diy solar

diy solar

Midnite Solar Announced their new 10kw AIO at Intersolar Today

@Hedges and @timselectric

I have contemplated re-purposing the transformer out of a Schneider SW inverter to use as a step-up "auto-transformer" to be able to charge with an inverter that does not accept 120V only input (needs to be 120/240V), using a 120V only generator such as a Honda EU3000. Any thoughts on this? What I was thinking is to to leave the low side of the transformer open (and capped off of course!), then just hook up to the 120/240V high side of the transformer same as you would on an auto-transformer. E.g. 120V from gen connected to L1 and N on transformer and also to inverter input L1 and N, then L2 from transformer would connect to inverter input L2.

Would this tend to be especially inefficient for any reason? Not that it is such a big deal anyway, if it is only used for a backup charging option...

Does the additional (low side) set of windings affect power when it is in an open state? I am assuming no since it would be able to introduce any amperage load in an open state, but I'm not a transformer expert.

The reason I would want to try this is that we have a number of SW inverters laying around with blown circuit boards, but perfectly fine transformers. So why wouldn't I try it out... 🤪 I have a standby gen at home and if it is not working for some reason I need to always re-configure my (4) Victrons to have a single inverter charging from a 2000-3000 watt 120V generator. While this works perfectly fine, it would be nice if my wife could switch over easily in a pinch, and a transformer would (should..???) do it.

On a side note, it's pretty cool how the Victrons operate in the above mentioned scenario! One inverter connects to the generator and charges while the other 3 stay in phase (with full 120/240V split phase!) and are inverting! So when my 240V well pump runs, the generator is providing one leg and the inverters on the other phase are providing the other one! Pretty amazing capability if you aske me!
 
Should work, within the 120V and 240V amperage range of the donor inverter.

Note that with an auto-transformer, neutral current is sum of hot leg current, I(N) = I(L1) + I(L2), and the to hot legs always carry equal current.
Does the transformer have two 120V windings fully accessible, 4 wires total? Or only 3 leads? If there is at least a loop of enameled wire for N, connect either 2 leads or 1 lead with 2x ampacity.

Probably the Schneider inverter already has leads allowing it to deliver full wattage at 120V (4kW?) So I think it can work as auto-transformer for up to 8kW or twice whatever Schneider is rated for.

If you were using it to create neutral from 240V source, I think it could turn 8kW 240V into 8kW 120V, given heavy enough neutral lead.
I think it is the same with 8kW 120V source turned into 8kW 240V. (But I'm starting to confuse myself doing it it my head, not drawing it out.)

Open circuit windings have absolutely no effect, operating at nominal frequency. High frequency harmonics maybe interwinding capacitance starts to make LC circuit.

(Shorted windings would absolutely have a deleterious effect!)
 
Hedges said:
Should work, within the 120V and 240V amperage range of the donor inverter.

Note that with an auto-transformer, neutral current is sum of hot leg current, I(N) = I(L1) + I(L2), and the to hot legs always carry equal current.
Does the transformer have two 120V windings fully accessible, 4 wires total? Or only 3 leads? If there is at least a loop of enameled wire for N, connect either 2 leads or 1 lead with 2x ampacity.

Probably the Schneider inverter already has leads allowing it to deliver full wattage at 120V (4kW?) So I think it can work as auto-transformer for up to 8kW or twice whatever Schneider is rated for.

If you were using it to create neutral from 240V source, I think it could turn 8kW 240V into 8kW 120V, given heavy enough neutral lead.
I think it is the same with 8kW 120V source turned into 8kW 240V. (But I'm starting to confuse myself doing it it my head, not drawing it out.)

Open circuit windings have absolutely no effect, operating at nominal frequency. High frequency harmonics maybe interwinding capacitance starts to make LC circuit.

(Shorted windings would absolutely have a deleterious effect!)
Click to expand...
I believe the Schneider inverters are rated to do <70% of rated output on a single leg, which would be ~2800W on single leg. I assume though that the transformer could possibly be overdriven..??? (Just kind of guessing, as the PoCos around here tend to undersize their cans, though that is a different kind of transformer altogether...)

The Schneider transformers have 4 leads coming out, so of course would need to keep straight which ones are Neutrals! Maybe once I try it out I'll make a thread on it, in case anyone else wants to do it.
 
Should be good for 5600W, half transferred through the transformer. Given similar cooling.

You can check out the polarity with a volt meter. So long as the windings aren't fully paralleled, only two (previously isolated) windings joined together, you can apply 120V and see if other leg is in phase or 180 degrees out of phase, making 240V.

(Of course don't short out one winding while powering up the other. That burns things up at 120V. With current limiting, like through a resistor and possibly at stepped-down voltage, short vs. open is part of measuring mutual vs. leakage inductance.)
 
