Why are turnkey Solar PV systems so ridiculously overpriced?

[TheTalkingMule]

Yep... even in a place like NM... importing wind energy from Oklahoma will likely always be cheaper than using MASSIVE batteries due to changes in solar insolation from storms or seasons.

You don't need massive batteries to get rid of utilities as we know them. So long as they simply manage the means to sell and shift supply between regions, most local needs can be handled by the third party installed/monitored micro-grid and oversized renewables. Haven't read up on it yet, but it looks like Germany's utils have already begun adapting by carving off all production and focusing on grid management.

Without the incentive to add greater and greater amounts of centralized production, the more logical and efficient solutions will naturally take over. How all that supply is traded.......who knows, but I don't see any way our system isn't rapidly decentralizing in 10 years. Once that ball gets rolling you'll likely see the long distance lines stretching as noted above. Spain at some point is logically going to want to stretch out as far as is humanly possible to get value for it's massive excess solar capacity.

 

[Skotty]

One of the big problems is just trying to get reputable solar installers in places that need solar the most. Note the graphic below. See the problem? How do we fix this?

Assuming I counted correctly, looking at the continental 48, Solar City is in 9 of the 14 lowest polluters, but in only 7 of the remaining 34 higher level polluters. They are in only 2 of the worst 17 states, 1 of which is itsy bitsy Delaware.

 

[strider]

One of the big problems is just trying to get reputable solar installers in places that need solar the most. Note the graphic below. See the problem? How do we fix this?

I would guess it has a lot to do with power pricing.

Here's electricity pricing for Oklahoma:
Base service charge: $20
June-October:
$0.02891/kWh for the first 1,350kWh
$0.03757/kWh all additional
November-May:
$0.0258/kWh for the first 475kWh
$0.0171/kWh for the next 775kWh
$0.0114/kWh all additional

Or you can go TOU:
Base service charge: $20
June-October:
$0.0782/kWh peak time (14:00-19:00 M-F)
$0.0171/kWh all other kWh
November-May:
$0.0258/kWh for the first 475kWh
$0.0171/kWh for the next 775kWh
$0.0114/kWh all additional

As long as Nat gas prices stay low I don't see this changing. PV will have to get a LOT cheaper to make this pencil out aside from small systems for self-consumption to take the sting out of that peak time rate.

 

[Skotty]

So because of the way my roof is, the solar installer was considering installing panels on my roof neither vertical nor horizontal, but at roughly a 45 degree angle on our south facing roof. This allows more panels to be installed (imagine a roof segment that is more diamond shaped than rectangular) Can anyone find any pictures of solar installed in this manner? I think it would be fine, but it would be nice to see a real world example. I haven't found any in my googling yet.

A quick reply to myself. I happened to run across a picture of panels installed at an angle, so thought I would post it.

http://kbnd.com/assets/images/Habitat Restore Solar.jpg

 

[ohmman]

A quick reply to myself. I happened to run across a picture of panels installed at an angle, so thought I would post it.

That's a really cool looking installation.

 

[miimura]

That's a really cool looking installation.

Technically pointless, but cool looking. The earlier examples shown at least had roof structures that made the angled installation sensible or necessary.

 

[FlasherZ]

I know it's really not the primary topic of the conversation, but since I started talking about it here I thought I would note that my project is finally complete...

28 x 240W monocrystalline SolarWorld panels. 6.7 kWp on a Delta Solivia inverter. Panels are flush mounted due east/west on a 1/12 pitch roof (~5 degrees). Yes, I expect to have to wash the silt off the panels once a year or so because of the shallow angle, but the goal was to make this an inexpensive install; tilt legs only added expense and reduced the estimated yield.

Yes, I'm slightly concerned about the rail spacing -- I can't control that as the rails must sit directly on top of the purlins (this roof doesn't have vertical rafters, instead it has horizontal purlins) and they're at 5' spacing. I did some pricing for vertical rails but it was far too expensive.

We commissioned the system at 12 pm; by 7:30, when the system was down to 150W or so, we had completed 25.25 kWh - and for us that means just over $2.75 in savings (11c per kWh). Maximum power seen was 5.775 kWh.

A big thank you to nwdiver for his encouragement! Payback on this system after tax credit will be about 4 years!

 

[FlasherZ]

Maximum power seen was 5.775 kWh.

That's supposed to read 5.775 kW, of course.

 

[strider]

FlasherZ, Awesome job!

I'm still going back and forth on micro vs string inverters. Once we get moved into our new place I'll do the math and determine just what the cost delta would be.

