As many of you, our adoring public, know we live in an off-grid house and build our tiny shelters from an off- grid workshop. In addition we have built several off-grid tiny houses, including our current build Tiny Tiger, so while we are not experts we do know a good bit about solar power. Here are some thoughts that may, or may not, be useful.
The first point to repeat is we are not solar experts. We have some knowledge, but when it really comes down to designing and installing a photovoltaic system you need a specialist! In our area that specialist is Kuno Kuenzle of Green Lizard , and without him we'd be lost.
With photovoltaic systems (PV systems) there are two basic set ups. One is a grid-tie where your house is still attached to the power grid and your PV system helps run your meter backwards so you are not getting as big a power bill. You can also have a hybrid system where you are attched to the grid but also have a small battery bank for times the grid is down. This gives you a bit of autonomy but you are still dependent on the grid.
In our case we take a different path in that we are not attached to the grid at all. (No power lines come to our house or workshop at all). This means we have to have a larger battery bank for storing our electricity and a back up generator should we need to top up the batteries. Our battery bank gives us on average 5 days of autonomy - meaning it holds 5 days of our average power consumption for both our house and workshop. This is generated by a 2000 watt array with power stored in a 35k watt battery bank wired for 24v. Our house is wired in standard 110v and to a visitor seems normal in that we do not read by candle light, or need to make toast over an open fire. The small differences are that we heat our water with an on-demand propane system, cook with gas, and do not have a clothes dryer. Our primary heat source is a wood kachelofen.
When sizing a PV system you do a load calculation - which determines how much power you use on an average day so you can build a system that meets those needs.The first thing you learn is that anytime you use electricity to produce heat (hot water, electric heat, clothes dryer) you use tons of power so these are usually the first things to be eliminated. To be honest, if you have wood heat it's easy to dry clothes inside and an on-demand hot water system is much more efficient than keeping water hot all day for your evening shower. AS for our workshop, it's not huge but we do have all the necessary tools, but all 110v ones. This isn't a huge commercial shop with big machines running all day long.
We also build off- grid tiny houses. These have the same basic design except because of the space constraints it cannot have a huge battery bank. For the most part we keep the systems simple and try to run as many things direct from 12v as possible, including lighting, refrigeration, and water pump. In addition we put in a small inverter that will create 110v power for small appliances, computers etc. For hot water we stick with on-demand propane, with a special unit designed for small spaces.
Alot of people ask about putting the solar panels on the roof, but our preference is to do a mobile ground mounted rack that is easy to move, easy to clear of snow and simple to orient towards solar south. For our current build we have a 825 watt array, 11k watt battery bank wired in 12v. This is designed to meet the clients needs and hold 4-5 days of power. There is also a charging input plug that would allow for hooking up to a power cord should one be available or a small portable generator and the batteries could be topped up this way if it's necessary.
It is true that when living and working off the grid one needs to be more aware of electricity, but to us that's a benefit not a drawback. We are all so used to flicking a switch, having everything powered up all the time, forgetting to turn things off that we forget that this power is being generated somewhere! There is no better feeling than when building a tiny house you stop and realize all the power that went into construction, that all the tools and machines used were powered directly by the sun!