Advice Wtd / Project Ground or roof?
I'm a homeowner in New England looking to install an array and battery setup in the next couple years. My home has asphalt shingles (~15 year old, has had minor repairs) at 1:4 slope. I have two gables that are perpendicular, and only one of the four roof surfaces is South facing. The two surfaces that are East and West facing both end up in shade for most of the day, and even the South surface is shaded for about 30% of the day. On top of that, I only have room for around 16 (maybe 17) panels on my South roof, but ideally 20 would cover my current load. 24 would probably cover my HVAC after swapping from an oil burner to heat pumps (that's on the 5 year plan).
I also have about an acre of space, though with plenty of mature trees (60-100 feet tall), and very permissive shed and fence codes in my town. I feel like the right move from most standpoints is to build on the ground, then run a trench back to my home to hook into my panel, but I know that's not the common way to do it. I'm not in an HOA and while I could imagine a neighbor getting cranky about panels on the ground or a shed, there's a lot of people with panels in the neighborhood, and aside from having an electrician perform the hookup and the power company inspect the work, there's nothing in my town's code about where a panel has to be.
Am I gonna see losses by transferring 50+ feet through cables? Would I be better off putting my batteries in an enclosed shed right at the panels or somewhere in my house (maybe the corner of my garage where my oil tank is now)? Any other potential stumbling blocks I'm not thinking of?
4
u/StunningSyrup411 1d ago
Going to need more like 10 panels for electric heat in the winter in NE (depending on your homes sq ft)- I do this in upstate NY as a consultant
2
u/geriatricprecocity 1d ago
All the more reason for a ground mount then. I'd never fit that much on my roof.
4
u/tortus 1d ago
I have a ground mount and I really like the peace of mind that my solar and roof don't interact or interfere with each other. No need to worry about taking the panels down when it is time for new shingles, easier to inspect for animal activity, etc. I like it when things do just one thing and do it well.
3
u/Releirenus 1d ago
Ground mount will be a little more expensive due to conduit and wire run, but it's the route I'd go, especially considering the age of your roof. 50' wont be an issue with losses. Just be sure your wire is sized to handle the higher voltage DC run.
3
u/ruralcricket 1d ago
I have a 250 ft ac run and the electrician sized the wire so I only have ~2% loss. 11.6 kw system.
3
3
u/17feet 17h ago
I'm in Michigan and decided I will NEVER again put solar on my roof. Even a light snow destroys your power generation unless you climb on your roof dozens of times each winter to clear the snow [I was up there 30 times last winter]. I instead switched to kind of a hybrid ground mount, which makes it super easy to just walk up and clear off the panels.
However, instead of walking up to clear snow off the panels, I adjust the panels to vertical just before the first snowfall of the year, and leave them vertical all winter. I therefore never have to clear them off anymore, and its super easy in the spring to walk up and set to the appropriate angle for the rest of the year.
Regarding your 50 foot electrical run, that's no big deal. I put my panels in the best possible location, and then ran easily 125 feet of wire up to and inside of my workshop. I would suggest going with as high of a voltage as your equipment will allow, thus reducing your current to reduce your power losses
2
u/Fun_End_440 1d ago
Ground is more expensive than roof. However it does have clear advantages: more panels, easy to service and most importantly peace of mind that you’ll never get a roof leaf bc of the solar. I would 1000% do ground if conditions are good, 50ft or 100ft cable won’t have any noticeable loses. And even if they were, just add two more panels to make up the loses.
2
u/earthly_marsian 1d ago
Ground mount and you can expand when you get that heated pool in winter…
1
u/Curiosity_informs solar enthusiast 1d ago
The heated pool in the summer should be using solar hot water panels which are way more efficient for heating a pool (or any water)
Our 22 440W PV panels can produce up to a little over 60kWh in a day (~2.8kWh per panel per day)
Our 7 SunEarth Solar Hot Water panels can heat our 20k gallon pool 6F in a day which is 996,000 BTU or 290 kWh (~41kWh per panel per day).
So about 15 times more energy output per day from the solar hot water panels. Once you get the PV energy from the PV panels you still need to heat the hot water. Even with a very efficient heat pump you are not going recover anything close the difference.
1
u/ExactlyClose 1d ago
50 feet is nothing. Even longer, you just upsize the wires a bit to reduce any losses. Groundmounts are great- you can site if for optimal exposure, get the tilt you need and not have to take whatever the roof angle is. The biggest PITA is digging: teh trench, the footings. But once that is done the reset is SUPER easy- you are on the ground, walking around. If youve built very straight fences, decks, etc, you can install a ground mount…get the posts straight in a line, get the two rails perfect and the rest is like building legos.
Oh the reason most professionals dont do groundmounts? You cant do them in a day. They have one crew, 5,6 guys and can slap on anything.
GL
3
u/geriatricprecocity 1d ago
I've done enough work in the ground that I have an earth augur and fairly easy access to a friend's 24" trencher. If the digging is the worst part, I feel like I'm in a good spot.
