Hacker News Reader

Comment by WillAdams | Hacker News Reader

Does anyone have a good link/step-by-step for doing some sort of home solar system where:

- it's sufficiently small-scale that no building permit is required

- it looks nice enough that neighbors won't complain

- the wiring is essentially plug-and-play

The best approach I've been able to come up with is to purchase a medium size battery pack such as is used for glamping (glamour camping), plug it into the wall and connect my refrigerator and a couple of other high-draw appliances to it (basement dehumidifier comes to mind), build a small roof for the back deck, using poured footings with short posts and then attaching the vertical pillars for the roof to that (which should side-step the need for a building permit since it's not a permanent structure), then placing the solar panels on that roof and running a wire to the battery placed in the kitchen.

View on HN

In Europe it's somewhat common to have a small solar panel just on your balcony (i.e. not permanent attached to the building) and simply plugs into a nearby wall receptacle. https://www.theverge.com/24150901/ecoflow-powerstream-review...

For those wondering, the article did discuss the safety matter of using a power outlet as an inlet. And the article also points out that while this is allowed in several countries in Europe it's not allowed in the U.S., but I suppose you could always plug appliances directly into the battery instead.

Wild. I wonder how they deal with the back feeding issue. Is there something about the home wiring in those countries that prevents it? (or do they just not care and line workers know to check if a line is truly dead?)

The device detects that and prevents back feeding. So in case of a power outage it completely shuts itself down.

So when the power goes out it no longer powers your fridge or whatever else you need powered. But it's easy enough to unplug the fridge from the wall and directly into the battery.

I feel the real danger of back feeding is not that american line workers can't be bothered to check if the line is truly dead before starting to work. It's that the line could be reenergized at any time.

Lineworkers will ground/earth the line with a very good connection (e.g. metal rod into the ground) before working on it, as far as I know.

(At least, this is what electricians working with 33kV in industry in Europe do, e.g. if doing maintenance on a cable to a datacentre.)

I haven't seen them doing that on power outage post storm line repairs near me, usually during those they're working as fast as possible because they have dozens of other spots they need to repair.

Hopefully they're bonding the line to their bucket at least.

Probably I've just not seen them ever drive in a ground rod while doing basic line repair work.

Also just the frequency with which work happens on the distribution grid. Most of Europe has almost all distribution lines underground (only running high-voltage transmission lines above ground), and unless somebody digs in the wrong spot they tend to just stay there. In the US meanwhile they are mostly above ground where they are susceptible to storms, falling trees, aluminum ladders and all kinds of other stuff that would cause a line worker to be called out

Automatic transfer switches are a thing, but generally you want the supplies sync’ed.

A manual break-before-make transfer switch will do the job. Not much help if you’re not home and the mains goes out and your food spoils, though fridges will stay cold for hours if left shut, and longer if there’s a lot of thermal mass in them - try to keep most of the empty space in your fridge and freezer filled with water bottles.

The microinverter just turns itself off if it doesn’t detect line voltage in the outlet. In the U.S. evidently it’s required to also have some sort of backflow preventer in the panel as well.

Fair, I always forget that most inverters require an existing line voltage to follow instead of being able to generate their own ex nihilo. I was also picturing one of the battery banks that do have the ability to create their own signal too.

if there is no power, the inverter shuts down and doesn't feed power in.

it is actually simpler. The inverter stops power flow if it does not detect a grid voltage.

The actual power coming from a balcony setup is tiny, a thousand watts ballpark. The typical house will consume the vast majority of that capacity.

Even if some flows back to the grid, it will likely be consumed by losses in the transformer and wires.

You’d be surprised how few watts a fridge and a TV draw, 500 watts combined, and that’s only while the compressor in the fridge is running. Don’t open the fridge very often, or keep a lot of thermal mass in the form of filled water bottles in there, and the compressor in a fridge will spend most its time not running.

Now I'm curious... Is your last suggestion correct? Wouldn't the time to cool down between pause intervals be proportionally longer due to the higher thermal mass and cancel out any savings gained by the long pause? Maybe the overall energy draw is even higher because the heat losses are higher when you spend a longer time with a high dT.

The water bottles don't warm up as quick as the air they replace that flows out of the fridge when you open it; so they have two effects first they take up space that new hot indoor air can't move into and second they then help chill that air slightly through their own thermal mass.