Cmiller said:
The Schneider transformers have 4 leads coming out, so of course would need to keep straight which ones are Neutrals! Maybe once I try it out I'll make a thread on it, in case anyone else wants to do it.
Click to expand...
Please do! I'd love to follow along to learn about what is inside my SW4048 (never even opened mine up!).
Pics would be great.
 
Hedges said:
Should be good for 5600W, half transferred through the transformer. Given similar cooling.
Click to expand...
I didn't think about cooling. It would just be "free air" for my initial test. 😁
Hedges said:
You can check out the polarity with a volt meter. So long as the windings aren't fully paralleled, only two (previously isolated) windings joined together, you can apply 120V and see if other leg is in phase or 180 degrees out of phase, making 240V.
Click to expand...
Good point!
 
Free air works while thermal mass takes its time.
Whatever fan cooling comes with the SW should be good.
You can select a self-resetting electromechanical thermostat.

Could it experience overtemperature? A manually resettable thermostat is available. Some might switch the currents involved, e.g. meant for a heating appliance. But you have to protect against lost neutral, or lost hot leg if 120 to 120/240 feeding both 240V loads and 120V loads. If only feeding a 240V load not a split-phase breaker panel, OK to just switch it out of circuit.

I got some 9kVA toroids that I think were from a UPS. With stepped down AC voltage into one pair of windings, I mapped out the multiple windings with their multiple taps. Then connected together one lead of each to also get phase.
 
First of all I would like to thank all here that are interested in our new upcoming inverter. We call it “The ONE”. I will try to answer whatever questions I can. I am a mechanical engineer and am not actually testing the ONE myself. Ryan, Logan and JimP all in Florida are in charge of the fine tunings of the ONE. bob and I have done our part for now and we are just as excited to get our hands on a production unit as you all are.
Below are some answers and comments after having read the 21 pages here. (In no particular order).
1. Yes, we listen to guys like you! If it wasn’t for comments and suggestions from installers and users we would not be able to make what you all actually want and need. In recognition of this, I am sure we will offer first adopters here with some incredible deals. This is how I started OutBack. Made deals to installers that they could not refuse. It devastated our competition. (Our former employer who fired us). That was fun!
2. We do not have our final costs from the factory yet, so it is hard to say the actual retail price. $5500 has been tossed around, but we will look to see if that can be improved? No promises yet.
3. Frequency shift in AC coupling mode. That is coming this summer. You can also use the programmable input/outputs to assist with AC coupling. We have Three programmable outputs and two AC programmable inputs, plus regular breakers outputs. Lots of options that will make you think how they can or should be used. I don’t think anyone else has something like this?
4. The first 20 units are sitting in Arlington WA now. A few will be going to DIY guys. At least one of which is on this thread. Most have to go to our distribution channel in order to secure future orders. This is really fun, but we have to figure out how to make this high stakes game profitable. MidNite is not a huge company with deep pockets, so we have to tend to business first. We will be giving some of the first units away and/or at great deals to you guys in the early days of this venture, so keep in touch.
5. Grid vs. offgrid. This unit is awesome! Some AIO inverters actually shut off for up to 90 seconds upon loss of grid. Not the ONE. It just keeps the lights on and the beer cold.
6. Charging from a generator is incredible. We have a lot of experience good and bad charging from generators over the last 35 years. This unit is incredible. One day we were testing with a generator that has wheels and handles ( we hate those kind). We forgot to push the choke back in. The generator was laughing and sputtering, but the ONE never disconnected. Boy we were not expecting that.
7. 1201 is asking tough questions. I would like one of of employees doing the testing and designing to answer his questions. By the way, the Sunny Island is a great inverter.
8. Someone said MidNite always overperforms. After having been intimately involved in the design of about 100 different inverters now from 5 companies I can truly say some designs were better than others. Most I am very proud of, but there were a few where I left the scene with my tail between my legs. Fortunately I try not to make the same mistakes again. I invent new ones. For the ONE, we are doing much more testing and changing than any inverter I have been involved in for 35 years. Things don’t always work the way you think they will, so we test, document and communicate back with the engineering team. Speaking of which, there is a lot of speculation on what company builds what. I enjoy reading all the theories here. We know who builds what! We have visited every one of the factories mentioned here and many more. You will not find another inverter made from our factory. The ONE is the only inverter available in North America coming from this factory. They are the best. Bar none. We have not discussed price to any extent as that would compromise all the special features and requests that are being designed into the ONE. We know it has to be competitive though. It will not be competitive with the tier 1 inverters that sell for $3000 though. They are not in the same class.
9. One of the owners of MidNite Solar spends half of his time now in China to insure we are getting things done to our spec.
10. One thing that we are paying attention to are menus. Many AIO inverters are really hard to figure out. We are fixing that. Another is how these are installed. We are saving 1.5 hours and $100 in parts on installing it to a gutter vs. other AIO inverter. Simple stuff, but very important to installers. They too have to be competitive and just those savings can make or break a sale.
11. Similar looks of different inverters don’t mean that the insides are the same? I beg to differ with you. If they are just a different color on the outside, they ARE the same on the insides. Just like our DIY series. That isn’t necessarily a bad thing, but don’t listen to the sales BS.
12. Output power: the ONE is 10,000 continuous at night and 11.4kw with PV in.
The big difference is that the ONE has really good surge power. That is more important than an extra 2000 watts continuous. Nobody tries to run their inverter continuously at full power. Batteries get sucked dry too quick.
13. 6500 feet altitude. It would do more, but that is just what we decided to have it tested at. It gets really expensive if you fail a test and then have to go back and retest. We conformal coat the boards and that helps insure arcing won’t happen. I am not worried about running at higher elevations. Some very expensive AIO inverters do not have conformal coating. I think that is criminal. Those units will not last but a few years!
14. Selling to the utility when it isn’t supposed to: yes, we have had the utilities show up at two of our test facilities. That is one reason it isn’t released yet.
15. Production is slated for early MAY.
16. Don’t be fooled by a 200 amp pass through. It normally doesn’t make sense and it is not less complicated or less expensive for the install. We too will eventually do this, but it does not make for a better or cheaper install!
17. So to sum it up, we did NOT paint a Chinese inverter our color. We have spent a ton of time and money to insure this inverter will be the best inverter on the market.
Thanks,
Robin Gudgel
President,
MidNite Solar
 
