Category: solar

Deconstructing Kitty

“Google called, and needs more cats.”


So today we look inside these amazing cats that can somehow keep on wavin’ using less than 15 microwatts (!) of power. If you are into either ultra low-power or extreme design-for-manufacture, the you will want to see what is inside of these guys!

“What I can not create with an Arduino, I do not understand”, so we then proceed to recreate a lucky cat under Arduino digital control.

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Not another fake plug in grid tie solar system…

Update 3/18/2017:

As of last week, the SOLARLIBERATOR.COM website is gone. Considering there has not been a indegogo update in more than a year, I’m calling this one done. :(


Every couple of years another plug-in grid tie system is announced with much fanfare (like here and here), and inevitably it ends up being either (best case) overly optimistic vaporware or (worst case) a fraudulent scam.

My friend Augie (who somehow knows about everything new that shows up on the entire Internet) just found the latest one here on Indiegogo

Solar Liberator claims to be offering a 500 watt grid-tie solar system that you plug-in into an outlet.

I do not know what you will get if you order this item, but I do know that you will not get a 500 watt grid-tie solar system that plugs into an outlet. No way.

First off, I can almost guarantee that no matter what you get, it will not include a 500 watt solar panel. I’ve bought a lot of solar panels – large and small – and I’ve been tracking the various sizes and types for the past 10 years, and there is no such thing as a 500 watt solar panel. There is a good reason for this – a 500 watt solar panel would be so large (about 50 square feet) that you would have to ship it (extremely carefully!) by freight truck which would probably cost as much as the panel itself. So maybe they meant they would send you two 250 watt panels…

The best case scenario is that you will get a Solar-in-Box clone. This seems very unlikely since I have never heard from the Solar Liberator people, and based on their Indiegogo site they do not seem to have a deep understanding about how this stuff actually works.

Maybe a box with a solar panel, a charge controller, and AC charging adapter, a battery, and an inverter tossed in. There are lots of these system currently available, so if this is what you want then just buy it on Amazon today and do not risk giving your $700 to Solar Liberator.

Most likely you will just wait a very long time to find out that there are all kinds of unforeseen design and production problems and you will end up getting nothing (or at least nothing like what you were promised).

How do I know this? There are lots and lots of signals I can point to looking at the pitch page, but the one I want to highlight here is simple – you can not make a safe residential plug in grid-tie system.

If one of the circuits in your house starts drawing more power than the wires on that circuit can safely handle, the breaker (or fuse) turns off the circuit before anything gets hot enough to start a fire….


If you add a solar system that feeds power into an outlet on that circuit, you prevent the breaker from seeing and sensing the overload and cutting power. Now the wires are carrying more current than they can safely handle so they get hot and can start a fire.

no overload

What if I make sure that I never plug anything into that circuit except for the solar panel?

That could technically work because it would be the electrical equivalent of a dedicated circuit, but do you know which outlets in your house are on the same circuit? Are you sure? Even if you do, can you absolutely guarantee that no one will plug something else into the other outlets? For the next 20 years?

This is  is why the National Electric Code (and every local code I know of) require a dedicated breaker for any back-feed power source. (This means that even if they did make the described product  that it could not be eligible for the Residential Renewable Energy Tax Credit.) I am no lover of codes, but this one does make sense.

That is why the design of Solar-in-a-Box is special. It never back feeds into the house wiring, and so all conductors are always protected from overload.

What if I derate the circuit and install a breaker that is smaller to account for the additional power generated by the solar backfeed?

You could do this, but opening up a service panel and swapping out breakers is not a plug-and-play job. If you are willing to open your panel, you can just install a dedicated circuit for a proper (and legal) solar backfeed.

What is the take away message?

If you ordered the Solar Liberator 500W system on Indegogo, you should try to cancel your order and get your money back.

Is there any good news?

The good news is that success of this campaign proves that there is market demand for a plug-in solar system. Maybe it is finally time for someone to mass produce Solar-in-a-Box?

New Questions:

If Solar in a Box is such a good product, why ISN’T it marketing itself through crowd-funding? (new)

I do not have the time or skills to manufacture, distribute, and market it. I’ve instead done everything I can to make it easy for someone who does have the time and the skills to do it. I’ve explicitly not patented anything about it. If you want to mass produce a Solar-In-The-Box design, the only payment I request is the right to purchase the first one off the line!

Its easy to be cynical, but advances are made all the time, and a 500w panel in is not that farfetched, especially with the stepped up R&D and production from China. (new)

According to the dimensions on the campaign page, the 500W panel would be 102”x52”x2.7”. That is 8.5 feet by 4.3 feet. Think about how big that is. Have you ever tried to carry a full sheet of drywall? Well, this solar panel would be bigger than that.