We are starting to have this in the US, in fact I have a company coming by to do an install of a system like this on Monday. Technically you should be able to mostly diy it, but it uses a smart panel that gets attached to the main to prevent backflow, which needs an electrician, and for now they are running its own circuit.

Some resources:

  * https://www.mobile-solarpower.com/
  * https://diysolarforum.com/

Note: You'll probably need a permit for the electrical work if it's more permanent and/or grid tied.

But watch the video at https://www.mobile-solarpower.com/mobile-48v-system.html for something similar to a Goal Zero or Jackery

There is a ton of DIY solar info online, but it is very much regionally dependent. Both for permits and system design.

Here in Florida, I can get high output from an average panel, but there are a lot of permit issues (and rightly so, a poorly installed panel can become a severe hazard in a hurricane).

Where I lived in Michigan, there weren't many permitting or zoning issues, but I'd need 3-4x the number of panels to get usable output in the winter time.

Most truly small scale solar systems don't provide enough output/value to be worth the effort, unless you're living a very low-power lifestyle.

True energy independence in even a small capacity has a value beyond just money.

True [x] independence in even a small capacity has a value beyond just money.

..water.. ..food.. ..housing.. ..information..

I get what you are trying to conveying, I just wanted to highlight the semantic generality of the statement if it stands alone.

If you have a house in the countryside, then water and food are relatively easy. You've got your own well and septic system for water, and plenty of room to stock up on food, plus you can supplement your diet by growing your own vegetables and raising chickens, fishing or hunting as seasonally appropriate per your local regulations.

The well and septic system require no real effort on your part once installed, though you may find harvesting your own food to be too time consuming or labor intensive to really be actually independent.

Lol. I grew up in a house in the countryside. Dealing with the well, water storage tank, and pressure booster pump were far from "easy". They required frequent maintenance and occasional large expenses. The well got clogged with sand. The pump motor burned out. The tank float sensor got stuck and caused an overflow (several times). The tank had to be emptied and cleaned. An earthquake caused a pipe to shear off and dumped thousands of gallons of water out of the tank. The pressure booster pump burned out. The pressure booster tank corroded and leaked. The water was hard and required a softener to prevent mineral buildup. Etc.

What is the water storage tank for? We've never needed one, and the only time I've heard of someone getting one was for trapping rainwater or they were a farmer.

I've lived with well water for all of my life except my college years and a few years after. In all that time, the only maintenance that's been needed has been to replace a water pressure tank (not a difficult job unless you've never seen hand tools before) and adding salt to the softener once a blue moon.

My sister in law had to get a new well put in, but that was because it needed a new well pump and the plumber she called told her he couldn't work on the existing one because it was out of code and her well wasn't grandfathered in.

The storage tank was for storing water. Obviously you don't want to run the well pump every time you flush the toilet.

Sure, that's what the pressure tank is for. The well pump keeps the 20 gallon tank pressurized, and as the pressure drops the pump kicks on until it is stable again.

Maybe you could get a bigger one if you have a large family, but I've never heard of one that would be large enough to dump that much water except for mountainside cabins that are too far from the water table for a well in the first place.

Yes, but on a limited budget solar may not always be the best option to some kind of energy independence. It really depends on what you are trying to solve for. Solar alone won't carry loads at night, the panels are generally not portable, they won't produce much output in the middle of a storm, etc.

As an example, during one of the hurricanes that came through FL last year we lost power shortly after the storm hit. I had a smallish leak with water coming in, it was entirely manageable with a wetvac, running off my generator. But solar panels would have been producing zero output at the same time. Even a large battery bank would have been sufficient.

IME, Solar is something where there is often a case where the minimum investment to get a truly worthwhile system is higher than other things like generators, or recently even battery banks. People often overlook all the situations where solar won't produce any output. I look at solar as more of a second-tier energy independence solution than a first-tier. And it worth nothing this is speaking primarily for applications in North America that have generally stable power. If you're in a remote area with no reliable power infrastructure then the parameters are way different.

I got a solar system installed at end of 2022 due to working from home and the large amount of load shedding South Africa was having at the time. Was absolutely justifiable for me:

https://imgur.com/a/hXeVAGr

(Worth noting that during load shedding only a subset of people are turned off depending on the stage of load shedding, but on average I experienced about 25% of those totals)

The money aspect is interesting.

Where I am the companies charge a ‘line charge’. It’s about 20-25% of the monthly bill.

