Generating Your Own Solar Estimate

Generating Your Own Solar Estimate

Generating a solar proposal for your own use case is pretty complicated, used specialized software, needs dedicated logins which cost money for a subscription, uses lots of AI to do analysis of your roof etc etc..

But there is a way that your can get a good idea of what you home can produce, and its totally free!!! How is this possible, you ask?

Well lets start with another use case that comes to us via a question on a DIY blog:

"I have an aquarium system that pulls .60Kw per hour, 24/7.

What sort of solar system would I need to power everything completely off solar year round? Is it doable? Thank you."

Now, there's a lot that could go into answering this question.

For example, as one poster points out you need to figure out the the draw which is 600 watts per hour operating 24/7 so 14.4 kw per day.

You can easily generate that in a day, but the question is how much battery storage will you need to run in at night when the sun isn't shining.

You have to make sure you have enough panels to both run the system and refill that batteries during the day and account for reduced production for days when it’s raining or cloudy and then also account for how many days of reduced production you might have. Is that clearer? It would help to know what part of the country you are in to estimate how much production you could have. 

You can get an estimate from the Google solar app. 

It’s will also tell you approximately how many panels you’d need and potential cost savings. 

https://solar-potential-kypkjw5jmq-uc.a.run.app/

You just type in your address and it will tell you information such the solar potential in terms of annual hours of solar sunshine, roof area, maximum panel count, Co2 savings, actual suggested panels, yearly energy production from those panels, yearly energy, installation size and estimated cost, how much it will offset %, estimated costs with and without solar, the savings (the difference), and also how many years it will take estimated automatical of how long it will take to pay it off.  And much more.

So by using this app the poster could get a very good idea of how much solar their house could produce and how that matches up with what his aquarium would use.

We'd have to do a bit of math on our own to figure out what kind of batteries he'd need to keep his aquarium running over night. For example, lets say that on average his system produced 15 kw per day, and that during the time from 9am to 5 pm. So now he has to run his 600w pump from 5pm to 9am when there is no solar production. That means it has to run for 16 hours at 600 w = 9.6 kwh. Of course he can't run it down to zero so he has to allow a maximum depth of this discharge of between 80-90%. If we ask the google machine for "typical residential battery storage sizes" it will tell us that average home battery capacity is likely going to be somewhere between 10 kWh and 15 kWh. Now 10kwh is clearly marginal in this use case, but 15kwh hours should give us enough of a buffer so the battery can discharge and still have between 10-20% left which is recommended for most LiFePo batteries, where as for lead acid, it is not advisable to go below 50%.

Now, unfortunately, it's a little more complicated than that, because this does not account for those days when the production is less than optimal due to rain, clouds, storms, snow etc. Question is, how long do you want it to run? We can get into a lot of fine grained analysis, or we can ball park it and say simply, yeah we should probably just double it, because we got our prized fish to protect. It's a substantial expense, but our fish are worth it, right?

So there you have it 30 kwh. 

How much is this all going to cost us to keep our fish alive? Well that's a whole other discussion that depends on a whole of other things like on the first order, do you want to be totally off grid or do you want the grid to supplement the system, because that will profoundly affect how much storage you need.

For example, a typical EG4® WallMount All Weather Battery is around $3,600 for 14.3kwh of storage. Double it and your close to $7,200 for batteries alone. Plus you need panel to produce 15 kw per day and an inverter charger etc.

If you are willing to be grid tied, you can do it for a lot less. And there are plenty of places that will sell you all kinds of kits for a DIY install, such as signaturesolar.com or shopsolarkits.com to name just a couple. (Not affiliated in anyway.)

Do your research, figure out what will work for you, and have fun. Or someone like me can design a system for you wither with or without installation. Just saying.

Good luck!