It is also 102” of length and 109” of girth. It would not be shippable by any standard carrier in the USA (USPS, FedEX, or UPS). Shipping problems aside, you would never want to make one that big anyway because it would be extremely large, fragile, and heavy.

You could easily ship two 250W panels for the same effect, but they make it clear though text and photos that this is not what they are offering. This is a very silly issue. To me, it indicates that, at the very least, they have not thought though the simplest practical details of actually manufacturing and distributing such a system.

I believe the reason the campaign has been so successful is that their answers feel authenticate and verifiable, and the technology seems viable, and the team has that feeling of dedication and fervor we all want to believe in. (new)

I agree – unfortunately there is a big difference between feeling authentic and seeming viable and actually being authentic and being viable. Actually making things like this takes a lot of work and effort and research – good sounding marking is not enough. It is not good enough to seem viable when you are taking $350K $412K worth of peoples’ money for a product that you actually have no idea how you will actually make. Keep in mind that Indiegogo does not do anything to vette these projects or try and give people their money back then the projects do not deliver. Indiegogo’s terms of use explicitly say… “Indiegogo does not represent, warrant or guarantee: (i)Perks will be delivered; (ii)Perks will be satisfactory to you”.  If you are one of the people who contributed towards this project, I’d strongly recommend that you try to cancel your contribution because it is extremely unlikely that you will ever get anything like what you expect and were promised.

If there’s a short, the breaker will still trip. (new)

Depends on the short. Most household fires are not caused by zero ohm busbar shorts. Most fires are caused by stuff like a nicked high gauge wire (closing a door on your x-mas tree light cord) or a loose conductor inside an appliance or junction box. Have you personally ever blown a breaker? If so, I bet it was not a zero ohm short – probably a 20-50 amp overload.

But that is not the problem I’d be most worried about – I think the more likely scenario is that someone plugs in a space heater while someone else is blow-drying their hair.  Have you ever blown a breaker in a situation like this? If you had a Solar Liberator or that breaker might not have blown, and you could have had a fire inside your wall instead.

In your example, I could determine which circuit the panel is plugged into and replace the breaker with one with a lower rating. (new)

First off, this would involve opening the service panel. This is not the plug-and-play solution promised and is probably illegal for many people (or at least requires a permit). Plus, if you are willing and able to crack your service panel, then you mind as well just install a proper and legal direct backfeed circuit and save all this hassle.

More importantly, this is a not real world solution since you would need some way make sure that the plug coming from the solar system could only ever get plugged into a derated circuit. That would mean inventing a brand new kind of plug for the solar system that would be rejected by a normal receptacle. You’d need to get this new plug type listed and manufactured and added to every electrical code in the county. Now you’d need to install this new kind of receptacle on the drated circuit. Essentially you are talking about effectively creating a dedicated circuit- just doing it a harder and impractical way. Again, this is not a plug-and-play solution and ends up being harder than just dropping a proper dedicated backfeed.

Keep in mind that codes and listings are all about making products failsafe in normal use case by people who do not know the codes. A 20A plug is designed so that it physically can not fit into a 15A receptacle because that could cause an overload. A standard prong plug means “the thing that is connected to this plug only draws power”.  You cannot get UL listing for any device that who’s safety depends on people never accidentally plugging a normal plug into a normal socket.

Also, the Solar Liberator says you can daisy chain up to 4 panels of 500 watts each. That’s a peak current of 16 amps. What this means is that you are going to overload a standard household NEMA 1-15 or 5-15 outlet BY DEFAULT just by plugging in on a sunny day. I know that you are then going to say that you could put a NEMA 1-20 plug on the solar thing. This is not what is shown in their pictures or mentioned in the text (“For grid-tie- Just plug into a wall socket!”) – clearly not something they even thought about.

What is your technical expertise/background, if you dont mind my asking? i am not trying to be snarky here (new)

I own a 10 acre, 25kw grid tie solar farm (huge at the time is was commissioned), I was amazed at how hard and expensive the process to install it was. My first thought was to make a plug-in grid-tie system like what Solar Liberator claims to be, but after doing a little research I discovered that it is impossible to make a safe and legal plug-in grid tie system. This means that the Solar Liberator founders either (1) did not do even cursory research or prototyping before listing the product they claim to be able to make, or (2) they know it is not possible and have no intention of ever producing it.  Either way the people who are contributing to them will like likely be disappointed with the outcome.