Ground ballast array along front of deck

Ghcoupons

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Hello everyone. New guy here. I just finished building my “forever home” and am in the beginning stages of planning for solar. Due to reasons I won’t go into, it wasn’t an option when we built.

Some history, 1600 sq ft Nudura ICF house, 20 SEER air heat pump, all LED, R48 attic insulation, wood burning stove, marathon water heater, etc. Currently use approx. 950 kWh per month according to our electric bill. (That was from summer and fall, it drops a fair amount when we enter the wood stove part of our winter as I burn with a lot of wood.)

We have a deck on the south side of the house that faces directly south. It is approx 40’ long and approx. 4-5’ off the ground as the gentle slope varies. I had planned to eventually put an array way out in the field that slopes down from our deck but the more I think about that, the less I like it. I don’t want a roof mount (house runs N to S) and don’t want to block the nice view we have. It just so happens that the area directly in front of our deck is a sort of “no mans land” as our leech field is about 6 feet out from the front of the deck. I had no plans to do anything with that area but had what I hope is a good idea and wanted to get feedback.

Depending on what online calculator you use, our ideal panel angle would be 50-53 degrees And some say use the latitude which would be just under 37 degrees. If I used a ground ballast set up I could run a 40’ long run of panels at that angle and they would not be seen by anyone in the house or as you drive up to it. Cosmetically it really is the ideal spot. That of course may not work logistically but that’s why I’m here. Another benefit is that I can run the wiring directly under the deck, into the crawlspace and into the garage where the current breaker box is and an inverter would be. I am capable of pouring the ballast (or using precast pole barn pads that weigh 250-300 each) and doing the frame work, securing the panels, etc, and I would hire an electrician to do the wire run and final connection.

My goal is not to be off grid but to offset some use age and mainly to have power if we lose it. We’re out in the country and when we lose power it can be for days. I also like the self reliance aspect of solar and recognize that it doesn’t necessarily make financial sense for us.

I THINK I want to go with a Solark inverter as I hear really great things about them, their customer service, ease of install and EMP hardening, but that’s not set in stone. Depending on what panel wattage is chosen and the layout (horizontal or vertical) I think a 5kw system would fit there, maybe more if I orient them long ways, but again, this idea is in its infancy. I will try to take pics and add them.

So, is there anything glaringly wrong with this idea? Thank you in advance for your assistance.
 

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svetz

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Depending on what online calculator you use, our ideal panel angle would be 50-53 degrees
I'd use SAM, it factors in the local weather and you can plug your monthly power consumption numbers in to match up generation with consumption. If it rains frequently during the month for the optimum tilt (like here) or if you use most of the power in a particular season you might need to set the tilt more in alignment to your needs. If you do use SAM, watch the tutorial videos; it's a very mature program (still free) and has a lot of confusing options.


My goal is not to be off grid but to offset some use age and mainly to have power if we lose it. We’re out in the country and when we lose power it can be for days. I also like the self reliance aspect of solar and recognize that it doesn’t necessarily make financial sense for us.
Generators are usually the lowest cost for emergency backup (particularly if you have natural gas piped in). But if you really want batteries, Lead Acid might work better in your case than Lithium. Take a look at the battery FAQ. Battery economics are tightly coupled to the number of cycles, if you're not cycling them everyday economics start to favor lead acid (although price fluctuations or incredible deals you come across might change things). Another factor to consider is that Lead Acid likes to be fully charged all the time. Lithium degrades a bit over time if you always keep it fully charged (see https://diysolarforum.com/threads/soc-degradation-of-lifepo4.13215/). I have Lithium for emergency backup, but I keep them charged to 60% capacity unless a storm is coming. Lithium can also be destroyed by charging in cold weather. Not that lead acid is a panacea, they don't like deep discharges, lose power in the cold, etc.

I THINK I want to go with a Solark inverter
Quality product and great support from what I've read too, If you haven't already seen their posts, @HighTechLab just did an install and blogged about his experiences. Similarly, I believe @ArthurEld is in the process of getting his done. I was going to go sol-ark, but at the time they weren't NEMA and my garage was to low for the BFE+1 local requirement (details).

