the features of my SolArk. I found a local supplier which had a very competitive price and of course I could pick it up, which saved freight. To me it is more of a risk management decision to go with Tier 1 components with support than the less expensive variations which may not have much support. When I first started posting on this forum most people just said, buy a generator.

              It all depends on where you are standing.
              Last edited by Ampster; 03-09-2023, 03:30 PM.
              9 kW solar, 42kWh LFP storage. EV owner since 2012

              Comment


              • #22
                I'm one of those people that say "buy a generator" if you're looking to keep the lights on if the grid goes down. If you choose batteries, do you have enough battery power to start your well pump or furnace? What is the weather forecast for the next 5 days? Better start saving battery power if it's not clear skies. What is the lifespan of the batteries? Will you still get 50% of their rated power 10 years down the road? Just thoughts to consider for the OP.

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                • #23
                  I get what you're saying about risk management. For me, the problem is that I have no faith in any company to offer good tech support, or to honor their guarantees or warrantees. This cynicism comes from experience, unfortunately.

                  Generators are great. Right now I have my eye on a WEN DF875iX inverter generator. It has most of the specs I'm looking for, and replacement parts are available so I can repair it myself if it breaks. The first stage of my plan is to install it like this:
                  Generator.png
                  Generators have one fatal flaw (at least from my point of view) if there's a fuel shortage, it doesn't work. Other less important issues I have are that fuel is expensive, and inconvenient to procure. Especially in bad weather. Generators are noisy, and easily stolen. Exhaust stinks, and you have to keep putting fuel in them. None of this will keep me from buying one. But I don't want to depend on one as my sole source of backup power.

                  Now, if the power outage is only a couple hours; no big deal. I'll wait it out with a flashlight and a good book. If it's longer, I'll want to start the generator to cool down the fridge and freezer, and charge a few batteries before shutting it off again. That could get me by for a couple days. Longer than that though, and folks are going to be flocking to the gas station to buy all the fuel. Will the gas station be able to keep up with demand? I don't know. Remember the toilet paper shortage? And storing gasoline is not really a good idea. Propane is better for storing, but won't produce as much energy as gasoline. At least with a dual fuel generator there's an option to buy one if the other is scarce.

                  I haven't written here much about generators because I'm mostly trying to learn about inverters. But any generator I get must have <5% THD, be dual fuel, produce 240V split-phase, at least 6kW, and be field repairable. The only thing I don't like about the Wen is that it has an open frame despite being an inverter generator. I haven't found any other generators that fit what I want in my price range though, and I plan to build a tiny shed for it anyway.

                  I'm still working on how the generator, battery, solar, and energy budget are all going to work together. Here's what I've got so far:
                  Appliances.png
                  As you can see, (I hope you can see it ok) it's not complete enough to be useful yet. What I really want to find are the peak Watts, measured Watts, and how many Wh/day I might use with all the things that would be nice to run during an outage, or to run less dependent on the grid during good times.

                  These totals must be selective though, as not all devices will be run at the same time. The most obvious example would be space heaters and air conditioners. Also, my power usage behavior during an outage could be much different than while power is plentiful. The amount of time each device is used is just as important as how much power they use. A person could get by for a long time on a small battery if they were to budget their usage accordingly.

                  For example, ration power to the fridge and freezer just enough to keep the food from spoiling. Turn off the water heater completely. Don't use the microwave, space heaters, A/Cs, cloths washer, or laptops at all. Only use 1 LED light. If the internet is down, turn off the gateway/router/wifi. Have only 1 cell phone on, and don't make calls. Text and check for power grid updates only. Assuming the cellular network is even functioning. I built myself a 40 hour battery for my CPAP for camping. (I kept getting noise complaints from the bears.) I could stretch that out to a week or two of sleeping if I had to.

                  Then again, if gasoline and solar power are plentiful, turn everything on and have a party.
                  Washington, all electric, solar hopeful.

                  Comment


                  • #24
                    I've realized a couple things. Firstly, I haven't added in the power used by the inverter to any of my calculations. Not catastrophic, but it does make a difference since it will be running 24 hr/day.

                    Another thing is that a feature who's term I don't know is going to be pretty important to me. I'm calling it load sharing unless someone can correct me. It's the ability for the inverter to split the power being used between two inputs. As in using solar and grid vs. using solar or grid. I've read through all the manuals available for the inverters I've been researching. Some are pretty clear that they either do or don't have this feature. (But none of them actually name it.) Other manuals are not clear at all.

                    This ability, along with the inverters ability to pass grid power strait through to the sub panel, will affect how many circuits I can put on the sub panel. I'd still be limited to a small number of devices during a power outage, but during normal times, I can potentially maximize my solar energy usage. I've ordered an energy monitor to help figure out how much load is on each circuit.
                    Washington, all electric, solar hopeful.