To add to Robins notes, Selling to the grid NEVER happens when you do not tell it to. In all cases we have messed with combinations of settings and made it sell. For example time of use, I accidently turned on discharge in time of use and it sold to the grid lol. I am now working on changing the word "Discharge" to "Sell" for example
 
Robin Gudgel said:
First of all I would like to thank all here that are interested in our new upcoming inverter. We call it “The ONE”. I will try to answer whatever questions I can. I am a mechanical engineer and am not actually testing the ONE myself. Ryan, Logan and JimP all in Florida are in charge of the fine tunings of the ONE. bob and I have done our part for now and we are just as excited to get our hands on a production unit as you all are.
Below are some answers and comments after having read the 21 pages here. (In no particular order).
1. Yes, we listen to guys like you! If it wasn’t for comments and suggestions from installers and users we would not be able to make what you all actually want and need. In recognition of this, I am sure we will offer first adopters here with some incredible deals. This is how I started OutBack. Made deals to installers that they could not refuse. It devastated our competition. (Our former employer who fired us). That was fun!
2. We do not have our final costs from the factory yet, so it is hard to say the actual retail price. $5500 has been tossed around, but we will look to see if that can be improved? No promises yet.
3. Frequency shift in AC coupling mode. That is coming this summer. You can also use the programmable input/outputs to assist with AC coupling. We have Three programmable outputs and two AC programmable inputs, plus regular breakers outputs. Lots of options that will make you think how they can or should be used. I don’t think anyone else has something like this?
4. The first 20 units are sitting in Arlington WA now. A few will be going to DIY guys. At least one of which is on this thread. Most have to go to our distribution channel in order to secure future orders. This is really fun, but we have to figure out how to make this high stakes game profitable. MidNite is not a huge company with deep pockets, so we have to tend to business first. We will be giving some of the first units away and/or at great deals to you guys in the early days of this venture, so keep in touch.
5. Grid vs. offgrid. This unit is awesome! Some AIO inverters actually shut off for up to 90 seconds upon loss of grid. Not the ONE. It just keeps the lights on and the beer cold.
6. Charging from a generator is incredible. We have a lot of experience good and bad charging from generators over the last 35 years. This unit is incredible. One day we were testing with a generator that has wheels and handles ( we hate those kind). We forgot to push the choke back in. The generator was laughing and sputtering, but the ONE never disconnected. Boy we were not expecting that.
7. 1201 is asking tough questions. I would like one of of employees doing the testing and designing to answer his questions. By the way, the Sunny Island is a great inverter.
8. Someone said MidNite always overperforms. After having been intimately involved in the design of about 100 different inverters now from 5 companies I can truly say some designs were better than others. Most I am very proud of, but there were a few where I left the scene with my tail between my legs. Fortunately I try not to make the same mistakes again. I invent new ones. For the ONE, we are doing much more testing and changing than any inverter I have been involved in for 35 years. Things don’t always work the way you think they will, so we test, document and communicate back with the engineering team. Speaking of which, there is a lot of speculation on what company builds what. I enjoy reading all the theories here. We know who builds what! We have visited every one of the factories mentioned here and many more. You will not find another inverter made from our factory. The ONE is the only inverter available in North America coming from this factory. They are the best. Bar none. We have not discussed price to any extent as that would compromise all the special features and requests that are being designed into the ONE. We know it has to be competitive though. It will not be competitive with the tier 1 inverters that sell for $3000 though. They are not in the same class.
9. One of the owners of MidNite Solar spends half of his time now in China to insure we are getting things done to our spec.
10. One thing that we are paying attention to are menus. Many AIO inverters are really hard to figure out. We are fixing that. Another is how these are installed. We are saving 1.5 hours and $100 in parts on installing it to a gutter vs. other AIO inverter. Simple stuff, but very important to installers. They too have to be competitive and just those savings can make or break a sale.
11. Similar looks of different inverters don’t mean that the insides are the same? I beg to differ with you. If they are just a different color on the outside, they ARE the same on the insides. Just like our DIY series. That isn’t necessarily a bad thing, but don’t listen to the sales BS.
12. Output power: the ONE is 10,000 continuous at night and 11.4kw with PV in.
The big difference is that the ONE has really good surge power. That is more important than an extra 2000 watts continuous. Nobody tries to run their inverter continuously at full power. Batteries get sucked dry too quick.
13. 6500 feet altitude. It would do more, but that is just what we decided to have it tested at. It gets really expensive if you fail a test and then have to go back and retest. We conformal coat the boards and that helps insure arcing won’t happen. I am not worried about running at higher elevations. Some very expensive AIO inverters do not have conformal coating. I think that is criminal. Those units will not last but a few years!
14. Selling to the utility when it isn’t supposed to: yes, we have had the utilities show up at two of our test facilities. That is one reason it isn’t released yet.
15. Production is slated for early MAY.
16. Don’t be fooled by a 200 amp pass through. It normally doesn’t make sense and it is not less complicated or less expensive for the install. We too will eventually do this, but it does not make for a better or cheaper install!
17. So to sum it up, we did NOT paint a Chinese inverter our color. We have spent a ton of time and money to insure this inverter will be the best inverter on the market.
Thanks,
Robin Gudgel
President,
MidNite Solar
Click to expand...
Very interested to see forum feedback from testers. I'm currently nailing down a "grid-assist" off-grid DIY setup now and grid feedback is something I want to avoid with a 20' pole.
 