I generate somewhere between 80-110% of the power I need, but in winter I only get half what I need from solar.

A larger system would cover this and negate the need for the line charge, suddenly saving a lot.

Also in Michigan.

I primarily want to generate enough solar to run my AC in the summer because that’s the dominant electricity consuming appliance in our house (except for the EV).

At least with DTE you receive credits for your production, which you can use within 12 months. So generating an excess in the summer to offset the winter is a viable strategy.

Michigan unfortunately represents a mismatch of when you need power vs when power is generated. Arizona, Texas, New Mexico are sweet spots. High power demand in the summer (A/C), relatively high proportion of sunny days.

Michigan is just like the south: highest electricity consumption is during summer.

This may change with increased use of heat pumps for heating, but it’s still a while out before seasonal electricity consumption patterns invert.

+/- on what effect electric cars will have: people drive more in summer but efficiency goes down in winter.

Arizona, Florida, etc are not really in a sweet spot we all think it is because PV efficiency/output goes marginally down when it’s really hot (ie: when A/C demand peaks). Unless you install the panels at high altitude.

we are likely there already.

Ontario, just to the north of Michigan, already has a winter peak very close to the summer peak. The provinces subsidises heat pumps. Ontario will be a winter peaking region in a couple of years.

Annual demand in Ontario peaked 20 years ago and has been overall flat for 3+ decades.

https://www.ieso.ca/power-data/demand-overview/historical-de...

Surprisingly difficult to find monthly data though :(

Interesting that PV efficiency is impacted by peak heat. Why are there so many solar farms in the desert near Las Vegas and in West Texas then? Serious question, would love to know the answer. Are these inefficiencies just now coming to light?

The effect has long been known, but it's pretty modest. Here's the data sheet for a typical modern solar panel:

https://static.trinasolar.com/sites/default/files/Datasheet_...

It loses about 0.29% of (relative) power output for every degree Celsius of temperature increase. If the module is operating at its maximum rated temperature of 85 degrees C, it's still about 83% as efficient as it would be under standard test conditions (25 degrees C).

Solar farms in sunny, hot regions generate more energy per year than identical installations in cooler, less sunny regions. The benefit of extra light dominates over the efficiency loss from higher temperatures. A location with as much sunlight as Las Vegas but the temperatures of Anchorage would be ideal, but there are few if any locations with those characteristics. That's why Las Vegas is still a good location for solar farms despite the heat.

That’s why you want high altitude to get the sun without the heat. I carefully left New Mexico out of my list of “not seeet spots” for that reason.

I did see some citizen science that showed a cooling fan added more power overall to panels, but I guess that’s another moving part and the way the subsidies work… who cares about increasing panel life.

Depends on your jurisdiction, but roof mounted solar installs generally don't need building permits. Electrical permits on the other hand are almost always required.

If you actually want to offset cost, don't buy a portable battery pack. Get an AIO solar inverter and a server rack battery. They're generally plug and play - wire the panels to it, connect the battery.

If you want to run your home loads, the cheapest/simplest way (without going grid-tie) is to have an electrician add a critical loads panel supplied by your inverter output, then plug your inverter in to the grid for backup (in case no solar or batteries are low).

cheapest/simplest way (without going grid-tie) is to have an electrician add a critical loads panel supplied

Cheaper way is have electrician wire a manual transfer switch at the existing panel. When you loose power, turn off non-essential breakers and then flip transfer switch.

Does that work?

Our solar inverter uses the 60hz AC from and grid to do the DC->AC conversion. The inverter stops functioning if the power is out. I thought they all did that for safety.

Those home batteries mush have some solution.

They don't all need the grid - https://news.ycombinator.com/item?id=44023226

https://eg4electronics.com/categories/inverters/eg4-18kpv-12...

You lose all benefits of solar/battery except for during a power outage and you have to flip all your breakers? (you also won't immediately know when the power is back).

Might as well save money and not install anything- use an extension cord for those rare times.

"If you want to run your home loads, the cheapest/simplest way (without going grid-tie) is to have an electrician add a critical loads panel supplied by your inverter output ..."

No, that's actually not the simplest.

Far simpler is to install a solar breaker in your main panel and a physical lockout[1] between utility power and the new solar breaker.

There is no ATX, there are no smarts, the power goes out and you flip two breakers. There is nothing simpler than this.