                    Comment


                    • #25
                      Originally posted by rebelrider.mike View Post
                      ..............

                      Another thing is that a feature who's term I don't know is going to be pretty important to me. I'm calling it load sharing unless someone can correct me. It's the ability for the inverter to split the power being used between two inputs. As in using solar and grid vs. using solar or grid. I've read through all the manuals available for the inverters I've been researching. Some are pretty clear that they either do or don't have this feature. (But none of them actually name it.).........
                      There is a whole new range of load panels that have smart capabilities that can be in a subpanel so that the decision on which loads you put in which sub panel is not as important. Sometimes this feature is called smart loads and some inverters can reconfigure a bidirectional port to be used for smart loads, a generator or AC coupled solar.
                      This ability, along with the inverters ability to pass grid power strait through to the sub panel, will affect how many circuits I can put on the sub panel. I'd still be limited to a small number of devices during a power outage, but during normal times, I can potentially maximize my solar energy usage. I've ordered an energy monitor to help figure out how much load is on each circuit.
                      I use one of those Emporia Energy monitor on both my sub panels and it is one of the most cost effective devices I have purchased.
                      9 kW solar, 42kWh LFP storage. EV owner since 2012

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                      • #26
                        I got the Emporia Vue installed a few days ago. So far it's doing well. One sensor came non functional. Emporia is sending me a new one. But I'm already getting lots of useful information.
                        Washington, all electric, solar hopeful.

                        Comment


                        • #27
                          My Generac standby generator runs off natural gas so unlimited fuel supply and it weighs more than 400 pounds and is screwed to a concrete slab. It is also behind a locked gate with a 2x2 inch metal frame. Pretty near impossible to steal by anyone.

                          The cost was the same as for a comparable output Tesla powerwall and the powerwall would provide power for at most two days and so not a good solution as we have power out for longer periods of time. Also there is not the fire hazard of the powerwall with the natural gas fueled generator.

                          I replaced my SunPower (actually a Sonny Boy rebranded) inverter that failed in September of 2022 with a Solis inverter I bought online. The Solis is far superior to current offerings from Sunpower and others and Solis provides but a modern interface to the inverter, but also wifi for remote diagnotics over the internet as well as a smartphone app. Their field engineers are not too bright but their in-house tech support people are very knowledgeable and supportive.

                          All I needed was a two MPPT charge controller with a capacity of 3.7 kW or greater and these are not difficult to find for immediate purchase by anyone. Fortunately the Sunpower dealer realized that Sunpower was dragging its feet on replacing my failed inverter, agreed to install whatever inverter I bought. After communicating with Sunpower people over the past 6 months it is obvious that it would be foolish to look for them for support. I paid for an extended warranty and that turned out to be a complete waste of money.

                          Something I failed to appreciate when it came time to replace my failed inverter was that in my area the solar installation businesses do not do any work on a system they did not themselves install. I had 4 different local companies refuse to install a replacement inverter. That is one situation where microinverters that one can easily replace themselves would be a big advantage.

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                          • #28
                            I've been pleased with the quality and support for Solis string inverters. They make a hybrid too (which I've never bought).
                            https://www.ginlong.com/energy_stora...k_s6_h_us.html

                            The Growatt 6000TL-XH-US may be worth looking at as well. I've installed one without batteries.

                            Comment


                            • #29
                              Originally posted by rebelrider.mike View Post
                              I don't know if this would be interesting or useful to folks, but its easy to share, so...

                              InverterSpecsA.png
                              These are the first of the specs I've compiled for each inverter I've researched. The cells I marked red are the deal-breakers for me. But they may not matter to others.

                              Anyway, 4 of these didn't get eliminated, and I'm looking into a few more specs to see if I can choose one over the others.
                              InverterSpecsB.png
                              As you can see, this list is still incomplete, and I've got to go back and take a closer look. I did my best to find at least 1 product from each popular brand that I'm aware of.
                              I don't believe the claimed 97% efficiency for the Deye 6K inverter. Get an inverter with a CEC efficiency rating, so you can verify it online.
                              https://www.energy.ca.gov/programs-a...quipment-lists

                              Comment


                              • #30
                                I bought the Solis as it had the latest and greatest engineering of the inverters I could research. I like that they have an external port where you can attach an adapter and use a USB drive to apply firmware updates yourself. The same port works with a Wifi adapter so you can access it over the internet or with a smartphone to monitor activity. The Solis customer support provided by phone is also very good and that is as important as any other aspect of a device.

                                I bought a 5G model that can charge a battery backup system in the future. At current battery prices it is not a good choice in my situation but as battery prices decrease it may be a good move in the future.

                                Solis also provides a 10-year warranty and is a large enough company to be around 10 years from now. Many inverters sell with a 5-year warranty and not something I would consider when others at the same price have a 10-year warranty.

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