The limits of solar energy

Mary Cook wrote:I really disagree with Brandon. Some people's situation won't accommodate solar, but the idea that you have to nix out your power bills within a few years for it to be worth it...is going to look very quaint in a few years when solar panels may not be available or affordable--unless you live in China, maybe--and the grid may be going down more often, grid power may be climbing rapidly in price...whereas panels are quite cheap now. The whole system, especially if you go off-grid, is not so cheap, especially if you have to pay expert installers and red tape fees, but could well be worth it.

I lean more to Mary's side.
We put solar panels on our roof in 2020.  Most months the payment for the panels plus the little electric bill we have left is smaller than our electric bill had been.  Year total is a little smaller than the electric bill by itself had been.  Every time they increase electric rates the further ahead we will be.  In 14 years when the system is paid off we will be way ahead.

Phil Swindler wrote:..... Every time they increase electric rates the further ahead we will be.  In 14 years when the system is paid off we will be way ahead.

We aren't off the grid and likely won't be in our lifetime, but you never know.  Nevertheless, now in our 60s/70s, we are at a point, assuming at least some of the affordability of solar remains for the next few years, that it seems worth adding a system stepwise to meet our needs.  We have some horrible electrical usage/bills that result from heating animal quarters and still using electric for kitchen range and hot water heating.  Granted, we use an air-fryer more now for baking along with the woodstove in winter, but the hot water heater is old, too large for our needs really, and so this resonates with the argument that reducing electrical needs is one part of making solar affordable and realistic.  Additionally, as Phil S noted above, grid pricing into the future looks pretty shaky.  As I type this, I have a bill in front of me from last May and the most recent one covering February.  We don't use AC and our usage in summer is still around 10 - 20 kwh per day, but this jumps bad in winter.  More importantly are two rate numbers and taxes:  Monthly facility charge went from $51 USD to $58 USD at the beginning of the year while the cost rate went from 12.5 cents per kwh to 13.3 cents per kwh. Taxes appear to hover around 10% of the cost of the kwh usage.  As I understand it, these rates are rather low, but are increasing steadily and due to other forces that most of us are witnessing, may jump quite suddenly in the days ahead.  For the present, we are a 'net-metering' state, so if we decide to grid-tie, we would get paid back at the retail rate for any production over what we use.  However, even with a strong public utility commission here in Minnesota, the coops have found ways to add extra facility/connection charges that one has to consider in the budgeting.

One disappointment when we had an installer out to quote to us a full-house solar system is the propensity to assume the full energy replacement of what the grid is providing is what will be quoted.  Certainly I understand the rationale behind this for most homeowners, but I was a bit surprised that no discussion ensued about simple reduction of power consumption via the solar set-up.  That was two years ago and now battery technology and cost enters the picture and we are wondering if we would want to grid-tie at all!  In this regard, and directing the next comment at someone in tune with recent policy changes, how did the state of Utah get legislation passed allowing for direct plug-in of inverted solar power directly into home outlets (solar power not more than 1,200W and assuming 120V)?  From an AI response upon searching:  "Utah law allows the direct plug-in of small-scale (<1.2 kW) solar inverters to reduce adoption costs, boost energy independence, and simplify access for renters and homeowners, removing the need for complex utility interconnection agreements. Enacted in 2025 (H.B. 340), this legislation promotes affordable, safe, and portable "balcony solar" technology."  These configurations with the micro-inverters avoid, for the most part, the risk of 'back-feeding' into a downed grid power line by virtue of shutting down the solar side when the grid goes down....thus minimizing shock of company linemen.  Are more states working on this?....Seems like it would be pretty significant in cost reductions depending of level of typical home power consumption.

But the bottom line for us, even as it's early days in planning, is to (a) install our solar electrical power initially off-grid in a scalar fashion with a few panels at a time, (b) take advantage of either home-built or pre-built battery storage from commercial vendors to back-up power for use when grid not available, (c) configure farm vehicles (electric) to run on 48VDC which can serve as power sources when plugged into master hybrid inverter for brief home power, and (d) continue to improve my 'sun dance' so that solar energy days are maximized and good vibes continue to foster improvements in the tecnnology, which seems to report breakthroughs almost weekly! ;-)  Based on my current fitness and dance steps, I'm not holding my breath regarding (d).... Ha!

Hi @ll,

I think there is another point here too. A lot of the commercial solar solutions people are offered simply do not pay for themselves in a sensible way, especially if the calculation already stretches to twenty years and that is before counting possible failures, maintenance, replacement of parts, or just the normal reality that no system stays perfect forever. That does not mean solar is useless. It just means that many of the commercial packages are designed and priced in a way that does not fit ordinary people very well.

The more realistic path is not trying to make everything “green” all at once, but thinking in a greener way and adapting things step by step. Most of us do not have unlimited money, so it makes more sense to replace and improve parts of our energy use gradually. For example, lights that need to stay on all night can often be taken off the main system entirely. There are already small LED floodlights with their own little panel and battery that can stay on all night in winter from only a few hours of sun. That kind of thing is not glamorous, but it works, and it is one less load on the house.

The same applies to a lot of other uses. Maybe the first step is not a whole-house solar installation, but a couple of panels for lighting, charging devices, or reducing the cost of hot water during the sunny part of the year. Maybe it is a small DIY system first, just to understand your own needs and gain confidence. I think that approach makes much more sense than waiting until you can afford some huge “complete solution” that may never really make economic sense.