On the question of cabling and commissioning, is there a book or guide that says plug this in first, that in second, etc? For example, in a string inverter scenario, my thinking is to wire the DC side from the string inverter input, up the conduit, and into some kind of J-box on the roof. Then from the J-box into male and female MC-4's. Separately when mounting the panels would connect the MC-4's in series. Then when everything else is done, the last (wiring) step would be to plug the MC-4's from the panels into the MC-4's going into the J-box on the roof. Then follow the commissioning steps in the inverter manual. That's the level of detail I'm looking for but in the reading I've done haven't seen that. Any pointers?

 

[FlasherZ]

On the question of cabling and commissioning, is there a book or guide that says plug this in first, that in second, etc? For example, in a string inverter scenario, my thinking is to wire the DC side from the string inverter input, up the conduit, and into some kind of J-box on the roof. Then from the J-box into male and female MC-4's. Separately when mounting the panels would connect the MC-4's in series. Then when everything else is done, the last (wiring) step would be to plug the MC-4's from the panels into the MC-4's going into the J-box on the roof. Then follow the commissioning steps in the inverter manual. That's the level of detail I'm looking for but in the reading I've done haven't seen that. Any pointers?

It depends because you have to do the design depending upon the panel ratings and inverter capacity. Take that system I just installed: it's configured as 2 strings (1x14 on west side, 1x14 on east side) of series-connected panels. But if I were to use a different brand of panel with a higher open-circuit voltage, I may end up having to use 4 strings (east becomes 2 parallel strings of 7, and west becomes 2 parallel strings of 7) because the inverter max is 600V. In most cases, I suggest a combiner box up on the roof rather than bringing 2 more pairs of wires down to the inverter. In other cases, the inverter may not have 2 sets of terminals for paralleling strings. So it depends upon the ratings of panels and features of the inverters you use.

In my case, I created one big loop of panels on each side of the roof. All panels in each row are connected in series with each other with their MC4 connectors. Then, on the north end of the roof, I connected the two rows together in series. On the south end of the rows, I then have 2 cables -- one positive, one negative. I ran a pair of #10 PV wires through conduit (along with a grounding conductor) and into the building where I connected it to the inverter's DC inputs. On the roof end, I crimped MC4 connectors on the appropriate wires (one positive, one negative) and connected them to the panels' connectors.

Then, on the AC side of the inverter, I connected a conduit with 3 #6 conductors (red/black/white) and 1 #10 green conductor (ground) to the L1/L2/N/G terminals on the inverter and took them out to the disconnect box on the exterior of the building. Another conduit containing the same conductors then connects the exterior disconnect to the backfeed breaker in the service panel.

 

[strider]

Thanks for the response! I'm feeling pretty good from a design standpoint. There are books and online resources to help with things like string sizing (using the Voc of the panels and inverter specs for start-up voltage, operating voltage, etc), wire sizing, etc. What I ahven't seen written down is a step-by-step install this, wire that, plug this in kind of guide. The inverter manual has some of that but we're dealing with high voltage DC and I want to minimize electrocution risk.

I'm planning to run appropriately-sized wire from the DC disconnect on the inverter, through conduit, and up into a junction/combiner box on the roof. Basically a weatherproof box with 2 sets of terminals (we'll assume 1 string). I screw that wire into the terminals. So far zero current potential. I then install my panels and daisy-chain the appropriate # of panels, positive to negative. At the end I have a male and a female MC-4 wire. I'm planning to go the route of buying an MC-4 extension cable and cutting it to provide my terminated MC-4 ends. I'll take the "bare" ends and attach them into the junction/combiner box. Here's the part where I'm confused. The panels have high current potential but I need to plug them into the wire running into the DC disconnect. Can I just plug the MC-4's in during the day? Should I do it at midnight (falling off the roof potential aside)? Do I need to tarp the panels? Or am I worrying about nothing and I should just get a good set of lineman's gloves and plug those suckers in?

 

[nwdiver]

Can I just plug the MC-4's in during the day? Should I do it at midnight (falling off the roof potential aside)? Do I need to tarp the panels? Or am I worrying about nothing and I should just get a good set of lineman's gloves and plug those suckers in?

All the contacts in the MC-4s are recessed so you'd really have to try to get shocked. The biggest hazard is disconnecting them under load or accidentally completing a circuit and shorting it... in which case you'll get a good arc. So long as you don't complete any circuits you're fine... terminating to a disconnect doesn't count.... so long as the disconnect is open

 

[FlatSix911]

A quick reply to myself. I happened to run across a picture of panels installed at an angle, so thought I would post it. http://kbnd.com/assets/images/Habitat Restore Solar.jpg

Interesting layout!

 

[FlasherZ]

Here's the part where I'm confused. The panels have high current potential but I need to plug them into the wire running into the DC disconnect. Can I just plug the MC-4's in during the day? Should I do it at midnight (falling off the roof potential aside)? Do I need to tarp the panels? Or am I worrying about nothing and I should just get a good set of lineman's gloves and plug those suckers in?

