Large residential DIY questions, Kansas

[rhsolar]

Hi everyone,

I'm doing a large ground mount DIY system and was hoping you guys could help answer some of my questions. Please excuse me if I sound like a novice.

• Here are the panels I found that I am considering: https://store.santansolar.com/produ...445w-144-half-cell-bifacial-mono-solar-panel/
• To be used with these: https://store.santansolar.com/product/enphase-iq8-microinverter/
• For the framing I am just going with 4x4's and 2x4's for a ground mount system. About 6' tall so I could access the inverters later if needed.
• My aim is to offset a small percentage of my usage with the option to expand in the future. I'd like to start with 100 of the 445w canadian panels above.
• My usage is 24.4kwh, 24/7/365.

My questions are:

1. Would I need to notify the power company and/or get a grid tie if I'll never back feed to the grid, using a zero export device?
2. Would I have to set these up in parallel due to the system size? If so, what is the maximum array size using the panels above?
3. If I set up in parallel, would I need a combiner box for each array? If so, what is the maximum sized combiner box available on the market?
4. Will I need any equipment besides these items: panels, microinverters, combiner box(es), cabling, mounting hardware, NEC labels?
5. My array will be approximately 100 yards away from the mains, what size cable should I bury? Is this distance even feasible?

My 2 goals with this are:

1. Offset electrical bill by the maximum percentage possible with my current budget.
2. Ensure system is expandable to ultimately reach 50% usage offset (during daylight hours of course).

I'm not committed to the IQ8 by any means, it was just the only microinverter I saw on SanTan.

My reasoning for choosing micro over string inverters was because I wasn't entirely sure how parallel arrays work with a central inverter, if multiple central inverters would be needed, and how those would tie in with the other components including our existing breaker box. If string makes more sense to you I'm all for it. I was just worried I'd end up with 20 inverter and combiner boxes or something strange like that.

In short, I am hoping to achieve a system of the fewest possible arrays, combiner boxes and tie-ins to the mains as possible. I'm having trouble finding information on what the limitations to these numbers are, so I haven't been able to put together a parts list yet.

If I forgot any information please excuse me again. Happy to fill in any blanks that might result in further advice. Thanks in advance forum people!

Ryan

 

[FilterGuy]

• My aim is to offset a small percentage of my usage with the option to expand in the future. I'd like to start with 100 of the 445w canadian panels above.
• My usage is 24.4kwh, 24/7/365.

Do you really mean 100 of the 445W panels? That would be 44.5KW. If we assume an insolation of 5 for your area, that is 222.5KWh.
Even at 10 of the panels, you would be producing 22.25KWh.

Are you planning any battery system to capture the excess while the sun is shining and use it later when the sun is not shining?

 

[rhsolar]

Do you really mean 100 of the 445W panels? That would be 44.5KW. If we assume an insolation of 5 for your area, that is 222.5KWh.
Even at 10 of the panels, you would be producing 22.25KWh.

Are you planning any battery system to capture the excess while the sun is shining and use it later when the sun is not shining?

Sorry for a novice question but what does isolation of 5 mean?

I will be doing 100 panels to start, eventually adding on another 100 panels. I am not planning on batteries, my usage is much higher than generation would be so there is no need for batteries. I am running 8 computer servers that use 3050w continuous power 24/7.

 

[FilterGuy]

Sorry for a novice question but what does isolation of 5 mean?

It represents the effective hours of full sun per day.

I will be doing 100 panels to start, eventually adding on another 100 panels. I am not planning on batteries, my usage is much higher than generation would be so there is no need for batteries. I am running 8 computer servers that use 3050w continuous power 24/7.

I still don't understand why you would do 100 panels. 3050/445=6.9. You only need 7 panels to drive the servers. However, let's double that to cover inefficiencies and give more power in the morning and late afternoon. 14 panels are all you need if you are not going to try to store the excess production.

 

[rhsolar]

It represents the effective hours of full sun per day.

I still don't understand why you would do 100 panels. 3050/445=6.9. You only need 7 panels to drive the servers. However, let's double that to cover inefficiencies and give more power in the morning and late afternoon. 14 panels are all you need if you are not going to try to store the excess production.

Got it. Yeah my isolation for my exact location is 4.4 I believe.

Also I have 8 servers not 1.
3050w * 8 servers = 24,400w continuous power draw

But it sounds like I did my math wrong, and I'd only need 55 panels total? I was figuring 24,400w * 4.4 hours of isolation = 240ish panels

This is why I'm posting in the forums before buying anything lol If I only need 55 panels that would be a huge relief!

 

[FilterGuy]

Also I have 8 servers not 1.
3050w * 8 servers = 24,400w continuous power draw

24400/445=54.8 or 55 panels if they are providing their full rated power.

You are more likely to get full-rated power out of bifacial panels, but that will only be for a small part of the day. If you do more panels you will cover the needs of the servers for a longer period during the day but there will be wasted power durring the peak of the day.

Now that I better understand your needs and situation, lets go back to some of your original questions.

Would I need to notify the power company and/or get a grid tie if I'll never back feed to the grid, using a zero export device?

That will vary by the power company and local ordinances. Here in CA they are *Very* restrictive.

1. Would I have to set these up in parallel due to the system size? If so, what is the maximum array size using the panels above?
2. If I set up in parallel, would I need a combiner box for each array? If so, what is the maximum sized combiner box available on the market?

Are you familiar with what a micro-inverter is? It is an inverter that is installed on the back of the panel (or near the panel) and outputs 240V. The 240V is run between each of the micro-inverters (in parallel) and then down to the main breaker box. However, I believe the enPhase micro inverters have a limit to the number of inverters on a single AC line. If you need to exceed that number, you just run another AC line. (Note: I have not worked with EnPhase inverters so I could be wrong about the limit).

Here is the rub: I don't think there is any way to limit the output of the micro-inverters with 'just' a sensor on the grid input. You are going to have to have something between the micro-inverters and the grid that will frequency shift the micro-inverters to tell them to reduce power. This gets rather complicated and is beyond my experience set.

Your best bet may be to go ahead and do a full grid tie system with permits and everything. That way the inverters can just dump any extra power onto the grid. If you have a good net-metering program you might even be able to get paid a little for it.