That was my initial thought. Run DC back to the house and then pickup the invertors there. If I do that is there any benefit other than looks to having the invertors mounted inside on the basement wall vs on the outside of the home. I know there can be some invertor loss with heat buildup but not sure how much of a concern that is. House wall with service and invertors is east facing.
A newbies DIY solar install
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That was my initial thought. Run DC back to the house and then pickup the invertors there. If I do that is there any benefit other than looks to having the invertors mounted inside on the basement wall vs on the outside of the home. I know there can be some invertor loss with heat buildup but not sure how much of a concern that is. House wall with service and invertors is east facing.
IXLR8
Elite Member
Which is going to have the higher currents, the DC or the AC. That should answer your question. If DC currents are going to be higher, inverters at the solar panels, if AC currents are going to be higher, inverters in the house. You want to minimize your losses.
ponytug
Super Member
These days most inverters are so efficient that I don't think it makes much of a difference where you locate them. If it were me, I would put them outside on your east facing wall, as I don't see any need to have them protected from weather or temperature.
It would also simplify any future expansion of batteries, transfer switches, more solar...
All the best,
Peter
It would also simplify any future expansion of batteries, transfer switches, more solar...
All the best,
Peter
ning
Elite Member
I set something up something similar last year (DIY; purchased from a licensed electrician and paid him for some consulting here and there).
The trench from my ground mount to my shop, where the service entrance is, is about 600'.
My system has 10kW of panels; with the inverter action happening at the array, the cables are running 240V, a maximum of 40A.
With 4/0 Aluminum, I've got a maximum voltage drop of 1.55%. I "sized up" on the cable because if we add an electrc car or two, I may end up adding another 5kW of panels to run on the same cables; 60A on 4/0 for 600' gives 2.32% drop. "Sizing up" probably added $200 which is cheaper than an empty conduit to pull a cable later and much less effort.
My system uses a microinverter for each panel tied to a box at the ground mount; the 4/0 aluminum goes from that box to the switch in my shop (actually, there's a junction box at the end of the trench where the cable hits the shop, and it goes to #4awg through the shop at that point - the #4 for 40' is a negligible voltage drop and it's WAY easier to handle through the bends necessary in that building - and a much smaller conduit). The microinverters together with the main control brains handle rapid-shutdown; there's no separate box for it (all components are Enphase other than the panels).
That switch functions as a microgrid interconnection device (it'll automatically disconnect the grid if it senses bad things or absence, and will regulate the output of the microinverters).
As far as I know, it's not sufficient to have "integrated inverters on the solar panels" (microinverters; typically not integrated to the panel but often attached one to one at the panel) to be able to run solar without the grid. There has to be some intelligence to throttle the solar production to the load. It's possible that this only works with batteries to serve as a buffer.
[Ground vs roof mount: My house is in trees and doesn't have enough good roof for 10kW, let alone a future extra 5kW. Also, the roof is OK for now but would need replacement before you'd do something serious like put solar on it. I also wanted to be able to easily clean the panels, and not have crap fall on them from trees all the time; my ground mount is in the middle of a field with great sun in the winter and even better in the summer. Ground mounts can be pointed and tilted exactly how you want them trivially (once), vs panels are pointed where the roof points on a house roof. Ground is probably easier to DIY, but it's definitely more expensive, and typically you need more panels to get the same kW as a ground mount because of direction and heat... and I already didn't have enough room on the house (2-story house)]
ning
Elite Member
There's good reason to use microinverters (one inverter per panel, at the panel), especially if there's shading or damage on one panel, the entire system can be affected otherwise. There's more up-front cost, but you'll likely get more out of your array overall with them (and the whole thing is more fault-toleratant as well). Some systems (like the enphase ensemble w/ battery & microgrid) require them.
Google "advantages of microinverters", the first few links should all show pros & cons (the con is pretty much just cost).
Wood_Butcher_Dav
Gold Member
Going on my second year for my 9.2KW system. This is what I know - Have 24 panels on two series circuits which will produce around 500v DC each. These feed the one inverter which feeds a meter base the 240 VAC then feeds main circuit panel in garage. The inverter and meter base are under lean-to on out side of garage. Not sure of Fronius model number. There is some noise/hum when the inverter is operating. My electric co-op is same way costs me around $.13 to buy and $.03 to sell back.
May need electrician to do final hook up, The Co-op also wanted there own solar meter.
Might want to check if there are any State grants for solar. Illinois Shines program save me an additional 40%.
Dave
May need electrician to do final hook up, The Co-op also wanted there own solar meter.
Might want to check if there are any State grants for solar. Illinois Shines program save me an additional 40%.
Dave
Made a quick phone call to my installer who is now out of solar but did our business 8 years ago. He says the long run should be AC.
Williy
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I have 9 250 watt panels, 4 batteries L16's 4k inverter run frig, computer, tv lights and in summer run two window a/c units and use induction cookers to cook with. e bill was just under $300 now in low $40 range
the two a/c units use together 9.2 amps and together put out 12,000 btu's get an a/c unit from walmart just a 5000 btu unit draws 15 amps. Will be expanding system and will not be grid tie cost too much for nothing
and you from what I have been told can't add power to the power company lines when the power goes out
its a health hazard for the workers.
willy
ning
Elite Member
In California you can't grid-tie without an automatic shutdown or disconnect any more.