The beauty of this is, you can keep scaling up your solar generation, adding panels as the years go by, and you are never locked into these ridiculous "preferred breakers" sub-panels.

Will you have to be smart about your total power use while you are on solar ? Yes, you will - just don't run the dryer and the microwave at the same time.

[1] https://www.amazon.com/QYZZRS-Generator-Interlock-Compatible...

Changing your usage pattern isn't simpler.

When I mean simplest, I meant a solution that doesn't rely on doing anything. If/when Solar isn't enough or your batteries deplete, it just falls back to grid. Power outage? Your critical items automatically are backed by solar/battery.

Having to think about your what high draw appliances are running and using additional power adds mental load (ie complexity) and is an immediate no for most people.

Changing your usage pattern is ultimately at the heart of any serious proposal for solving energy scarcity. We have enough energy to power our civilisation without catastrophe: we're just using it in an extremely inefficient manner.

'Simple' and 'Easy' are very different things

I'm interested in doing something like this as well. Build a pergola with a solar roof instead of just a metal one from Costco. I've seen a few videos online doing a similar sized system with like a Jackert or Anker Solix. Realistically with 2-3 harbor freight panels they're only enough to power like your home office. A fridge will burn through the battery pretty fast. I do believe you can have them do input and output straight into your wall outlet and you don't have to plug right the appliances into the battery/inverter.

I agree, a solar pergula would be good and hardly noticeable.

A fidge is only going to use 1.5-2kWh per day. A medium sized pergola would give you more power than that. Since you aren't opening and closing the fridge in the middle of the night, a 1 kWh battery would keep it running all day on normal days.

Companies like Ecoflow sell mobile battery packs which you can connect foldable/small panels to by just plugging them in. No roof installation required. Those panels can be bought as a bundle with the packs. Those packs can then be connected to extension cords. It’s a starting point for short term outages.

That is the company whose products I've been considering --- my idea was to attach the solar panels to the roof so as to not need to fold/unfold, and to be able to take advantage of them all day without any further clutter on the deck (gaining a roofed area on the deck is a nice bonus).

Before buying a "glamping battery", you'll want to ensure that it can be run unattended in your desired configuration.

I previously had a Bluetti EB70S and while it almost did what I wanted, it could only charge from AC or Solar, but not both and didn't have a way to set desired levels.

Now I have a Bluetti Apex 300, and I can set it to charge to X% off AC during overnight off-peak rates, and never drop below Y%.

That actually sounds like a pretty good plan.

I did something similar with my lawn mower. I bought a battery and a single solar panel from Harbor Freight, along with the controller and wires need to hook it all together. I'd set the panel in the yard when I needed to charge the mower's batteries.

The whole thing, including the mower, cost less than half a year's fees from a yard crew, and I ended up saving money overall.

After the experiment was done (and I realized the mower was too low for my grass and was harming it) I sold the mower and gave the rest to my father-in-law for his shed.

We then got professionally installed solar panels for our house and a full-house battery. (It isn't strong enough for the air conditioner, but oh well.)

If I had it to do over again on the small scale, I'd buy an Ecoflow battery (which I have actually bought) and a solar panel made for it, and your fridge idea is a good one. It'd probably also power a fan, a light, and some light entertainment, I think.

Edit: Might go with "Anker" or "Jackery" instead of Ecoflow now, as it might be cheaper for the same thing.

For comparing those brands (EcoFlow, Anker, Jackery), you might want to check the wh/$ ratio - it's basically the best way to compare power station value (for newer LFP systems). I went through this same analysis recently - gearscouts.com [1] has a pretty good comparison table that tracks actual street prices vs capacity.

I've found the sweet spot is usually in the 500-1000Wh range for emergency backup. Enough to run a fridge for 8-12 hours but not so big that the solar panel costs get crazy. The LFP (LiFePO4) models tend to last way longer than the regular lithium ones - worth the extra cost if you're planning to use it regularly.

Your lawn mower experiment sounds like it was a good learning experience! Those small Harbor Freight panels are great for tinkering. I started with something similar before going to a full house system.

[1] https://gearscouts.com/power-stations

In my jurisdiction, you don't need a permit if you're doing it yourself, and it's on your side of the panel.

So the plan I came up with is essentially the plan you have, but I connect my refrigerator to the battery by the panel rather than running an extension cord from my kitchen to the battery.