Robin Gudgel said:
It will not be competitive with the tier 1 inverters that sell for $3000 though.
Click to expand...
If that is the case, then you are saying your inverter is better than tier 1?

>>We call it “The ONE”
As a Matrix fan, you are making the bar quite high.

>>Speaking of which, there is a lot of speculation on what company builds what. I enjoy reading all the theories here. We know who builds what! We have visited every one of the factories mentioned here and many more. You will not find another inverter made from our factory.

As potential buyer his does not make me feel better about your product.
Any reference to a known, reliable manufacturer is gone.
I probably wouldn't repeat this ! :)

Your company has a reputation for good support, which is important.
What about warranty for this product? What are you thinking?

Conformal Coatings:
Can you clarify this? I have seen various coatings used on boards. Some appear to be a heavy plastic like material. Other coatings are simply to prevent corrosion and quite thin. That is commonly used in things like industrial VFDs, etc, to prevent corrosion.

My inverter will live a nice life in a controlled temp environment, so adding a heavy conformal coating suitable for installation in an unheated garage environment is a total overkill for my application. If you are spending serious $$ on conformal coatings I would offer that as an option.

I'm with Banjoman; Many of us need to avoid grid feedback to avoid legal entanglements at the local level.
In some flyover states, the local utilities are trying to dissuade solar installations by promoting ridiculous installation requirements and inspections.
Here, building a house is legally easier than installing a solar system.

Thanks!
 
Robin Gudgel said:
2. We do not have our final costs from the factory yet, so it is hard to say the actual retail price. $5500 has been tossed around, but we will look to see if that can be improved? No promises yet.

Robin Gudgel
President,
MidNite Solar
Click to expand...
I was very excited to see this product, but at that price point I would totally lose interest.
 
I screwed up when I said we won’t be competitive to a tier 1 inverter. I meant to say tier 2 and 3.
As for conformal coating, we have been doing this on all the Trace. Xantrex, OutBack and Magnum inverters since 1990. It helps to lengthen their lifespan. In an unheated space, you will draw in small amounts of moisture when it cools off. That eventually allows green stuff to grow (corrosion). Two things kill inverters. Too much heat caused be many things including poor design and corrosion. One or the other is going to get you at some point. The ONE has a 10 year warranty.
 
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