Depending on what panel wattage is chosen and the layout (horizontal or vertical) I think a 5kw system would fit there, maybe more if I orient them long ways, but again, this idea is in its infancy. I will try to take pics and add them.
Hopefully the area is shade-free year around. BTW, just because the roof line runs north/south doesn't mean you can't have an east/west bank on your roof. You can run the numbers in SAM to see what sort of hit you take, but generally adding another panel or two to make up the difference is pretty cheap given everything else. I like them on the roof, but I have a pretty flat roof that's easy to walk on.
 

Ghcoupons

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I'd use SAM, it factors in the local weather and you can plug your monthly power consumption numbers in to match up generation with consumption. If it rains frequently during the month for the optimum tilt (like here) or if you use most of the power in a particular season you might need to set the tilt more in alignment to your needs. If you do use SAM, watch the tutorial videos; it's a very mature program (still free) and has a lot of confusing options.



Generators are usually the lowest cost for emergency backup (particularly if you have natural gas piped in). But if you really want batteries, Lead Acid might work better in your case than Lithium. Take a look at the battery FAQ. Battery economics are tightly coupled to the number of cycles, if you're not cycling them everyday economics start to favor lead acid (although price fluctuations or incredible deals you come across might change things). Another factor to consider is that Lead Acid likes to be fully charged all the time. Lithium degrades a bit over time if you always keep it fully charged (see https://diysolarforum.com/threads/soc-degradation-of-lifepo4.13215/). I have Lithium for emergency backup, but I keep them charged to 60% capacity unless a storm is coming. Lithium can also be destroyed by charging in cold weather. Not that lead acid is a panacea, they don't like deep discharges, lose power in the cold, etc.


Quality product and great support from what I've read too, If you haven't already seen their posts, @HighTechLab just did an install and blogged about his experiences. Similarly, I believe @ArthurEld is in the process of getting his done. I was going to go sol-ark, but at the time they weren't NEMA and my garage was to low for the BFE+1 local requirement (details).


Hopefully the area is shade-free year around. BTW, just because the roof line runs north/south doesn't mean you can't have an east/west bank on your roof. You can run the numbers in SAM to see what sort of hit you take, but generally adding another panel or two to make up the difference is pretty cheap given everything else. I like them on the roof, but I have a pretty flat roof that's easy to walk on.
Thank you very much for your detailed reply. I will download SAM and see what feedback I get.
I am all electric and do have a generator, I’d just like to take things to the next level so to speak. The eventual goal is to have batteries but the cost is still quite high. just Getting the panels and inverter are my first step.

yes the area along the front of the house is totally shade free, which is why it seems like the ideal spot. I don’t want a roof mount system. My roof is decently steep and cleaning them of dirt, snow, etc just seems like a hassle I’d like to avoid if possible. The older I get the less time I like to spend on a ladder. Lol.

Ive been wondering two specific things with regard to my planned system.

1) Does Solark work with Enphase panels so I can slowly add panels as I can afford them?

2) Do concrete pole barn pads work for ground ballasts? Depending on the size, they can weigh over 400 lbs each. Would be easy to frame up a rack with these as the ballasts.

Thank you.
 

Hedges

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Ground mount, ballasted?
How about a rack mounted off the "wall" of the deck, since that faces south?
Take in to account how high you will let vegetation grow.

"Leech" field?
I'm not sure I'd be comfortable living in the vicinity of leeches.
 

svetz

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1) Does Solark work with Enphase panels so I can slowly add panels as I can afford them?
Enphase makes inverters like Sol-Ark does (also batteries and a few other things), but not panels. @GXMnow has a blog where his enphase system is hooked up with a Schneider, but I believe Sol-Ark does that too (but it's a retrofit, since you're starting out best to go one way or another). Enphase's inverters are microinverters, they mount directly behind the panel. They bring a lot of advantages (e.g., don't have to worry about string logistics, easy to add new panels, no need to worry about shade or where it falls), but they also have disadvantages (can't DIY your battery yet).