In addition, the "smart" meters that most people have won't "run backwards" if you're grid-tied and have excess production and the meter isn't configured for net metering - the utility will charge you for the over production as if it was a draw on the grid (ie if you're producing 5kW and using 1kW, that 4kW extra will count against you)... and you can't get configured for net metering without the disconnects.
(as opposed to the old fashioned meters that weren't digitally and would literally run backwards if you overproduced... and potentially endanger linesmen)
We will have to add the auto/rapid shutdown module to our system as well even though it looks like the fronius invertors themselves are rapid shutdown compliant per NEC 2014. Meter will calculate both solar production and grid use. Any overproduction gets a credit but not much. Around .02 to .03 cents a Kwh.
beowulf
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My solar panel system is in California. I have two separate meters on the property which were linked together (they refer to it as aggregated) - meaning whatever solar energy I generate is credited to the total usage from both meters combined. I understand that any excess energy generated by a solar panel system - at the end of the plan-year (what they call a True-up), can be sold back to the power company. However, I was also told that because I have an 'aggregated' system (the two meters) they will not buy the excess generation. Not sure why that is, but I confirmed it.
Anyway, my solar company told me not to worry about selling energy back because the power company only pays a few cents per kwh, even though they charge many times that amount for the KWh they sell you. I asked the power company about the discrepancy in what they pay and what they charge and they said they pay solar customers what it costs them to buy their energy from whatever source - and that the difference was the cost of delivering the power and maintaining their system and more.
And - as others have stated, when the power goes down, the solar shuts off - a safety feature to protect anyone working on the lines.
Anyway, my solar company told me not to worry about selling energy back because the power company only pays a few cents per kwh, even though they charge many times that amount for the KWh they sell you. I asked the power company about the discrepancy in what they pay and what they charge and they said they pay solar customers what it costs them to buy their energy from whatever source - and that the difference was the cost of delivering the power and maintaining their system and more.
And - as others have stated, when the power goes down, the solar shuts off - a safety feature to protect anyone working on the lines.
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CobyRupert
Super Member
orezok
Super Member
I’m in SCE here in CA. Grid tied and net metering. Per the attached I am charged/credited $0.26 during solar charging hours, $0.37 during “peak” hours (4 to 9 PM) and $0.28 during the rest of the day. Difference for net metering isn’t too bad but rates are ridiculous.
Oh, and these are winter rates. Summer rates jump to $0.27 and $0.54. They like to screw us desert dwellers.
Oh, and these are winter rates. Summer rates jump to $0.27 and $0.54. They like to screw us desert dwellers.
ning
Elite Member
California, PG&E, EV2A rate :
bmaverick
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So glad I'm not solar connected to the grid. WHEW ! Your hard earned money, time and solar resources getting a few cents of investment and with a power outage you are in the dark too! Makes no sense.
ponytug
Super Member
Time to install batteries to shift the solar output to peak times, don't you think? 
It is what the PUC and SCE/PG&E are pushing us toward.
All the best, Peter
It is what the PUC and SCE/PG&E are pushing us toward.
All the best, Peter
bmaverick
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Time to install batteries to shift the solar output to peak times, don't you think?
It is what the PUC and SCE/PG&E are pushing us toward.
All the best, Peter
OMG, more investment with cents on the dollar for a return.
ponytug
Super Member
Depends on where you live. A lot.OMG, more investment with cents on the dollar for a return.
Here in northern California, PG&E territory, the financial payback is less than two years. Plus, there is the enhanced ability to ride through outages, which is the prime reason we have gone to batteries.
Definitely a "your mileage may vary". With a stable grid, reliable service, not much of a difference between off peak and peak electrical pricing, and no utility incentives, yes, the financial ROI is going to be very different. But early adopters often have atypical reasons for being there. Some folks have standby generators, some folks don't. Some folks have tornado shelters, and some don't. Individual decisions for individual reasons. A tornado came a few hundred feet from air lifting a close relative, and you can still see the path through the woods. Yes, I get why you might want a tornado shelter or basement. "Oh you are on dialysis." "Oh, you need oxygen." Very different view of how valuable water and electricity are.
I will point out that adding grid tied batteries anywhere the grid helps shift generation capacity to when the utilities need the peak power. Charging electric vehicles overnight helps, too, by keeping baseline loads up. Is it even more cost effective for the utilities to install mega packs of batteries near substations? Of course. But that isn't where we are here in the US. Australia has gone that direction for much lower cost. The UK has had their relatively large residential electric water heaters on off peak power for decades.
I hope, and think, that the next thirty years are going to have some big changes the way power is supplied in the US; more grid interconnections, more transmission lines, more solar, more batteries, more wind power. But also big changes in how energy is used; more electric vehicles, more electric heat pumps, more induction stoves.
GM says it will be 100% electric vehicles by 2035. I think we are in the early days.
Two thumbs up for @jk96 for putting in his own solar.
All the best,
Peter
Currently waiting on the electrical diagrams to come back. Ended up hiring this out and is the only thing I'm waiting on to complete the application for approval to our utility. Hopefully it's a fast approval so I can get the equipment order placed.
Orezok those rates are crazy. We are .13 cents year round with no peak or off peak and that's higher than most around because we are on the local coop. My business is with evergy and rates are .09.