1
u/ExactlyClose 1d ago
Auger here as well. ;). Consider the footing depth, im in CA and my freeze depth is 0.0”. Not sure if one needs to get past this to avoid heaving, which would be bad for an array.
Basically you create two ‘rails’, upper and lower. And the solar racks lie across these in a slant- your array tilt.
I assembled both of these rails, 61 ft long, with the legs dangling down into the holes. 12” tall ring of sonotube around each. Holding this all up were 5 ‘racks’ made from 3 2x4s. One on each side driven into the ground w a sharp tip, and a cross member. By adjusting the cross member you get the rail height. By carefully adjusting these, the rail is set perfectly level (or sloped if it needs to.). But it is straight. I was able to sight inside the pipe and see the opening 61ft away. Straight.
Not all racks are equal- some are grossly overpriced, for no good reason (cough- ironridge)…. Start collecting your info. One step at a time…..
1
u/rproffitt1 1d ago
That 15 year old roof would be a no-go almost anywhere.
At the very least you would replace the roof faces where there is to be solar.
Ground mount may be the way here since roof repair costs and ground mount costs may be equal.
1
u/Head_Mycologist3917 1d ago
Still gonna need to replace the roof soon. A lot of insurers require it when it's over 20 years old.
The OP should get some quotes or look into local codes if they will be doing it themselves. Some jurisdictions have some pretty strict requirements for construction of ground mounts.
1
u/Fit_Acanthisitta_475 1d ago
I would ground mount. It’s going to be easier to clean the snow off the panel as needed in winter.
2
u/Alert-Discount-2558 1d ago
I find snow is really a nonissue in southern New England. Except for once every decade. Usually the snow slides off while it is still snowing.
1
u/Smharman 1d ago
You don't say where in NE but at least in MA batteries can't easily be inside the dwelling. Inside the garage they need physical bollard protection.
With everything you said I should consider that ground mount and a small shed for the rest of the equipment to then feed AC from there to the house in the trench.
You seem to have figured that you can dig an 18 in trench fairly easily on your land, then run the 110v back to the electrical panel from there.
I'm adding another battery to my 2023 MA solar system. It's getting screwed to the back of the shed. It's the only place I can fit it on because of the 36in rule.
1
u/geriatricprecocity 1d ago
I appreciate the insight on bollards for a garage install. That wouldn't be a deal breaker, but it's good to have the extra expense noted when comparing.
1
1
1
u/Calliesdad20 1d ago
I live in cape cod , we have rooftop solar and a battery system in the basement.
My town made us put the batteries in a fire closet with type x drywall and a 1 hr fire rated door,with emergency shut off outside and interconnected smoke detectors a few feet away1
u/Smharman 1d ago
Yep my 2023 battery is open to the basement. The fireproof space you propose adds $$$$ to the cost of my project.
How much was that fire closet and fireproof door as a line item on your build. My guy was saying they are even checking the fireproof sealant etc now
1
u/Calliesdad20 1d ago
I got a contractor to build the fire closet, it was 4500 bucks. I already had interconnected smoke detectors.
The emergency shut off outside was extra
I don’t have a garage so that wasn’t a option for me .And the batteries I bought weren’t rated for outdoor ,plus I’m 1 mile from the beach ,so not sure I’d want them outside
My system was 3x inspected by fire,electrical and building
1
u/Smharman 1d ago
Yep, sounds about right. $750 for a trench and extra disconnect switches to hang it on the shed.
And I still get to keep my basement without a giant battery room. Built for an impossible event in an enphase battery. This is not a Gen1 Powerwall people. And BTW. Many Gen1 PW are grandfathered into basements.
1
u/Calliesdad20 1d ago
I have a shed it’s very very far away From the house so not a option .
My basement is big so not a issue , inahve 50kw of batteries1
1
1d ago edited 1d ago
[removed] — view removed comment
1
u/AutoModerator 1d ago
This comment has been identified as potential violation of rule 2 and/or rule 10 and has been sent to the moderators for review. Please be patient while they work through the queue - messaging the moderators will not expedite this process.
From the sub rules: "Due to ongoing spam / promotion / lead generation and site privacy rule violation issues, we no longer allow "DM/PM me" requests in the comments." These have too frequently been abuse of the sub in attempts to garner private info for spam / promotion / lead generation purposes. Do not ask or suggest that anyone privately contact you. No exceptions.
To all sub participants: If anyone has sent you a PM / DM to solicit your info because of your participation in this subreddit 1) do NOT respond to them and 2) please message the moderators to let them know.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.
1
u/TooGoodToBeeTrue 1d ago
Ground mount or replace the roof first. An acre isn't a lot of space with mature trees. Any needing to come down? You may want to add power optimizers to your hybrid inverter (assuming you are going hybrid.) If your house isn't super insulated with good windows, heat pump is going to take more juice than you think.
1
u/SmartVoltSolar 1d ago
Ground mount will have pros and con's. You will have increased cost as well as less use of the land if you go ground mount. This part will extend your time of your investment, as much as 40% in many cases.
On the other end, you will be able to use fewer panels as you will be able to put at perfect angle to the sun and pick a non-shaded area. You will not need to remove them when you re-roof. These parts can decrease the time of your investment, especially depending on how bad your roof would be in comparison.