2) Do concrete pole barn pads work for ground ballasts? Depending on the size, they can weigh over 400 lbs each. Would be easy to frame up a rack with these as the ballasts.
No clue, sorry. Hopefully folks that have done ground arrays can chime in.
 

Ampster

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How about a rack mounted off the "wall" of the deck, since that faces south?
@Hedges beat me to that idea. A lot of the engineering calculations have to do with wind loads and the deck may have enough strength to support the top portion of the row of panels. The bottom could be ballast mounted. I have also heard good things about the SolArk. If you don't need that much power, an Outback Skybox might be a choice. There are many other good choices.
 

Ghcoupons

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Ground mount, ballasted?
How about a rack mounted off the "wall" of the deck, since that faces south?
Take in to account how high you will let vegetation grow.

"Leech" field?
I'm not sure I'd be comfortable living in the vicinity of leeches.
Lol, I meant to say leach field. For the septic system.
if the panels were low on the deck supports, it would be ideal. I need to get out there and see what the various degree recommendations look like, I’m not sure what kind of weight a solar array will be so don’t quite know how best to reinforce the posts.
 

Ghcoupons

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The deck has periodic footings. 2x4 or metal extending out and up from each footing could hold a rail for the bottom.
It does, every 8’. So a 2x4 would work to support the panels? I had envisioned at least 4x4’s but I tend to overbuild everything.
 

Hedges

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Here's a typical panel:


370W, 77" x 39", 50 pounds.

2x4 as a strut only under compression not torsion would of course be plenty strong, one coming off the base of each footing.
Or 1" rigid/imt conduit.

The horizontal maybe I'd use 2x6. If a single row of panels in "portrait" mode and supporting one end of each panel, about 60 pounds distributed across each 8'. Between the deck and the rail on struts, 120 pounds every 8 feet plus the lumber or other structure.

My racks are mostly 2" rigid conduit verticals, diagonals, and horizontals. I use unirac rails with bottom clips.
One is a 1" conduit along top of a fence and another along a block wall.

Some people do pole mounts with a single pipe or 4x4, but I use triangles so it's a truss.

A fixed angle would typically be your latitude (assuming facing due South), unless your needs are more power summer or winter.
 

Ghcoupons

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Enphase makes inverters like Sol-Ark does (also batteries and a few other things), but not panels. @GXMnow has a blog where his enphase system is hooked up with a Schneider, but I believe Sol-Ark does that too (but it's a retrofit, since you're starting out best to go one way or another). Enphase's inverters are microinverters, they mount directly behind the panel. They bring a lot of advantages (e.g., don't have to worry about string logistics, easy to add new panels, no need to worry about shade or where it falls), but they also have disadvantages (can't DIY your battery yet).


No clue, sorry. Hopefully folks that have done ground arrays can chime in.
I’ve been reading up on Enphase as I like the ability to add panels as we can. That certainly makes it cheaper to get my foot in the solar door and add as we want. The microinverters seem like a good option, but I don’t imagine it’s a huge savings vs one inverter? It sure does seem simpler. I may build a shop at some point in the coming years which would provide another location for directly south facing panels, albeit on the roof. The issue I have with enphase, from what I can gather as I read, is that if in the future I want to add batteries, I am kind of locked in to their products. Am I correct in that assumption? I despise being locked in to a proprietary system like that. One of the main reasons for me going solar is to have power when the grid is down. Not some, or basic power for lights that’s doled out by some company’s program, but all,the power I can produce. I understand protection of linemen, I don’t want to do anything unsafe, just access my power. Is Enphase my best route for checking the boxes I have or would I be best suited to look elsewhere? Thanks for everyone’s helpful replies.
 

Ghcoupons

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Here's a typical panel:


370W, 77" x 39", 50 pounds.

2x4 as a strut only under compression not torsion would of course be plenty strong, one coming off the base of each footing.
Or 1" rigid/imt conduit.

The horizontal maybe I'd use 2x6. If a single row of panels in "portrait" mode and supporting one end of each panel, about 60 pounds distributed across each 8'. Between the deck and the rail on struts, 120 pounds every 8 feet plus the lumber or other structure.