Here's how I do it... plug all the panels to each other to create your serial strings. There's no risk in connecting them during the day. Before making the final connection (usually the + leg down to the inverter), use a meter to look at your voltage on the string and make sure it looks roughly correct, somewhere near (#panels * (Voc-2)). You can then plug in the final connector and power up the inverter at any time of day.

As noted by nwdiver, there is a risk that you grab the wrong connector and create a dead short of all panels - that's bad - but as long as you've kept track of wiring it shouldn't be a problem.

Never, under any circumstances, pull an MC4 connector pair apart under load (when the system is producing). If the inverter is powered off, there's no risk in disconnecting during the day.

One other thing to look out for is that you correctly wire the panels in. Remember that the "+" connector on the *solar PV panel* is the one carrying positive voltage. You will need a "-" MC4 half to connect to it, but the wire itself is the "+" wire! I've seen a few cases where people have gotten confused because they crimped a "-" connector on it, then attached it to the inverter's "-" terminal. That'll give a polarity error.

 

[strider]

Thanks for the confirmation! As usual I was overthinking it. Good reminder about using the opposite gender of the MC-4 to go into the combiner/junction box.

 

[nwdiver]

Good reminder about using the opposite gender of the MC-4 to go into the combiner/junction box.

That still makes me think twice... that the negative MC4 on the roof is landed on the positive terminal at the inverter...

 

[neroden]

In my case, no. It reflects a restructuring of fixed infrastructure costs vs. variable costs, so that it's relatively fair for those with and without distributed generation.

I am member/owner of a co-op utility. Over the past decade, the operations team has been restructuring their pricing so that it more accurately reflects fixed costs vs. variable costs. Our fixed "meter charge" is $45/mo; the operations team tells us this is the most accurate reflection of their fixed costs. When structured this way, net metering is neither subsidized nor penalized - if you run a net zero bill, you pay $45/mo for the infrastructure to be grid-connected; if you consume more than you generate, you pay the cost of the power you consumed from the grid; if you generate more than you consume, you get credits banked for up to 3 months.

This is fascinating. At $45/month, however, the economics of buying Powerwalls and going off grid starts getting very advantageous.

Your area must be quite rural. My utility is doing the same thing, shifting a larger amount of the bill to the fixed monthly cost, but it's nowhere *near* that high (<$20/month). I guess we have better economies of scale because we're less rural?

 

[FlasherZ]

This is fascinating. At $45/month, however, the economics of buying Powerwalls and going off grid starts getting very advantageous.

Your area must be quite rural. My utility is doing the same thing, shifting a larger amount of the bill to the fixed monthly cost, but it's nowhere *near* that high (<$20/month). I guess we have better economies of scale because we're less rural?

Not for me, it doesn't... In the following thread I describe what it would take for me to put a system in place to go off-grid... 2-3 times a year, the weather has me running a 200+ kWh deficit over 5 day stretches with a 40 kW system (enough to offset my use).

Philosophical questions that highlight how absurd a fee on self-generation is.

As for the meter charge, it's likely to be a combination of economies of scale and continued subsidization of some fixed costs from variable usage costs. The co-op tells us that they've finished shifting to the meter charge.

 

[neroden]

Not for me, it doesn't... In the following thread I describe what it would take for me to put a system in place to go off-grid... 2-3 times a year, the weather has me running a 200+ kWh deficit over 5 day stretches with a 40 kW system (enough to offset my use).

I'm going to bet you have electric heat, because otherwise your daily electric usage seems too high. I'm also assuming that it's a heat pump and that your house is already superinsulated, because otherwise the usage seems too low. Of course, it's possible you haven't done the "low hanging fruit" upgrades, but I'm assuming you have.

So the difference between being able to go off-grid and not is, I'm guessing, mostly the electric heat. If you're willing and able to coast on thermal mass during these 5-day cold periods, that would probably make the difference. I wonder how much it would cost for you to implement a thermal mass wall of some sort.

$45/month is $540/year, or $5400 over ten years just for "substituting for one week of bad production" capability from the grid.

 

[FlasherZ]

I'm going to bet you have electric heat, because otherwise your daily electric usage seems too high. I'm also assuming that it's a heat pump and that your house is already superinsulated, because otherwise the usage seems too low. Of course, it's possible you haven't done the "low hanging fruit" upgrades, but I'm assuming you have.

Bad assumption. Two-zone Propane boiler heat, standard A/C. 4,600 sq ft. including basement. 25 year old home, insulated well. 2 Teslas + 5 refrigeration units (upright freezer, 2 refrigerators, 1 Eurocave, and 1 cold plate for soda fountain / frozen beverage machines, all relatively new). Peak of usage is typically Jun-Jul-Aug.