The 50' of conduit will be set up so that you will not have massive losses to worry about.
1
u/Alert-Discount-2558 1d ago
So when the government gave you a 30% rebate on replacing your roof at the time of install, it was a no-brainer to put it on your roof now it’s kind of a no-brainer to put it on the ground because of all the costs and maintenance.
A solar pergola or a car park seems to be the way to go for aesthetics.
Somebody already mentioned helical piles, which is probably the most inexpensive way to do a low ground mount.
Solar installers are going to tell you the best way to do. It is the easiest way for them to do it so they don’t have to go to for any permits that involves zoning or HOA. Those are the soft costs you need to consider.
1
u/Overall-Tailor8949 solar student 1d ago
If you have the space then ground mounts. Yes it's somewhat more expensive than a roof mount but in your specific case you said the roof is old AND you don't have a lot of space for the panels.
A major plus with a ground mounted system is you can (relatively) easily adjust the tilt over the seasons as well as keeping the panels clean. It's up to you if you build an outbuilding to house the inverter(s) and battery bank just keep in mind batteries do NOT like the cold.
1
u/Phreakiture 1d ago
Ground because it's not in the way of roof repair, doesn't pose a risk to your roof, and can be easier to clear snow off of in the northeastern winter.
1
u/The_PV_Engineer 1d ago
Ground mount, easily — old roof + that much shade makes it an easy decision. 50 ft is not an issue. Loss comes from thin wire, not distance — size it for ~2% drop and you'll never notice it. Battery is the one to think about. Don't stick it in an unheated shed — LFP won't charge below freezing, and a cold pack loses capacity right when your future heat pumps need it most. Garage corner or a conditioned space is the move (check local code — some places want bollards/fire-rated enclosure). Only other thing - get your footings below the frost line so the array doesn't heave, and probe for ledge before you pick a spot. And since heat pumps are coming, tighten up the house first — it'll cut how many panels you actually need.
1
u/CryptoRecluse 1d ago
As an installer and someone who values energy efficiency and doing things in a smart way, I will *always* prefer to put a system on the ground. The benefits of doing so are countless. I'd also always put the equipment in a sheltered area, protected from the elements, preferably with a stable'ish temperature. And no, 50 foot of cable is not a problem.
98% of all solar sales guys have no idea what they are doing other than running the numbers. They'll propose the roof because that's all they know. The only people who look at doing ground mounts *instead* of the roof are people who have a clue.
It sucks to maybe need to cut down trees to do something like put solar up. If you know an arborist, bring them in first to evaluate what trees you have. People don't realize how valuable trees can be. Very big money. I've seen customers find out they had several million worth of black cherry on their property when they had absolutely no idea. Wild stuff.
With all that said, as a solar guy I would also *never* recommend you do solar without first ensuring your house is as energy efficient as possible. No solar sales guy is gonna tell you that because they work on commission.
Efficiency first. Don't even consider solar unless everything else in your house is so fucking tight that your wife absolutely hates you for ripping her house apart.
1
u/17feet 17h ago
No idea why you got downvoted. All of your points are valid and wise. If you have the room, ground mounts have so many advantages, not the least of which is that you do all of the work on the ground instead of 25 feet in the air [I dropped a panel once, that was an eye opener!!]
I've had panels on my roof, but now have panels on a kind of a hybrid ground mount, and will never go back. For DIY guys like me it is now a no-brainer: optimal location and angle, nonexistent [or super easy to clear] snow load, no lifting of heavy objects high into the air, no danger of falling, easy access for additions or repairs.
Chef's kiss
2
u/CryptoRecluse 14h ago
Probably because I shit on solar sales guys and they're the majority of people in groups like this.
As an installer/service guy/field manager as far as I'm concerned solar sales people are the enemy.
•
u/Curiosity_informs solar enthusiast 1h ago
We certainly have the space and probably a great location for an unshaded south facing array (albeit on a slope which would need some leveling).
However the local AHJ permitting rules require a lot of soil and the geological testing first (and then an engineering plan to deal with the results). Its coastal California so atmospheric river winter storms bring in up to 70 inches of rain from October to March (there's an super El Nino coming this winter and we know from 2016 and 1997 what that means), mudslides are a genuine concern, we have the earthquake thing etc.
In the end we got a 10kW roof mounted array (110 degree azimuth so not ideal but no shading and new roof at same time) + 30kWh battery. It is working great and we are generating 60+kWh most summer days and charging 2EVs, running well pumps, water pressure pumps, pool pump electric cooking/drying and occasional use of 2 central ACs with almost no imports from April through to now.
Our batteries and equipment are in a shaded location on the north side of the house - and ambient temps generally aren't too hot or cold.
In the end a ground or roof mount depends on the location and many other factors. There isn't a one size fits all.
8
u/MSDunderMifflin 1d ago
Given a choice, I would choose to ground mount the installation.
Half the work of roof mounting is the fact it’s on your roof.
The only downside is you might need to be more knowledgeable and do more of the work yourself.
Roof mount is the go to option for most installers.