My racks are mostly 2" rigid conduit verticals, diagonals, and horizontals. I use unirac rails with bottom clips.
One is a 1" conduit along top of a fence and another along a block wall.

Some people do pole mounts with a single pipe or 4x4, but I use triangles so it's a truss.

A fixed angle would typically be your latitude (assuming facing due South), unless your needs are more power summer or winter.
What would be my best approach for adding weight to reduce wind damage/ uplift? Most of our bad spring/summer weather comes from the south, southwest, directly into the face or at a slight angle of a panel. My thought behind the pole barn pads is that they’re precast, inexpensive, they can be moved with two people and a breaker bar/one person and a small tractor, and they weigh a lot, especially when you add them up along the front of the array. Here’s an example,of what I’m referring too.
 

svetz

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The microinverters seem like a good option, but I don’t imagine it’s a huge savings vs one inverter?
They're very efficient and $/W usually just a bit more than other inverters, but when you take out the MPPT, RSS, and factor in the wiring it usually comes out a bit less overall. YMMV

It sure does seem simpler.
It is. Beyond the plug and Play you get individual panel diagnostics...far easier than trying to diagnose a string of panels at a time.

... in the future I want to add batteries, I am kind of locked in to their products. Am I correct in that assumption?
No. Currently Tesla (who has the lowest installed solar advertised price points, sometimes cheaper than DIY so you might want to check) has a compatible system. Tesla, like the IQ8s, can phase-shift the power causing the solar-inverters to reduce power output. Phase shifting inverters isn't new, it's how utilities can control power from renewables and all the big-name inverters support phase shifting on the grid output too. Given you're not ready now, and that NEC 2020 might prevent you from a DIY battery, Tesla might be your solution anyway.

Enphase just came out with their Ensemble this year, I bet we start seeing add-on AC batteries that support phase shifting pretty soon. See Incrementally Adding AC Batteries for some serious wild guesses 😉.

... Is Enphase my best route for checking the boxes...?
There is no "one best". There are a number of great products out there.

But personally, after having microinverters I don't see myself going to string inverters given the advantages. One not mentioned is that inverters fail, and it's annoying when something fails and you need it. With a string inverter you typically have 1 big inverter; if it goes you have no power. With microinverters you have one per panel. If one or two or three fail, no big deal, you still have some power.
 

Hedges

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Enphase of course duplicates most circuitry for every panel. That makes it a challenge for them to be competitive in terms of cost and efficiency but they may be close. They do use all ceramic capacitors so don't have the issue of electrolytics drying out.

With a high voltage string inverter (e.g. Sunny Boy like I have), you connect multiple panels in series by means of their MC4 connectors until voltage adds up to something between 155 minimum Vmp on a hot day and 600 maximum Voc on a cold day (minimum voltage varies by model; higher wattage units have higher minimum). There are two or three MPPT inputs, so additional strings can be different lengths or different orientations. Virtually any model, voltage, amperage panel can be used; just connect multiple panels which add up to full capability of the inverter. Any single string has to be a single orientation. DC disconnect switch is included. No fuses required. AC goes to a breaker in utility panel. Shading of any panel(s) or portion of a panel simply reduces voltage for that diode-bypassed portion of the panel(s). So long as enough remain to exceed minimum Vmp, the rest produce full power.


String inverters are very simple to use.

Enphase micro inverters can be on panels of random orientation, and only a shaded panel is affected.
A handful of models are available. Large panels today are larger than any of the Enphase inverters, which are listed according to the largest panel they can tolerate rather than the AC power they can produce. One might say it is for up to 500W panel. But, it can only put out 320W AC, so during peak sun output is clipped to 320W.

Do you want battery backup? If you want quality and are either willing to pay the price or shop eBay new in the box bargains (especially Sunny Island), I suggest SMA.

For grid-tie inverters, you need to know what rules apply in your area. California has "Rule 21" which changes the grid voltage/frequency deviations the inverter must ride through, remain connected for a period of time. If similar in your area, the grid tie (e.g.) Sunny Boy must be a recent model.
 