To me, every small improvement counts.

Even a modest change can improve quality of life, lower the bill, reduce dependence, help a little with emissions, and give people a sense that they are capable of building something better with their own hands. That part matters too. Sometimes the value of a system is not only in strict payback, but also in resilience, learning, and the confidence that comes from making your home work a little more on your own terms.

Roble Andamos wrote:
....The same applies to a lot of other uses. Maybe the first step is not a whole-house solar installation, but a couple of panels for lighting, charging devices, or reducing the cost of hot water during the sunny part of the year. Maybe it is a small DIY system first, just to understand your own needs and gain confidence. I think that approach makes much more sense than waiting until you can afford some huge “complete solution” that may never really make economic sense.

.....and give people a sense that they are capable of building something better with their own hands. That part matters too. Sometimes the value of a system is not only in strict payback, but also in resilience, learning, and the confidence that comes from making your home work a little more on your own terms.

Very much agree with these sentiments.  In addition to what I posted above, I've been weighing the pros and cons of different battery sizes...voltages, amperages, etc...for a DIY build.  Although much is available now for DIY LiFePO4 batteries, I asking myself how much I would use 12V batteries if they are not used in a series string to get higher voltage.  Too many reasons at present to go with 48V but then may just go with a pre-packaged battery for that and use a 12V battery as a DIY learning example.  And it's not that we would have *no* use for 12V:  I've already purchased and am using 12V LED light bulbs in standard 120V reading lamps by reconfiguring some wiring.....all good.  Also, lots of items like trail cameras that run on 12VDC and can be powered by such batteries enclosed in weatherproof cases.  What gets a bit more daunting is how to selectively put household loads that are already part of a grid-tied system and breaker panel onto selective circuits that one can power, at will, from solar/battery/inverter set-ups.  Here, the well-pump (220VAC) and furnace (120VAC) would be priorities.  But it's in the journey, not the destination....right? :-)  Must admit, it's the very fun 'gift-that-keeps-on-giving' retirement project I never saw coming 20 years ago!

Hi!

I’d suggest looking into the documentation for modern inverter systems, because things have changed a lot in the last 15 years. I’m an electronics engineer, and even I have had to admit that the market and the technology have moved on quite a bit. These days, inverter systems can do much more than just convert DC into AC. Depending on how the system is built, they can work together with solar charging, use the available solar energy first, draw from the battery when needed, and even lean on the grid if the demand goes beyond what your solar and battery setup can provide. They can also top the battery up gently from the grid after several cloudy days if that is how you choose to configure it.

I use Victron myself, and one of the things I like is that they have built a whole ecosystem around the hardware. You can monitor the installation from your phone, have the information on a dedicated screen, and tune the system so it behaves in a way that makes sense for your real daily consumption instead of some theoretical perfect scenario. A lot of the early progress in this area came from boats and campers, because those systems spend most of their time fully or partly off grid, so they had to become smarter earlier than domestic systems. But now the same ideas are becoming much more common in houses too, especially where people want a bit more resilience or flexibility.

If you already have a breaker panel with circuits separated in a sensible way, it is not especially complicated in principle to move some predictable loads onto the inverter backed system while leaving the rest on the grid. Lighting is often a simple place to start, and other steady and easy to predict loads can also make sense. The more demanding loads need a bit more thought, especially anything with motors, pumps or high starting surges, because sometimes the challenge is not the normal running power but the moment they first kick in. That is where people can get caught out if they only look at the label and not at how the equipment really behaves.

I would still say it is important to be careful and to follow the local rules and standards wherever you are, because once you start mixing batteries, solar, inverters and existing household wiring, you want to be sure everything is properly protected and done in a safe way. Cable sizing, fuses, breakers, connections and isolation all matter, not just for performance but to avoid damage or fire. That is one reason I often prefer smaller or more self contained systems rather than trying to rework an entire house in one go. Starting with a more isolated setup lets you learn a lot without having to interfere too much with the main installation. And yes, there is still a very good reason why so many people move toward 48 volt systems. For the same amount of power, the current is lower, so the cables between batteries and inverter do not need to be so heavy, losses are reduced, and everything generally behaves better. Cable runs matter too, of course. The longer the distance, the more loss and heating you get, so keeping the panels, batteries and inverter laid out sensibly makes a real difference.

I’d also be careful about building lithium batteries yourself, especially if we are talking about LiPo. Personally, I do not think that is a very prudent place to start unless someone already has real experience and understands exactly what they are doing. With that kind of battery, a proper BMS is not optional, it is essential, because it has to manage charging, discharging, balancing and temperature, and those things are exactly what stop a battery pack from becoming dangerous. When lithium batteries go wrong, the fire is not just a small technical problem, it is serious, very hard to control, and nasty both in terms of toxic fumes and sheer fire intensity. That is why I would rather use something that comes with real guarantees and a proper safety design, even if you begin with a fairly small amount of storage. If you find that you are actually using it and it makes sense in daily life, you can always add more later and duplicate the capacity in a safer and more controlled way.

I do not know if that helps move the idea forward, but I think you are looking at it in the right way. It takes a bit of patience, but honestly that is part of the fun !