I disconnected the fridge and 2 other circuits from the panel, and terminated them with a nema 5-15p inlet receptacle like this: http://www.levitonproducts.com/catalog/model_5278-CWP.htm

I then put 4 solar panels on a 45 degree angle on the ground leaning against a south facing wall, anchored to the wall and ground.

The "solar generator" I used is this one: https://www.indiegogo.com/projects/apex-300#/

It's similar to the glamping batteries you refer to, but is more targeted to home backup / off-grid / RV use than glamping.

The answers here have been pretty solid, a lot of what you want depends on where you live. For example, it is very likely that this is not possible if you're property is covered by an HOA. The definition of "it looks nice" is super hard to pin down (neighbors will complain at everything), and unless you're doing something really small, there is going to be some wiring involved. None of that should discourage you however.

"Zero emission generators" (aka battery boxes) are pretty easy to build, and even a 2kW inverter is relatively easy to hide/disguise. If you're doing this in a home situation (vs a camping situation) the 6V "golf cart" lead/acid batteries are really solid. A couple of those will give you 240 AHrs of 12V that can run a bunch of stuff. 240W panels can be stored at night and brought out during the day so keep them 'temporary.' Etc. Victron[1] makes nice chargers and monitors and are popular in the RV / Vanlife communities. Lots of online resources for hooking them up. And generally things you can roll around your property to different places are pretty easily defined as 'not a building' so immune from the permitting process generally.

[1] https://www.victronenergy.com/chargers

I have a massive array+battery (20kWh generation, 19kWh storage) and while it's great, some things to pay consider:

- if you need roof repair/replacement, do it before you get solar. Alternatively, make your array free standing

- prioritize the circuits you want to cover. Not every one is critical but health & safety (water, fridge, cooking capabilities) are key

- MOST jurisdictions won't require permitting for the grid (especially if it's not connected to your house) but MOST will require an inspection if you want to connect to the grid

- if you connect to the grid, make sure you understand how your electricity provider addresses net metering. I wrote about it here: https://geekamongthetrees.com/what-is-solar-net-metering-or-...

Pretty much exactly what you’ve described.

Where I am ya don’t been a permit for a shed if it’s under a 18 square metres, so 6x3m sheds are common.

You could look in to off-grid / caravan appliances, thereby saving on a smaller inverter, but they tend to be around 3x the price of regular appliances.

Highly recommended going for 48v system if you’re starting from scratch to save on ridiculously large diameter cables and stupidly high amperage you’ll be dealing with with a 12v system.

I did a repair this week on a poorly designed 12v system that had a 12v to 230v 7amp (1600 watt) inverter powering a 230v 10amp cook top in a camper van. That cooktop was pulling 235 amp from the battery through a very hot 175amp slow blow fuse.

Which is great if you want to melt the fuse post and the supply cables and… I found the fault before the fire started.

Hybrid Inverter. Main power and solar power go in, house power goes out.

No feeding of solar power to the grid so no permits.

You can add a battery if you want to reduce your reliance on the grid. Or use it with a battery but without solar panels as a whole house UPS.

>No feeding of solar power to the grid so no permits.

If it becomes popular the slimy solar farm developers and the utility will join hands to hire a lobbyist who will ensure the rules get changed to close the loophole.

> no building permit is required

This will be the main issue. No matter what you're going to be doing work inside the main service panel on your house adding new feeds and you'll need to install a transfer switch to disconnect your house in case of a power outage. Most electrical work inside a panel like adding circuits will require a permit in the US. Seems like your plan doesn't involve any of that though so you should be ok permit wise except maybe needing one for the pad and structure.

It would also be nice to think of your neighbors in terms of not starting a fire and someone capable of doing permitted work will be handy when you go to sell the place and bright red flags show up during inspection.

Depending on where you live, that you can buy solar panels+battery kits that plug into the wall and feed the circuit that way, no need to run extension cords to plug in individual appliances. However I don't think those types of setups are legal in the US, they don't trust the backfeed protection

https://craftstrom.com/how-it-works/ is closest to what you want.

You don't need permit, and you don't even need new wiring.

How is "using poured footings with short posts" not a permanent structure? Are you pouring the footings into buckets and not into the ground?

Guessing that code doesn't mind the footings if they don't stick out, and then whatever is on top is removable.

The glamping approach is probably your best bet if you want to avoid paperwork. The equipment has gotten very good and quite cheap in the last few years.

Reply on news.ycombinator.com