Hedges

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What would be my best approach for adding weight to reduce wind damage/ uplift? Most of our bad spring/summer weather comes from the south, southwest, directly into the face or at a slight angle of a panel. My thought behind the pole barn pads is that they’re precast, inexpensive, they can be moved with two people and a breaker bar/one person and a small tractor, and they weigh a lot, especially when you add them up along the front of the array. Here’s an example,of what I’m referring too.

Instead of a pre-cast footing, consider digging post holes and setting wood or pipe posts like a fence.

If you make a triangular structure properly secured to your deck, it isn't going to go anywhere. The compression/tension strength of a 2x4 or 1" conduit every 8' is all that will be needed to support a rail running horizontally supporting the panels about 2/3 to 3/4 of their length.

You can use commercial mounting rails like these with top or bottom clips to hold panels. With top clips, mount rails in fixed locations, slap panels on top, clamp from top anywhere. With bottom, slide rails to align with holes in panels, hook clip in slot of rail, bolt to panel:


Or you could use pipe and u-bolts, drilling extra holes in panels. Or unistrut (slotted channel). Or wood, maybe carefully locating studs with machine screws to mount panels. Whatever material and design you come up with.

You can look up wind loading at your maximum wind speed. The force it applies is manageable. Only pole-top mounts bending the pole, or very long clear spans, tend to be a problem.
 

Ampster

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The issue I have with enphase, from what I can gather as I read, is that if in the future I want to add batteries, I am kind of locked in to their products
Not at all. A hybrid inverter can AC couple to the Enphase micros. It is less expensive to leverage any GT inverter with a UL 1741 hybrid inverter than use a hybrid inverter for all your system. My system has Enphase and a SolarEdge GT inverter AC coupled to my Outback Skybox.
 

Hedges

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Not at all. A hybrid inverter can AC couple to the Enphase micros. It is less expensive to leverage any GT inverter with a UL 1741 hybrid inverter than use a hybrid inverter for all your system. My system has Enphase and a SolarEdge GT inverter AC coupled to my Outback Skybox.
Does the Enphase linearly reduce AC output as frequency increases, and ramp production back up without delay when it decreases?

Vendors (Including SMA) will claim the frequency shift works with any UL1741 GT inverter. But they don't place nicely unless the GT inverter has a backup or off-grid mode. "Rule 21" compliant inverters are either not much better or no better. I think one implementation is simply to tolerate frequency excursions for a period of time, then drop off for 5 minutes like for earlier code revisions. That doesn't help at all.

When you have Battery inverters and GT inverters that do frequency shift right, it works great.
 

Ampster

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What would be my best approach for adding weight to reduce wind damage/ uplift?
Originally I thought ballast mount, but @Hedges idea of forming a triangle is wort investigating. A strut would support a rail along the bottom. The strut would go from the deck footing to the bottom of the solar panel. The next leg would be the panel itself from the bottom rail to a rail attached to the fascia above the upper posts supporting the deck.
 
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Ampster

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Does the Enphase linearly reduce AC output as frequency increases, and ramp production back up without delay when it decreases?
Modern Enphase inverters modulate or ramp up and down with frequency shift if they meet UL 1741 SA. Older micros just dropped off.
 

Ampster

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When you have Battery inverters and GT inverters that do frequency shift right, it works great
I am a little rusty on this, but Rule 21 is a California requirement. I should have been more specific that the latest UL 1741SA is the one that includes frequency shift with modulation. The other term used is frequency/Watt if I remember correctly. Before anyone tries this they should investigate. Just two letters at the end of a specification can make a big difference.
I am not familiar with the term of back up or off grid mode for a GT inverter. It sounds more like a marketing term than a specification. Neither of my GT inverters use that term but they are UL 1741SA compliant.

AC coupling is a concept that needs a spec to work well. I agree, when they work right it is great.
Outback Power just did a webinar on the evolution of these standards. It did not talk about frequency shifting per say but the direction it was all heading toward was even more interoperability.
 
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